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Available online at www.sciencedirect.com

Journal of Science and Medicine in Sport xxx (2012) xxx–xxx

Original research

A hitchhiker’s guide to assessing sedentary behaviour among youngpeople: Deciding what method to use

Louise L. Hardy a,∗, Andrew P. Hills b, Anna Timperio c, Dylan Cliff d, David Lubans e,Philip J. Morgan e, Barry J. Taylor f, Helen Brown c

a Prevention Research Collaboration, University of Sydney, Sydney, Australiab Centre for Nutrition and Exercise, Mater Medical Research Institute and Griffith Health Institute, Griffith University, Brisbane, Australia

c Centre for Physical Activity and Nutrition Research, Deakin University, Burwood, Australiad Interdisciplinary Educational Research Institute, Faculty of Education, University of Wollongong, Wollongong, Australia

e Priority Research Centre in Physical Activity and Nutrition, School of Education, University of Newcastle, Newcastle, Australiaf Department of Women’s and Children’s Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand

Received 12 March 2012; received in revised form 7 May 2012; accepted 13 May 2012

bstract

bjective: To provide a user’s guide for selecting an appropriate method to assess sedentary behaviours among children and adolescents.esign: While recommendations regarding specific instruments are not provided, the guide offers information about key attributes and

onsiderations for objective (accelerometry; inclinometers; direct observation; screen monitoring devices) and subjective (self-report; parenteport; and time use diaries/logs) approaches to assess sedentary behaviour Attributes of instruments and other factors to be considered inhe selection of assessment instruments include: population (age); sample size; respondent burden; method/delivery mode; assessment timerame; physical activity information required (data output); data management; measurement error; cost (instrument and administration) andther limitations.ethods: Expert consensus among members of the Australasian Child and Adolescent Obesity Research Network’s (ACAORN) Physicalctivity and Sedentary Behaviour Special Interest Group.esults: We developed decision flow charts to assist researchers and practitioners select an appropriate method of assessing sedentaryehaviour, identified attributes of each method and described five real-life scenarios to illustrate considerations associated with the selectionf each method of measurement.

onclusions: It is important that researchers, practitioners and policy makers understand the strengths and limitations of different methodsf assessing sedentary behaviour among youth, and are guided on selection of the most appropriate instrument/s to suit their needs.rown Copyright © 2012 Published by Elsevier Ltd on behalf of Sports Medicine Australia. All rights reserved.

eywords: Sedentary behaviour; Sitting; Screen time; Measurement; Methodology; Children

tbta

. Introduction

In recent decades, significant societal changes have cre-ted a reduced demand for physical activity with a profound

1

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what method to use. J Sci Med Sport (2012), http://dx.doi.org/10.1016/j

esultant impact on the behaviour of children and youth.hysical inactivity has been described as the biggest pub-

ic health problem of our time.2,3 There is strong evidence

∗ Corresponding author.E-mail address: louise.hardy@sydney.edu.au (L.L. Hardy).

saibtc

440-2440/$ – see front matter. Crown Copyright © 2012 Published by Elsevier Ltttp://dx.doi.org/10.1016/j.jsams.2012.05.010

hat physical activity is associated with numerous healthenefits in youth4 and, similarly, that excessive seden-ary behaviour is likely to be independently related to

number of health-related conditions5,6 including weighttatus and adverse metabolic profiles cross-sectionally7–9

nd prospectively.10,11 However, considerably more research

to assessing sedentary behaviour among young people: Deciding.jsams.2012.05.010

s required to assess the benefits of reducing sedentaryehaviour, for example sitting less and standing more,12 andhe nature of sedentary behaviours tracking across the lifeourse.13

d on behalf of Sports Medicine Australia. All rights reserved.

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Despite the apparent simplicity of the term, seden-ary behaviour is complex and not limited to a singleehaviour.14,15 Time spent in sedentary behaviour is distinctrom lack of physical activity and, sedentary behaviours havenique behavioural constructs that have independent rela-ionships to various health outcomes.16,17 The importance ofefining sedentary behaviour and using the term consistentlys illustrated by the fact that many studies which purport toddress ‘sedentary’ behaviour incorrectly assume individu-ls who are less active or do not meet recommended physicalctivity guidelines are sedentary. Rather, these individuals areinsufficiently active’, or ‘inactive’ if no physical activity iseported.

Sitting is the predominant sedentary behaviour, but theerm ‘sedentary’ has typically referred to any activity whichoes not increase resting energy expenditure appreciablybove the resting metabolic rate (i.e., 1.0–1.5 metabolicquivalent units (METs)).18 It is also important to distin-uish sedentary behaviour from the energy expenditure ofight-intensity physical activity (1.5–2.9 METs).15 The mostommon sedentary activities include watching televisionTV), playing video/computer games, surfing the Internet,eading, and playing a musical instrument.19

Measurement of sedentary behaviour is notoriously chal-enging as it requires an understanding of which behavioursre being undertaken, along with the context and the dura-ion. In young people, a substantial amount of time is spentatching TV, however, this alone fails to capture the diver-

ity of sedentary behaviours.14 A wide range of measuresave been used to quantify TV viewing, including directbservation, self/proxy and real-time data capture,14 but con-iderable work is needed in this area.20 Furthermore, recentystematic reviews of sedentary behaviour measures haveighlighted the poor validity and reliability of many of thexisting measures.6,21

Sedentary time is a relatively new area in health behaviouresearch and there is a need to expand the evidence-base toetter understand the epidemiology and health consequences,nd determine effective intervention strategies.22,23 The evi-ence must come from accurate measurement, and whilehere is scope for the improvement of measures of sedentaryehaviour in children and adolescents, there are currently aide variety of approaches being utilized.20,21 There is cur-

ently no guide detailing the characteristics and discussinghe suitability of common measures to assist researchers andractitioners interested in measuring this behaviour. The pur-ose of this paper is to provide a user’s guide for selectingethods to assess sedentary behaviour among children and

dolescents.

. Methods

Please cite this article in press as: Hardy LL, et al. A hitchhiker’s guide

what method to use. J Sci Med Sport (2012), http://dx.doi.org/10.1016/j

In 2011, members of the Australasian Child and Adoles-ent Obesity Research Network’s (ACAORN) Measurementf Physical Activity and Sedentary Behaviours Special

pToT

edicine in Sport xxx (2012) xxx–xxx

nterest Group met to discuss how best to assist other stake-olders in child health who may be interested in measuringedentary behaviour among children and adolescents. Therst step of this process was to undertake a systematic review

o identify the validity and reliability of common methodssed to measure sedentary behaviour in young people.21 Theecond step was to highlight the decision making processhat researchers and practitioners need to consider when

easuring sedentary behaviour in young people, such aseciding on the type of measurement instrument, the purposef the assessment, and the practical considerations.

Fig. 1 illustrates the two methods (i.e., objective andubjective) used to assess sedentary behaviour in young peo-le and the potential cost and sample size associated withach measurement method. Each method comprises differ-nt instruments, and the key attributes and the limitationsnd practical considerations of each instrument are listed inables 1 and 2 , respectively.

Objective measures of sedentary time may include motionevices (inclinometer, accelerometer), observation (direct,ideo) and other electronic devices such as TV time managerse.g., ‘TV Allowance’®)24 specifically designed to measurelectronic media use or screen time (ST). The primary reasonor selecting objective measures is to minimise measurementrror, however objective measures are typically more costlynd therefore more likely to be used when assessing smallerumbers of children, although large funded trials may alsoonsider objective measures.

The limitation of motion devices is their inability torovide contextual information (i.e., setting and type ofctivity). Accelerometers have traditionally been used toeasure physical activities rather than measuring sedentary

ime. There is, however, some evidence that information onedentariness (includes standing) can be reasonably deter-ined from accelerometers (i.e., cut point < 100 cpm).25,26

ore recently inclinometers, which assess anatomical posi-ion in three planes (lying, sitting, standing) and posturalhanges (sitting/standing) are being explored as a methodo measure sedentary time in children.25 A limitation is thatnclinometers, which are taped or strapped to the thigh, maybencomfortable to wear for prolonged periods.

An additional consideration regarding motion devices isndividual compliance; typically, these small devices areorn for approximately one week, and can pose a degreef participant burden, which may result in missing data whenhe device is not worn. Further, there are times when theseevices may malfunction, leading to a loss of data. Whilehere has been an increase in use of motion devices to mea-ure sedentary time, a significant research gap is the lack oftandardised monitoring protocols (e.g., wear time) and dataeduction strategies (e.g., which algorithm).27,28

Observation methods entail an observer recording29

to assessing sedentary behaviour among young people: Deciding.jsams.2012.05.010

articipants’ activities while watching the participant.his may be completed by a trained individual directlybserving the child or indirectly by videoing the child.he benefit of using video recording is that multiple views

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Table 1Key attributes of common methods for measuring sedentary behaviour among young people.

Characteristic Objective methods Subjective methods

Accelerometers Inclinometers Screen monitoring devices Direct observation Self-report Parent report Time use diary/log

Population age 1.5–18 years 3–18 years 3–18 years 3–18 years ≥12 years 1.5–12 years 13–18 yearsSample size Small to large Small to large Small Small Small to large Small to large Small to mediumMethod Prospective/current. Prospective/current. Prospective/current. Prospective/current Retrospective Retrospective Prospective/current

Monitor usually wornon a belt over righthip.

Monitor usually worn onright thigh using a strap oradhesive pads.

Unit attached to eachscreen, e.g., TV, computer.Individuals need to log-inusing unique codes

Naked eye or video/filmobservation. Electronicrecording forms.

Recall: yesterday,usual week, pastweek, etc.

Recall: yesterday,usual week, pastweek, etc.

Momentarytime-sampling (e.g.,multiple 3–15 sobservations).

Assessment time Typically 7 days tocapture habitualbehaviour.

Typically 7 days to capturehabitual behaviour.

Variable (from one day toseveral weeks)

Variable (from one tomultiple days)

One-off One-off Typically 7 days tocapture habitualbehaviour.

Data output Counts bodymovement(accelerations) in realtime; algorithms usedto convert to durationsof less than auser-identifiedcutpoint to indicatethe upper limit of‘sedentary’

Time spent in differentpostures, including sitting,in real time. Number ofsit-to-stand transitions.Bouts of sitting time.

Total time spent viewingelectronic screen for eachindividual code overmonitoring period (e.g., 1week).

Time spent in differentpostures/intensities,includingsitting/sedentary.

Averagefrequency and/orduration ofoverall sitting, orof specificsedentarybehaviours.Weekday andweekend daysusually askedseparately. Canprovide contextspecificinformation

Average frequencyand/or duration ofoverall sitting, or ofspecific sedentarybehaviours.Weekday andweekend daysusually askedseparately. Canprovide contextspecificinformation

Minutes spent inspecific behavioursin ‘real-time’.

Data entry and datareductioncomplexity

High – datadownloaded tocomputer and reducedusing specialisedsoftware

High – data downloadedto computer and reducedusing proprietary software

Low – data recorded bydevice

Low – manual dataentry

Low – manualdata entry orscanned entry

Low – manual dataentry or scannedentry

High – substantialdata entry and datareduction required

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Table 2Limitations and practical considerations associated with common methods of measuring sedentary behaviour among young people.

Characteristic Objective methods Subjective methods

Accelerometers Inclinometers Screen monitoringdevices

Direct observation Self-report Teacher/carer proxyreport

Diaries/logs

Cost High High High High Low Low LowSources of error and

limitations ondimensions of SBcaptured

Unable to distinguishbetween standing stilland sitting. Nostandard protocol fordata management orreduction. Somemodels notwater-proof. Nocontextualinformation (e.g., typeof behaviour).Participants may needsupport to ensurecompliance.

Unable to distinguishbetween lying andsitting. No contextualinformation (e.g., typeof behaviour). Notsuitable for wateractivities.

Assumption thatparticipant issedentary whileengaged in ‘screentime’. Screen-basedmedia does notentirely capture thevariety of ways youngpeople can besedentary (e.g.,talking on the phone,listening to music).

Potential forparticipant reactivity.Data collectionmethod can beconsidered invasive.

Poor respondentmemory and/ormotivation.Susceptibility tosocially desirableresponses. Incompleteentries/missing data.Computer availabilityfor electronic dataentry varies amongschools. Literacylevels amongrespondents can varywidely.

Potential for bias.Potential poorteacher/carer memory,judgment ormotivation.Incompleteentries/missing data.Possibility thatrespondent is unawareor was not present toobserve behaviour ofthe child during all ofthe recall period.

Potential forparticipant reactivity.Poor respondentmotivation.Susceptibility tosocially desirableresponses.Under-estimation ofincidental activities.Under orover-estimation oftime spent sedentary.Age limitation formemory.

Additionalconsiderations

Must be individuallyprogrammed. Mayrequire log/diary torecord times when notworn. Complianceissues (especiallyamong adolescentsand obeseparticipants) cansubstantially reducefinal sample.

Must be individuallyprogrammed. Mayrequire log/diary torecord times when notworn. Complianceissues (especiallyamong adolescentsand obeseparticipants) cansubstantially reducefinal sample.

May require othermethods to be used inconjunction to recordtype of behaviour andposture. Researchersrequired to visitparticipants’ homes toinstall and retrievedevice. Each screenused by participantrequires a separatedevice. Parents/childneed to adhere toprotocol of notsharing log-ins.

Obtaining ethicsapproval to observechildren may beproblematic. Mayrequire additionalpre-monitoring periodto reduce participantreactivity.

Lists of SB cues needto be culturallyappropriate. Cautionshould be taken whenestimating total timespent in SB due toyoung peopleengaging in multipleSB’s simultaneously.

Respondents andresearchers mustshare commonunderstanding ofterms used (e.g.,sedentary behaviour)

Poor compliance tomonitoring protocolsmay limit amount ofuseful data and/or thesample size

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Table 2 (Continued)

Characteristic Objective methods Subjective methods

Accelerometers Inclinometers Screen monitoringdevices

Direct observation Self-report Teacher/carer proxyreport

Diaries/logs

Tips to improvecompliance and/ordata quality

Incentives forcompliance. Dailytext messages toparents to remindchildren, or (directlyto adolescents) towear device.

Incentives forcompliance. Daily textmessages to parents toremind children towear device.

Conduct repeatedobservations wherepossible/relevant.Non-intrusiveobservation needed toreduce reactivity.

Shorten the recallperiod (althoughestimates may thennot clearly representhabitual behaviour)

As per self-report. Ensure diary/log entrymethod is simple,visually appealing andclear for young tofollow. ‘Blocked time’diaries may be usefulto reduce participantburden. Daily textmessages to parents toremind children tocomplete diaries (ordirect text messagesto adolescents).

Intervieweradministeredself-report mayimprove quality ofparticipants’responses.

In addition, ensurerecall period is duringa time the respondentis likely to have beenaware of the child’sbehaviour. Ensureappropriaterespondent is selected(e.g., the parent that ishome immediatelyafter school)

Consider use ofpictures/diagrams toassist.

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Fig. 1. Decision flow chart to select approaches

otentially improve objectivity and aspects of behaviour cane reviewed. Irrespective, both observation methods requireystematic recording of observations. This may be achievedsing a simple observation method where the observer has

list to record the child’s posture, the domain (or setting)nd the activity. It is worth noting that in some jurisdictions,mploying observation methods may be prohibited bynstitutional ethics committees.

Subjective measures rely on self-report, or, in the casef children aged <10 years where recall is not reliableecause of cognitive development, proxy reporting by ahird party (usually a parent).30 Subjective measures areenerally cheaper so are therefore often used in the assess-ent of larger groups, but may also be selected for smaller

roups when budgetary constraints prevail. A significantenefit of self/proxy report methods is that contextual infor-ation can be collected which allows the researcher to

xamine a broad range of sedentary behaviours, or spe-ific sedentary activities such as ST passive transport. Its worth noting that while self-report measures may pro-ide reliable estimates of sedentary behaviour or ST, theiralidity remains largely untested.21 The major limitation ofelf/proxy report is the potential for significant measurementrror arising from recall errors, deliberate misrepresentationsnd social desirability.31 Logs/diaries, where the participantrospectively records the main activity undertaken during a

Please cite this article in press as: Hardy LL, et al. A hitchhiker’s guide

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pecified time interval (e.g., 30 min blocks) have the poten-ial to reduce measurement error, but this method carriesonsiderable respondent burden and is not appropriate for

obt

uure sedentary behaviour among young people.

ounger age groups. Furthermore, because all activities areecorded, this method requires the extraction of sedentaryctivities.

Scenarios The following scenarios have been selected toepresent a range of circumstances and should be read inonjunction with Fig. 1 and Tables 1 and 2 which providereater detail to help guide the most appropriate choice ofnstrument(s).

Scenario A: screen time intervention among preschoolers;esearchers plan to design and evaluate the potential effi-acy of a 12-week intervention to reduce ST in children aged–3 years in the home setting. Children will be randomiseds a family unit to either an intervention or control group.T will be assessed among approximately 80 children (40

n each group) at baseline and at 3-month post-interventionime points. The aims of this research are to (i) determine ifhe intervention results in reduced total ST at home and, (ii)etermine duration by each screen type.

In this scenario, the researchers are assessing changesn children’s ST using a randomised controlled trial (RCT)esign. Key outcomes of interest are the duration and contextf the ST participation at home. The sample comprises chil-ren who are too young to self-report, and the study requiresetails of types of ST behaviour. Objective measurementsing inclinometers or accelerometers are not appropriate ashese methods will not provide the context of the behaviour

to assessing sedentary behaviour among young people: Deciding.jsams.2012.05.010

r whether the sedentary time was ST or other sedentaryehaviours. An appropriate approach is a parent proxy ques-ionnaire using recall over a certain number of days.

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The number of days that represent an accurate estimate ofabitual ST behaviours in this age group and in this settings unknown, and will depend on day-to-day variations in theome context. Ideally, weekday and weekend day ST shoulde captured. However, despite recognised limitations, parentroxy self-report recall instruments can be used to provide anstimate of minutes spent in ST and assess compliance withuidelines and determine the types of ST in which childrenngage.21

Scenario B: school-based RCT to reduce sitting duringchool class-time; Traditional classroom teaching techniquesredominantly involve children being seated for sustainederiods. Evidence among adults suggests that sustained sit-ing may be detrimental to health and that interrupting sittingime may reduce such risks.32 Researchers have planned a-month RCT to test strategies to reduce classroom sittingn primary school children through alternative teaching prac-ices. The RCT involves two classes within each year levelt six schools (three control and three intervention schools),nd approximately 300 students.

To determine the effectiveness of the intervention,esearchers must detect changes in time spent ‘sitting’ dur-ng class time between baseline and post-intervention. Keyonsiderations in the selection of appropriate measurementnstruments include: the age of the participants, the need toetect behaviour within particular periods, the need to dif-erentiate sitting from other postures, potential burden toarticipants and minimisation of class disruption. In thiscenario, self-report measures may be inappropriate dueo participant age (cognitive limitations). Proxy-reports byeachers may also be inappropriate as they would only provideroup-level information rather than data about individuals.he use of self-report logs/diaries may be burdensome dur-

ng class-time, may disrupt class activities and could result ineactivity. Accelerometry may also be inappropriate becausehey quantify ‘movement’ and do not provide any posturalnformation. Low movement counts are indicative of limitedovement and not necessarily ‘sitting’.In this scenario, inclinometers and direct observation may

e the most appropriate measurement tools. Inclinometersnable researchers to determine time spent sitting or lyingbased on postural information), can be worn over long peri-ds (e.g., one week) and allow researchers to extract datarom specific periods of interest (e.g., class times). Directbservation would provide the same ‘information’ with thedditional opportunity to value-add by documenting specificehaviours undertaken in each posture (e.g., reading, writ-ng, art, craft, etc.). However, direct observation may resultn reactivity as participants know they are being observed, and

ay be costly given the number of observations that woulde required (each period across the school day for each classt each school) on multiple school days. Further, the number

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f days of observations required is not established.Scenario C: treatment program for overweight/obese pri-

ary school children; A researcher is seeking to evaluatehe effects of a 10-week family-centred sedentary behaviour

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eduction intervention on adiposity in overweight/obese–12-year-old children. The feasibility study is a single-rm experiment involving 30 overweight/obese children withssessments of sedentary behaviour taken pre- and post-ntervention, and the researcher wants to determine if thentervention reduced children’s sedentary time (i) overallaily and (ii) outside of school hours.

For this intervention, the researcher needs to selects annstrument that is both accurate and objective, and sensitivenough to detect the hypothesised changes in sedentary time.lthough the sample size is relatively small, direct observa-

ion would not be feasible because it is likely that the childrenttend different schools, and because the researcher is alsonterested in understanding the effects of the intervention onedentary time outside of school hours. Self-report question-aires offer a cost-effective option, but the assessments woulde vulnerable to recall-bias because of the age of the partici-ants. Parent-proxy reports would also not be recommendedecause their estimates might be influenced by social desir-bility bias and this could result in under-reporting of theehaviour, or parents’ understanding of the desired effects ofhe intervention might result in under-reporting at post-test.t would also be difficult to accurately assess children’s totaledentary time, which occurs in many settings and contextsnd not always in the presence of parents.

An objective measure is recommended and monitor-ng devices worn on the body, such as inclinometers orccelerometers, would be most suitable. The use of an incli-ometer would allow the researcher to examine time spentn different postures, and from this changes in sitting/lyingime as a result of the intervention could be evaluated. Ifccelerometers are chosen, the researcher can apply age-ppropriate cut-points to determine sedentary time. Theeal-time data acquisition from objective monitoring devicesould allow the researcher to specifically examine seden-

ary time that occurs outside of school hours, in addition tohildren’s overall or total sedentary time per day.

Scenario D: primary prevention of adolescent screen timen clinical settings; A general practitioner (GP) is concernedbout the metabolic profile of an obese adolescent patientresenting markedly overweight and with obvious signs ofnsulin resistance. During the consultation the GP ascertainsrom the adolescents’ parents and the adolescent that the ado-escent spends most of their time sitting on the couch playing-games, watching TV/DVDs.

Access to adolescent obesity management clinics is lim-ted, and because the GP has a small, busy practice is unableo provide on-going long consultations to the adolescent. TheP decides that the best management strategy will be basedn regular brief counselling consultations that incorporateoal setting. The adolescent’s parents are asked to help thedolescent set realistic ST reduction goals and to help monitor

to assessing sedentary behaviour among young people: Deciding.jsams.2012.05.010

rogress towards reducing ST.Objective measures are not suitable for several reasons.

irstly, motion sensors do not capture contextual informa-ion and, the cost of motion sensors is prohibitive to the

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ractice budget. Furthermore, the GP does not have the timend expertise to interpret the data collected by objectivenstruments. Rather, the most feasible line of interventions for the GP to ask the adolescent to complete a time useiary, or suitable structured questionnaire, about their ST.

This baseline information will identify the duration spentn ST and the time of day spent on ST. The GP can usehis information to help the adolescent set realistic goalsimed at reducing ST. The GP can monitor the adolescent’srogress towards reducing ST at on-going consultations forhe monitoring the obese adolescents’ progress.

Scenario E: population prevalence of screen time amongdolescents; Health and education professionals have con-erns about non-school recreational ST among adolescents.n order to determine whether investments should be allo-ated to develop a school-based intervention to encouragedolescents to reduce their ST, the first step is to ascertainow prevalent ST is, and whether there are sociodemographicifferences in teenagers’ ST. To determine the populationrevalence, a large sample of adolescents (i.e., several hun-red) from a range of high school years, across differentducational sectors, and geographical and socioeconomicreas is required to determine population estimates whichre generalisable.

In this scenario, objective measures such as accelerome-ers and inclinometers are inappropriate for several reasons.irst and foremost, objective measures do not provide con-

extual information, so will not discriminate between STctivities, or other sitting behaviours, therefore self-report ishe most desirable method of measurement. Unlike youngerhildren, adolescents are capable of self-report, albeit recallan be affected by social desirability, and estimates of timere subject to large error. Questionnaires have the ability toiscriminate between ST activities and to determine habitualon-school ST on week and weekend days. In school envi-onments, questionnaires can be administered either as pennd paper, or via computers/smart boards.

A significant issue to consider when asking students toeport ST activities is the concept of multi-tasking. For exam-le, an adolescent may play on their computer while watchingV – so during the administration of the questionnaire it is

mportant to instruct respondents to allocate the time propor-ionally spent on each screen activity. An alternative methodo measure ST behaviour is with time use diaries/log, or eco-ogical momentary assessment (EMA), where respondentseport activities undertaken during a specified time interval.

limitation of this method is that all activities are reported,enerating large volumes of data from which ST data arextracted.

. Concluding remarks

Please cite this article in press as: Hardy LL, et al. A hitchhiker’s guide

what method to use. J Sci Med Sport (2012), http://dx.doi.org/10.1016/j

Sedentariness is a multi-faceted construct and is notonsidered a single behaviour or the opposite of physicalctivity. Given recent evidence highlighting the health-related

edicine in Sport xxx (2012) xxx–xxx

onsequences that are independently associated with timepent in sedentary behaviours, the accurate measurementf sedentary behaviour is particularly important. However,easurement is complex and requires an understanding of

ontext, duration and which behaviours are being under-aken. No single, currently available assessment tool capturesnd describes every aspect of sedentary behaviour. Objec-ive measures of sedentary time may include motionevices, observation and other electronic devices specifi-ally designed to measure ST. Subjective measures rely onelf-report, or proxy reporting by a third party (usually a par-nt). Researchers and practitioners need to consider the typef measurement instrument, the purpose, the intended out-omes, and a host of practical considerations when selectinghe instrument(s) which best suit their needs.

ractical implications

Accurate assessment of sedentary behaviour in youth isecessary to:

determine prevalence and trends examine associations with health outcomes

identify correlates, determinants, potential mediators andevaluate the effectiveness of interventions.

cknowledgments

Preparation for this guide was funded by The Aus-ralasian Child and Adolescent Obesity Research NetworkACAORN) (http://sydney.edu.au/medicine/acaorn). Dylanliff is funded by a National Heart Foundation of Australia -acquarie Postdoctoral Research Fellowship (PH 09S 4603).nna Timperio is supported by a VicHealth Public Healthesearch Fellowship.

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