Experimental Gerontology 53 (2014) 1–6

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Experimental Gerontology

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Short report

Muscle quality index improves with resistance exercise training inolder adults

Maren S. Fragala ⁎, David H. Fukuda, Jeffrey R. Stout, Jeremy R. Townsend, Nadia S. Emerson, Carleigh H. Boone,Kyle S. Beyer, Leonardo P. Oliveira, Jay R. HoffmanInstitute of Exercise Physiology and Wellness, University of Central Florida, Orlando, FL, USA

Abbreviations: AED, Automatic external defibrillatoCardio-pulmonary resuscitation; DEXA, Dual energyIntra-class correlation coefficients; LBM, Lean body maSTS, Sit to stand; SEM, Standard error ofmeasurement; SW⁎ Corresponding author at: Sport and Exercise Scienc

4000 Central Florida Blvd, Orlando, FL 32816, USA. Tel.: +E-mail address: Maren.fragala@ucf.edu (M.S. Fragala).

0531-5565/$ – see front matter © 2014 Elsevier Inc. All rihttp://dx.doi.org/10.1016/j.exger.2014.01.027

a b s t r a c t

a r t i c l e i n f o

Article history:

Received 21 October 2013Received in revised form 2 January 2014Accepted 29 January 2014Available online 6 February 2014

Section Editor: Christiaan Leeuwenburgh

Keywords:SarcopeniaPowerInterventionAgingElderlyStrengthResistance training

Introduction: Sarcopenia is currently best described as an age-related decline in skeletal muscle mass andfunction. However, no consensus exists as to how to best quantify muscle function in older adults. The musclequality index (MQI) was recently recommended as an ideal evidence-based assessment of functional status inolder adults. Nevertheless, the usefulness of MQI to assess physical function is limited by whether it is reflectiveof muscle qualitative changes to an intervention. Thus, the purpose of this investigation was to determinewhetherMQI changes in response to resistance exercise training and detraining andhow such changes correspondto other recommended measures of physical function proposed by suggested definitions of sarcopenia.Methods: Twenty-five older adults (70.6 ± 6.1 y; BMI = 28.1 ± 5.4 kg · m−2) completed a 6-week resistancetraining program in a wait-list controlled, cross-over design. MQI was determined as power output from timedsit to stand (STS), body mass, and leg length. Gait speed, hand grip strength, get-up-and-go and lean body mass(LBM) were evaluated before and after exercise training and detraining. MQI and functional changes to traininganddetrainingwere evaluatedwith repeatedmeasures ANOVA and clinical interpretations ofmagnitude based in-ferences.Results: Short term resistance training significantly and clinically improved MQI (203.4 ± 64.31 to 244.3 ±82.92W), gait time (1.85±0.36 to 1.66±0.27 s) and sit to stand performance (13.21±2.51 to 11.05 ± 1.58 s).

Changes in LBM and hand grip strength were not significant or clinically meaningful. De-training for 6-weeks did not result in significant changes in any measure from post-training performance.

© 2014 Elsevier Inc. All rights reserved.

1. Introduction

Sarcopenia, the age-related loss in skeletal muscle mass is closelyrelated tomobility and functional impairments commonwith advancedage (Fiatarone et al., 1994; Foldvari et al., 2000; Janssen, 2006).The rel-ative importance of muscle function for sarcopenic outcomes has led tomore recent approaches to define sarcopenia incorporating musclefunction into the diagnostic criteria (Cruz-Jentoft et al., 2010; Lauretaniet al., 2003). However, the ability to diagnose sarcopenia and developmeaningful treatments has been complicated by the complexities ofmuscle function and differing rates of age-related changes. In particular,the rate that muscle strength declines is faster than the rate that musclemass declines (Goodpaster et al., 2006). Similarly, the rate at whichmuscle power declines is even more rapid than the concomitant lossof muscle strength and mass (Frontera et al., 1991; Goodpaster et al.,

r; BMI, Body mass index; CPR,X-ray absorptiometry; ICC,

ss; MQI, Muscle quality index;C, Smallestworthwhile change.e, University of Central Florida,1 407 823 3877.

ghts reserved.

2006; Hakkinen et al., 1996). Such temporal discrepancies reveal moreintricate musculoskeletal changes associated with sarcopenia andaging than simply a loss of muscle tissue. Such changes are likely attrib-uted to the quality of the muscle tissue (Goodpaster et al., 2001).

Skeletal muscle quality has been described in many ways rangingfrom muscle composition and density to muscle function per musclemass to muscle's metabolic processes (Barbat-Artigas et al., 2012).Muscle quality is often assessed indirectly as a relative performanceindicator defined as muscle strength per muscle mass (Moritani anddeVries, 1979). When defined in this way, muscle quality declines areassociated with advanced age (Lindle et al., 1997; Lynch et al., 1999).While aging attenuates muscle's hypertrophic responses to resistancetraining (Welle et al., 1996), it does not appear to impair muscle qualityadaptations to resistance exercise in older adults (Welle et al., 1996).Hence, muscle quality may present a meaningful, informative, and sen-sitive target to monitor sarcopenia status and treatment efficacy,beyond routinemeasures of muscle mass. In particular, a simplemusclequalitative assessment that can be conducted feasibly during routineclinical examinations may have the broadest impact for assessmentand evaluation. Functional measures, by way of muscle quality estima-tion, may allow for clinicians to account for the interaction betweendeclining muscularity and intramuscular fat infiltration which may be

2 M.S. Fragala et al. / Experimental Gerontology 53 (2014) 1–6

misinterpreted or neglected for by standard sarcopenic evaluationinvolving only muscle mass in aging adults.

Recently, Barbat-Artigas et al. (2012) reviewed and recommendedthe muscle quality index (MQI) as a “clinical screening tool to detectindividuals at risk of physical incapacities based on muscle quality.”The MQI calculates muscle power from anthropometric measures(e.g. leg length and body mass) and timed chair rises (Takai et al.,2009). The MQI assessment is particularly informative in comparisonto othermeasures because it evaluates specific lower extremity functionthat is related to ambulation, as opposed to non-muscle group specificmeasures of handgrip strength. In addition, the MQI is a more completeindex of muscle quality than relative strength since it incorporates thevelocity at which muscle shortens (i.e. muscle power), which is reflec-tive of the neuromuscular component. Furthermore, the assessment isclinically relevant, since it is calculated from the common sit to standtest. Utilizing the familiar timed sit to stand test, the assessment isappropriate for older personswhomay have physical limitations, safetyconcerns and/or sarcopenia. Moreover, prior research has shown thatthe ability to rise from a chair is related to functional independence inolder adults (Corrigan and Bohannon, 2001). MQI can be distinguishedfrom the common sit to stand test as, as it incorporates anthropometricmeasures of body mass and leg length to which have previously beenshown to alter the relationship between chair rise performance andleg strength (Takai et al., 2009). TheMQI has been shown to be stronglycorrelated to the cross-sectional area of the knee extensors (r= 0.801)and force of the knee extensors (r= 0.730) in older adults, while timedsit to stand was not (Takai et al., 2009).

While theMQI has been recommended as the “best clinical measureto assess muscle power” (Barbat-Artigas et al., 2012), no proposeddefinitions of sarcopenia have incorporated the potentially more sensi-tivemuscle quality measure of muscle power into the proposed criteria.For muscle quality to become an appropriate target of treatment strate-gies for sarcopenia, we need to generate a better understanding of theadaptability of aspects of muscle quality at the clinical level. Hence,the purpose of the present investigation was to examine if and howMQI changes in response to a resistance training and detrainingintervention in older adults and how such changes compare to othermeasures of physical function commonly measured in older adults.

2. Materials and methods

2.1. Experimental approach to the problem

To determine the effects of resistance training and detraining onmuscle quality index (MQI), older adult volunteers completed twophases of the experimental protocol, both of which included a 6-weekresistance training program, in a wait-list controlled, cross-over design(Fig. 1). Volunteers were randomized into exercise group 1 or exercisegroup 2. Exercise group 1 completed 6-weeks of resistance training inPhase 1 and 6-weeks of detraining (no resistance training) in Phase 2.Exercise group 2 completed a 6-week control period of no resistance

Fig. 1. Study

exercise intervention where they were instructed to maintain theirnormal daily activities in Phase 1 followed by 6-weeks of resistanceexercise training in Phase 2. All participants were tested at 3 time pointsseparated by 6-weeks of resistance exercise training either proceededby detraining (Phase 1) or preceded by a control condition (Phase 2).MQI and functional measures were determined before and after Phase1 and Phase 2 at weeks 0, 6, and 12. Reliability intra-class correlationcoefficients (ICC) and standard error of measurements (SEM) werecomputed from 11 participants in the control group.

2.2. Participants

Twenty-five older adults volunteered for the study (70.5 ± 6.2 y;168.4 ± 9.4 cm; 81.4 ± 19.0 kg). Participants were recruited from avariety of sources including word of mouth, flyers, and informationalpresentations. Participants were required to be over age 60 y and phys-ically cleared for exercise participation according to a health historyquestionnaire or physicians clearance. Physician clearancewas requiredfor any participant over age 70 y or any potentially positive risk factoras indicated on the medical history questionnaire. Individuals classifiedas “high risk” for exercise by having a cardiovascular, pulmonary, ormetabolic disease, or one or more cardiovascular signs and symptomswere excluded from participation. Participants were randomly assignedto either group 1 (n = 13) or group 2 (n = 12). Participants wererecruited so that an equal number of men and womenwas randomizedto each group. During both phases of the protocol, all participants wereinstructed to follow their normal diets. Two women completed pre-testing but did not complete all time points due to personal reasonsnot associated with the study. One man chose not to complete theweek 12 DEXA test. Thus, 23 individuals were included in the final anal-ysis, with n = 22 for the body composition analysis. Participants wereinformed of study procedures, and provided written informed consentprior to enrolling in the study. All study procedures were reviewedand approved by the Institutional Review Board for the Protection ofHuman Subjects at the University of Central Florida.

2.3. Measures

2.3.1. AnthropometricsBody mass and stature were measured following standardized

anthropometric protocols on a digital scale and anupright standiometerduring each testing occasion. Body mass index was calculated fromthese measures as kg · m−2.

2.3.2. Dual-energy X-ray absorptiometryTotal body composition was evaluated using dual energy X-ray

absorptiometry (DEXA) technologies obtained on a whole body scan.All DEXA scans were ordered by a licensed physician in the state ofFlorida and were performed in the Body Composition Laboratory bya technician licensed in the state of Florida.

design.

Fig. 2.Magnitude based inferences for improvement or reduction in functional measures.Data are reported as [mean (post-pre) ± 90% confidence limits].The smallest worthwhilechange (SWC) trivial zone was set at 20% of the pre-training standard deviation for eachvariable. For figure clarity, changes were represented as a factor of the SWC in orderto compare values of differing units and determined by dividing the mean and 90%confidence intervals of each variable by its corresponding SWC value. LBM = Lean bodymass, GUG=Get-up and go, Gait= Gait time, Grip=Hand grip strength, MQI=Musclequality index.

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2.3.3. Hand grip strengthHand-grip strength was measured in kilograms (kg) as maximal

isometric force achieved on a hand grip dynamometer (JAMAR 5030J1)(ICC3,1 = 0.959, SEM= 3.1 kg). This test was administered with partic-ipants sitting square in a standard chair with feet flat on thefloor and theelbow bent at 90°. The dynamometer was placed in the hand and adjust-ed so the palm side of the grip was at the palm and the front end waslined up between the joints of the medial and distal phalanges. Thegrip size was adjusted so that the second metacarpals were flat witha 90° bend at the knuckles. Participants were asked to squeeze thestrength gauge as hard as possible for 3–5 s. Three trials on each handwere performed with 30-s of rest given between trials. The maximumvalue attained from any trial was used in subsequent analysis.

2.3.4. Gait timeGait time was recorded as the time in seconds required to walk an

8-ft course at normalwalking gait speed (ICC3,1 = 0.689, SEM=0.19 s).Participants were allowed to use any usual walking aids. Spotterswalked along the side of the older volunteer's during the test to ensuresafety if balance was in question. Time was recorded with the BrowerTiming Systems (Draper, Utah) laser timing device. Time began whenthe volunteer began tomove and lift a foot off of the sensor and stoppedwhen one foot (completely) crosses the end line (8-ft mark). Two trialswere completed. The average of the two trials was used in subsequentanalysis.

2.3.5. Get-up & GoThe Get-up & Go test measured the time taken in seconds for

participants to stand from a seated position in a chair, walk 3 m,turn, return to the chair and sit (ICC3,1 = 0.783, SEM= 0.42 s). Duringthis test participants were not allowed to use their arms to push off ofthe chair or for support during the test. Spotters were in place to ensurethat older participants could safely complete the test.

2.3.6. Timed sit to standTime to complete five consecutive full chair rises from a seated

position in a standard armless chair was measured in seconds(ICC3,1 = 0.723, SEM = 1 s). Participants were instructed to standas fast as possible from a sitting position in a chair five times consecu-tively with the arms folded across the chest so that they could not assistwith the movement. Spotters were in place to ensure that participantswere not at risk of falling and the testing chair was secured againsta plyometric block to ensure that it remained secured throughoutthe test.

2.3.7. Muscle quality indexMuscle quality index (MQI) was measured according to methods

devised by Takai et al. (Takai et al., 2009) (ICC3,1 = 0.907, SEM =21.91 W). MQI uses timed sit to stand, individual body mass, andleg length to calculate a power index reported in watts (W). Accordingto the following equation (Takai et al., 2009):

MQI ¼ leg length x 0:4ð Þ � body mass� gravity� 10ð Þ=Time sit‐stand

where leg lengthwas defined as the distance (inmeters) from the greattrochanter of the femur to themalleolus lateralis as determined from thefull body scan on scan on theDEXA. The coefficient of 0.4 (m) representsthe height of the standard chair used for the chair rise test, the forceof gravity was represented by 9.81 m s−2, and 10 represents a con-stant from the original equation (Takai et al., 2009). The validityand reliability of the MQI measure have been previously reported(Takai et al., 2009).

2.3.8. Strength training protocolBefore beginning the resistance training program, all participants

completed two familiarization sessions where proper form and tech-nique of each exercise were learned and the starting load resistancefor each exercise was assigned. Training intensity was set to a loadcorresponding to perceived moderate intensity. The OMNI scale ofperceived exertion was used to assess perceived difficulty (0 = sittingor no exertion to 10 = all-out effort). The program consisted of twoworkouts per week with sessions lasting 1 to 1 ½ h. Each workoutwas separated by at least 48 h to allow for adequate recovery. The train-ing program consisted of an individualized, periodized, full-bodyprogram including exercises of varying progressions of all of themajor muscle groups. Exercises included machine-based exercises(leg extensions, leg curls, seated rows, and lat pull-downs), bodyweightexercises (squats, split squats, abdominals, calf raises, and modifiedstiff-legged dead-lifts) and free weight exercises (biceps curls, chestpresses, shoulder presses, triceps extensions and progressions forbody weight exercises). Acute program variables varied progressivelythroughout the 6-weeks, but generally consisted of three (3) sets of 8to 15 repetitions of 7 to 8 exercises at moderate intensity (perceivedexertion of 5–6 on a 10 point scale). Resistance was adjusted to allowfor the completion of the designated repetition range and to ensurethat participants were challenged to the specified perceived exertionrating. Each workout session began with a standardized dynamicwarm-up consisting of body weight squats, high knee walking, andlimb rotations and terminatedwith an appropriate cool down. The exer-cise program followed the recommended guidelines for older adults bythe American College of Sports Medicine and the National Strengthand Conditioning Association and was supervised by National Strengthand Conditioning Association's Certified Strength and ConditioningSpecialists, who were also certified in cardio-pulmonary resuscitation(CPR) and automatic external defibrillation (AED).

2.3.9. Control period protocolDuring the 6-week control (Phase 1) or detraining period (Phase 2),

participants completed all testing procedures and were instructed tomaintain their normal level of daily physical activity throughout thestudy period. Participants assigned to exercise group 2 were told thatthey were on the “wait-list” for the exercise program and were able toenroll in the exercise program following mid-testing.

2.4. Analysis

Data were analyzed using separate repeated measures ANOVA toevaluate dependent variable changes by intervention and group forPhase 1 and Phase 2. In the event of a significant F score, a post-hocpaired t-test was used to determine pairwise differences. Independentsample t-tests were run to evaluate baseline differences between the

4 M.S. Fragala et al. / Experimental Gerontology 53 (2014) 1–6

groups. In order to compare the relative changes of each functionaloutcome, the combined values of the training periods for each group(n=23) were evaluated using a magnitude-based inference approach.Changes in functional measures were analyzed using magnitude basedinferences, calculated from 90% confidence intervals, as previously de-scribed (Hopkins et al., 2009). Change scores reflecting improvementor reduction in functionality were analyzed using the p value fromdependent t-tests to determine a mechanistic inference. Qualitativeinferences were based upon the chances that the true magnitude ofthe effect at post-training was substantially improved or reduced com-pared to pre-training values, and was assessed as: b1% almost certainlyreduced, 1–5% very likely reduced, 5–25% likely reduced, 25–75% possi-bly improved, 75–95% likely improved, 95–99% very likely improvedand N99% almost certainly improved. If there was a greater than 5%chance that the true value was both improved and reduced, the effectwas considered mechanistically unclear. The smallest non-trivialchange, or smallest worthwhile change, was set at 20% of the pre-training standard deviation. Significance for this study was set a prioriat p ≤ 0.10. A significance of p ≤ 0.10 was elected to reduce the likeli-hood of accepting the null hypothesis and missing detection of animportant change in this first study to explore changes in MQI. Dataare presented as mean ± SD unless otherwise stated.

3. Results

The baseline descriptive characteristics and physical function mea-sures of the study participants are shown in Tables 1 and 2, respectively.Groups were similar in age, anthropometrics and physical function atbaseline, with the exception of get-up and go time where Group 2 wasfaster (p = 0.042).

3.1. Phase 1 (training vs. control)

Significant interactions between exercise training and controlwere observed for MQI (p = 0.062), gait speed (p = 0.035), and sitto stand time (p = 0.042) (Table 2). MQI increased by 22% (199.06to 242.88 W), gait speed improved by 15% (1.92 to 1.64 s), and sitto stand time improved by 18% (14.19 to 11.57 s) from pre to post-testing after 6-weeks of resistance exercise in group 1. No inter-vention by time interactions were observed for hand grip strength,get up and go or LBM in phase 1 (p N 0.10). No significant changesin functional measures were observed in the control group (group2) during phase 1.

3.2. Phase 2 (training vs. de training)

Significant interactions between training and de-training were ob-served for MQI (p = 0.001), sit to stand (p = 0.000), and gait speed(p = 0.076) in phase 2. MQI increased by 18% (208.18 to 244.99 W),sit to stand time improved by 14% (12.14 to 10.48 s), and gaitspeed improved by 5% (1.77 to 1.68 s) from pre to post-testingafter 6-weeks of resistance exercise in group 2. No intervention bytime interactions were observed for hand grip strength, get up andgo or LBM in phase 2 (p N 0.10). Post-hoc pairwise comparisons re-vealed that six weeks of detraining did not result in significant losses(p N 0.10) in improvements that were attained during the training

Table 1Baseline descriptive characteristics of study participants.

Group 1 (N = 12) Group 2 (N = 11)

Age (y) 70.8 ± 6.8 69.6 ± 5.5Women:Men W = 4; M = 8 W = 6; M = 5Body mass (kg) 84.5 ± 20.8 78.5 ± 17.9Height (m) 1.71 ± 0.11 1.67 ± 0.08BMI (kg · m−2) 28.6 ± 5.5 28.2 ± 5.4Body fat (%) 36.2 ± 9.2 35.2 ± 9.5

regimen (Table 2). Performance measures changed by 1.0 to 4.8%between post-training (week 6) and detraining (week 12) in group 1.

3.3. Clinical changes in functional measures

Magnitude-based inference analyses of changes in functional mea-sures for the combined training groups (n = 23) are presented inFig. 2 and Table 3. Clinical interpretations based on smallestworthwhilechange limits reveal that MQI and STS “most likely improved” and GUGand gait speed, “very likely improved,”while changes in LBM and handgrip strength were “unclear” or “trivial” in response to resistance exer-cise training. The likelihood of improvement in MQI and STS was N99%and GUG and gait speed was N95%. Changes in grip strength and LBMwere primarily trivial (74.9 to 79.9%).

4. Discussion

In order to provide evidence-based support for the previously rec-ommended muscle quality index, we primarily sought to determinewhether MQI changes in response to resistance exercise trainingand detraining. Secondarily, we sought to determine how changes inMQI compared to other recommended measures of physical function(sit to stand, gait speed, and grip strength) and muscularity (leanbody mass) suggested by the proposed definitions of sarcopenia. Ourresults show that MQI increases with resistance exercise training inolder adults to a greater magnitude and presents higher reliabilitythan other functional measures. Additionally, improvements weremaintained during the detraining period. These findings may havefuture clinical implications for quantifying muscle function as asymptom of sarcopenia during routine physical examinations.

Our main results show that muscle quality index (MQI), a clinicalassessment of physical function, increases with 6-weeks of resistanceexercise in older adults. This is the first investigation to our knowledgeto evaluate change in MQI to any intervention. As MQI measures theforce generating capacity of the knee extensor muscles (Takai et al.,2009), we had expected to see improvements as a result of the trainingprogram. The muscle groups responsible for leg extension were trainedwith modified squat, split squat, and machine leg extension exercisesduring the full body progressive exercise training regimen. As we previ-ously reported, laboratory-based measures of leg extension strengthand relative strength significantly increased 32% and 31%, respectively,from the implemented training regimen (Scanlon et al., 2013). The sen-sitivity and reliability of the MQI to detect improvements, as shown inthe present study, highlight the potential clinical utility of this newmeasure. As an elaborative clinical measure of the more common andsimple measure of timed sit to stand, MQI also incorporates the anthro-pometric measures of body mass and leg length. Previously, body sizehas been shown to alter the relationship between chair rise perfor-mance and leg strength (Takai et al., 2009). MQI incorporates body di-mensions in its computation; therefore, it may be a more informativemeasure despite the diversity of body size observed in human popula-tions. Although, no significant body mass or composition changeswere detected in the present study, inclusion of anthropometricsmakes MQI a comparative relative measure among individuals of vary-ing body sizes, especially men and women. While the present studyincluded bothmen andwomen tomaximize the potential generalizabil-ity of the findings and was not statistically powered to run analyses bygender, gender is an important consideration in interpreting responsesto interventions for sarcopenia.

The observed magnitude of change in MQI was greater than othermeasures of physical function (e.g. gait speed, grip strength, timedchair rise, get-up and go) or muscle status (e.g. lean body mass). As itis ideal for functional measures of muscular status to be both specificto measure relevant characteristics and sensitive to respond to directedintervention, our preliminary results support the MQI measure to befurther evaluated. While measures of gait speed, grip strength, and

Table 2Changes in measures of physical function observed from during Phase 1 and Phase 2.

Baseline Phase 1 Phase 2

Muscle quality index (W) Group 1 199.06 ±69.14 242.88 ±97.13# 245.58 ±100.87⁎

Group 2 199.59 ±80.71 208.18 ±61.58⁎ 244.99 ±75.38 #

Hand grip strength (kg) Group 1 36.25 ±10.94 39.17 ±13.58 # 40.08 ±15.72Group 2 32.82 14.17 34.18 ±16.48 35.55 ±15.71 #

Gait time (s) Group 1 1.92 ±0.44 1.64 ±0.28 # 1.70 ±0.34⁎

Group 2 1.75 ±0.41 1.77 ±0.24⁎ 1.68 ±0.27Sit-to-stand (S) Group 1 14.19 ±2.84 11.57 ±1.66# 11.39 ±1.77⁎

Group 2 12.92 ±2.17 12.14 ±1.61⁎ 10.48 ±1.35 #

Get-up and go (s) Group 1 8.67 ±2.57^ 7.52 ±1.28 # 7.16 ±1.29Group 2 8.41 ±0.86 7.79 ±0.94 7.12 ±0.79 #

Lean body mass (kg) Group 1 47.70 ±10.67 47.92 ±10.51 49.19 ±10.88Group 2 49.58 ±13.48 49.51 ±13.23 48.97 ±12.84

^p = 0.042 between groups at baseline.#p b 0.10 from previous time-point.⁎p b 0.10 for interaction between groups at specified time-point.Group 1 exercised during Phase 1 and detrained during Phase 2.Group 2 completed the control condition during Phase 1 and exercised during Phase 2.

Table 3Changes in functional measures pre- and post-training.

Percent

Measure n Pre Post p Difference Pos Triv Neg

Muscle quality index (W) 23 203.43 ± 64.31 244.25 ± 82.92 0.000 41 ± 19 99.7 0.3 0.0Hand grip strength (kg) 23 35.26 ± 13.58 37.43 ± 14.42 0.010 2.2 ± 1.6 25.1 74.9 0.0Sit-to-stand (s) 23 13.21 ± 2.51 11.05 ± 1.58 0.000 −2.2 ± 0.93 0.0 0.0 100.0†

Gait time (s) 23 1.85 ± 0.36 1.66 ± 0.27 0.005 −0.19 ± 0.13 0.0 4.9 95.1†

Get-up and go (s) 23 8.25 ± 1.98 7.33 ± 1.07 0.002 −0.92 ± 0.57 0.0 3.7 96.3†

Lean body mass (kg) 23 48.4 ± 11.91 48.7 ± 11.54 0.869 0.3 ± 3.6 12.8 79.9 7.3

n=sample size; Pre=pre-training; Post=post-training; p=significance; Pre and Post values presented asmean±SD. Difference values presented asmean±90% confidence intervals.Pos = % positive change; Triv = % trivial change; Neg = % negative change. †Note for timed tests of STS, Gait, and GUG a reduction in time (s) corresponds to improved performance.

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lean body mass are evidence-based measures from cross-sectional andlongitudinal studies, their sensitivities to detect improvements to inter-ventions require further evaluation. The establishment of specific andsensitive functionalmeasures for sarcopenia is needed for future clinicaltrials of pharmaceutical interventions. As a first step to compare chang-es among measures, MQI may provide new additive information to themore commonly acceptedmeasures. MQI provides a clinical estimate oflower body muscular power, which previous studies have shown ismore adversely affected by aging and sarcopenia (Frontera et al.,1991; Goodpaster et al., 2006; Hakkinen et al., 1996). Additionally, theability to generate muscle power of the lower body is involved inmany tasks of daily living like climbing stairs or rising from bed andwas recently recommended as the best measure of muscle quality(Barbat-Artigas et al., 2012). Thus, in comparison to other commonmeasures of muscle status, MQI is a clinically feasible muscle specificmeasure of power.

Six weeks of detraining did not result in significant losses in theimprovement that were attained during the training regimen in anyvariable. Similarly, Henwood and Taaffe (Henwood and Taaffe, 2008)previously reported that older adults were able to maintain functionalbenefits and improvements in strength and power after detraining.Although a positive finding, the preservation of improvements after6-weeks of cessation of training was contrary to our initial hypothesis.We had expected to see some decrements in functional performancein the follow-up measure. However, results could be explained bydaily activities in the “de training” period. Our “de training” periodonly involved the cessation of resistance exercise training for 6-weekswith instructions to maintain normal daily activities. It is possible thatthe initial 6-week training period resulted in increases in functionalcapacities that inherently increased daily activities during the detrainingperiod—a variable not measured in the present study. Nevertheless, theobserved functional maintenance in the current and prior investigationshas important translational relevance to daily activities in older adults.

5. Conclusion

In conclusion, MQI significantly changes in response to short termresistance exercise training to a clinically meaningful magnitude inolder adults. Improvements in MQI exceeded those of other measuresof muscular function and status. Additionally, because MQI is based onthe timed sit to stand test, it has high potential clinical applicability.Thus, the feasibility, sensitivity and reliability of MQI assessment makeit an informative and potentially useful tool for clinical and interven-tional assessments of the functional status associated with sarcopenia.Future studies should further evaluate thismeasurewith others in addi-tional interventional trials. Interestingly, no performance decrementswere observed in 6-weeks of detraining in older adults. Thus, functionalimprovements attained from short term resistance training can poten-tially be sustained for up to 6-weeks following cessation. Future studiesare needed to determine if the results are due to residual adaptations orincreased functional capacities translated to daily living.

Conflict of interest

Authors have no financial or personal conflicts of interest to reportwhich may be perceived to influence the results.

Acknowledgments

This research was supported by the Learning Institute for the Elders,the University's Office of Research, and the Toni Jennings ExceptionalEducational Institute.

References

Barbat-Artigas, S., Rolland, Y., Zamboni, M., Aubertin-Leheudre, M., 2012. How to assessfunctional status: a new muscle quality index. J. Nutr. Health Aging 16, 67–77.

6 M.S. Fragala et al. / Experimental Gerontology 53 (2014) 1–6

Corrigan, D., Bohannon, R.W., 2001. Relationship between knee extension force andstand-up performance in community-dwelling elderly women. Arch. Phys. Med.Rehabil. 82, 1666–1672.

Cruz-Jentoft, A.J., Baeyens, J.P., Bauer, J.M., Boirie, Y., Cederholm, T., Landi, F., Martin, F.C.,Michel, J.P., Rolland, Y., Schneider, S.M., Topinkova, E., Vandewoude, M., Zamboni,M., Cruz-Jentoft, A.J., Baeyens, J.P., Bauer, J.M., Boirie, Y., Cederholm, T., Landi, F.,Martin, F.C., Michel, J.P., Rolland, Y., Schneider, S.M., Topinkova, E., Vandewoude, M.,Zamboni, M., 2010. European Working Group on Sarcopenia in Older, P. Sarcopenia:European consensus on definition and diagnosis: Report of the European WorkingGroup on Sarcopenia in Older People. Age Ageing 39, 412–423.

Fiatarone, M.A., O'Neill, E.F., Ryan, N.D., Clements, K.M., Solares, G.R., Nelson, M.E., Roberts,S.B., Kehayias, J.J., Lipsitz, L.A., Evans, W.J., 1994. Exercise training and nutritionalsupplementation for physical frailty in very elderly people. N. Engl. J. Med. 330,1769–1775.

Foldvari, M., Clark, M., Laviolette, L.C., Bernstein, M.A., Kaliton, D., Castaneda, C., Pu, C.T.,Hausdorff, J.M., Fielding, R.A., Singh, M.A., 2000. Association of muscle power withfunctional status in community-dwelling elderly women. J. Gerontol. A Biol. Sci.Med. Sci. 55, M192–M199.

Frontera, W.R., Hughes, V.A., Lutz, K.J., Evans, W.J., 1991. A cross-sectional study ofmuscle strength and mass in 45- to 78-yr-old men and women. J. Appl. Physiol. 71,644–650.

Goodpaster, B.H., Carlson, C.L., Visser, M., Kelley, D.E., Scherzinger, A., Harris, T.B., Stamm,E., Newman, A.B., 2001. Attenuation of skeletal muscle and strength in the elderly:The Health ABC Study. J. Appl. Physiol. 90, 2157–2165.

Goodpaster, B.H., Park, S.W., Harris, T.B., Kritchevsky, S.B., Nevitt, M., Schwartz, A.V.,Simonsick, E.M., Tylavsky, F.A., Visser, M., Newman, A.B., 2006. The loss of skeletalmuscle strength, mass, and quality in older adults: the health, aging and bodycomposition study. J. Gerontol. A Biol. Sci. Med. Sci. 61, 1059–1064.

Hakkinen, K., Kraemer, W.J., Kallinen, M., Linnamo, V., Pastinen, U.M., Newton, R.U., 1996.Bilateral and unilateral neuromuscular function and muscle cross-sectional area in

middle-aged and elderly men and women. J. Gerontol. A Biol. Sci. Med. Sci. 51,B21–B29.

Henwood, T.R., Taaffe, D.R., 2008. Detraining and retraining in older adults followinglong-term muscle power or muscle strength specific training. J. Gerontol. A Biol.Sci. Med. Sci. 63, 751–758.

Hopkins, W.G., Marshall, S.W., Batterham, A.M., Hanin, J., 2009. Progressive statistics forstudies in sports medicine and exercise science. Med. Sci. Sports Exerc. 41, 3–13.

Janssen, I., 2006. Influence of sarcopenia on the development of physical disability: theCardiovascular Health Study. J. Am. Geriatr. Soc. 54, 56–62.

Lauretani, F., Russo, C.R., Bandinelli, S., Bartali, B., Cavazzini, C., Di Iorio, A., Corsi, A.M.,Rantanen, T., Guralnik, J.M., Ferrucci, L., 2003. Age-associated changes in skeletalmuscles and their effect on mobility: an operational diagnosis of sarcopenia. J. Appl.Physiol. 95, 1851–1860.

Lindle, R.S., Metter, E.J., Lynch, N.A., Fleg, J.L., Fozard, J.L., Tobin, J., Roy, T.A., Hurley, B.F.,1997. Age and gender comparisons of muscle strength in 654 women and menaged 20–93 yr. J. Appl. Physiol. 83, 1581–1587.

Lynch, N.A., Metter, E.J., Lindle, R.S., Fozard, J.L., Tobin, J.D., Roy, T.A., Fleg, J.L., Hurley, B.F.,1999. Muscle quality. I. Age-associated differences between arm and leg musclegroups. J. Appl. Physiol. 86, 188–194.

Moritani, T., deVries, H.A., 1979. Neural factors versus hypertrophy in the time course ofmuscle strength gain. Am. J. Phys. Med. 58, 115–130.

Scanlon, T.C., Fragala, M.S., Stout, J.R., Emerson, N.S., Beyer, K.S., Oliveira, L.P., Hoffman, J.R.,2013.Muscle architecture and strength: adaptations to short term resistance training.Muscle Nerve, Jul 28. doi: 10.1002/mus.23969. [in press] [Epub ahead of print][PMID:23893353].

Takai, Y., Ohta, M., Akagi, R., Kanehisa, H., Kawakami, Y., Fukunaga, T., 2009. Sit-to-standtest to evaluate knee extensor muscle size and strength in the elderly: a novelapproach. J. Physiol. Anthropol. 28, 123–128.

Welle, S., Totterman, S., Thornton, C., 1996. Effect of age on muscle hypertrophy inducedby resistance training. J. Gerontol. A Biol. Sci. Med. Sci. 51, M270–M275.