74

Shaw Bronner PT PhD OCS Director ADAM Center and Associate Professor Department of Physical Therapy Bouveacute College of Health Sciences Northeastern University Boston Massachusetts and Director Physical Therapy Services Alvin Ailey American Dance Theater New York New York Sheyi Ojofeitimi PT DPT OCS Alvin Ailey American Dance Theater New York New York Jennifer Bailey Lora PT DPT Physical Therapy amp Sports Medicine Center Palisades Medical Center North Bergen New Jersey Heather Southwick PT Director Physical Therapy Services Boston Ballet Boston Massachusetts Michelina Cassella Kulak PT Department of Physical and Occupational Therapy Services Childrenrsquos Hospital Boston Massachusetts Jennifer Gamboa PT DPT OCS President of Body Dynamics Inc Arlington Virginia and Director Health and Wellness Services The Washington Ballet and The Washington School of Ballet Washington DC Megan Rooney PT DPT NovaCare Rehabilitation St Paul Minnesota Greg Gilman ATC LAT Director of Operations Texas Healthcare Bone and Joint Physical Therapy and Medical Consultant at the Texas Ballet Theater Fort Worth Texas Richard Gibbs MD Medical Director at the San Francisco Ballet San Francisco California

Correspondence Shaw Bronner PhD PT OCS Department of Physical Therapy Bouve College of Health Sciences Northeastern University 360 Huntington Avenue Boston Massachusetts 02115 shawbronnergmailcom

Copyright copy 2014 J Michael Ryan Publishing Inc httpdxdoiorg10126781089-313X18274

AbstractWhile studies have investigated the physical demands of dance in terms of cardiorespiratory fitness there are no recent comparisons of cardiorespiratory response to exercise among professional dancers of different genres Our purpose was to 1 develop a cardiorespiratory pro-file of professional dancers 2 investigate differences in peak and recovery heart rate (HR) between professional modern and ballet dancers using an accelerated 3-minute step test 3 demonstrate the relationship between cardiorespiratory variables and 4 investigate the effects of company and work variables on the dancersrsquo cardiorespiratory profiles We hypothesized greater cardiorespiratory fitness in modern dancers than in bal-

let dancers due to the nature of their repertory Furthermore we hypothesized that company profiles would reflect dif-ferences in work variables Two hundred and eleven dancers (mean age 246 plusmn 47) from nine companies (two modern and seven ballet) performed a 3-minute step test Demographics height mass blood pressure (BP) smoking history and rest-ing peak and recovery HR were recorded Body mass index (BMI) and fitness category were calculated Independent t-tests were used to compare differences in demographics and cardiorespiratory variables due to genre MANOVA were conducted to compare differences due to company and correlations were calculated to determine the relationships between cardiorespiratory variables (p lt 005)

Modern dancers demonstrated higher mass and BMI lower BP lower resting HR and HR recovery and a higher per-centage were categorized as ldquofitrdquo compared to ballet dancers (p lt 003) There were differences between companies in age experience BMI BP resting peak and recovery HR and fitness category (p lt 0001) The differences in cardiorespira-tory fitness levels that may be related to rigor of repertory rehearsal and per-formance seasons or off-season exercise training are discussed Results support the need for comprehensive physical fitness screening to identify dancers who could benefit from aerobic conditioning to en-hance overall performance preparedness and to minimize fatigue effects

Pre-season screening is widely accepted as an effective means of assessing a dancerrsquos overall

health status1-8 The main purpose of the pre-season screening is to identify potential health problems and areas of concern with the goal of addressing those issues prior to the start of a busy work season In 2005 the DanceUSA Task Force on Dancer Health developed and implemented an annual post-hire pre-season health screen for profes-sional dancers58 To meet company needs this screen was designed to be brief and conducted on-site with minimal equipment Currently the DanceUSA screen allows only 20 minutes in total per dancer for the assessment of medical history vital signs muscular strength joint flex-

A Preseason Cardiorespiratory Profile of Dancers in Nine Professional Ballet and Modern Companies Shaw Bronner PT PhD OCS Sheyi Ojofeitimi PT DPT OCS Jennifer Bailey Lora PT DPT Heather Southwick PT Michelina Cassella Kulak PT Jennifer Gamboa PT DPT OCS Megan Rooney PT DPT Greg Gilman ATC LAT and Richard Gibbs MD

75Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

ibility aerobic fitness and other physi-ologic measures in order to allow 10 minutes to review the findings and make recommendations Cardiorespiratory fitness is of particular interest due to differences in demands relative to dance genre9 Historically modern dance companies perform choreography with continu-ous movement for up to 30 minutes whereas dancers in ballet companies perform more traditional full-length works composed of shorter 3 to 5 minute sections19 A recent time motion analysis reported differences in exercise intensity during classi-cal ballet and contemporary dance performance9 Ballet incorporated higher intensity movement periods punctuated with longer rest periods while contemporary dance displayed longer continuous movement periods at moderate intensity9 Endurance requirements for performing different types of modern dance repertory may vary considerably from one another and from those of ballet As the dance community increas-ingly acknowledges health and well-ness as an important component of a successful dance career investigators are developing fitness profiles for dancers of various genres and levels of expertise Measurement of maxi-mal exercise intensity in conjunction with maximal oxygen consumption (VO2max) is the criterion for assessing aerobic capacity and cardiorespiratory fitness10 However this may be neither practical nor economically feasible for testing large groups of professional dancers who are rehearsing for many hours on the same day as testing and cannot compromise their work Separate dance-specific fitness tests have been developed and tested some specifically focused on either ballet or contemporary dance genres11-14 The ar-gument for using such tests is that dance is an intermittent activity therefore us-ing a steady state activity to test aerobic fitness is not appropriate Conversely it has been argued that using dance-specific fitness tests may only be appropriate for one dance form require a familiarization period and be lengthy to administer (up to 20 minutes)12-14

Field tests such as walking cycling running or step tests are considered acceptable for estimating cardiorespi-ratory fitness in large groups in a safe efficient and functional manner15-19 Step tests have demonstrated signifi-cant test-retest reliability and validity correlations between peak heart rate (HRpeak) and VO2max when compared with maximal treadmill tests1620-24 Step test intensity is determined by step height and rate as controlled by a metronome or pre-recorded counts and results are based on the sub-jectrsquos HRpeak and heart rate recovery (HRrecov) Recently an ldquoacceleratedrdquo 3-minute step test with a rate of 112 beatsmiddotmin-1 was validated against an incremental maximal treadmill test using a telemetric gas analysis system and HR monitor with high correla-tions between HRpeak and moderate correlations between HRrecov25 Thus this step test offers a convenient and practical way of assessing cardiorespira-tory fitness in dance companies with time and space limitations (although it does not capture nuances of capac-ity and endurance in the manner of a 20-minute test such as the Dance Specific Aerobic Fitness Test [DAFT]) Increased awareness of fitness participation in prevention and cross training programs and greater aerobic demands of new repertoire on profes-sional dancers warrant understanding of the current cardiorespiratory fitness of these individuals The purposes of this study were to 1 develop a cardio-respiratory profile of professional danc-ers 2 investigate differences in peak and recovery heart rate (HR) between professional modern and ballet danc-ers using an accelerated 3-minute step test 3 demonstrate the relationship between cardiorespiratory variables and 4 investigate the effects of com-pany and work variables on the dancersrsquo cardiorespiratory profiles Based on the repertory performed by DanceUSA member companies we hypothesized that modern dancers would exhibit greater cardiorespiratory fitness than ballet dancers Furthermore we hy-pothesized that certain companies would demonstrate differences in cardiorespiratory profiles potentially

reflecting differences in work variables and that a linear relationship would ex-ist between cardiorespiratory variables

MethodsData for this study were collected from part of the larger 30 minute post-hire health screen for profes-sional dancers developed by the DanceUSA Taskforce on Dancer Health The screen consists of a gen-eral demographic and medical history questionnaire followed by physical assessment Detailed guidelines for ad-ministration of the screen are provided to ensure uniform testing The screens for this study were conducted at the rehearsal studios of each participating company and administered by health-care professionals from the DanceUSA Task Forcemdashmostly physical therapists involved in the creation of this standardized screen and its guide-lines Information regarding each companyrsquos number of dancers weeks of work workday hours number of performances and touring weeks was collected from company administra-tors Average hours of exposure were calculated based on the number of workweeks times the number of work-day hours for each company

SubjectsData were collected from 211 out of a potential 241 dancers (88) in nine professional dance companies two modern dance (M1 and M2) and seven ballet (B1ndashB7) Subjects were currently employed by their dance company medically cleared for full dance activity and participated voluntarily in the study Dancers who did not participate were injured or unavailable during the screening period Each subject gave informed written consent in compliance with the guidelines of an umbrella Internal Review Board provided by Boston Childrenrsquos Hospital All screens were completed in a single session during the rehearsal period at the start of each companyrsquos contract year

ProtocolCardiorespiratory fitness was tested using an accelerated 3-minute step

76 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

test previously validated against an incremental treadmill test comparing HRpeak HRrecov VO2 peak and VO2 recovery25 Subjects wore running shoes and were given 5 minutes to sit quietly before resting HR (HRrest) and blood pressures (BP) were recorded HR was measured using Polar USA (Warminster PA) HR monitors secured to each subjectrsquos chest with a receiver-watch worn on his or her wrist Subjects were tested using a 0305 m (12) step for 3 minutes at a rate of 112 stepsmiddotmin-1 maintained by a metronome The metronome was started prior to the test to allow the subjects to familiarize themselves with the tempo They were instructed to step ldquoup up down downrdquo to the beat of the metronome Peak HR was recorded at 3 minutes Subjects were seated immediately after completing the test and HRrecov was recorded at 1 minute after completion of the step test Height and mass were measured and demographic information (eg age gender years of professional ex-perience smoking or non-smoking and asthmatic status) was collected for each participant as part of the screen intake

Data AnalysisBody mass index (BMI) was calcu-lated from each subjectrsquos height and mass Each subject was assigned a

fitness category based on gender age and HRrecov step test results accord-ing to YMCA guidelines26 The seven-category interpretation as defined by the YMCA protocol is 0 = Excellent 1 = Good 2 = Above Average 3 = Average 4 = Below average 5 = Poor and 6 = Very Poor For example for males between 18 to 25 years ldquoExcel-lentrdquo was HRrecov lt 79 beatsmiddotmin-1 ldquoGoodrdquo was HRrecov between 79 to 89 beatsmiddotmin-1 etc Subjects were charac-terized as ldquofitrdquo if their fitness category was 0 1 or 2 and ldquoCR-recrdquo (cardio-respiratory training recommended) if their category was 3 4 5 or 6 Comparisons were made between genres with respect to age years of professional experience height (m) mass (kg) BMI BP (systolic and dia-stolic) HRrest HRpeak HRrecov and fitness category using independent samples t-tests (genre modern versus ballet) for each of the 11 dependent variables (DV) listed above (SPSS 160 SPSS Inc Chicago IL 60606 USA) Comparisons were made between companies and the same dependent variables in a 9 (company) X 2 (gender) X 11 (DV) MANOVA Post hoc Bonferroni comparisons were conducted where appropriate After checking for normal distribution of the data Pearson product moment correlations were used to determine whether there was a relationship

between subjectsrsquo resting systolic and diastolic BP HRrest or HRpeak and their HRrecov Non-parametric Spear-manrsquos rho correlations were used to determine whether there was a rela-tionship between HRrest or HRpeak and fitness category Significance was considered at p lt 005 for all tests

ResultsGenre Company and Subject CharacteristicsThe nine companies ranged in size from 6 to 72 dancers M2 B2 and B5 were junior companies to M1 B1 and B4 Most of the companies had a 30 hour work week not includ-ing daily technique classes (Table 1) Technique classes generally last 15 hours but were optional for most of the companies with the exception of B3 and B5 Dancers worked 393 plusmn 45 (range 32 to 47) weeks per year touring 74 plusmn 71 (range 0 to 20) of those weeks This resulted in 12187 plusmn 1533 (range 960 to 15275) hours of dance exposure annually (note this calculation did not include the optional daily technique classes taken by most dancers) There were 853 plusmn 366 (range 53 to 169) performances per year A total of 211 subjects were screened (103 male 108 female 171 ballet 40 modern dancers) with a mean age of 247 plusmn 48 years (range

Table 1 Company Profiles

Company SizeHours per

WeekWork Weeks

Per YearWeeks

TouringPerformances

Per YearHours of Exposure Annually

Per Dancerdagger

M1 30 30 41 19 169 1230 12915M2 12 30 35 20 58 1050 11025B1 38 30 41 8 98 1230 12915B2 6 30 41 8 98 1230 12915B3 16 325 47 65 58 15275 15275B4 23 30 32 1 53 960 1008B5 8 37 35 1 67 1281 13335B6 36 30 38 0 55 1140 1197B7 72 30 44 3 112 1320 1386Mean plusmn SD 268 plusmn 194 311 plusmn 21 393 plusmn 45 74 plusmn 71 853 plusmn 363 12187 plusmn 1533

Mandatory technique class 15 hoursday In other companies technique class was optional but most dancers took one technique class daily daggerThe second value is exposure with 5 classes per week included in the calculations Abbreviations M 1-2 modern dance company 1-2 B1-B7 ballet company 1-7

77Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

16 to 39) and a mean of 63 plusmn 48 years (range 0 to 24) of professional experi-ence (Table 2) Dancers were 171 plusmn 009 m (subject range 152 to 193) in height 623 plusmn 121 kg (subject range 447 to 900) in mass with a BMI of 211 plusmn 22 The majority of companies had an equal ratio of male and female dancers There were differences due to genre (modern versus ballet dancers) in age mass and BMI (p le 003) Modern dancers were older (26 plusmn 44 versus 24 plusmn 48 years) and had greater mass and BMI compared to ballet dancers (Table 2) There were differences due to com-pany in age years of experience and

BMI (p lt 0001) Post hoc analysis revealed M1 dancers were older than M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 were all older than B2 and B5 (p le 0038) M1 B1 B3 and B4 dancers had longer profes-sional careers (experience) than M2 B2 and B5 (p le 0010) M1 B4 B7 also had longer professional careers than B6 (p le 0035) M1 dancers had greater BMI than B1 B2 B5 and B7 (p le 0050) There were no differences between companies in height Gender differences included height mass and BMI (p lt 0001 for each variable) Fourteen percent of the dancers reported that they smoked which was equally distributed between genders

Smokers comprised 25 of modern dancers and 18 of ballet dancers While asthma data were unavailable for two ballet companies 19 of 153 dancers (twice as many females as males) reported that they had asthma

Blood Pressure Resting Heart Rate Peak Heart Rate Five subjects were unable to attend the step test portion of the screening due to rehearsal therefore data from 206 subjects are reported (98 male 108 female 166 ballet 40 modern dancers) Mean BP for all dancers was 10967 mmHg (Table 3) Mean HRrest of all participants was 74 plusmn 12 beatsmiddotmin-1 (subject range 43 to 109)

Table 2 Demographics of Screening ParticipantsGender Age Experience Height Mass

Company (company ) (years) (years) (m) (kg) BMI Smoking Asthma

M1 14F (50) 283 plusmn 35 82 plusmn 35 168 plusmn 009 649 plusmn 118 229 plusmn 20 1F yes 1F 2M yes14M (50) 277 plusmn 41 93 plusmn 37 174 plusmn 010 675 plusmn 117 226 plusmn 22 97 no 25 yes

M2 6F (50) 217 plusmn 12 27 plusmn 14 163 plusmn 005 5445 plusmn 628 207 plusmn 12 0F 0M yes 4F 2M yes6M (50) 217 plusmn 19 22 plusmn 10 182 plusmn 008 76805 plusmn 710 233 plusmn 16 100 no 21 yes

B1 20F (53) 241 plusmn 44 59 plusmn 39 165 plusmn 004 505 plusmn 30 185 plusmn 09 2F 2M yes 5F 4M yes18M (47) 256 plusmn 42 78 plusmn 46 179 plusmn 005 702 plusmn 58 219 plusmn 11 89 no 24 yes

B2 2F (33) 185 plusmn 07 10 plusmn 00 169 plusmn 009 514 plusmn 77 179 plusmn 08 2M yes 0F 0M yes4M (67) 185 plusmn 21 10 plusmn 08 175 plusmn 006 609 plusmn 59 198 plusmn 13 67 no 0 yes

B3 8F (53) 274 plusmn 29 77 plusmn 47 164 plusmn 009 535 plusmn 51 200 plusmn 18 2F 1M yes 2F 0M yes7M (47) 243 plusmn 35 61 plusmn 36 172 plusmn 005 716 plusmn 75 241 plusmn 17 80 no 13 yes

B4 11F (50) 265 plusmn 50 88 plusmn 61 165 plusmn 006 532 plusmn 48 195 plusmn 11 1F 1M yes 4F 0M yes11M (50) 247 plusmn 50 64 plusmn 53 179 plusmn 003 726 plusmn 69 227 plusmn 17 91 no 18 yes

B5 6F (75) 182 plusmn 15 00 plusmn 00 167 plusmn 002 540 plusmn 46 193 plusmn 13 1F 1M yes NA2M (25) 205 plusmn 07 10 plusmn 14 174 plusmn 002 657 plusmn 03 217 plusmn 06 75 no NA

B6 16F (50) 238 plusmn 57 56 plusmn 54 163 plusmn 004 528 plusmn 55 195 plusmn 16 0F 5M yes 5F 2M yes16M (50) 217 plusmn 34 40 plusmn 28 175 plusmn 007 751 plusmn 176 226 plusmn 23 86 no 19 yes

B7 25F (50) 251 plusmn 51 75 plusmn 53 165 plusmn 005 533 plusmn 50 196 plusmn 12 3F 8M yes NA25M (50) 253 plusmn 46 70 plusmn 48 178 plusmn 006 724 plusmn 72 227 plusmn 13 78 no NA

Modern 40 M amp F 261 plusmn 44a 69 plusmn 43 171 plusmn 010 661 plusmn 120b 226 plusmn 20c 98 no 7 yesBallet 171 M amp F 243 plusmn 48a 62 plusmn 49 171 plusmn 008 611 plusmn 110b 208 plusmn 22c 85 no 19 yesTotal 108F (51) 247 plusmn 48 63 plusmn 48Dagger 171 plusmn 009 623 plusmn 121part 211 plusmn 22 10F 20M yes 21F 10M

103M (49) 86 no 19 yes

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 F females M males BMI body mass index NA not avail-able aAge significant differences between genres (t [df 1 199] = 2176 p = 0031) bMass significant differences between genres (t [df 1204] = 2416 p = 0017) cBMI significant differences between genres (t [df 1199] = 4351 p = 0001) Age significant differences between companies (F[8190] = 6351 p lt 0001) Post hoc M1 vs M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 vs B2 and B5 (p le 0038) DaggerExperience significant differences between companies (F[8190] = 5450 p lt 0001) Post hoc M1 B1 B3 and B4 vs M2 B2 and B5 (p le 0010) M1 B4 B7 vs B6 (p le 0035) partBMI significant differences between companies (F[8190] = 4606 p lt 0001) Post hoc M1 vs B1 B2 B5 and B7 (p le 0050)

78 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

There were differences due to genre in systolic and diastolic BP and HRrest (p lt 0001) Modern dancers dem-

onstrated lower BP (10260 versus 11169 mmHg) and lower HRrest (67 versus 76 beatsmiddotmin-1) compared

to ballet dancers (Table 3) Between companies there were differences in systolic and diastolic BP

Table 3 Mean plusmn SD Blood Pressure and Heart Rate VariablesBP Resting HR Peak HR HR Recovery

Company Gender (mmHg) (beatsmiddotmin-1) (beatsmiddotmin-1) (beatsmiddotmin-1)

M1 Female 10070 68 plusmn 14 140 plusmn 11 78 plusmn 8Male 8250 66 plusmn 8 129 plusmn 17 77 plusmn 13Total 9957 67 plusmn 12 135 plusmn 15 77 plusmn 11

M2 Female 10368 70 plusmn 8 145 plusmn 9 86 plusmn 14Male 11465 65 plusmn 10 134 plusmn 14 83 plusmn 16Total 10867 65 plusmn 10 137 plusmn 13 85 plusmn 14

B1 Female 10259 82 plusmn 15 144 plusmn 15 84 plusmn 14Male 10367 79 plusmn 14 129 plusmn 10 83 plusmn 12Total 10263 81 plusmn 14 137 plusmn 15 83 plusmn 13

B2 Female 9662 76 plusmn 6 146 plusmn 14 82 plusmn 11Male 9557 81 plusmn 11 130 plusmn 8 82 plusmn 18Total 9559 80 plusmn 10 136 plusmn 12 82 plusmn 14

B3 Female 10255 66 plusmn 7 143 plusmn 12 88 plusmn 11Male 10960 62 plusmn 3 122 plusmn 7 74 plusmn 11Total 10657 64 plusmn 6 133 plusmn 15 82 plusmn 13

B4 Female 11774 68 plusmn 8 112 plusmn 21 74 plusmn 11Male 12581 77 plusmn 10 110 plusmn 23 76 plusmn 12Total 12177 72 plusmn 10 111 plusmn 21 75 plusmn 11

B5 Female 11572 66 plusmn 10 115 plusmn 13 71 plusmn 11Male 11172 68 plusmn 17 108 plusmn 17 72 plusmn 17Total 11472 67 plusmn 9 113 plusmn 13 71 plusmn 11

B6 Female 11677 82 plusmn 6 157 plusmn 11 102 plusmn 15Male 12876 76 plusmn 7 150 plusmn 14 90 plusmn 13Total 12176 79 plusmn 7 154 plusmn 13 97 plusmn 15

B7 Female 10670 74 plusmn 9 142 plusmn 12 87 plusmn 15Male 11471 78 plusmn 11 137 plusmn 16 89 plusmn 17Total 11070 76 plusmn 10 139 plusmn 14 88 plusmn 16

Modern 102a 60b 67 plusmn 1c 136 plusmn 14 80 plusmn 12d

Ballet 11169 76 plusmn 11 136 plusmn 20 85 plusmn 16Mean all companies Female 10667 74 plusmn 12 140 plusmn 18 85 plusmn 15

Male 11268 74 plusmn 12 131 plusmn 18 83 plusmn 15All 10967Dagger 74 plusmn 12part 135 plusmn 19∆ 84 plusmn 15sect

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies aSystolic BP significant differences between genres (t [df 1 204] = 3687 p = 0001) bDiastolic BP significant differences between genres (t [df 1 204] = 4720 p = 0001) cHRrest significant differences between genres (t [df 1 202 1] = 4141 p lt 0001) dHRrecov significant differences between genres (t [df 1 204] = 2006 p = 0046) Systolic BP significant differences between companies (F[8191] = 10015 p lt 0001) Post hoc M1 vs B4 B6 and B7 (p le 0027) M2 vs B4 (p lt 0003) B1 and B2 vs B6 and B7 (p lt 0001) B3 vs B4 and B6 (p lt 0014) DaggerDiastolic BP significant differences between companies (F[8191] = 15799 p lt 0001) Post hoc M1 and B3 vs B4 B5 B6 and B7 (p le 0010) B1 vs B4 B7 B6 (p lt 0008) B2 vs B6 and B7 (p le 0001) partHRrest significant differences between companies (F[8192] = 6905 p lt 0001) Post hoc M1 vs B1 B6 and B7 (p lt 005) B3 vs B1 B6 B7 (p lt 0012) ∆HRpeak significant differences between companies (F[8192] = 15094 p lt 0001) Post hoc B4 vs M1 M2 B1 B2 B3 B6 B7 (p lt 0018) B5 vs M1 M2 B1 B6 B7 (p lt 0030) M1 B1 B3 B7 vs B6 (p lt 0003) sectHRrecov significant differences between companies (F[8192] = 6029 p = 0001) Post hoc M1 B1 B3 B4 B5 vs B6 (p lt 0035) B4 vs B7 (p lt 0019)

79Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

(p lt 0001) In post hoc analysis M1 systolic BP was lower than B4 B6 and B7 (p le 0027) M2 was lower than B4 (p lt 0003) B1 and B2 were lower than B6 and B7 (p lt 0001) and B3 was lower than B4 and B6 (p lt 0014) M1 and B3 diastolic BPs were lower than B4 B5 B6 and B7 (p le 0010) B1 was lower than B4 B7 and B6 (p lt 0008) and B2 was lower than B6 and B7 (p le 0001) There were also differences in sys-tolic BP between genders (p = 0016) Female systolic BP was lower than males (10767 versus 11268 mmHg) Smokers had higher systolic and diastolic BP than non-smokers (p lt 0001 for both variables) Between companies there were also differences in HRrest (p lt 0001) in post hoc analysis the resting HR of M1 and B3 were lower than B1 B6 and B7 (p lt 0012) There were no differences between genders in HRrest Peak HR was 135 plusmn 19 beatsmiddotmin-1

(subject range 76 to 181 Table 3) There were no differences due to genre but differences between com-panies were significant (p lt 0001) In post hoc analysis HRpeak in company B6 (154 plusmn 13 beatsmiddotmin-1) exceeded that of all other companies (p le 0003) HRpeak in companies B4 and B5 (111 plusmn 21 and 113 plusmn 13 beatsmiddotmin-1 respectively) were lower than the other companies (p le 0030) with the exception of B3 There were also HRpeak differences due to gender (p = 0001) females reached a higher HRpeak than males (140 plusmn 18 ver-sus131 plusmn 18 beatsmiddotmin-1)

Heart Rate Recovery and Fitness CategoriesHR recovery for all participants av-eraged 84 plusmn 15 beatsmiddotmin-1 (subject range 54 to 131 Table 3) There were differences due to genre with lower HRrecov (80 versus 85 beatsmiddotmin-1 p = 0046) and a higher percentage

categorized as ldquofitrdquo (92 versus 89 p = 0021) in modern dancers compared to ballet dancers There were differences in HRrecov related to company (p = 001) In post hoc analysis dancers in M1 B1 B3 B4 and B5 all had lower HRrecov than dancers in B6 (p le 0035) In addition B4 had lower HRrecov than B7 (p le 0019) There were no differences in HRrecov or fitness category related to gender There were also no differences in fitness related to work weeks per year number of performances per year or annual hours of exposure per dancer One hundred eighty-four of 206 dancers (89) were categorized as ldquofitrdquo (category 0 1 or 2 Table 4) Fifty-two percent of dancers were in fitness category 0 25 in category 1 and 11 in category 2 Approxi-mately 12 of dancers were in CR rec (cardio-respiratory training recom-mended) categories 3 4 5 or 6 The

Table 4 Number of Subjects () by Fitness CategoryFitness Category

Company Gender 0 1 2 3 4 5 6

M1 Female 12 (86) 2 (14)Male 9 (64) 3 (21) 1 (7) 1 (7)

M2 Female 4 (66) 1 (17) 1 (17)Male 2 (33) 3 (50) 1 (17)

B1 Female 12 (60) 5 (25) 2 (10) 1 (5)Male 7 (39) 6 (33) 4 (22) 1 (6)

B2 Female 1 (50) 1 (50)Male 2 (50) 1 (25) 1 (25)

B3 Female 4 (50) 3 (37) 1 (12)Male 5 (71) 1 (14) 1 (14)

B4 Female 10 (91) 1 (9)Male 8 (73) 3 (27)

B5 Female 6 (100)Male 1 (50) 1 (50)

B6 Female 3 (18) 3 (18) 5 (29) 2 (12) 2 (12) 1 (6)Male 3 (25) 3 (25) 3 (25) 2 (17) 1 (8)

B7 Female 11 (44) 10 (40) 2 (8) 2 (8)Male 8 (32) 6 (24) 4 (16) 2 (8) 4 (16) 1 (4)

Total Female 63 (58) 26 (24) 9 (8) 5 (5) 4 (4) 1 (1) 0Male 45 (46) 25 (24) 16 (16) 7 (7) 5 (5) 0 1 (1)

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

75Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

ibility aerobic fitness and other physi-ologic measures in order to allow 10 minutes to review the findings and make recommendations Cardiorespiratory fitness is of particular interest due to differences in demands relative to dance genre9 Historically modern dance companies perform choreography with continu-ous movement for up to 30 minutes whereas dancers in ballet companies perform more traditional full-length works composed of shorter 3 to 5 minute sections19 A recent time motion analysis reported differences in exercise intensity during classi-cal ballet and contemporary dance performance9 Ballet incorporated higher intensity movement periods punctuated with longer rest periods while contemporary dance displayed longer continuous movement periods at moderate intensity9 Endurance requirements for performing different types of modern dance repertory may vary considerably from one another and from those of ballet As the dance community increas-ingly acknowledges health and well-ness as an important component of a successful dance career investigators are developing fitness profiles for dancers of various genres and levels of expertise Measurement of maxi-mal exercise intensity in conjunction with maximal oxygen consumption (VO2max) is the criterion for assessing aerobic capacity and cardiorespiratory fitness10 However this may be neither practical nor economically feasible for testing large groups of professional dancers who are rehearsing for many hours on the same day as testing and cannot compromise their work Separate dance-specific fitness tests have been developed and tested some specifically focused on either ballet or contemporary dance genres11-14 The ar-gument for using such tests is that dance is an intermittent activity therefore us-ing a steady state activity to test aerobic fitness is not appropriate Conversely it has been argued that using dance-specific fitness tests may only be appropriate for one dance form require a familiarization period and be lengthy to administer (up to 20 minutes)12-14

Field tests such as walking cycling running or step tests are considered acceptable for estimating cardiorespi-ratory fitness in large groups in a safe efficient and functional manner15-19 Step tests have demonstrated signifi-cant test-retest reliability and validity correlations between peak heart rate (HRpeak) and VO2max when compared with maximal treadmill tests1620-24 Step test intensity is determined by step height and rate as controlled by a metronome or pre-recorded counts and results are based on the sub-jectrsquos HRpeak and heart rate recovery (HRrecov) Recently an ldquoacceleratedrdquo 3-minute step test with a rate of 112 beatsmiddotmin-1 was validated against an incremental maximal treadmill test using a telemetric gas analysis system and HR monitor with high correla-tions between HRpeak and moderate correlations between HRrecov25 Thus this step test offers a convenient and practical way of assessing cardiorespira-tory fitness in dance companies with time and space limitations (although it does not capture nuances of capac-ity and endurance in the manner of a 20-minute test such as the Dance Specific Aerobic Fitness Test [DAFT]) Increased awareness of fitness participation in prevention and cross training programs and greater aerobic demands of new repertoire on profes-sional dancers warrant understanding of the current cardiorespiratory fitness of these individuals The purposes of this study were to 1 develop a cardio-respiratory profile of professional danc-ers 2 investigate differences in peak and recovery heart rate (HR) between professional modern and ballet danc-ers using an accelerated 3-minute step test 3 demonstrate the relationship between cardiorespiratory variables and 4 investigate the effects of com-pany and work variables on the dancersrsquo cardiorespiratory profiles Based on the repertory performed by DanceUSA member companies we hypothesized that modern dancers would exhibit greater cardiorespiratory fitness than ballet dancers Furthermore we hy-pothesized that certain companies would demonstrate differences in cardiorespiratory profiles potentially

reflecting differences in work variables and that a linear relationship would ex-ist between cardiorespiratory variables

MethodsData for this study were collected from part of the larger 30 minute post-hire health screen for profes-sional dancers developed by the DanceUSA Taskforce on Dancer Health The screen consists of a gen-eral demographic and medical history questionnaire followed by physical assessment Detailed guidelines for ad-ministration of the screen are provided to ensure uniform testing The screens for this study were conducted at the rehearsal studios of each participating company and administered by health-care professionals from the DanceUSA Task Forcemdashmostly physical therapists involved in the creation of this standardized screen and its guide-lines Information regarding each companyrsquos number of dancers weeks of work workday hours number of performances and touring weeks was collected from company administra-tors Average hours of exposure were calculated based on the number of workweeks times the number of work-day hours for each company

SubjectsData were collected from 211 out of a potential 241 dancers (88) in nine professional dance companies two modern dance (M1 and M2) and seven ballet (B1ndashB7) Subjects were currently employed by their dance company medically cleared for full dance activity and participated voluntarily in the study Dancers who did not participate were injured or unavailable during the screening period Each subject gave informed written consent in compliance with the guidelines of an umbrella Internal Review Board provided by Boston Childrenrsquos Hospital All screens were completed in a single session during the rehearsal period at the start of each companyrsquos contract year

ProtocolCardiorespiratory fitness was tested using an accelerated 3-minute step

76 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

test previously validated against an incremental treadmill test comparing HRpeak HRrecov VO2 peak and VO2 recovery25 Subjects wore running shoes and were given 5 minutes to sit quietly before resting HR (HRrest) and blood pressures (BP) were recorded HR was measured using Polar USA (Warminster PA) HR monitors secured to each subjectrsquos chest with a receiver-watch worn on his or her wrist Subjects were tested using a 0305 m (12) step for 3 minutes at a rate of 112 stepsmiddotmin-1 maintained by a metronome The metronome was started prior to the test to allow the subjects to familiarize themselves with the tempo They were instructed to step ldquoup up down downrdquo to the beat of the metronome Peak HR was recorded at 3 minutes Subjects were seated immediately after completing the test and HRrecov was recorded at 1 minute after completion of the step test Height and mass were measured and demographic information (eg age gender years of professional ex-perience smoking or non-smoking and asthmatic status) was collected for each participant as part of the screen intake

Data AnalysisBody mass index (BMI) was calcu-lated from each subjectrsquos height and mass Each subject was assigned a

fitness category based on gender age and HRrecov step test results accord-ing to YMCA guidelines26 The seven-category interpretation as defined by the YMCA protocol is 0 = Excellent 1 = Good 2 = Above Average 3 = Average 4 = Below average 5 = Poor and 6 = Very Poor For example for males between 18 to 25 years ldquoExcel-lentrdquo was HRrecov lt 79 beatsmiddotmin-1 ldquoGoodrdquo was HRrecov between 79 to 89 beatsmiddotmin-1 etc Subjects were charac-terized as ldquofitrdquo if their fitness category was 0 1 or 2 and ldquoCR-recrdquo (cardio-respiratory training recommended) if their category was 3 4 5 or 6 Comparisons were made between genres with respect to age years of professional experience height (m) mass (kg) BMI BP (systolic and dia-stolic) HRrest HRpeak HRrecov and fitness category using independent samples t-tests (genre modern versus ballet) for each of the 11 dependent variables (DV) listed above (SPSS 160 SPSS Inc Chicago IL 60606 USA) Comparisons were made between companies and the same dependent variables in a 9 (company) X 2 (gender) X 11 (DV) MANOVA Post hoc Bonferroni comparisons were conducted where appropriate After checking for normal distribution of the data Pearson product moment correlations were used to determine whether there was a relationship

between subjectsrsquo resting systolic and diastolic BP HRrest or HRpeak and their HRrecov Non-parametric Spear-manrsquos rho correlations were used to determine whether there was a rela-tionship between HRrest or HRpeak and fitness category Significance was considered at p lt 005 for all tests

ResultsGenre Company and Subject CharacteristicsThe nine companies ranged in size from 6 to 72 dancers M2 B2 and B5 were junior companies to M1 B1 and B4 Most of the companies had a 30 hour work week not includ-ing daily technique classes (Table 1) Technique classes generally last 15 hours but were optional for most of the companies with the exception of B3 and B5 Dancers worked 393 plusmn 45 (range 32 to 47) weeks per year touring 74 plusmn 71 (range 0 to 20) of those weeks This resulted in 12187 plusmn 1533 (range 960 to 15275) hours of dance exposure annually (note this calculation did not include the optional daily technique classes taken by most dancers) There were 853 plusmn 366 (range 53 to 169) performances per year A total of 211 subjects were screened (103 male 108 female 171 ballet 40 modern dancers) with a mean age of 247 plusmn 48 years (range

Table 1 Company Profiles

Company SizeHours per

WeekWork Weeks

Per YearWeeks

TouringPerformances

Per YearHours of Exposure Annually

Per Dancerdagger

M1 30 30 41 19 169 1230 12915M2 12 30 35 20 58 1050 11025B1 38 30 41 8 98 1230 12915B2 6 30 41 8 98 1230 12915B3 16 325 47 65 58 15275 15275B4 23 30 32 1 53 960 1008B5 8 37 35 1 67 1281 13335B6 36 30 38 0 55 1140 1197B7 72 30 44 3 112 1320 1386Mean plusmn SD 268 plusmn 194 311 plusmn 21 393 plusmn 45 74 plusmn 71 853 plusmn 363 12187 plusmn 1533

Mandatory technique class 15 hoursday In other companies technique class was optional but most dancers took one technique class daily daggerThe second value is exposure with 5 classes per week included in the calculations Abbreviations M 1-2 modern dance company 1-2 B1-B7 ballet company 1-7

77Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

16 to 39) and a mean of 63 plusmn 48 years (range 0 to 24) of professional experi-ence (Table 2) Dancers were 171 plusmn 009 m (subject range 152 to 193) in height 623 plusmn 121 kg (subject range 447 to 900) in mass with a BMI of 211 plusmn 22 The majority of companies had an equal ratio of male and female dancers There were differences due to genre (modern versus ballet dancers) in age mass and BMI (p le 003) Modern dancers were older (26 plusmn 44 versus 24 plusmn 48 years) and had greater mass and BMI compared to ballet dancers (Table 2) There were differences due to com-pany in age years of experience and

BMI (p lt 0001) Post hoc analysis revealed M1 dancers were older than M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 were all older than B2 and B5 (p le 0038) M1 B1 B3 and B4 dancers had longer profes-sional careers (experience) than M2 B2 and B5 (p le 0010) M1 B4 B7 also had longer professional careers than B6 (p le 0035) M1 dancers had greater BMI than B1 B2 B5 and B7 (p le 0050) There were no differences between companies in height Gender differences included height mass and BMI (p lt 0001 for each variable) Fourteen percent of the dancers reported that they smoked which was equally distributed between genders

Smokers comprised 25 of modern dancers and 18 of ballet dancers While asthma data were unavailable for two ballet companies 19 of 153 dancers (twice as many females as males) reported that they had asthma

Blood Pressure Resting Heart Rate Peak Heart Rate Five subjects were unable to attend the step test portion of the screening due to rehearsal therefore data from 206 subjects are reported (98 male 108 female 166 ballet 40 modern dancers) Mean BP for all dancers was 10967 mmHg (Table 3) Mean HRrest of all participants was 74 plusmn 12 beatsmiddotmin-1 (subject range 43 to 109)

Table 2 Demographics of Screening ParticipantsGender Age Experience Height Mass

Company (company ) (years) (years) (m) (kg) BMI Smoking Asthma

M1 14F (50) 283 plusmn 35 82 plusmn 35 168 plusmn 009 649 plusmn 118 229 plusmn 20 1F yes 1F 2M yes14M (50) 277 plusmn 41 93 plusmn 37 174 plusmn 010 675 plusmn 117 226 plusmn 22 97 no 25 yes

M2 6F (50) 217 plusmn 12 27 plusmn 14 163 plusmn 005 5445 plusmn 628 207 plusmn 12 0F 0M yes 4F 2M yes6M (50) 217 plusmn 19 22 plusmn 10 182 plusmn 008 76805 plusmn 710 233 plusmn 16 100 no 21 yes

B1 20F (53) 241 plusmn 44 59 plusmn 39 165 plusmn 004 505 plusmn 30 185 plusmn 09 2F 2M yes 5F 4M yes18M (47) 256 plusmn 42 78 plusmn 46 179 plusmn 005 702 plusmn 58 219 plusmn 11 89 no 24 yes

B2 2F (33) 185 plusmn 07 10 plusmn 00 169 plusmn 009 514 plusmn 77 179 plusmn 08 2M yes 0F 0M yes4M (67) 185 plusmn 21 10 plusmn 08 175 plusmn 006 609 plusmn 59 198 plusmn 13 67 no 0 yes

B3 8F (53) 274 plusmn 29 77 plusmn 47 164 plusmn 009 535 plusmn 51 200 plusmn 18 2F 1M yes 2F 0M yes7M (47) 243 plusmn 35 61 plusmn 36 172 plusmn 005 716 plusmn 75 241 plusmn 17 80 no 13 yes

B4 11F (50) 265 plusmn 50 88 plusmn 61 165 plusmn 006 532 plusmn 48 195 plusmn 11 1F 1M yes 4F 0M yes11M (50) 247 plusmn 50 64 plusmn 53 179 plusmn 003 726 plusmn 69 227 plusmn 17 91 no 18 yes

B5 6F (75) 182 plusmn 15 00 plusmn 00 167 plusmn 002 540 plusmn 46 193 plusmn 13 1F 1M yes NA2M (25) 205 plusmn 07 10 plusmn 14 174 plusmn 002 657 plusmn 03 217 plusmn 06 75 no NA

B6 16F (50) 238 plusmn 57 56 plusmn 54 163 plusmn 004 528 plusmn 55 195 plusmn 16 0F 5M yes 5F 2M yes16M (50) 217 plusmn 34 40 plusmn 28 175 plusmn 007 751 plusmn 176 226 plusmn 23 86 no 19 yes

B7 25F (50) 251 plusmn 51 75 plusmn 53 165 plusmn 005 533 plusmn 50 196 plusmn 12 3F 8M yes NA25M (50) 253 plusmn 46 70 plusmn 48 178 plusmn 006 724 plusmn 72 227 plusmn 13 78 no NA

Modern 40 M amp F 261 plusmn 44a 69 plusmn 43 171 plusmn 010 661 plusmn 120b 226 plusmn 20c 98 no 7 yesBallet 171 M amp F 243 plusmn 48a 62 plusmn 49 171 plusmn 008 611 plusmn 110b 208 plusmn 22c 85 no 19 yesTotal 108F (51) 247 plusmn 48 63 plusmn 48Dagger 171 plusmn 009 623 plusmn 121part 211 plusmn 22 10F 20M yes 21F 10M

103M (49) 86 no 19 yes

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 F females M males BMI body mass index NA not avail-able aAge significant differences between genres (t [df 1 199] = 2176 p = 0031) bMass significant differences between genres (t [df 1204] = 2416 p = 0017) cBMI significant differences between genres (t [df 1199] = 4351 p = 0001) Age significant differences between companies (F[8190] = 6351 p lt 0001) Post hoc M1 vs M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 vs B2 and B5 (p le 0038) DaggerExperience significant differences between companies (F[8190] = 5450 p lt 0001) Post hoc M1 B1 B3 and B4 vs M2 B2 and B5 (p le 0010) M1 B4 B7 vs B6 (p le 0035) partBMI significant differences between companies (F[8190] = 4606 p lt 0001) Post hoc M1 vs B1 B2 B5 and B7 (p le 0050)

78 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

There were differences due to genre in systolic and diastolic BP and HRrest (p lt 0001) Modern dancers dem-

onstrated lower BP (10260 versus 11169 mmHg) and lower HRrest (67 versus 76 beatsmiddotmin-1) compared

to ballet dancers (Table 3) Between companies there were differences in systolic and diastolic BP

Table 3 Mean plusmn SD Blood Pressure and Heart Rate VariablesBP Resting HR Peak HR HR Recovery

Company Gender (mmHg) (beatsmiddotmin-1) (beatsmiddotmin-1) (beatsmiddotmin-1)

M1 Female 10070 68 plusmn 14 140 plusmn 11 78 plusmn 8Male 8250 66 plusmn 8 129 plusmn 17 77 plusmn 13Total 9957 67 plusmn 12 135 plusmn 15 77 plusmn 11

M2 Female 10368 70 plusmn 8 145 plusmn 9 86 plusmn 14Male 11465 65 plusmn 10 134 plusmn 14 83 plusmn 16Total 10867 65 plusmn 10 137 plusmn 13 85 plusmn 14

B1 Female 10259 82 plusmn 15 144 plusmn 15 84 plusmn 14Male 10367 79 plusmn 14 129 plusmn 10 83 plusmn 12Total 10263 81 plusmn 14 137 plusmn 15 83 plusmn 13

B2 Female 9662 76 plusmn 6 146 plusmn 14 82 plusmn 11Male 9557 81 plusmn 11 130 plusmn 8 82 plusmn 18Total 9559 80 plusmn 10 136 plusmn 12 82 plusmn 14

B3 Female 10255 66 plusmn 7 143 plusmn 12 88 plusmn 11Male 10960 62 plusmn 3 122 plusmn 7 74 plusmn 11Total 10657 64 plusmn 6 133 plusmn 15 82 plusmn 13

B4 Female 11774 68 plusmn 8 112 plusmn 21 74 plusmn 11Male 12581 77 plusmn 10 110 plusmn 23 76 plusmn 12Total 12177 72 plusmn 10 111 plusmn 21 75 plusmn 11

B5 Female 11572 66 plusmn 10 115 plusmn 13 71 plusmn 11Male 11172 68 plusmn 17 108 plusmn 17 72 plusmn 17Total 11472 67 plusmn 9 113 plusmn 13 71 plusmn 11

B6 Female 11677 82 plusmn 6 157 plusmn 11 102 plusmn 15Male 12876 76 plusmn 7 150 plusmn 14 90 plusmn 13Total 12176 79 plusmn 7 154 plusmn 13 97 plusmn 15

B7 Female 10670 74 plusmn 9 142 plusmn 12 87 plusmn 15Male 11471 78 plusmn 11 137 plusmn 16 89 plusmn 17Total 11070 76 plusmn 10 139 plusmn 14 88 plusmn 16

Modern 102a 60b 67 plusmn 1c 136 plusmn 14 80 plusmn 12d

Ballet 11169 76 plusmn 11 136 plusmn 20 85 plusmn 16Mean all companies Female 10667 74 plusmn 12 140 plusmn 18 85 plusmn 15

Male 11268 74 plusmn 12 131 plusmn 18 83 plusmn 15All 10967Dagger 74 plusmn 12part 135 plusmn 19∆ 84 plusmn 15sect

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies aSystolic BP significant differences between genres (t [df 1 204] = 3687 p = 0001) bDiastolic BP significant differences between genres (t [df 1 204] = 4720 p = 0001) cHRrest significant differences between genres (t [df 1 202 1] = 4141 p lt 0001) dHRrecov significant differences between genres (t [df 1 204] = 2006 p = 0046) Systolic BP significant differences between companies (F[8191] = 10015 p lt 0001) Post hoc M1 vs B4 B6 and B7 (p le 0027) M2 vs B4 (p lt 0003) B1 and B2 vs B6 and B7 (p lt 0001) B3 vs B4 and B6 (p lt 0014) DaggerDiastolic BP significant differences between companies (F[8191] = 15799 p lt 0001) Post hoc M1 and B3 vs B4 B5 B6 and B7 (p le 0010) B1 vs B4 B7 B6 (p lt 0008) B2 vs B6 and B7 (p le 0001) partHRrest significant differences between companies (F[8192] = 6905 p lt 0001) Post hoc M1 vs B1 B6 and B7 (p lt 005) B3 vs B1 B6 B7 (p lt 0012) ∆HRpeak significant differences between companies (F[8192] = 15094 p lt 0001) Post hoc B4 vs M1 M2 B1 B2 B3 B6 B7 (p lt 0018) B5 vs M1 M2 B1 B6 B7 (p lt 0030) M1 B1 B3 B7 vs B6 (p lt 0003) sectHRrecov significant differences between companies (F[8192] = 6029 p = 0001) Post hoc M1 B1 B3 B4 B5 vs B6 (p lt 0035) B4 vs B7 (p lt 0019)

79Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

(p lt 0001) In post hoc analysis M1 systolic BP was lower than B4 B6 and B7 (p le 0027) M2 was lower than B4 (p lt 0003) B1 and B2 were lower than B6 and B7 (p lt 0001) and B3 was lower than B4 and B6 (p lt 0014) M1 and B3 diastolic BPs were lower than B4 B5 B6 and B7 (p le 0010) B1 was lower than B4 B7 and B6 (p lt 0008) and B2 was lower than B6 and B7 (p le 0001) There were also differences in sys-tolic BP between genders (p = 0016) Female systolic BP was lower than males (10767 versus 11268 mmHg) Smokers had higher systolic and diastolic BP than non-smokers (p lt 0001 for both variables) Between companies there were also differences in HRrest (p lt 0001) in post hoc analysis the resting HR of M1 and B3 were lower than B1 B6 and B7 (p lt 0012) There were no differences between genders in HRrest Peak HR was 135 plusmn 19 beatsmiddotmin-1

(subject range 76 to 181 Table 3) There were no differences due to genre but differences between com-panies were significant (p lt 0001) In post hoc analysis HRpeak in company B6 (154 plusmn 13 beatsmiddotmin-1) exceeded that of all other companies (p le 0003) HRpeak in companies B4 and B5 (111 plusmn 21 and 113 plusmn 13 beatsmiddotmin-1 respectively) were lower than the other companies (p le 0030) with the exception of B3 There were also HRpeak differences due to gender (p = 0001) females reached a higher HRpeak than males (140 plusmn 18 ver-sus131 plusmn 18 beatsmiddotmin-1)

Heart Rate Recovery and Fitness CategoriesHR recovery for all participants av-eraged 84 plusmn 15 beatsmiddotmin-1 (subject range 54 to 131 Table 3) There were differences due to genre with lower HRrecov (80 versus 85 beatsmiddotmin-1 p = 0046) and a higher percentage

categorized as ldquofitrdquo (92 versus 89 p = 0021) in modern dancers compared to ballet dancers There were differences in HRrecov related to company (p = 001) In post hoc analysis dancers in M1 B1 B3 B4 and B5 all had lower HRrecov than dancers in B6 (p le 0035) In addition B4 had lower HRrecov than B7 (p le 0019) There were no differences in HRrecov or fitness category related to gender There were also no differences in fitness related to work weeks per year number of performances per year or annual hours of exposure per dancer One hundred eighty-four of 206 dancers (89) were categorized as ldquofitrdquo (category 0 1 or 2 Table 4) Fifty-two percent of dancers were in fitness category 0 25 in category 1 and 11 in category 2 Approxi-mately 12 of dancers were in CR rec (cardio-respiratory training recom-mended) categories 3 4 5 or 6 The

Table 4 Number of Subjects () by Fitness CategoryFitness Category

Company Gender 0 1 2 3 4 5 6

M1 Female 12 (86) 2 (14)Male 9 (64) 3 (21) 1 (7) 1 (7)

M2 Female 4 (66) 1 (17) 1 (17)Male 2 (33) 3 (50) 1 (17)

B1 Female 12 (60) 5 (25) 2 (10) 1 (5)Male 7 (39) 6 (33) 4 (22) 1 (6)

B2 Female 1 (50) 1 (50)Male 2 (50) 1 (25) 1 (25)

B3 Female 4 (50) 3 (37) 1 (12)Male 5 (71) 1 (14) 1 (14)

B4 Female 10 (91) 1 (9)Male 8 (73) 3 (27)

B5 Female 6 (100)Male 1 (50) 1 (50)

B6 Female 3 (18) 3 (18) 5 (29) 2 (12) 2 (12) 1 (6)Male 3 (25) 3 (25) 3 (25) 2 (17) 1 (8)

B7 Female 11 (44) 10 (40) 2 (8) 2 (8)Male 8 (32) 6 (24) 4 (16) 2 (8) 4 (16) 1 (4)

Total Female 63 (58) 26 (24) 9 (8) 5 (5) 4 (4) 1 (1) 0Male 45 (46) 25 (24) 16 (16) 7 (7) 5 (5) 0 1 (1)

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

76 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

test previously validated against an incremental treadmill test comparing HRpeak HRrecov VO2 peak and VO2 recovery25 Subjects wore running shoes and were given 5 minutes to sit quietly before resting HR (HRrest) and blood pressures (BP) were recorded HR was measured using Polar USA (Warminster PA) HR monitors secured to each subjectrsquos chest with a receiver-watch worn on his or her wrist Subjects were tested using a 0305 m (12) step for 3 minutes at a rate of 112 stepsmiddotmin-1 maintained by a metronome The metronome was started prior to the test to allow the subjects to familiarize themselves with the tempo They were instructed to step ldquoup up down downrdquo to the beat of the metronome Peak HR was recorded at 3 minutes Subjects were seated immediately after completing the test and HRrecov was recorded at 1 minute after completion of the step test Height and mass were measured and demographic information (eg age gender years of professional ex-perience smoking or non-smoking and asthmatic status) was collected for each participant as part of the screen intake

Data AnalysisBody mass index (BMI) was calcu-lated from each subjectrsquos height and mass Each subject was assigned a

fitness category based on gender age and HRrecov step test results accord-ing to YMCA guidelines26 The seven-category interpretation as defined by the YMCA protocol is 0 = Excellent 1 = Good 2 = Above Average 3 = Average 4 = Below average 5 = Poor and 6 = Very Poor For example for males between 18 to 25 years ldquoExcel-lentrdquo was HRrecov lt 79 beatsmiddotmin-1 ldquoGoodrdquo was HRrecov between 79 to 89 beatsmiddotmin-1 etc Subjects were charac-terized as ldquofitrdquo if their fitness category was 0 1 or 2 and ldquoCR-recrdquo (cardio-respiratory training recommended) if their category was 3 4 5 or 6 Comparisons were made between genres with respect to age years of professional experience height (m) mass (kg) BMI BP (systolic and dia-stolic) HRrest HRpeak HRrecov and fitness category using independent samples t-tests (genre modern versus ballet) for each of the 11 dependent variables (DV) listed above (SPSS 160 SPSS Inc Chicago IL 60606 USA) Comparisons were made between companies and the same dependent variables in a 9 (company) X 2 (gender) X 11 (DV) MANOVA Post hoc Bonferroni comparisons were conducted where appropriate After checking for normal distribution of the data Pearson product moment correlations were used to determine whether there was a relationship

between subjectsrsquo resting systolic and diastolic BP HRrest or HRpeak and their HRrecov Non-parametric Spear-manrsquos rho correlations were used to determine whether there was a rela-tionship between HRrest or HRpeak and fitness category Significance was considered at p lt 005 for all tests

ResultsGenre Company and Subject CharacteristicsThe nine companies ranged in size from 6 to 72 dancers M2 B2 and B5 were junior companies to M1 B1 and B4 Most of the companies had a 30 hour work week not includ-ing daily technique classes (Table 1) Technique classes generally last 15 hours but were optional for most of the companies with the exception of B3 and B5 Dancers worked 393 plusmn 45 (range 32 to 47) weeks per year touring 74 plusmn 71 (range 0 to 20) of those weeks This resulted in 12187 plusmn 1533 (range 960 to 15275) hours of dance exposure annually (note this calculation did not include the optional daily technique classes taken by most dancers) There were 853 plusmn 366 (range 53 to 169) performances per year A total of 211 subjects were screened (103 male 108 female 171 ballet 40 modern dancers) with a mean age of 247 plusmn 48 years (range

Table 1 Company Profiles

Company SizeHours per

WeekWork Weeks

Per YearWeeks

TouringPerformances

Per YearHours of Exposure Annually

Per Dancerdagger

M1 30 30 41 19 169 1230 12915M2 12 30 35 20 58 1050 11025B1 38 30 41 8 98 1230 12915B2 6 30 41 8 98 1230 12915B3 16 325 47 65 58 15275 15275B4 23 30 32 1 53 960 1008B5 8 37 35 1 67 1281 13335B6 36 30 38 0 55 1140 1197B7 72 30 44 3 112 1320 1386Mean plusmn SD 268 plusmn 194 311 plusmn 21 393 plusmn 45 74 plusmn 71 853 plusmn 363 12187 plusmn 1533

Mandatory technique class 15 hoursday In other companies technique class was optional but most dancers took one technique class daily daggerThe second value is exposure with 5 classes per week included in the calculations Abbreviations M 1-2 modern dance company 1-2 B1-B7 ballet company 1-7

77Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

16 to 39) and a mean of 63 plusmn 48 years (range 0 to 24) of professional experi-ence (Table 2) Dancers were 171 plusmn 009 m (subject range 152 to 193) in height 623 plusmn 121 kg (subject range 447 to 900) in mass with a BMI of 211 plusmn 22 The majority of companies had an equal ratio of male and female dancers There were differences due to genre (modern versus ballet dancers) in age mass and BMI (p le 003) Modern dancers were older (26 plusmn 44 versus 24 plusmn 48 years) and had greater mass and BMI compared to ballet dancers (Table 2) There were differences due to com-pany in age years of experience and

BMI (p lt 0001) Post hoc analysis revealed M1 dancers were older than M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 were all older than B2 and B5 (p le 0038) M1 B1 B3 and B4 dancers had longer profes-sional careers (experience) than M2 B2 and B5 (p le 0010) M1 B4 B7 also had longer professional careers than B6 (p le 0035) M1 dancers had greater BMI than B1 B2 B5 and B7 (p le 0050) There were no differences between companies in height Gender differences included height mass and BMI (p lt 0001 for each variable) Fourteen percent of the dancers reported that they smoked which was equally distributed between genders

Smokers comprised 25 of modern dancers and 18 of ballet dancers While asthma data were unavailable for two ballet companies 19 of 153 dancers (twice as many females as males) reported that they had asthma

Blood Pressure Resting Heart Rate Peak Heart Rate Five subjects were unable to attend the step test portion of the screening due to rehearsal therefore data from 206 subjects are reported (98 male 108 female 166 ballet 40 modern dancers) Mean BP for all dancers was 10967 mmHg (Table 3) Mean HRrest of all participants was 74 plusmn 12 beatsmiddotmin-1 (subject range 43 to 109)

Table 2 Demographics of Screening ParticipantsGender Age Experience Height Mass

Company (company ) (years) (years) (m) (kg) BMI Smoking Asthma

M1 14F (50) 283 plusmn 35 82 plusmn 35 168 plusmn 009 649 plusmn 118 229 plusmn 20 1F yes 1F 2M yes14M (50) 277 plusmn 41 93 plusmn 37 174 plusmn 010 675 plusmn 117 226 plusmn 22 97 no 25 yes

M2 6F (50) 217 plusmn 12 27 plusmn 14 163 plusmn 005 5445 plusmn 628 207 plusmn 12 0F 0M yes 4F 2M yes6M (50) 217 plusmn 19 22 plusmn 10 182 plusmn 008 76805 plusmn 710 233 plusmn 16 100 no 21 yes

B1 20F (53) 241 plusmn 44 59 plusmn 39 165 plusmn 004 505 plusmn 30 185 plusmn 09 2F 2M yes 5F 4M yes18M (47) 256 plusmn 42 78 plusmn 46 179 plusmn 005 702 plusmn 58 219 plusmn 11 89 no 24 yes

B2 2F (33) 185 plusmn 07 10 plusmn 00 169 plusmn 009 514 plusmn 77 179 plusmn 08 2M yes 0F 0M yes4M (67) 185 plusmn 21 10 plusmn 08 175 plusmn 006 609 plusmn 59 198 plusmn 13 67 no 0 yes

B3 8F (53) 274 plusmn 29 77 plusmn 47 164 plusmn 009 535 plusmn 51 200 plusmn 18 2F 1M yes 2F 0M yes7M (47) 243 plusmn 35 61 plusmn 36 172 plusmn 005 716 plusmn 75 241 plusmn 17 80 no 13 yes

B4 11F (50) 265 plusmn 50 88 plusmn 61 165 plusmn 006 532 plusmn 48 195 plusmn 11 1F 1M yes 4F 0M yes11M (50) 247 plusmn 50 64 plusmn 53 179 plusmn 003 726 plusmn 69 227 plusmn 17 91 no 18 yes

B5 6F (75) 182 plusmn 15 00 plusmn 00 167 plusmn 002 540 plusmn 46 193 plusmn 13 1F 1M yes NA2M (25) 205 plusmn 07 10 plusmn 14 174 plusmn 002 657 plusmn 03 217 plusmn 06 75 no NA

B6 16F (50) 238 plusmn 57 56 plusmn 54 163 plusmn 004 528 plusmn 55 195 plusmn 16 0F 5M yes 5F 2M yes16M (50) 217 plusmn 34 40 plusmn 28 175 plusmn 007 751 plusmn 176 226 plusmn 23 86 no 19 yes

B7 25F (50) 251 plusmn 51 75 plusmn 53 165 plusmn 005 533 plusmn 50 196 plusmn 12 3F 8M yes NA25M (50) 253 plusmn 46 70 plusmn 48 178 plusmn 006 724 plusmn 72 227 plusmn 13 78 no NA

Modern 40 M amp F 261 plusmn 44a 69 plusmn 43 171 plusmn 010 661 plusmn 120b 226 plusmn 20c 98 no 7 yesBallet 171 M amp F 243 plusmn 48a 62 plusmn 49 171 plusmn 008 611 plusmn 110b 208 plusmn 22c 85 no 19 yesTotal 108F (51) 247 plusmn 48 63 plusmn 48Dagger 171 plusmn 009 623 plusmn 121part 211 plusmn 22 10F 20M yes 21F 10M

103M (49) 86 no 19 yes

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 F females M males BMI body mass index NA not avail-able aAge significant differences between genres (t [df 1 199] = 2176 p = 0031) bMass significant differences between genres (t [df 1204] = 2416 p = 0017) cBMI significant differences between genres (t [df 1199] = 4351 p = 0001) Age significant differences between companies (F[8190] = 6351 p lt 0001) Post hoc M1 vs M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 vs B2 and B5 (p le 0038) DaggerExperience significant differences between companies (F[8190] = 5450 p lt 0001) Post hoc M1 B1 B3 and B4 vs M2 B2 and B5 (p le 0010) M1 B4 B7 vs B6 (p le 0035) partBMI significant differences between companies (F[8190] = 4606 p lt 0001) Post hoc M1 vs B1 B2 B5 and B7 (p le 0050)

78 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

There were differences due to genre in systolic and diastolic BP and HRrest (p lt 0001) Modern dancers dem-

onstrated lower BP (10260 versus 11169 mmHg) and lower HRrest (67 versus 76 beatsmiddotmin-1) compared

to ballet dancers (Table 3) Between companies there were differences in systolic and diastolic BP

Table 3 Mean plusmn SD Blood Pressure and Heart Rate VariablesBP Resting HR Peak HR HR Recovery

Company Gender (mmHg) (beatsmiddotmin-1) (beatsmiddotmin-1) (beatsmiddotmin-1)

M1 Female 10070 68 plusmn 14 140 plusmn 11 78 plusmn 8Male 8250 66 plusmn 8 129 plusmn 17 77 plusmn 13Total 9957 67 plusmn 12 135 plusmn 15 77 plusmn 11

M2 Female 10368 70 plusmn 8 145 plusmn 9 86 plusmn 14Male 11465 65 plusmn 10 134 plusmn 14 83 plusmn 16Total 10867 65 plusmn 10 137 plusmn 13 85 plusmn 14

B1 Female 10259 82 plusmn 15 144 plusmn 15 84 plusmn 14Male 10367 79 plusmn 14 129 plusmn 10 83 plusmn 12Total 10263 81 plusmn 14 137 plusmn 15 83 plusmn 13

B2 Female 9662 76 plusmn 6 146 plusmn 14 82 plusmn 11Male 9557 81 plusmn 11 130 plusmn 8 82 plusmn 18Total 9559 80 plusmn 10 136 plusmn 12 82 plusmn 14

B3 Female 10255 66 plusmn 7 143 plusmn 12 88 plusmn 11Male 10960 62 plusmn 3 122 plusmn 7 74 plusmn 11Total 10657 64 plusmn 6 133 plusmn 15 82 plusmn 13

B4 Female 11774 68 plusmn 8 112 plusmn 21 74 plusmn 11Male 12581 77 plusmn 10 110 plusmn 23 76 plusmn 12Total 12177 72 plusmn 10 111 plusmn 21 75 plusmn 11

B5 Female 11572 66 plusmn 10 115 plusmn 13 71 plusmn 11Male 11172 68 plusmn 17 108 plusmn 17 72 plusmn 17Total 11472 67 plusmn 9 113 plusmn 13 71 plusmn 11

B6 Female 11677 82 plusmn 6 157 plusmn 11 102 plusmn 15Male 12876 76 plusmn 7 150 plusmn 14 90 plusmn 13Total 12176 79 plusmn 7 154 plusmn 13 97 plusmn 15

B7 Female 10670 74 plusmn 9 142 plusmn 12 87 plusmn 15Male 11471 78 plusmn 11 137 plusmn 16 89 plusmn 17Total 11070 76 plusmn 10 139 plusmn 14 88 plusmn 16

Modern 102a 60b 67 plusmn 1c 136 plusmn 14 80 plusmn 12d

Ballet 11169 76 plusmn 11 136 plusmn 20 85 plusmn 16Mean all companies Female 10667 74 plusmn 12 140 plusmn 18 85 plusmn 15

Male 11268 74 plusmn 12 131 plusmn 18 83 plusmn 15All 10967Dagger 74 plusmn 12part 135 plusmn 19∆ 84 plusmn 15sect

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies aSystolic BP significant differences between genres (t [df 1 204] = 3687 p = 0001) bDiastolic BP significant differences between genres (t [df 1 204] = 4720 p = 0001) cHRrest significant differences between genres (t [df 1 202 1] = 4141 p lt 0001) dHRrecov significant differences between genres (t [df 1 204] = 2006 p = 0046) Systolic BP significant differences between companies (F[8191] = 10015 p lt 0001) Post hoc M1 vs B4 B6 and B7 (p le 0027) M2 vs B4 (p lt 0003) B1 and B2 vs B6 and B7 (p lt 0001) B3 vs B4 and B6 (p lt 0014) DaggerDiastolic BP significant differences between companies (F[8191] = 15799 p lt 0001) Post hoc M1 and B3 vs B4 B5 B6 and B7 (p le 0010) B1 vs B4 B7 B6 (p lt 0008) B2 vs B6 and B7 (p le 0001) partHRrest significant differences between companies (F[8192] = 6905 p lt 0001) Post hoc M1 vs B1 B6 and B7 (p lt 005) B3 vs B1 B6 B7 (p lt 0012) ∆HRpeak significant differences between companies (F[8192] = 15094 p lt 0001) Post hoc B4 vs M1 M2 B1 B2 B3 B6 B7 (p lt 0018) B5 vs M1 M2 B1 B6 B7 (p lt 0030) M1 B1 B3 B7 vs B6 (p lt 0003) sectHRrecov significant differences between companies (F[8192] = 6029 p = 0001) Post hoc M1 B1 B3 B4 B5 vs B6 (p lt 0035) B4 vs B7 (p lt 0019)

79Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

(p lt 0001) In post hoc analysis M1 systolic BP was lower than B4 B6 and B7 (p le 0027) M2 was lower than B4 (p lt 0003) B1 and B2 were lower than B6 and B7 (p lt 0001) and B3 was lower than B4 and B6 (p lt 0014) M1 and B3 diastolic BPs were lower than B4 B5 B6 and B7 (p le 0010) B1 was lower than B4 B7 and B6 (p lt 0008) and B2 was lower than B6 and B7 (p le 0001) There were also differences in sys-tolic BP between genders (p = 0016) Female systolic BP was lower than males (10767 versus 11268 mmHg) Smokers had higher systolic and diastolic BP than non-smokers (p lt 0001 for both variables) Between companies there were also differences in HRrest (p lt 0001) in post hoc analysis the resting HR of M1 and B3 were lower than B1 B6 and B7 (p lt 0012) There were no differences between genders in HRrest Peak HR was 135 plusmn 19 beatsmiddotmin-1

(subject range 76 to 181 Table 3) There were no differences due to genre but differences between com-panies were significant (p lt 0001) In post hoc analysis HRpeak in company B6 (154 plusmn 13 beatsmiddotmin-1) exceeded that of all other companies (p le 0003) HRpeak in companies B4 and B5 (111 plusmn 21 and 113 plusmn 13 beatsmiddotmin-1 respectively) were lower than the other companies (p le 0030) with the exception of B3 There were also HRpeak differences due to gender (p = 0001) females reached a higher HRpeak than males (140 plusmn 18 ver-sus131 plusmn 18 beatsmiddotmin-1)

Heart Rate Recovery and Fitness CategoriesHR recovery for all participants av-eraged 84 plusmn 15 beatsmiddotmin-1 (subject range 54 to 131 Table 3) There were differences due to genre with lower HRrecov (80 versus 85 beatsmiddotmin-1 p = 0046) and a higher percentage

categorized as ldquofitrdquo (92 versus 89 p = 0021) in modern dancers compared to ballet dancers There were differences in HRrecov related to company (p = 001) In post hoc analysis dancers in M1 B1 B3 B4 and B5 all had lower HRrecov than dancers in B6 (p le 0035) In addition B4 had lower HRrecov than B7 (p le 0019) There were no differences in HRrecov or fitness category related to gender There were also no differences in fitness related to work weeks per year number of performances per year or annual hours of exposure per dancer One hundred eighty-four of 206 dancers (89) were categorized as ldquofitrdquo (category 0 1 or 2 Table 4) Fifty-two percent of dancers were in fitness category 0 25 in category 1 and 11 in category 2 Approxi-mately 12 of dancers were in CR rec (cardio-respiratory training recom-mended) categories 3 4 5 or 6 The

Table 4 Number of Subjects () by Fitness CategoryFitness Category

Company Gender 0 1 2 3 4 5 6

M1 Female 12 (86) 2 (14)Male 9 (64) 3 (21) 1 (7) 1 (7)

M2 Female 4 (66) 1 (17) 1 (17)Male 2 (33) 3 (50) 1 (17)

B1 Female 12 (60) 5 (25) 2 (10) 1 (5)Male 7 (39) 6 (33) 4 (22) 1 (6)

B2 Female 1 (50) 1 (50)Male 2 (50) 1 (25) 1 (25)

B3 Female 4 (50) 3 (37) 1 (12)Male 5 (71) 1 (14) 1 (14)

B4 Female 10 (91) 1 (9)Male 8 (73) 3 (27)

B5 Female 6 (100)Male 1 (50) 1 (50)

B6 Female 3 (18) 3 (18) 5 (29) 2 (12) 2 (12) 1 (6)Male 3 (25) 3 (25) 3 (25) 2 (17) 1 (8)

B7 Female 11 (44) 10 (40) 2 (8) 2 (8)Male 8 (32) 6 (24) 4 (16) 2 (8) 4 (16) 1 (4)

Total Female 63 (58) 26 (24) 9 (8) 5 (5) 4 (4) 1 (1) 0Male 45 (46) 25 (24) 16 (16) 7 (7) 5 (5) 0 1 (1)

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

77Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

16 to 39) and a mean of 63 plusmn 48 years (range 0 to 24) of professional experi-ence (Table 2) Dancers were 171 plusmn 009 m (subject range 152 to 193) in height 623 plusmn 121 kg (subject range 447 to 900) in mass with a BMI of 211 plusmn 22 The majority of companies had an equal ratio of male and female dancers There were differences due to genre (modern versus ballet dancers) in age mass and BMI (p le 003) Modern dancers were older (26 plusmn 44 versus 24 plusmn 48 years) and had greater mass and BMI compared to ballet dancers (Table 2) There were differences due to com-pany in age years of experience and

BMI (p lt 0001) Post hoc analysis revealed M1 dancers were older than M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 were all older than B2 and B5 (p le 0038) M1 B1 B3 and B4 dancers had longer profes-sional careers (experience) than M2 B2 and B5 (p le 0010) M1 B4 B7 also had longer professional careers than B6 (p le 0035) M1 dancers had greater BMI than B1 B2 B5 and B7 (p le 0050) There were no differences between companies in height Gender differences included height mass and BMI (p lt 0001 for each variable) Fourteen percent of the dancers reported that they smoked which was equally distributed between genders

Smokers comprised 25 of modern dancers and 18 of ballet dancers While asthma data were unavailable for two ballet companies 19 of 153 dancers (twice as many females as males) reported that they had asthma

Blood Pressure Resting Heart Rate Peak Heart Rate Five subjects were unable to attend the step test portion of the screening due to rehearsal therefore data from 206 subjects are reported (98 male 108 female 166 ballet 40 modern dancers) Mean BP for all dancers was 10967 mmHg (Table 3) Mean HRrest of all participants was 74 plusmn 12 beatsmiddotmin-1 (subject range 43 to 109)

Table 2 Demographics of Screening ParticipantsGender Age Experience Height Mass

Company (company ) (years) (years) (m) (kg) BMI Smoking Asthma

M1 14F (50) 283 plusmn 35 82 plusmn 35 168 plusmn 009 649 plusmn 118 229 plusmn 20 1F yes 1F 2M yes14M (50) 277 plusmn 41 93 plusmn 37 174 plusmn 010 675 plusmn 117 226 plusmn 22 97 no 25 yes

M2 6F (50) 217 plusmn 12 27 plusmn 14 163 plusmn 005 5445 plusmn 628 207 plusmn 12 0F 0M yes 4F 2M yes6M (50) 217 plusmn 19 22 plusmn 10 182 plusmn 008 76805 plusmn 710 233 plusmn 16 100 no 21 yes

B1 20F (53) 241 plusmn 44 59 plusmn 39 165 plusmn 004 505 plusmn 30 185 plusmn 09 2F 2M yes 5F 4M yes18M (47) 256 plusmn 42 78 plusmn 46 179 plusmn 005 702 plusmn 58 219 plusmn 11 89 no 24 yes

B2 2F (33) 185 plusmn 07 10 plusmn 00 169 plusmn 009 514 plusmn 77 179 plusmn 08 2M yes 0F 0M yes4M (67) 185 plusmn 21 10 plusmn 08 175 plusmn 006 609 plusmn 59 198 plusmn 13 67 no 0 yes

B3 8F (53) 274 plusmn 29 77 plusmn 47 164 plusmn 009 535 plusmn 51 200 plusmn 18 2F 1M yes 2F 0M yes7M (47) 243 plusmn 35 61 plusmn 36 172 plusmn 005 716 plusmn 75 241 plusmn 17 80 no 13 yes

B4 11F (50) 265 plusmn 50 88 plusmn 61 165 plusmn 006 532 plusmn 48 195 plusmn 11 1F 1M yes 4F 0M yes11M (50) 247 plusmn 50 64 plusmn 53 179 plusmn 003 726 plusmn 69 227 plusmn 17 91 no 18 yes

B5 6F (75) 182 plusmn 15 00 plusmn 00 167 plusmn 002 540 plusmn 46 193 plusmn 13 1F 1M yes NA2M (25) 205 plusmn 07 10 plusmn 14 174 plusmn 002 657 plusmn 03 217 plusmn 06 75 no NA

B6 16F (50) 238 plusmn 57 56 plusmn 54 163 plusmn 004 528 plusmn 55 195 plusmn 16 0F 5M yes 5F 2M yes16M (50) 217 plusmn 34 40 plusmn 28 175 plusmn 007 751 plusmn 176 226 plusmn 23 86 no 19 yes

B7 25F (50) 251 plusmn 51 75 plusmn 53 165 plusmn 005 533 plusmn 50 196 plusmn 12 3F 8M yes NA25M (50) 253 plusmn 46 70 plusmn 48 178 plusmn 006 724 plusmn 72 227 plusmn 13 78 no NA

Modern 40 M amp F 261 plusmn 44a 69 plusmn 43 171 plusmn 010 661 plusmn 120b 226 plusmn 20c 98 no 7 yesBallet 171 M amp F 243 plusmn 48a 62 plusmn 49 171 plusmn 008 611 plusmn 110b 208 plusmn 22c 85 no 19 yesTotal 108F (51) 247 plusmn 48 63 plusmn 48Dagger 171 plusmn 009 623 plusmn 121part 211 plusmn 22 10F 20M yes 21F 10M

103M (49) 86 no 19 yes

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 F females M males BMI body mass index NA not avail-able aAge significant differences between genres (t [df 1 199] = 2176 p = 0031) bMass significant differences between genres (t [df 1204] = 2416 p = 0017) cBMI significant differences between genres (t [df 1199] = 4351 p = 0001) Age significant differences between companies (F[8190] = 6351 p lt 0001) Post hoc M1 vs M2 B2 B5 and B6 (p le 0032) B1 B3 B4 and B7 vs B2 and B5 (p le 0038) DaggerExperience significant differences between companies (F[8190] = 5450 p lt 0001) Post hoc M1 B1 B3 and B4 vs M2 B2 and B5 (p le 0010) M1 B4 B7 vs B6 (p le 0035) partBMI significant differences between companies (F[8190] = 4606 p lt 0001) Post hoc M1 vs B1 B2 B5 and B7 (p le 0050)

78 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

There were differences due to genre in systolic and diastolic BP and HRrest (p lt 0001) Modern dancers dem-

onstrated lower BP (10260 versus 11169 mmHg) and lower HRrest (67 versus 76 beatsmiddotmin-1) compared

to ballet dancers (Table 3) Between companies there were differences in systolic and diastolic BP

Table 3 Mean plusmn SD Blood Pressure and Heart Rate VariablesBP Resting HR Peak HR HR Recovery

Company Gender (mmHg) (beatsmiddotmin-1) (beatsmiddotmin-1) (beatsmiddotmin-1)

M1 Female 10070 68 plusmn 14 140 plusmn 11 78 plusmn 8Male 8250 66 plusmn 8 129 plusmn 17 77 plusmn 13Total 9957 67 plusmn 12 135 plusmn 15 77 plusmn 11

M2 Female 10368 70 plusmn 8 145 plusmn 9 86 plusmn 14Male 11465 65 plusmn 10 134 plusmn 14 83 plusmn 16Total 10867 65 plusmn 10 137 plusmn 13 85 plusmn 14

B1 Female 10259 82 plusmn 15 144 plusmn 15 84 plusmn 14Male 10367 79 plusmn 14 129 plusmn 10 83 plusmn 12Total 10263 81 plusmn 14 137 plusmn 15 83 plusmn 13

B2 Female 9662 76 plusmn 6 146 plusmn 14 82 plusmn 11Male 9557 81 plusmn 11 130 plusmn 8 82 plusmn 18Total 9559 80 plusmn 10 136 plusmn 12 82 plusmn 14

B3 Female 10255 66 plusmn 7 143 plusmn 12 88 plusmn 11Male 10960 62 plusmn 3 122 plusmn 7 74 plusmn 11Total 10657 64 plusmn 6 133 plusmn 15 82 plusmn 13

B4 Female 11774 68 plusmn 8 112 plusmn 21 74 plusmn 11Male 12581 77 plusmn 10 110 plusmn 23 76 plusmn 12Total 12177 72 plusmn 10 111 plusmn 21 75 plusmn 11

B5 Female 11572 66 plusmn 10 115 plusmn 13 71 plusmn 11Male 11172 68 plusmn 17 108 plusmn 17 72 plusmn 17Total 11472 67 plusmn 9 113 plusmn 13 71 plusmn 11

B6 Female 11677 82 plusmn 6 157 plusmn 11 102 plusmn 15Male 12876 76 plusmn 7 150 plusmn 14 90 plusmn 13Total 12176 79 plusmn 7 154 plusmn 13 97 plusmn 15

B7 Female 10670 74 plusmn 9 142 plusmn 12 87 plusmn 15Male 11471 78 plusmn 11 137 plusmn 16 89 plusmn 17Total 11070 76 plusmn 10 139 plusmn 14 88 plusmn 16

Modern 102a 60b 67 plusmn 1c 136 plusmn 14 80 plusmn 12d

Ballet 11169 76 plusmn 11 136 plusmn 20 85 plusmn 16Mean all companies Female 10667 74 plusmn 12 140 plusmn 18 85 plusmn 15

Male 11268 74 plusmn 12 131 plusmn 18 83 plusmn 15All 10967Dagger 74 plusmn 12part 135 plusmn 19∆ 84 plusmn 15sect

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies aSystolic BP significant differences between genres (t [df 1 204] = 3687 p = 0001) bDiastolic BP significant differences between genres (t [df 1 204] = 4720 p = 0001) cHRrest significant differences between genres (t [df 1 202 1] = 4141 p lt 0001) dHRrecov significant differences between genres (t [df 1 204] = 2006 p = 0046) Systolic BP significant differences between companies (F[8191] = 10015 p lt 0001) Post hoc M1 vs B4 B6 and B7 (p le 0027) M2 vs B4 (p lt 0003) B1 and B2 vs B6 and B7 (p lt 0001) B3 vs B4 and B6 (p lt 0014) DaggerDiastolic BP significant differences between companies (F[8191] = 15799 p lt 0001) Post hoc M1 and B3 vs B4 B5 B6 and B7 (p le 0010) B1 vs B4 B7 B6 (p lt 0008) B2 vs B6 and B7 (p le 0001) partHRrest significant differences between companies (F[8192] = 6905 p lt 0001) Post hoc M1 vs B1 B6 and B7 (p lt 005) B3 vs B1 B6 B7 (p lt 0012) ∆HRpeak significant differences between companies (F[8192] = 15094 p lt 0001) Post hoc B4 vs M1 M2 B1 B2 B3 B6 B7 (p lt 0018) B5 vs M1 M2 B1 B6 B7 (p lt 0030) M1 B1 B3 B7 vs B6 (p lt 0003) sectHRrecov significant differences between companies (F[8192] = 6029 p = 0001) Post hoc M1 B1 B3 B4 B5 vs B6 (p lt 0035) B4 vs B7 (p lt 0019)

79Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

(p lt 0001) In post hoc analysis M1 systolic BP was lower than B4 B6 and B7 (p le 0027) M2 was lower than B4 (p lt 0003) B1 and B2 were lower than B6 and B7 (p lt 0001) and B3 was lower than B4 and B6 (p lt 0014) M1 and B3 diastolic BPs were lower than B4 B5 B6 and B7 (p le 0010) B1 was lower than B4 B7 and B6 (p lt 0008) and B2 was lower than B6 and B7 (p le 0001) There were also differences in sys-tolic BP between genders (p = 0016) Female systolic BP was lower than males (10767 versus 11268 mmHg) Smokers had higher systolic and diastolic BP than non-smokers (p lt 0001 for both variables) Between companies there were also differences in HRrest (p lt 0001) in post hoc analysis the resting HR of M1 and B3 were lower than B1 B6 and B7 (p lt 0012) There were no differences between genders in HRrest Peak HR was 135 plusmn 19 beatsmiddotmin-1

(subject range 76 to 181 Table 3) There were no differences due to genre but differences between com-panies were significant (p lt 0001) In post hoc analysis HRpeak in company B6 (154 plusmn 13 beatsmiddotmin-1) exceeded that of all other companies (p le 0003) HRpeak in companies B4 and B5 (111 plusmn 21 and 113 plusmn 13 beatsmiddotmin-1 respectively) were lower than the other companies (p le 0030) with the exception of B3 There were also HRpeak differences due to gender (p = 0001) females reached a higher HRpeak than males (140 plusmn 18 ver-sus131 plusmn 18 beatsmiddotmin-1)

Heart Rate Recovery and Fitness CategoriesHR recovery for all participants av-eraged 84 plusmn 15 beatsmiddotmin-1 (subject range 54 to 131 Table 3) There were differences due to genre with lower HRrecov (80 versus 85 beatsmiddotmin-1 p = 0046) and a higher percentage

categorized as ldquofitrdquo (92 versus 89 p = 0021) in modern dancers compared to ballet dancers There were differences in HRrecov related to company (p = 001) In post hoc analysis dancers in M1 B1 B3 B4 and B5 all had lower HRrecov than dancers in B6 (p le 0035) In addition B4 had lower HRrecov than B7 (p le 0019) There were no differences in HRrecov or fitness category related to gender There were also no differences in fitness related to work weeks per year number of performances per year or annual hours of exposure per dancer One hundred eighty-four of 206 dancers (89) were categorized as ldquofitrdquo (category 0 1 or 2 Table 4) Fifty-two percent of dancers were in fitness category 0 25 in category 1 and 11 in category 2 Approxi-mately 12 of dancers were in CR rec (cardio-respiratory training recom-mended) categories 3 4 5 or 6 The

Table 4 Number of Subjects () by Fitness CategoryFitness Category

Company Gender 0 1 2 3 4 5 6

M1 Female 12 (86) 2 (14)Male 9 (64) 3 (21) 1 (7) 1 (7)

M2 Female 4 (66) 1 (17) 1 (17)Male 2 (33) 3 (50) 1 (17)

B1 Female 12 (60) 5 (25) 2 (10) 1 (5)Male 7 (39) 6 (33) 4 (22) 1 (6)

B2 Female 1 (50) 1 (50)Male 2 (50) 1 (25) 1 (25)

B3 Female 4 (50) 3 (37) 1 (12)Male 5 (71) 1 (14) 1 (14)

B4 Female 10 (91) 1 (9)Male 8 (73) 3 (27)

B5 Female 6 (100)Male 1 (50) 1 (50)

B6 Female 3 (18) 3 (18) 5 (29) 2 (12) 2 (12) 1 (6)Male 3 (25) 3 (25) 3 (25) 2 (17) 1 (8)

B7 Female 11 (44) 10 (40) 2 (8) 2 (8)Male 8 (32) 6 (24) 4 (16) 2 (8) 4 (16) 1 (4)

Total Female 63 (58) 26 (24) 9 (8) 5 (5) 4 (4) 1 (1) 0Male 45 (46) 25 (24) 16 (16) 7 (7) 5 (5) 0 1 (1)

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

78 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

There were differences due to genre in systolic and diastolic BP and HRrest (p lt 0001) Modern dancers dem-

onstrated lower BP (10260 versus 11169 mmHg) and lower HRrest (67 versus 76 beatsmiddotmin-1) compared

to ballet dancers (Table 3) Between companies there were differences in systolic and diastolic BP

Table 3 Mean plusmn SD Blood Pressure and Heart Rate VariablesBP Resting HR Peak HR HR Recovery

Company Gender (mmHg) (beatsmiddotmin-1) (beatsmiddotmin-1) (beatsmiddotmin-1)

M1 Female 10070 68 plusmn 14 140 plusmn 11 78 plusmn 8Male 8250 66 plusmn 8 129 plusmn 17 77 plusmn 13Total 9957 67 plusmn 12 135 plusmn 15 77 plusmn 11

M2 Female 10368 70 plusmn 8 145 plusmn 9 86 plusmn 14Male 11465 65 plusmn 10 134 plusmn 14 83 plusmn 16Total 10867 65 plusmn 10 137 plusmn 13 85 plusmn 14

B1 Female 10259 82 plusmn 15 144 plusmn 15 84 plusmn 14Male 10367 79 plusmn 14 129 plusmn 10 83 plusmn 12Total 10263 81 plusmn 14 137 plusmn 15 83 plusmn 13

B2 Female 9662 76 plusmn 6 146 plusmn 14 82 plusmn 11Male 9557 81 plusmn 11 130 plusmn 8 82 plusmn 18Total 9559 80 plusmn 10 136 plusmn 12 82 plusmn 14

B3 Female 10255 66 plusmn 7 143 plusmn 12 88 plusmn 11Male 10960 62 plusmn 3 122 plusmn 7 74 plusmn 11Total 10657 64 plusmn 6 133 plusmn 15 82 plusmn 13

B4 Female 11774 68 plusmn 8 112 plusmn 21 74 plusmn 11Male 12581 77 plusmn 10 110 plusmn 23 76 plusmn 12Total 12177 72 plusmn 10 111 plusmn 21 75 plusmn 11

B5 Female 11572 66 plusmn 10 115 plusmn 13 71 plusmn 11Male 11172 68 plusmn 17 108 plusmn 17 72 plusmn 17Total 11472 67 plusmn 9 113 plusmn 13 71 plusmn 11

B6 Female 11677 82 plusmn 6 157 plusmn 11 102 plusmn 15Male 12876 76 plusmn 7 150 plusmn 14 90 plusmn 13Total 12176 79 plusmn 7 154 plusmn 13 97 plusmn 15

B7 Female 10670 74 plusmn 9 142 plusmn 12 87 plusmn 15Male 11471 78 plusmn 11 137 plusmn 16 89 plusmn 17Total 11070 76 plusmn 10 139 plusmn 14 88 plusmn 16

Modern 102a 60b 67 plusmn 1c 136 plusmn 14 80 plusmn 12d

Ballet 11169 76 plusmn 11 136 plusmn 20 85 plusmn 16Mean all companies Female 10667 74 plusmn 12 140 plusmn 18 85 plusmn 15

Male 11268 74 plusmn 12 131 plusmn 18 83 plusmn 15All 10967Dagger 74 plusmn 12part 135 plusmn 19∆ 84 plusmn 15sect

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies aSystolic BP significant differences between genres (t [df 1 204] = 3687 p = 0001) bDiastolic BP significant differences between genres (t [df 1 204] = 4720 p = 0001) cHRrest significant differences between genres (t [df 1 202 1] = 4141 p lt 0001) dHRrecov significant differences between genres (t [df 1 204] = 2006 p = 0046) Systolic BP significant differences between companies (F[8191] = 10015 p lt 0001) Post hoc M1 vs B4 B6 and B7 (p le 0027) M2 vs B4 (p lt 0003) B1 and B2 vs B6 and B7 (p lt 0001) B3 vs B4 and B6 (p lt 0014) DaggerDiastolic BP significant differences between companies (F[8191] = 15799 p lt 0001) Post hoc M1 and B3 vs B4 B5 B6 and B7 (p le 0010) B1 vs B4 B7 B6 (p lt 0008) B2 vs B6 and B7 (p le 0001) partHRrest significant differences between companies (F[8192] = 6905 p lt 0001) Post hoc M1 vs B1 B6 and B7 (p lt 005) B3 vs B1 B6 B7 (p lt 0012) ∆HRpeak significant differences between companies (F[8192] = 15094 p lt 0001) Post hoc B4 vs M1 M2 B1 B2 B3 B6 B7 (p lt 0018) B5 vs M1 M2 B1 B6 B7 (p lt 0030) M1 B1 B3 B7 vs B6 (p lt 0003) sectHRrecov significant differences between companies (F[8192] = 6029 p = 0001) Post hoc M1 B1 B3 B4 B5 vs B6 (p lt 0035) B4 vs B7 (p lt 0019)

79Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

(p lt 0001) In post hoc analysis M1 systolic BP was lower than B4 B6 and B7 (p le 0027) M2 was lower than B4 (p lt 0003) B1 and B2 were lower than B6 and B7 (p lt 0001) and B3 was lower than B4 and B6 (p lt 0014) M1 and B3 diastolic BPs were lower than B4 B5 B6 and B7 (p le 0010) B1 was lower than B4 B7 and B6 (p lt 0008) and B2 was lower than B6 and B7 (p le 0001) There were also differences in sys-tolic BP between genders (p = 0016) Female systolic BP was lower than males (10767 versus 11268 mmHg) Smokers had higher systolic and diastolic BP than non-smokers (p lt 0001 for both variables) Between companies there were also differences in HRrest (p lt 0001) in post hoc analysis the resting HR of M1 and B3 were lower than B1 B6 and B7 (p lt 0012) There were no differences between genders in HRrest Peak HR was 135 plusmn 19 beatsmiddotmin-1

(subject range 76 to 181 Table 3) There were no differences due to genre but differences between com-panies were significant (p lt 0001) In post hoc analysis HRpeak in company B6 (154 plusmn 13 beatsmiddotmin-1) exceeded that of all other companies (p le 0003) HRpeak in companies B4 and B5 (111 plusmn 21 and 113 plusmn 13 beatsmiddotmin-1 respectively) were lower than the other companies (p le 0030) with the exception of B3 There were also HRpeak differences due to gender (p = 0001) females reached a higher HRpeak than males (140 plusmn 18 ver-sus131 plusmn 18 beatsmiddotmin-1)

Heart Rate Recovery and Fitness CategoriesHR recovery for all participants av-eraged 84 plusmn 15 beatsmiddotmin-1 (subject range 54 to 131 Table 3) There were differences due to genre with lower HRrecov (80 versus 85 beatsmiddotmin-1 p = 0046) and a higher percentage

categorized as ldquofitrdquo (92 versus 89 p = 0021) in modern dancers compared to ballet dancers There were differences in HRrecov related to company (p = 001) In post hoc analysis dancers in M1 B1 B3 B4 and B5 all had lower HRrecov than dancers in B6 (p le 0035) In addition B4 had lower HRrecov than B7 (p le 0019) There were no differences in HRrecov or fitness category related to gender There were also no differences in fitness related to work weeks per year number of performances per year or annual hours of exposure per dancer One hundred eighty-four of 206 dancers (89) were categorized as ldquofitrdquo (category 0 1 or 2 Table 4) Fifty-two percent of dancers were in fitness category 0 25 in category 1 and 11 in category 2 Approxi-mately 12 of dancers were in CR rec (cardio-respiratory training recom-mended) categories 3 4 5 or 6 The

Table 4 Number of Subjects () by Fitness CategoryFitness Category

Company Gender 0 1 2 3 4 5 6

M1 Female 12 (86) 2 (14)Male 9 (64) 3 (21) 1 (7) 1 (7)

M2 Female 4 (66) 1 (17) 1 (17)Male 2 (33) 3 (50) 1 (17)

B1 Female 12 (60) 5 (25) 2 (10) 1 (5)Male 7 (39) 6 (33) 4 (22) 1 (6)

B2 Female 1 (50) 1 (50)Male 2 (50) 1 (25) 1 (25)

B3 Female 4 (50) 3 (37) 1 (12)Male 5 (71) 1 (14) 1 (14)

B4 Female 10 (91) 1 (9)Male 8 (73) 3 (27)

B5 Female 6 (100)Male 1 (50) 1 (50)

B6 Female 3 (18) 3 (18) 5 (29) 2 (12) 2 (12) 1 (6)Male 3 (25) 3 (25) 3 (25) 2 (17) 1 (8)

B7 Female 11 (44) 10 (40) 2 (8) 2 (8)Male 8 (32) 6 (24) 4 (16) 2 (8) 4 (16) 1 (4)

Total Female 63 (58) 26 (24) 9 (8) 5 (5) 4 (4) 1 (1) 0Male 45 (46) 25 (24) 16 (16) 7 (7) 5 (5) 0 1 (1)

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

79Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

(p lt 0001) In post hoc analysis M1 systolic BP was lower than B4 B6 and B7 (p le 0027) M2 was lower than B4 (p lt 0003) B1 and B2 were lower than B6 and B7 (p lt 0001) and B3 was lower than B4 and B6 (p lt 0014) M1 and B3 diastolic BPs were lower than B4 B5 B6 and B7 (p le 0010) B1 was lower than B4 B7 and B6 (p lt 0008) and B2 was lower than B6 and B7 (p le 0001) There were also differences in sys-tolic BP between genders (p = 0016) Female systolic BP was lower than males (10767 versus 11268 mmHg) Smokers had higher systolic and diastolic BP than non-smokers (p lt 0001 for both variables) Between companies there were also differences in HRrest (p lt 0001) in post hoc analysis the resting HR of M1 and B3 were lower than B1 B6 and B7 (p lt 0012) There were no differences between genders in HRrest Peak HR was 135 plusmn 19 beatsmiddotmin-1

(subject range 76 to 181 Table 3) There were no differences due to genre but differences between com-panies were significant (p lt 0001) In post hoc analysis HRpeak in company B6 (154 plusmn 13 beatsmiddotmin-1) exceeded that of all other companies (p le 0003) HRpeak in companies B4 and B5 (111 plusmn 21 and 113 plusmn 13 beatsmiddotmin-1 respectively) were lower than the other companies (p le 0030) with the exception of B3 There were also HRpeak differences due to gender (p = 0001) females reached a higher HRpeak than males (140 plusmn 18 ver-sus131 plusmn 18 beatsmiddotmin-1)

Heart Rate Recovery and Fitness CategoriesHR recovery for all participants av-eraged 84 plusmn 15 beatsmiddotmin-1 (subject range 54 to 131 Table 3) There were differences due to genre with lower HRrecov (80 versus 85 beatsmiddotmin-1 p = 0046) and a higher percentage

categorized as ldquofitrdquo (92 versus 89 p = 0021) in modern dancers compared to ballet dancers There were differences in HRrecov related to company (p = 001) In post hoc analysis dancers in M1 B1 B3 B4 and B5 all had lower HRrecov than dancers in B6 (p le 0035) In addition B4 had lower HRrecov than B7 (p le 0019) There were no differences in HRrecov or fitness category related to gender There were also no differences in fitness related to work weeks per year number of performances per year or annual hours of exposure per dancer One hundred eighty-four of 206 dancers (89) were categorized as ldquofitrdquo (category 0 1 or 2 Table 4) Fifty-two percent of dancers were in fitness category 0 25 in category 1 and 11 in category 2 Approxi-mately 12 of dancers were in CR rec (cardio-respiratory training recom-mended) categories 3 4 5 or 6 The

Table 4 Number of Subjects () by Fitness CategoryFitness Category

Company Gender 0 1 2 3 4 5 6

M1 Female 12 (86) 2 (14)Male 9 (64) 3 (21) 1 (7) 1 (7)

M2 Female 4 (66) 1 (17) 1 (17)Male 2 (33) 3 (50) 1 (17)

B1 Female 12 (60) 5 (25) 2 (10) 1 (5)Male 7 (39) 6 (33) 4 (22) 1 (6)

B2 Female 1 (50) 1 (50)Male 2 (50) 1 (25) 1 (25)

B3 Female 4 (50) 3 (37) 1 (12)Male 5 (71) 1 (14) 1 (14)

B4 Female 10 (91) 1 (9)Male 8 (73) 3 (27)

B5 Female 6 (100)Male 1 (50) 1 (50)

B6 Female 3 (18) 3 (18) 5 (29) 2 (12) 2 (12) 1 (6)Male 3 (25) 3 (25) 3 (25) 2 (17) 1 (8)

B7 Female 11 (44) 10 (40) 2 (8) 2 (8)Male 8 (32) 6 (24) 4 (16) 2 (8) 4 (16) 1 (4)

Total Female 63 (58) 26 (24) 9 (8) 5 (5) 4 (4) 1 (1) 0Male 45 (46) 25 (24) 16 (16) 7 (7) 5 (5) 0 1 (1)

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

80 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

highest fitness category rankings were held by B5 (categories 0 and 1) fol-lowed by M1 B1 and B3 (categories 0 1 and 2) and then M2 B2 and B3 (categories 0 to 3 Table 5) The lowest fitness category rankings were held by B4 B6 and B7 There were differences in fitness category related to genre (p = 021) Thirty-six out of 39 modern danc-ers (92) were categorized as ldquofitrdquo compared to 136 out of 167 ballet dancers (87) There were also dif-ferences due to company Company B6 reflected lower fitness levels than M1 M2 B1 B3 B4 and B5 (p le

0030) B7 reflected lower fitness lev-els than M1 B4 and B5 (p le0009) There was no effect of gender on the fitness categories of the participants However there were differences in fitness category due to cigarette smok-ing non-smokers were more fit than smokers (p le 0003) Pearson product moment cor-relations revealed moderate correla-tions between HRrest and HRrecov (r = 0624 p = 0001) and HRpeak and HRrecov (r = 0685 p = 0001 Fig 1) Spearmanrsquos rho correlations determined a moderate relationship between HRrest and fitness category

(r =0598 p = 0001) HRpeak and fitness category (r = 0591 p = 0001) and HRrecov and fitness category (r = 0889 p = 0001) but little correla-tion between subjectsrsquo resting BP and fitness category (systolic r = 0247 and 0255 ns) There were no correlations between number of contract weeks (r = -0091 ns) or number of per-formances (r = 0128 ns) and fitness category

DiscussionThis is the largest study to date to de-velop a profile comparing pre-season cardiorespiratory fitness in profes-sional modern and ballet dancers Modern dancers displayed higher age mass and BMI lower resting BP lower HRrest and higher percentages were categorized as ldquofitrdquo compared to ballet dancers Fourteen percent of all participating dancers smoked A greater number of ballet dancers reported smoking (18) compared to only 25 of modern dancers These numbers may reflect attempts at weight control due to the thin aesthetic required in ballet versus the aerobic demands found in some modern dance repertoire According to the Center for Disease Control and Prevention report for 2011 19 of adults in the USA over 18 years of age continue to smoke cigarettes27

Table 5 Mean plusmn SD Recovery Heart Rate (beatsmiddotmin-1) by Fitness Category

Fitness CategoryCompany 0 1 2 3 4 5 6

M1 73 plusmn 81 86 plusmn 55 94 plusmn 00 105 plusmn 00

M2 76 plusmn 88 86 plusmn 22 110 plusmn 35

B1 74 plusmn 77 89 plusmn 52 96 plusmn 52 112 plusmn 00 109 plusmn 00

B2 70 plusmn 42 90 plusmn 10 104 plusmn 00

B3 74 plusmn 69 88 plusmn 70 96 plusmn 00 111 plusmn 00

B4 71 plusmn 67 96 plusmn 00 95 plusmn 23

B5 69 plusmn 105 84 plusmn 00

B6 78 plusmn 48 87 plusmn 56 101 plusmn 43 105 plusmn 47 119 plusmn 61 131 plusmn 00

B7 71 plusmn 82 91 plusmn 54 97 plusmn 38 101 plusmn 07 109 plusmn 37 129 plusmn 00

Total 73 plusmn 78 89 plusmn 53 98 plusmn 45 107 plusmn 51 112 plusmn 89 131 plusmn 00 129 plusmn 00

Abbreviations M1-2 modern dance company 1-2 B1-B7 ballet company 1-7 M2 B2 B5 junior companies Note Female values were higher than males within any given recovery heart rate category

Figure 1 Relationship of heart rate (HR) recovery to peak HR

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

81Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

Although the number of ballet smok-ers was higher than modern smokers the lower percentage of all dancers who smoke compared to the national average suggests that smoking cessa-tion programs and increased emphasis on wellness in dance companies may be having a positive effect along with the increased athletic requirements of their occupation Nineteen percent of dancers reported having asthma None of the dancers with asthma said that they smoked This study also provides descriptive information about small and large sized companies and their respective dancers

Heart Rate as an Indicator of FitnessWhile VO2max is considered the cri-terion for measuring aerobic capacity and cardiorespiratory fitness HR has a positive relationship to energy expen-diture during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand28 How HR declines from either maximal or submaximal exercise to resting levels (HRrecov) is strongly correlated with VO2max29-32 More rapid HRrecov is found in trained athletes as it is fa-cilitated by enhanced oxygen uptake capacity30-32

A wide range of step tests has dem-onstrated high correlations ranging from 070 to 095 when comparing HRrecov to direct measurement of VO2max202333-44 Maximal or peak HR should demonstrate a similar relationship to HRrecov trained per-sons with lower HRrest and HRpeak should exhibit lower HRrecov By graphing the HRpeak to HRrecov re-lationship we demonstrated a similar linear relationship with a correlation of 0685 (Fig 1)

Genre and Company DifferencesModern dancers represented a higher percentage of ldquofitrdquo dancers compared to the ballet genre (92 and 87 respectively) This difference was significant even though ballet danc-ers outnumbered modern dancers by more than five to one In addition modern dancers displayed lower BP and lower HRrest another indicator

of aerobic training effect In contrast ballet dancers had lower BMI The sylphlike aesthetic of ballet encour-ages leanness whereas the athleticism of modern repertoire may require and permit a more athletic muscular aesthetic A review of direct measurement of VO2max in professional dancers sup-ports our findings of differences in car-diorespiratory fitness between modern and ballet dancers Researchers have reported a range of VO2max values of 39 to 53 and 46 to 59 mlmiddotkg-1middotmin-1 in female and male professional bal-let dancers respectively45-48 In con-trast VO2max values of 52 and 67 mlmiddotkg-1middotmin-1 were reported for female and male professional modern danc-ers25 indicating that female modern dancers exhibit values at the high end of those reported for female ballet dancers while male modern dancers exhibit higher values than their ballet counterparts When examining the results of dif-ferent companies one regional ballet company with relatively young danc-ers (B6) was noteworthy for lower fitness values eg higher BP HRrest HRpeak and HRrecov In this com-pany 29 of the dancers were in the ldquoCR recrdquo fitness category They had comparable hours per exposure per dancer to that of the other companies but fewer performances Alternatively one modern company (M1) with the oldest dancers and higher BMI dis-played low BP HRrest HRrecov and 96 of the dancers fell into the ldquofitrdquo categories This company also had the highest number of performances per year and touring weeks per year It has been suggested that much of the aerobic conditioning required during performance may actually occur during performance because technique classes and rehearsal alone do not provide a sufficient training effect49 This study cannot tease apart these relationships therefore further research is needed We hypothesized that the en-durance requirements necessary to perform modern repertory may be greater than those for ballet We anticipated that an aerobically chal-

lenging workload would favorably affect fitness levels in M1 and M2 While our hypothesis was supported by our results we speculate that the explanation for differences between companies is not as simple as the genre or time on task (eg work weeks per year and annual number of perfor-mances) Choreographic styles now cross genres with ballet companies performing ldquomodernrdquo dance reper-toire A recent example is the ballet ldquoGolden Sectionrdquo with aerobically demanding choreography by Twyla Tharp It has been performed by both modern and ballet companies Many dancers participate in cross training activities that emphasize aero-bic training as well B4 and B5 empha-size and reward dancer participation in cross training programs which was manifested in the lowest HRpeak and HRrecov and highest fitness category measured across companies They also perform an eclectic repertoire In con-trast B6 with no touring weeks and the lowest number of performances per year performed more traditional ballet choreography all of which may reflect these results A confounding factor is that participants did not report their off season physical activ-ity nor the amount of supplementary fitness training performed as part of their daily regimen Those who par-ticipated in additional dance or other athletic activities may have been better conditioned than those participating in little to no activity prior to the time of testing The companies studied covered a broad range of sizes Some ballet companies employ even larger num-bers of dancers (90 to100) which may dictate the number of performances or ballets in which dancers perform In large ballet companies corps dancers usually perform more frequently than principal dancers Conversely a recent analysis of mean exercise intensity during a rehearsal day reported that dancers in the corps de ballet spent most of their day at low workloads compared to soloists and princi-pals50 In such cases the number of hours danced per week may need to be assessed individually The largest

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

82 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

company in this study was B7 with 70 dancers Compared to most of the other companies they had relatively high HRrecov and low fitness category rankings These results may be reflec-tive of less actual time dancing Disparities in gender relative to cardiorespiratory fitness have been attributed to differences in blood volume heart size hemoglobin con-centrations and age-related changes in HR and stroke volume51-54 In this study only HRpeak but not HRrest or HRrecov differed between men and women The 0305 m height of the step used in testing may have been more challenging for women rela-tive to their height For this reason researchers have studied step tests that are height adjusted333839 However comparisons of height adjusted step tests with the standard test found little difference in correlations with VO2max For the sake of simplicity the DanceUSA screen uses a stan-dard step height To eliminate any effect due to gender data were also analyzed in terms of fitness category which normalizes for age and gender creating an equal basis for comparison of groups There were no differences between genders in either HRrecov or fitness categories

Aerobic FitnessThe Compendium of Physical Ac-tivities a coding scheme that classi-fies physical activity by rate of energy expenditure lists a broad range of metabolic equivalent (MET) intensity levels from 09 (sleeping) to 18 (run-ning)55 Ballet and modern dance are rated at 48 MET and considered to be moderate intensity activities55 In actuality energy requirements of bal-let or modern exercise vary through-out a technique class56-58 MET levels of 525 and 486 in males and females respectively during barre exercises and 752 and 573 during center floor exercises have been reported56 (Note 30 MET is sitting quietly greater than 60 MET is considered vigorous activity59) The consensus is that the static components of modern and ballet exercise during technique class with

the intermittent burst of sprint-like activity of center and across the floor dancing stimulate only modest aero-bic capacity This produces VO2max values within the range of other non-endurance athletes5760-63 A recent study of university and professional dancers found physiologic responses to modern dance class to be similar to those of classical ballet class58 There were significant differences between modern dance class and performance in VO2max HR and work The in-vestigators concluded that class does not physiologically provide sufficient cardiorespiratory stress to prepare dancers for performance The dif-ferences found between modern and ballet dancers in this profile support that conclusion and emphasize the importance of supplementary aerobic training A search of the literature revealed one study examining the relationship between aerobic fitness and incidence of self-reported dance injury in bal-let students64 Low levels of fitness determined by the use of a dance-specific aerobic fitness test revealed a positive correlation (r = 059) with an increased number of injuries over a 15-week period Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common vari-able cited by dancers6566 Greater cardiorespiratory fitness might serve to reduce the fatigue effect The rela-tionship between aerobic fitness and musculoskeletal injury has been well studied in the military6768 Prospec-tive studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury (relative risk 24 95 CI 192 to 305)67 A clear relationship remains to be demonstrated for dance

LimitationsIn this study we have categorized as ldquofitrdquo any dancer who met the HRrecov criteria of the accelerated step test That test has a relatively low inten-sity reflected by a mean HRpeak of 135 beatsmiddotmin-1 However it is being employed as a general pre-season test with the expectation that dancers

will be undergoing aerobic activity during the rehearsal period and in supplementary fitness training We did not analyze the interaction of time-off with fitness Due to the nature of performance bookings the number of layoffs and vacations can vary widely from year to year and from company to company and was beyond the scope of this study It is likely that dancers complete their performance season at a level of greater fitness than when they return to begin their next researsal period but this has yet to be demonstrated Furthermore we did not record or analyze the relationship of self-reported cross training with fitness Previous researchers did not find a relationship between self-reported supplemental training and peak VO248

Although our results report pre-season cardiorespiratory fitness in each dancer it should be noted that this estimate is relative to physical fit-ness criteria and does not indicate the participantrsquos level of skill-related fit-ness Skill-related fitness a subcom-ponent of physical fitness involves the ability to efficiently perform specific motor tasks based on agility coordination balance power speed and reaction time Previous studies have demonstrated that high levels of physical fitness do not correlate with skill-based fitness in other sports ac-tivities69 Interestingly a recent study reported that a supplementary fitness intervention in contemporary danc-ers resulted in improvement in both aerobic fitness and ldquoaesthetic compe-tencerdquo70 However aesthetic compe-tence is not necessarily the same as skill-based fitness Our results should not be considered a direct indicator of performance ability Instead these findings should be used to estimate a participantrsquos relative preparedness for skill performance as maximal oxygen consumption has been found to be a factor contributing to higher levels of skill-related fitness71

Resting HR has been reported in several studies on professional bal-let companies ranging from 46 to 70 beatsmiddotmin-1465662 The HRrest in

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

83Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

this study ranged from 43 to 109 beatsmiddotmin-1 While the mean HRrest in this study was 74 beatsmiddotmin-1 some of the higher values may have been due to dancer nervousness or insufficient quiet time to allow the HR to drop This may require further standardization in the future

ConclusionDifferences in pre-season cardiore-spiratory fitness levels exist between modern and ballet dancers Length of lay-off off-season exercise train-ing cross training during the em-ployment year or variations in the amount of required dancing (eg casting workweeks performances) may influence these differences Ad-ditionally specific repertoire may dif-fer with respect to aerobic challenge Step tests are a simple safe and efficient method for estimating cardiorespiratory fitness in large populations The accelerated step test used in this screen appears to accurately reflect cardiorespiratory fitness with sensitivity to discern dif-ferences across the sampled dancers Our results support the continued inclusion of this accelerated step test as part of a comprehensive physical fitness pre-season screen to identify dancers who could benefit from aero-bic conditioning to enhance overall performance preparedness as they enter their rehearsal period Dancers and company healthcare providers found the post-hire pre-season screening to be helpful in providing a review of past medical history making recommendations for training and providing refer-rals to other health professionals (nutritionists psychologists physi-cians etc) to address specific needs Dancers in fitness categories 3 to 6 (average to very poor) were advised that they could benefit from aerobic conditioning In the future dance medicine researchers will be able to glean additional information about specific dance companies as com-pared to the industry norm to make broader recommendations about health and fitness Further studies should investigate the relationship

of cardiorespiratory fitness to risk of injury

References1 Bronner S Ojofeitimi S Rose D

Injuries in a modern dance company effect of comprehensive manage-ment on injury incidence and time loss Am J Sports Med 2003 May-Jun31(3)365-73

2 Bronner S Ojofeitimi S Spriggs J Occupational musculoskeletal disorders in dancers Phys Ther Rev 2003857-68

3 Fuller M Peirce D Screening prac-tices in dance Applying the research Paper presented at Dance Dialogues Conversations across Cultures Art-forms and Practices Brisbane Aus-tralia 2008

4 Gamboa JM Roberts LA Maring J Fergus A Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics J Orthop Sports Phys Ther 2008 Mar38(3)126-36

5 Kadel N Southwick H Cole HH Update on the annual post-hire health screen for professional danc-ers DanceUSA Taskforce on Dancer Health Annual Dance USA Con-ference Chicago IL Dance USA 2011

6 Molnar M Esterson J Screen-ing students in a pre-professional ballet school J Dance Med Sci 19971118-21

7 Southwick H Cassella M Boston ballet student screening clinic an aid to injury prevention Orthop Phys Ther Pract 20021414-16

8 Southwick H Gibbs R Bronner S Cassella M Update on the annual post-hire health screen for profes-sional dancers DanceUSA Task-force on Dancer Health In Solomon R Solomon J (eds) Abstracts of the 18th Annual Meeting of the Interna-tional Association for Dance Medicine and Science 2008 Cleveland OH IADMS 2008 p 8

9 Wyon MA Twitchett E Angioi M et al Time motion and video analysis of classical ballet and contemporary dance performance Int J Sports Med 2011 Nov32(11)851-5

10 American College of Sports Medi-cine Health-related Physical Fitness Testing and Interpretation Guidelines for Exercise Testing and Perscription (7th ed) Philadelphia Lippincott

Williams amp Wilkins 2005 pp 55-92

11 Olson MS Williford HN Blessing DL et al A test to estimate VO2max in females using aerobic dance heart rate BMI and age J Sports Med Phys Fitness 1995 Sep35(3)159-68

12 Wyon M Redding E Abt G et al Development reliability and validity of a multistage dance specific aerobic fitness test (DAFT) J Dance Med Sci 2003780-4

13 Twitchett E Nevill A Angioi M et al Development validity and reliability of a ballet-specific aero-bic fitness test J Dance Med Sci 201115123-7

14 Redding E Weller P Ehrenberg S et al The development of a high intensity dance performance fitness test J Dance Med Sci 2009133-9

15 Kasch FW Phillips WH Ross WD et al A comparison of maximal oxy-gen uptake by treadmill and step-test procedures J Appl Physiol 1966 Jul21(4)1387-8

16 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

17 Siconolfi SF Garber CE Lasater TM Carleton RA A simple valid step test for estimating maximal oxygen uptake in epidemiologic studies Am J Epidemiol 1985 March121(3)382-90

18 Zwiren LD Freedson PS Ward A et al Estimation of VO2max a comparative analysis of five exer-cise tests Res Q Exerc Sport 1991 Mar62(1)73-8

19 Mazic S Zivotic-Vanovic M Igracki I et al A simple and reliable step-test for indirect evaluation of aerobic capacity Med Pregl 2001 Nov-Dec54(11-12)522-9

20 Latin RW Berg K Kissinger K et al The accuracy of the ACSM stair-stepping equation Med Sci Sports Exerc 2001 Oct33(10)1785-8

21 Liu C-M Lin K-F Estimation of VO2max a comparative analysis of post-exercise heart rate and physical fitness index from a 3-min step test J Exerc Sci Fit 20075118-23

22 Santo AS Golding LA Predicting maximum oxygen uptake from a modified 3-minute step test Res Q

84 Volume 18 Number 2 2014 bull Journal of Dance Medicine amp Science

Exerc Sport 2003 Mar74(1)110-15

23 Shapiro A Shapiro Y Magazanik A A simple step test to predict aerobic capacity J Sports Med Phys Fitness 1976 Sep16(3)209-14

24 Watkins J Step tests of cardiorespira-tory fitness suitable for mass testing Br J Sports Med 1984 Jun18(2)84-9

25 Bronner S Rakov S An accelerated step test to assess dancer pre-season aerobic fitness J Dance Med Sci 2014(18)112-28

26 Golding L Myers C Sinning WE The YMCA Physical Fitness Test Bat-tery Yrsquos Way to Physical Fitness (4th ed) Champaign IL Human Kinet-ics 1989 pp 61-138

27 Schiller JS Lucas JW Peregory JA Summary Health Statistics for US Adults National Health Interview Survey Vital Health Stat 10 2012 Jan(252)1-207 PubMed PMID 22834228

28 Strath SJ Swartz AM Bassett DR Jr et al Evaluation of heart rate as a method for assessing moder-ate intensity physical activity Med Sci Sports Exerc 2000 Sep32(9 Suppl)S465-70

29 Hagberg JM Hickson RC Ehsani AA Holloszy JO Faster adjustment to and recovery from submaximal exercise in the trained state J Appl Physiol Respir Environ Exerc Physi-ol 1980 Feb48(2)218-24

30 Darr KC Bassett DR Morgan BJ Thomas DP Effects of age and train-ing status on heart rate recovery after peak exercise Am J Physiol 1988 Feb254(2 Pt 2)H340-3

31 Du N Bai S Oguri K et al Heart rate recovery after exercise and neural regulation of heart rate variability in 30-40 year old female marathon runners J Sports Sci Med 2005 Mar 14(1)9-17

32 Short KR Sedlock DA Excess postexercise oxygen consumption and recovery rate in trained and untrained subjects J Appl Physiol (1985) 1997 Jul83(1)153-9

33 Ashley CD Smith JF Reneau PD A modified step test based on a func-tion of subjectsrsquo stature Percept Mot Skills 1997 Dec85(3 Pt 1)987-93

34 Astrand PO Measurement of maxi-mal aerobic capacity Can Med Assoc J 1967 Mar96(12)732-5

35 Astrand PO Ryhming I A nomo-gram for calculation of aerobic capac-

ity (physical fitness) from pulse rate during sub-maximal work J Appl Physiol 1954 Sep7(2)218-21

36 Brouha L The step test a simple method of measuring physical fitness for muscular work in young men Res Q 19431431-6

37 Culpepper MI Francis KT An anatomical model to determine step height in step testing for estimating aerobic capacity J Theor Biol 1987 Nov 7129(1)1-8

38 Francis K Brasher J A height-adjusted step test for predicting maximal oxygen consumption in males J Sports Med Phys Fitness 1992 Sep32(3)282-7

39 Francis K Cuipepper M Validation of a three minute height-adjusted step test J Sports Med Phys Fitness 1988 Sep28(3)229-33

40 Goldberg DI Shephard RJ Stroke volume during recovery from up-right bicycle exercise J Appl Physiol Respir Environ Exerc Physiol 1980 May48(5)833-7

41 Hui SS Cheung PP Comparison of the effect of three stepping cadences on the criterion-related validity of a step test in Chinese children Meas Phys Educ Exerc Sci 20048(3)167-79

42 McArdle WD Katch FI Pechar GS et al Reliability and inter-relationships between maximal oxygen intake physical work capac-ity and step-test scores in college women Med Sci Sports 1972 Winter4(4)182-6

43 Sykes K Roberts A The Chester step test - a simple yet efffective tool for prediction of aerobic capacity Physiotherapy 200490183-8

44 Tuxworth W Shahnawaz H The design and evaluation of a step test for the rapid prediction of physical work capacity in an unsophisticated industrial work force Ergonomics 1977 Mar20(2)181-91

45 Cohen JL Segal KR Witriol I McArdle WD Cardiorespiratory responses to ballet exercise and the VO2max of elite ballet dancers Med Sci Sports Exerc 198114(3)212-17

46 Micheli LJ Gillespie WJ Walaszek A Physiologic profiles of female professional ballerinas Clin Sports Med 1984 Jan3(1)199-209

47 Schantz P Astrand P Physiolog-ic characteristics of classical bal-let Med Sci Sports Exerc 1984 Oct16(5)472-6

48 Wyon MA Deighan MA Nevill AM et al The cardiorespiratory anthro-pometric and performance charac-teristics of an internationalnational touring ballet company J Strength Cond Res 2007 May21(2)389-93

49 Wyon MA Abt G Redding E et al Oxygen uptake during modern dance class rehearsal and perfor-mance J Strength Cond Res 2004 Aug18(3)646-9

50 Twitchett E Angioi M Koutedakis Y Wyon M The demands of a work-ing day among female professional ballet dancers J Dance Med Sci 201014(4)127-32

51 Cureton KJ Sparling PB Distance running performance and metabolic responses to running in men and women with excess weight experi-mentally equated Med Sci Sports Exerc 198012(4)288-94

52 Evans WJ Winsmann FR Pandolf KB Goldman RF Self-paced hard work comparing men and women Ergonomics 1980 Jul23(7)613-21

53 Freedson P Katch VL Sady S Welt-man A Cardiac output differences in males and females during mild cycle ergometer exercise Med Sci Sports 1979 Spring11(1)16-19

54 Lewis DA Kamon E Hodgson JL Physiological differences between genders Implications for sports conditioning Sports Med 1986 Sep-Oct3(5)357-69

55 Ainsworth BE Haskell WL Whitt MC et al Compendium of physi-cal activities an update of activity codes and MET intensities Med Sci Sports Exerc 2000 Sep32(9 Suppl)S498-504

56 Cohen JL Segal KR McArdle WD Heart rate response to ballet stage performance Phys Sportsmed 198210120-33

57 Schantz P Astrand P Physiolog-ic characteristics of classical bal-let Med Sci Sports Exerc 1984 Oct16(5)472-6

58 Wyon MA Head A Sharp NC Redding E The cardiorespiratory responses to modern dance classes Differences between university graduate and professional classes J Dance Med Sci 2002641-5

59 Ainsworth BE Haskell WL Her-rmann SD et al 2011 Compendium of physical activities a second update of codes and MET values Med Sci Sports Exerc 2011 Aug43(8)1575-81

85Journal of Dance Medicine amp Science bull Volume 18 Number 2 2014

60 Cohen JL Segal KR Witriol I McArdle WD Cardiorespiratory responses to ballet exercise and the VO2max of elite ballet dancers Med Sci Sports Exerc 198114(3)212-17

61 Dahlstroumlm M Physical effort dur-ing dance training A comparison between teachers and students J Dance Med Sci 19971(4)143-8

62 Mostardi RA Porterfield JA Green-berg B et al Musculoskeletal and cardiopulmonary characteristics of the professional ballet dancer Phys Sports Med 19831153-61

63 Novak LP Magill LA Schutte JE Maximal oxygen intake and body composition of female dancers Eur J Appl Physiol Occup Physiol 1978 Oct 2039(4)277-82

64 Twitchett E Brodrick A Nevill

AM et al Does physical fitness affect injury occurrence and time loss due to injury in elite vocational ballet students J Dance Med Sci 201014(1)26-31

65 Liederbach M Compagno J Physi-ological aspects of fatigue-related injuries in dancers J Dance Med Sci 20015(4)116-20

66 Laws H Fit to Dance 2mdashReport of The Second National Inquiry Into Dancersrsquo Health and Injury in the UK London UK 2005

67 Bell NS Mangione TW Hemenway D et al High injury rates among female army trainees a function of gender [Dissertation] Natick MA Army Research Inst of Environ-mental Medicine Harvard School of Public Health 1994

68 Knapik J Ang P Reynolds K Jones B Physical fitness age and injury incidence in infantry soldiers J Oc-cup Med 1993 Jun35(6)598-603

69 Gabbett T Kelly J Pezet T Rela-tionship between physical fitness and playing ability in rugby league players J Strength Cond Res 2007 Nov21(4)1126-33

70 Angioi M Metsios GS Twitchett EA et al Effects of supplemental training on fitness and aesthetic com-petence parameters in contemporary dance Med Probl Perform Art 2012 Mar27(1)3-8

71 Riezebos ML Paterson DH Hall CR Yuhasz MS Relationship of selected variables to performance in womenrsquos basketball Can J Appl Sport Sci 1983 Mar8(1)34-40