Determinants of Physical Activity in SingaporeanAdolescents

Kok Sonk Lee & Paul D. Loprinzi & Stewart G. Trost

Published online: 4 September 2009# International Society of Behavioral Medicine 2009

AbstractBackground An understanding of the factors that influencephysical activity behavior is an important prerequisite for thedesign and implementation of physical activity interventions inadolescents. To date, no studies have investigated the factorsthat influence physical activity participation in Singaporeanadolescents.Purpose The purpose of this study was to identify thepsychosocial and environmental factors that influence physicalactivity in a representative sample of Singaporean adolescents(N=1,814, 919 boys, 895 girls, mean age 14.41.1 years).Methods Participants completed the Three-Day PhysicalActivity Recall and a questionnaire measuring hypothesizedpsychosocial and environmental correlates of physicalactivity.Results Hierarchical regression revealed self-efficacy, en-joyment of physical activity, parental support, and partic-ipation in sport teams to be significant correlates ofphysical activity.Conclusion Interventions promoting physical activity inSingaporean adolescents should aim to increase self-efficacy perceptions by offering enjoyable, developmentally

appropriate physical activity options that promote masteryand adopt policies that increase parental support andawareness of community physical activity programs.

Keywords Exercise . Youth . Health promotion .

Self-efficacy . Enjoyment

Introduction

Chronic diseases such as cancer, coronary heart disease,and stroke are the leading causes of death in Singaporetoday [1]. In 2000, these three conditions accounted forapproximately 60% of all deaths in Singapore [1]. Regularparticipation in physical activity is associated with anumber of positive health outcomes. Among adults, regularphysical activity reduces the risk of many chronic diseases,including coronary heart disease, hypertension, stroke,depression, type 2 diabetes, and certain cancers [2]. Theevidence linking physical activity and health outcomes inchildren and adolescents is less consistent. Emergingevidence suggests that physical activity has beneficialeffects on weight status, blood lipids and lipoproteins, bonehealth, and psychological well-being [3, 4]. Moreover,because several health outcomes associated with physicalactivity track from childhood into adulthood, regularphysical activity may be important in the prevention ofchronic diseases later in life [5, 6].

Despite the health benefits of physical activity, Singaporeanadolescents are not participating in physical activity on aregular basis. The results of a recent national study indicatethat significant percentages of Singaporean high schoolstudents do not meet public health guidelines for physicalactivity. Currently, 37% of Singaporean adolescents fail tomeet the current physical activity guideline of 60 min of

K. S. LeeSchool of Human Movement Studies,The University of Queensland,Brisbane, Queensland 4072, Australiae-mail: LEE_Kok_Sonk@moe.gov.sg

P. D. Loprinzi : S. G. Trost (*)Department of Nutrition and Exercise Sciences,Oregon State University,203D Womens Building,Corvallis, OR 97331, USAe-mail: stewart.trost@oregonstate.edu

P. D. Loprinzie-mail: loprinzp@onid.orst.edu

Int.J. Behav. Med. (2010) 17:279286DOI 10.1007/s12529-009-9060-6

daily moderate to vigorous physical activity (MVPA), andapproximately 50% report no participation in vigorousphysical activity on a daily basis [7]. On average, girlsparticipate in 20% less daily MVPA than boys [7].Although the percentage of Singaporean adolescents meet-ing the 60-min MVPA guideline (63%) is somewhat higherthan that reported for high school students in the USA(34%) [8] and 1315 year olds participating in the WorldHealth Organizations 20012002 Health Behavior inSchool-Aged Children survey (34%) [9], the observed lowprevalence of sustained vigorous physical activity and themarked gender differences in MVPA underscore the needfor effective physical activity intervention programs for thispopulation.

An important prerequisite to designing and implement-ing physical activity intervention programs is to understandthe factors that influence physical activity. Several compre-hensive reviews on the correlates of physical activity inyouth have identified physical activity self-efficacy, beliefsabout physical activity, attitude towards physical activity,social norms, enjoyment of physical activity, parentalsupport, sport equipment at home/access to equipment andfacilities, supervised school sports, and participation insports teams as significant influences on physical activitybehavior [2, 10, 11]. However, because the majority ofstudies included in these reviews were conducted in thewestern countries such as the USA, it is uncertain whetherthese findings can be generalized to Singaporean adoles-cents. Currently, we are aware of no studies that haveinvestigated the correlates of physical activity in a sampleof Singaporean adolescents. To address this research gap,the purpose of this study was to identify the psychosocialand environmental correlates of physical activity behaviorin Singaporean high school students aged 13 to 16 years.

Materials and Methods

Participants and Settings

A stratified two-stage cluster sample design was used toselect a representative sample of Singaporean adolescents.The first stage involved the random selection of six schoolsfrom each geographical region, and the second stageinvolved selecting two classes per level in each school.All 1,902 students (100%) from the randomly selected classgroups agreed to participate in the study. After deletions forincomplete or missing data, the final sample consisted of1,814 students (95.4%). The demographic characteristicsof the initial and final sample remained unchanged bythe exclusion of these students. Prior to participation in thestudy, written informed consent was obtained fromthe principal of each school and the students. This study

was approved by the University of Queensland MedicalResearch Ethics Committee and the Ministry of Education,Singapore.

Measurement of Physical Activity

Physical activity was assessed using Three-Day PhysicalActivity Recall (3DPAR). This instrument requires studentsto recall their past physical activity behavior from each ofthe three previous days, beginning with the most recent day.Each day is segmented into 30-min time blocks (7:00 a.m.to midnight), which, in turn, are grouped into broader timeperiods such as morning, afternoon, and evening. Theinstrument provides a list of 53 commonly performedactivities grouped into the following categories: sleep/bathing, eating, work, interschool/spare time/hobbies,transportation, and physical activities/sports. For each blockof each day, the student entered the main activity for whichthey participated during that 30-min period. The mainactivity was defined as the activity that occupied themajority of the 30-min period. Participants also rated therelative intensity of the designated activity as light,medium, hard, or very hard. To help participants selectthe correct intensity level, the instrument provides pictorialrepresentation of four levels of relative intensity.

All students completed the 3DPAR instrument on aWednesday, recalling activities from the immediate preced-ing Tuesday, Monday, and Sunday. Each 30-min block onthe 3DPAR instrument was assigned a literature-basedmetabolic equivalent (MET) task value based on thereported activity and level of intensity [12]. MET valuesfrom all 34 blocks were then averaged to derive an estimateof mean activity level during each day. The 3DPAR wascustomized to include activities typically performed bySingaporean adolescents and has shown to be reliable andvalid in Singaporean youth [13].

Correlates of Physical Activity

Students completed a questionnaire designed to measurehypothesized demographic, psychosocial, and environmen-tal correlates of physical activity. Variables were selected onthe basis of Social Cognitive Theory [14] and the Theory ofReasoned Action/ Planned Behavior [15]. A brief descrip-tion of these scales, the number of items, possible range ofscores, testretest reliability coefficients, internal consisten-cy statistics (Cronbachs alpha) are provided in Table 1.

The measures of physical activity self-efficacy, attitudetowards physical activity, and social norms regardingphysical activity were modeled on the measurement scalesdeveloped by Saunders and coworkers [16]. The self-efficacy measure consisted of eight items rated on a five-point Likert-type scale anchored by 1 (strongly disagree)

280 Int.J. Behav. Med. (2010) 17:279286

to 5 (strongly agree). The attitude measure included eightitems that consisted of belief and corresponding valuestatements. The belief statements were rated also on a five-point Likert-type scale anchored by 1 (strongly disagree)to 5 (strongly agree); value statements were rated on a five-point Likert-type scale with responses ranging from 1 (verybad) to 5 (very good). Attitude scores were computed bymultiplying the response for each belief statement with itscorresponding value response and averaging the products.The social norms measure included eight items that consistedof normative beliefs and corresponding motivation tocomply statements. Normative belief statements and moti-vation to comply statements were rated on five-point Likert-type scales anchored by 1 (strongly disagree) and 5(strongly agree). Social norms scores were computed byaveraging by the product of each normative belief andmotivation to comply rating. The enjoyment of physicalactivity measure was modeled on the 14-item scale devel-oped by Motl and colleagues [17]. Responses to each itemwere reported on a five-point Likert-type scale with endpoints ranging from 1 (strongly agree) to 5 (strongly

disagree). Scores for enjoyment of physical activity werecomputed by averaging the responses to each item.

Hypothesized physical and social environmental corre-lates included items designed to measure parental support,sporting/fitness equipment at home, access to sports/fitnessfacilities, perceived neighborhood walkability, perception ofneighborhood safety, availability of supervised schoolsports, and participation in sport teams. These items weremodified from measures used in the National Children andYouth Fitness Study [18] and the CDC Youth Risk BehaviorSurvey [19]. When any of these measures consisted ofmultiple items, scores were computed by averaging theresponses to each item. The psychometric properties ofthese measures have been reported elsewhere [20, 21].

Study Protocol

Data were collected during two classroom visits completedwithin a single week. Students completed the 3DPARduring the first visit and the correlates of physical activityquestionnaire during the second visit. Each instrument took

Table 1 Description of scales used to measure correlates of physical activity

Name of scale No. ofitems

Range of possiblescores

Testretest Cronbachsalpha

Sample questions

Self-efficacy 8 15 0.89 0.80 I can be physically active duringmy free time on most days

Attitude 8 (125) 0.88 0.78 If I were to be physically active duringmy free time on most days...

It would be fun Having fun is...

Social norms 8 (125) 0.73 0.88 My fellow students think I should bephysically active during my free timeon most days I want to do whatmy fellow students want me to do

Parental support 5 (04) 0.94 0.82 During a typical week, how often hasyour parent encouraged you to dophysical activity or sports?

Sport equipment at home 1 (15) 0.86 NA At home there are enough supplies andpieces of sports equipment (e.g., balls,bicycles, skates) to use for physical activity

Access to facilities 1 (15) 0.89 NA There are playgrounds, parks, or gyms closeto my home that I can get to easily

Neighborhood safety 1 (15) 0.78 NA It is safe to walk or jog alone in myneighborhood during the day

Perceived walkability 1 (15) 0.73 NA It is difficult to walk or jog in myneighborhood because of things like traffic,no sidewalks, dogs, or gangs

School activity programs 3 (01) 0.83 0.61 At your school, are there supervised physicalactivity programs (e.g., mass walking,mass jogging) for all interested students?

Participation in sports teams 2 (03) 0.97 0.59 During the past 12 months, how many sportsteams run by your school did you play on?

Enjoyment of physical activity 14 (15) 0.90 0.91 When I am active ... I enjoy it

NA not applicable

Int.J. Behav. Med. (2010) 17:279286 281

approximately 30 to 45 min to complete. Prior to datacollection, both instruments were piloted to ensure that thereading level and response format were appropriate forSingaporean adolescents.

Statistical Analysis

All data were analyzed using STATA, version 7.0.Descriptive statistics were calculated for mean MET levelsand physical activity correlate variables. Due to positivelyskewed data, mean METs was log-transformed. Crudeassociations between mean METs and the hypothesizedcorrelates of physical activity were assessed using Pearsonproductmoment correlation coefficients. Hierarchical line-ar regression analysis was conducted to determine whetherthe demographic, psychological, and environment variablesexhibiting significant univariate relationships were inde-pendently associated with participation in physical activity.Analyses were performed separately for boys and girls.Significance was set at an alpha level of 0.05.

Results

Descriptive statistics for the physical activity and correlatevariables are presented in Table 2. On average, boysreported significantly higher mean MET scores than girls.Boys also scored significantly higher than girls on the self-efficacy and social norms scales. No significant genderdifferences were observed for the remaining variables.

Simple correlations between physical activity and thehypothesized correlates are shown in Table 3. For boys,self-efficacy, attitude, social norms, enjoyment of physicalactivity, parental support, sport equipment at home, access

to sports, safety concerns, availability of supervised schoolsports, and participation in sports teams were significantpositive correlates of physical activity. Correlations rangedfrom 0.06 for social norms to 0.26 for self-efficacy. Forgirls, self-efficacy, attitude, social norms, enjoyment ofphysical activity, parental support, sport equipment athome, access to sports, neighborhood safety, and participa-tion in sports teams were significant positive correlates ofphysical activity. Correlations ranged from 0.07 for accessto sports to 0.20 for parental support. Low perceptions ofneighborhood walkability exhibited a weak but significantinverse correlation with physical activity behavior.

Table 4 presents the results of the hierarchical regressionanalysis for boys. On step 1, the demographic influences ofrace, grade level, and socioeconomic status accounted for

Variable Boys (n=919) Girls (n=895)Mean (95% CI) Mean (95% CI)

Activity

Mean METs 1.98 (1.942.02) 1.83 (1.801.85)*

Correlates

Self-efficacy 3.38 (3.313.45) 3.26 (3.233.29)*

Attitude 15.87 (15.3916.35) 15.52 (15.2515.78)

Social norms 11.20 (10.7311.67) 10.31 (9.9410.67)*

Enjoyment of physical activity 3.95 (3.884.02) 3.85 (3.813.90)

Parental support 0.95 (0.851.06) 0.99 (0.811.18)

Sport equipment at home 3.49 (3.363.62) 3.36 (3.243.48)

Access to facilities 3.61 (3.553.67) 3.75 (3.673.82)

Neighborhood Safety 3.86 (3.724.01) 3.67 (3.493.85)

Perceived walkability 2.49 (2.392.59) 2.48 (2.302.65)

School activity programs (%) 51.6 (48.854.4) 53.5 (49.957.1)

Participation in sports teams (%) 61.8 (57.466.2) 61.1 (57.265.0)

Table 2 Gender differences inmean METs and correlates ofphysical activity in Singaporeanadolescents

*p

only 1% of the variance with physical activity (F(3, 914)=3.57, p=0.014), with race being the only significantindependent predictor. When self-efficacy, attitude, socialnorms, and enjoyment of physical activity were entered onstep 2, it significantly increased the predictive power of themodel (incremental F(4, 911)=19.46, p

An important finding was that self-efficacy was posi-tively associated with physical activity in both boys andgirls. Our results are consistent with previous studies,showing that self-efficacy is an important intrapersonalinfluence on physical activity behavior [10]. Bungum andcolleagues [22] found self-efficacy to be a key correlate ofphysical activity behavior in both male and female youth.Similarly, Allison and colleagues [23] reported self-efficacyto be positively associated with participation in vigorousphysical activity in Canadian high school students. Inaccordance with the major tenets of Social CognitiveTheory [14], self-efficacy perceptions can be derived frompast performances, vicarious experiences (modeling), ver-bal persuasion, and physiological state. Therefore, toincrease physical activity self-efficacy in Singaporeanadolescents, intervention programs should: (1) provideenjoyable, developmentally appropriate positive physicalactivity experiences (e.g., emphasize moderate to vigorousintensity activities such as brisk walking); (2) createopportunities to observe significant others (e.g., parents,peers, teachers) perform physical activity; (3) providereinforcement to participate in physical activity (e.g., welldone, keep it up); and (4) reduce any anxiety associated with

the participation of physical activity by reducing oreliminating competitions and inappropriate testing practices.

Enjoyment of physical activity has long been considered animportant influence on physical activity. Consistent withresults from previous investigations [22, 24, 25], enjoymentof physical activity was positively associated with physicalactivity behavior in both boys and girls. Interventionsdirected at Singaporean adolescents should aim to promoteenjoyment of physical activity by offering a wide variety oftraditional and nontraditional physical activity options thatmeet their needs and interests of students. Examples oftraditional physical activity options include team andindividual sports such as basketball, soccer, swimming, andbadminton. Examples of nontraditional physical activityoptions include after-school walking programs, skateboard-ing, and exergames such as Dance Dance Revolution.

The present study found that parental support was a keyinfluence on physical activity behavior for both boys andgirls. This finding is in accordance with results of previousinvestigations [26]. The positive effects of parental supportfor physical activity suggest that health practitioners andeducators should aim to increase parental supportivebehaviors when designing and implementing physical

Variables b SE (b) Std beta Adj R2 Model R2

Step 1

Race* 0.008 0.003 0.093 0.010 0.013Grade level 0.006 0.005 0.044Socio economic status (SES) 0.008 0.005 0.052Step 2

Race* 0.006 0.003 0.076 0.052 0.059Grade 0.004 0.005 0.032Socio economic status (SES) 0.007 0.005 0.049Self-efficacy* 0.012 0.004 0.105

Attitude 0.001 0.010 0.049

Social norms 0.000 0.001 0.010

Enjoyment of physical activity* 0.012 0.005 0.106

Step 3

Race 0.004 0.003 0.045 0.082 0.096Grade 0.003 0.005 0.019Socio economic status (SES) 0.001 0.005 0.004Self-efficacy* 0.008 0.004 0.070

Attitude 0.001 0.001 0.037

Social norms 0.000 0.001 0.025Enjoyment of physical activity* 0.010 0.005 0.082

Parental support* 0.011 0.003 0.129

Sport equipment at home* 0.006 0.002 0.090

Access to facilities 0.017 0.003 0.025Neighborhood safety 0.004 0.003 0.049

Perceived walkability 0.002 0.005 0.032Participation in sports teams* 0.012 0.005 0.083

Table 5 Hierarchical regressionanalyses for the prediction oflog mean METS amongSingaporean adolescent girls(N=895)

*p

activity intervention programs. This can be accomplishedby teaching parents to: (1) facilitate access to physicalactivity opportunities by signing up their child for physicalactivity programs; (2) provide transportation to recreationalfacilities (e.g., parks); (3) observe their child participate inphysical activity; (4) counsel their child that physicalactivity is good for health; and (5) provide appropriatelevels of positive reinforcement for their childs masteryattempts in physical activity.

In the present study, involvement in school sports was asignificant positive correlate of physical activity in boys andgirls. Our results are similar to that of previous studies,showing that participation in community sports and physicalactivity programs are significant predictors of moderate tovigorous physical activity among school-aged children [27,28]. This suggests that an effective way to increase physicalactivity in adolescent boys and girls is to promote greateraccess of physical activity programs in schools andcommunities. To achieve this, community programs shouldprovide a range of developmentally appropriate physicalactivities that cater to the needs of adolescents. To increaseawareness of community-based sports and physical activityprograms, local recreational community centers shouldactively collaborate with schools to educate parents andstudents of their physical activity programs.

An interesting finding from the present study was thataccess to sports/fitness equipment at home was a significantpositive correlate of physical activity among girls, but notboys. Previous investigations have reported similar results. Ina 5-year longitudinal study of Canadian adolescent girls,Butcher [29] observed availability of sports equipment to bea significant positive predictor of sustained involvement inphysical activity. In their examination of the correlates ofphysical activity in the fifth- and sixth-grade students,Stucky-Ropp and DiLorenzo [24] observed the number ofexercise-related items in the home to be positively associatedwith physical activity in girls, but not boys. Similarly, Trostand colleagues [30] reported access to sporting/fitnessequipment to be positively associated with objectivelymeasured moderate physical activity in girls. No relationshipwas observed for physical activity of any intensity in boys.

The positive association between sporting/fitness equip-ment at home and activity behavior in girls but not boysmay, in part, be related to gender differences in preferencesfor activity. The results of two prospective studies indicatethat girls are more likely than boys to participate inindividual activities that are more likely to require fitness/sporting equipment at home [31, 32]. Alternatively, giventhe cross-sectional study design, our finding may be afunction of reverse causality. Parents with daughters whoare physically active may be more likely to providesporting/fitness equipment than those with low-activedaughters. Notably, when DiLorenzo et al. [25] longitudi-

nally examined the correlates of physical activity over a 3-year period, access to exercise-related items measured inthe fifth and sixth grades was not a significant predictor ofphysical activity behavior among girls in the eighth andninth grades.

This study had a number of limitations that warrantconsideration. First, the cross-sectional design of the presentstudy precluded us from inferring a causal relationshipbetween the hypothesized correlates and physical activitybehavior. Second, the use of self-report measure of physicalactivity may be subject to recall bias and social desirabilityeffects. Third, we were only able to explain a smallpercentage of the variance in physical activity behavior (i.e.,10% in boys and 8% in girls). This latter observation suggeststhat other variables not measured in this study could be salientinfluences on physical activity behavior in Singaporeanadolescents. It is likely that time spent outdoors, sedentaryopportunities, the built environment, and land use policies(e.g., activity friendly community design programs thatpromote physical activity) are important influences onphysical activity behavior among Singaporean adolescents.Therefore, in addition to the influences examined in thepresent study, future investigations should evaluate therelative importance of environmental and policy influenceson activity levels among Singaporean youth. Notwithstandingthese limitations, we have identified a number of importantcorrelates of physical activity that can be targeted byintervention programs for Singaporean high school students.

In summary, physical activity self-efficacy, enjoyment ofphysical activity, parental support, and participation in sportsteams were key correlates of physical activity in Singaporeanadolescents. To further increase our understanding ofphysical activity behavior in Singaporean youth, futurestudies should examine the influence of policy and the builtenvironment on physical activity behavior and, wherepossible, utilize objective measures of physical activity.Additionally, future studies should examine the correlates ofphysical activity in other age groups of Singaporean youthsuch as preschoolers and elementary school children.

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