Prevalence of overweight/obesity and its association with sedentary behavior in children

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Revista

Portuguesa

de

Cardiologia

Portuguese

Journal

of

Cardiology

www.revportcardiol.org

ORIGINAL

ARTICLE

Prevalence

of

overweight/obesity

and

its

association

with

sedentary

behavior

in

children

Catarina

Vasques

a,∗

,

Maria

Mota

b

,

Teresa

Correia

c

,

Vítor

Lopes

a

aResearchCenterinSportsSciences,HealthSciencesandHumanDevelopment,PolytechnicInstituteofBraganc¸a,Department ofSportsScience,Braganc¸a,Portugal

bResearchCenterinSportsSciences,HealthSciencesandHumanDevelopment,UniversityofTrás-os-MontesandAltoDouro, SchoolofHealth,Braganc¸a,Portugal

cResearchCenterinSportsSciences,HealthSciencesandHumanDevelopment,PolytechnicInstituteofBraganc¸a,School ofHealth,Braganc¸a,Portugal

Received26January2012;accepted18March2012 Availableonline13November2012

KEYWORDS

Bodymassindex; Riskfactors; Sedentarylifestyle

Abstract

Objective: Theaimofthisstudywastodeterminetheprevalenceofoverweightandobesity inchildreninthenortheastregionofPortugal,andtoexamineitsassociationwithsedentary behavior.

Methods:Datawerecollectedon1786children(907boys,879girls)aged6to13years.Body massindexwascalculatedfrommeasuredheightandweight(weightinkg/heightinmsquared). Overweight andobesity were determined usingthe InternationalObesity Task Forcecutoff values.Sedentarybehaviorwasassessedbasedonmeansoftransporttoandfromschooland timespentwatchingTVandplayingvideogames(TVPC).

Results:The prevalences ofoverweight andobesitywere 22.6% and9.4%respectively. The differencesbetweenthesexesforbothoverweightandobesitywerenotsignificant.Mostof thechildren (78.4%)go toschoolby car.Boys spendmoretimeonTVPCthangirls, bothon weekdaysandonweekends.Thelogisticregressionmodelindicatedasignificanteffectof1.5 hoursofTVPCbyboysduringweekdays(OR=0.246;p=0.015).Boyswhospentlessthan1.5hours onweekdaysonTVPCwere75.4%lesslikelytobeoverweightthanthosewhospentmorethan 1.5hours.

Conclusion: Theprevalenceofoverweight andobesitywas 32%.Only12.2% ofthechildren spendlessthan1.5hoursonTVPC.Boyswhospendlessthan1.5hoursonTVPCare75.4%less likelytobeoverweight/obesethanthosewhospendmorethan1.5hours.

© 2012 Sociedade Portuguesa de Cardiologia Published by Elsevier España, S.L. All rights reserved.

Correspondingauthor.

E-mailaddress:catarinav@ipb.pt(C.Vasques).

0870-2551/$–seefrontmatter©2012SociedadePortuguesadeCardiologiaPublishedbyElsevierEspaña,S.L.Allrightsreserved.

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PALAVRAS-CHAVE Índicedemassa corporal; Fatoresderisco; Estilodevida sedentário

Prevalênciadesobrepeso/obesidadeemcrianc¸aseasuaassociac¸ão

comcomportamentossedentários

Resumo

Objectivo:determinaraprevalênciadesobrepeso/obesidadeemcrianc¸asdaregiãoNordeste dePortugal,eanalisarsuaassociac¸ãocomosedentarismo.

Métodos: Osdadosforamrecolhidosem1786crianc¸as(n=907meninos,meninasn=879)com idadesentreos6e13 anos,oíndicedemassacorporalfoicalculadoapartirdaestaturae peso[massacorporal(kg)/Altura(m2)]medidos.Osobrepeso/obesidadeforamdeterminados usandoosvaloresdecortedaIOTF.Ocomportamentosedentáriofoiavaliadotendoemconta: omeiodetransporteetempogastoavertelevisão/jogarvideojogos(TVPC).

Resultados: aprevalênciadesobrepeso/obesidade foide 22,6%e 9,4%,respetivamente.As diferenc¸asentreossexos,tantoparaosobrepesocomoparaaobesidade,nãoforam significa-tivas.Amaioriadascrianc¸asusaoautomóvel(78,4%)parairàescola.Osmeninosgastarammais tempoemTVPCqueasmeninas,tantoduranteasemanacomonosfinsdesemana.Omodelo deregressãologísticaindicouumefeitosignificativode1,5horasdeTVPCpara osmeninos, duranteasemana(OR=0,246;p=0,015).Osmeninosquegastarammenosde1,5horasdurante asemanaemactividadesTVPCforam75,4%menospropensosaseremobesosdoqueaqueles quegastarammaisde1,5horas.

Conclusão:aprevalênciadesobrepeso/obesidadeatinge32%.Apenas12,2%gastammenosde 1,5horasemTVPC. Osmeninosque passammenosde 1,5horasem TVPCsão75,4% menos propensosatersobrepeso/obesidadedoqueaquelesquegastammaisde1,5horas.

© 2012 SociedadePortuguesa de Cardiologia. Publicado por Elsevier España, S.L.Todos os direitosreservados.

Introduction

A majority of western countries and those undergoing economic transition have experienced an increase in the prevalenceofchildhoodobesity.1Aslongagoas1997, obe-sitywasidentifiedasapublichealthprobleminbothadults andyouth.2

There is a large group of chronic diseases asso-ciated with obesity, including cardiovascular disease, diabetes, and hypertension.3,4 The main causes of obe-sityarelow levelsofdaily physical activityand excessive intake of high-calorie food,5 leading to imbalances that increase body fat mass. The problem has several dimen-sions,includingbiological,socialandpsychosocialaspects, and affects all age ranges, genders and socioeconomic levels.6

Several studies conducted in Portugal7---9 in children aged between 3 and 14 reveal the extent of the prob-lem.Apartfromthebiologicalandculturalcharacteristics of the samples, the prevalence of overweight ranged between 13% and 30%, and the prevalence of obesity was 4---14%. These studies also indicated that females ---adults and children --- are more affected by this epi-demic.

Despitethisnationaltrend,thesituationinthenortheast regionofPortugalisstillunknown.Thus,themaingoalof thisstudywastodeterminetheprevalence ofoverweight andobesityanditsassociation withsedentary behaviorin children of the northeast region of Portugal, as assessed by the type of transportation used between school and homeandtimespentwatchingTVandplayingvideogames (TVPC).

Methods

Population

Thesampleconsistedof1786subjects---879femaleand907 male---agedbetween 6and 13years.This number corre-spondstoallchildrenattendingpublicschoolsinthetowns of Braganc¸a andMacedodeCavaleirosin thenortheastof Portugal. Onlychildren who didnot attend schoolon the daysofdatacollectionwerenotincluded.

The data were collected during the 2008 school year. Authorization was obtained from the Executive Board of each school and informed consent was obtained from all childrenandtheirparents.Thestudywasapprovedbylocal educationauthoritiesandtheethicscommitteeofthe Poly-technicInstituteofBraganc¸a.

Heightandweightassessment

Allindividualswereassessedwithoutshoesandwith mini-malclothing(T-shirtandshorts).ASECAscale,model885, wasusedtomeasureweight,and thevalue wasrecorded inkilogramswithapproximationtohectograms.Heightwas measuredusingawall-mountedstadiometer;theresultwas recordedincentimeters.

Bodymassindex(BMI)(weightinkg/heightinmsquared) was calculated and the International Obesity Task Force (IOTF) cut-off values12 for overweight and obesity were used.

Assessmentofsedentarybehaviors

Allindividualsinthesampleansweredaquestionnaireabout their travelto and from school (whether theywalked or

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Table1 Meanvaluesandstandarddeviationsofweight(kg),height(cm)andBMI(kg/m2)inthestudypopulation,bygender

andage.

Age(years) Girls Boys

n Weight Height BMI n Weight Height BMI

6 98 26.0±5.4 122.0±4.7 17.4±3.0 77 26.1±4.9 122.0±5.3 17.4±2.4 7 137 28.0±5.8 126.7±4.9 17.4±3.0 149 28.0±5.3 127.9±5.6 17.0±2.4 8 127 31.2±5.9 132.1±5.7 17.8±2.7 131 32.4±6.5 133.1±6.3 18.1±2.7 9 135 35.0±8.1 137.7±6.5 18.3±3.3 130 35.2±6.8 137.2±6.1 18.6±2.8 10 125 39.7±8.4 143.7±7.3 19.1±3.1 138 39.7±7.7 142.6±7.7 19.4±3.5 11 137 45.8±10.3 150.3±8.1 20.1±3.6 154 43.2±11.2 148.1±7.4 19.5±4.0 12 79 48.0±9.1 154.0±6.4 20.1±3.0 93 48.8±10.4 154.2±7.1 20.5±3.8 13 40 54.9±12.6 157.7±6.3 21.9±4.1 31 50.1±10.8 160.0±9.0 19.4±3.1

cycledorwent bycarorbus) andthetimetheyspent,in hoursduringweekdaysandonweekends,watching televi-sion and playing video games (TVPC). The children were helped by the researchteam tocomplete their question-naires.

Statisticalanalysis

First,anexploratorydataanalysiswascarriedoutto iden-tifypossibleerrorsintheinformationinput,thepresenceof outliersandthenormalityofthedistributions.

Descriptivestatisticswerecalculatedforweight,height andBMI(meanandstandarddeviations).Apercentage anal-ysiswasalsocarriedoutonthetransportationusedandthe numberofhoursofTVPCuse.

As the variablesdidnot present normalityintheir dis-tributions,theKruskal---Wallistestwasusedtoanalyzethe differencesbetweenagegroupsandsexes.

To estimatetheassociationof TVPCandtransportused with overweight and obesity, logistic regression was usedseparatelyfor eachgender while controllingtheage effecttoobtainadjustedoddratios(OR).Forthispurpose, theTVPCvariablewascategorizedaccordingtothenumber ofhoursspentduringweekdaysandonweekends(upto1.5; 2.5;3.5;4.5;5.5;6.5and7.5hours).

Thesignificancelevelwasdefinedasp≤0.05.

Results

Table 1 presents the descriptive statistics (mean and standard deviation) of the population characteristics (weight,heightandBMI)byagesandgender.

Figure1presentstheprevalencesofoverweightand obe-sity according togender and age. The prevalences in the

overall population were respectively 22.6% and 9.4%. In boys,theprevalenceofoverweightwas23.2%andofobesity was8.7%.Ingirls,theprevalenceofoverweightwas22.1% andofobesitywas10.0%(Figure1).

Althoughtherewerenosignificantdifferencesbetween thesexes in overweightand obesity,there wasa general tendencyinboystohavehigheroverweightprevalenceatall ages,exceptattheagesof10,11and13years.Forobesity theconversewasseen;girlshadhighervaluesthanboysat allages,exceptattheagesof10,11and12years.

Nosignificantdifferenceswereobservedbetweenagesin overweightandobesity,buttherewasalowerprevalenceof obesityinoldersubjects.Regardingoverweight,thevalues wereverycloseatallages.

Thepercentagesbygenderandageofchildrenwhogoto andfromschoolbycarversusthosewhowalkor cycleare presentedinFigure2.

Car or buswasthe means oftransport for 78.4%.Only 21.6%ofthe childrenwalkedtoandfromschool.The car wasalsothe mostcommonmeans of transportinat least oneofthedailyjourneystoschool(56.3%).Thedifferences between thesexes werenot significant. Walking wasless commoninbothsexes:10.3%ofgirlsand11.3%ofboys.

Analysisof thedifferencebetween agesinthe typeof transportationtoandfromschoolindicates significant dif-ferencesbetween agesonly whentheyusethesametype of transportation both to and from school (chi-square(7)

Z=14.688;p=0.040).Olderchildrenlessfrequentlytraveled bycar.

Figure3presentsby ageandgender themeannumber ofhourschildrenspenteachweekdayandonweekendson TVPC.

Duringtheweek,themeanvalueswerelower,especially forboys(3.06hoursforgirlsand3.64hoursforboys),than ontheweekend(3.50hoursforgirlsand4.44hoursforboys).

Obesity 30% 20% 10% 0% Girls Boys Age (years) Prevalence Overweight 30% 20% 10% 0% Girls Boys Age (years) Prevalence 6 7 8 9 10 11 12 13 6 7 8 9 10 11 12 13

Figure1 Prevalenceofoverweightandobesityinthestudypopulation,accordingtotheInternationalObesityTaskForcevalues,10

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Girls 0% 20% 40% 60% 80% 100% Boys Pre v a lence 0% 20% 40% 60% 80% 100% Pre v a lence 6 Age (years) 7 8 9 10 11 12 13 6 Age (years) 7 8 9 10 11 12 13 car car/walk walk car car/walk walk

Figure2 Percentagesofchildrenwhogobycar(car)orwalk(walk)toandfromschool,orgotoschoolbycarandwalkhome (car/walk),bygenderandage.

Age (years) TVPC (hours) TVPC (hours) Weekdays Weekends 6 8 6 4 2 0 8 6 4 2 0 7 8 9 10 11 12 13 Girls Boys Girls Boys Age (years) 6 7 8 9 10 11 12 13

Figure3 Meannumberofhoursspentwatchingtelevisionandplayingvideogamesonweekdaysandweekends,bygenderand age.

Boysspentsignificantlymoretimethangirlsinsedentary activities(TVPC),bothonweekdays(chi-square(1)Z=11.647;

p=0.001)andonweekends(chi-square(1)Z=7.817;p=0.005).

Older children spent significantly more time than younger children on TVPC both during weekdays (chi-square(7)Z=30.740;p=0.000)andonweekends(chi-square(7)

Z=25.495;p=0.001),with theexception of seven-year-old childrenonweekends.

Consideringtheoverallpopulation,only12.2%ofchildren spentlessthan1.5hoursonTVPC,whetheronweekdaysor onweekends.

The logisticregressionmodel didnotindicatea signifi-canteffectofthe‘‘transport’’variable;itonlyindicateda significanteffectof1.5hoursofTVPCbyboysonweekdays (OR=0.246;p=0.015),whichmeansthatboyswhospentless than1.5hoursonweekdayswatching televisionorplaying videogameswere75.4%lesslikelytobeoverweight/obese thanthosewhospentmorethan1.5hours.

Discussion

Theaimof thisstudywastodeterminethe prevalenceof overweightandobesityrelatedtosedentarybehaviorin chil-drenfromthenortheastregionofPortugal,namelythetype oftransportationtoandfromschoolandtimespent watch-ingtelevisionandplayingvideo games.The prevalenceof overweightandobesitywasdeterminedthroughBMI,using theIOTFreferencevalues.10

Thesamplewasnotrandom,andnoattemptwasmade tofinda representativesample ofchildren in the region; theintentionwasrathertoevaluateallchildrenaged6to 13attending publicschools in the towns of Braganc¸aand Macedo de Cavaleiros. Only children who did not attend schoolonthedaysofdatacollectionwerenotincluded.

The prevalences of overweight and obesity in children inthisregionofPortugalwere22.6%and9.4%,respectively. Theseresultsareinagreementwiththosefromotherstudies

carried out in Portugal11,12 that indicate a prevalence of overweightandobesityofaround30%.

Somestudies13,14 indicate ahigher prevalence of over-weightandobesityinfemalesthaninmales.Inthepresent study, girls had a higherprevalence of obesity than boys at almost all ages,but the prevalence of overweightwas higherinboysthaningirls,althoughthedifferencewasnot significant.

Thisstudy analyzedthe timespentwatching television andplaying videogames andthemeans oftransportused toandfromschool.Asexpected,childrenspentmoretime watching televisionand playingvideo gamesonweekends thanonweekdays.Boysspentmoretimeinbothcasesthan girls,andyoungerchildrenofbothsexesspentlesstimethan olderonesintheseactivities.

Asedentary lifestyleasidentified inthis study corrob-orates the findings of other studies,15,16 particularly with regardtotheimportanceofinactivityasariskfactor asso-ciatedwithobesityinchildren.

An association between excess weight and sedentary activitiessuchaswatchingtelevisionhasbeenreportedin numerous studies.17,18 Infact, screen timecompeteswith physicalactivitytime,19 leadingtoreducedlevelsof exer-ciseinchildren.20,21Besidestheassociationbetweenscreen timeandoverweight/obesity,foodintakeduringthisactivity canmakethisassociationevenmoresignificant.22

Inyoungerchildren,overweight/obesityseemsto aggre-gate in families.23 The daily pattern of parents’ physical inactivityandactivitycaninfluencetheirchildren’s behav-ior. At olderages,aschildrenbecome moreindependent, theirchoicesareoftenmoreinfluencedbytheirpeersthan bytheirparents.24

Televisionviewingisfrequently usedasanindicator of inactivityin epidemiologicandinterventionstudies.25 This parametercorrelatesstronglywithobesityinchildhood.26,27 Inourstudy,thiscorrelationwasalsoidentifiedinboys.A significant effect of 1.5hours of TVPC wasobserved dur-ingweekdays,withboyswhospendlessthan1.5hourson

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weekdayswatchingtelevisionandplayingvideogamesbeing 75.4% less likelyto be overweight/obese than those who spendmorethan1.5hours.Withgirls,nosuchassociation wasobserved.

Twomainexplanationsmaybeadvancedforthisresult: (1) girlsusually spend theirleisure time in activities that requirelowerenergyexpenditurethanboys,28contributing tothehigherincidenceofobesityingirls;and(2)although themain sedentary behaviorscitedin theliterature were assessed,otherhabits,possiblymorecloselyrelatedtogirls’ choices,werenotconsideredinthisstudy.Soproblemswith assessmentoftotalsedentarybehaviorsmayexplainwhy,in thisstudy,girlsseemtobelessinactivebutaremoreoften obese.

Sincechildrenspendsomuchtimeplayingvideogames, it would be helpful for parents and educators toprovide childrenwithinteractivegames.Althoughnotproven,there seemstobeacorrelationbetweentheuseofvideogames andobesity,butsomeauthorsstatethattheenergy expendi-tureofplayingvideogamesissimilartothatofwalkingand running.29 Regularlyplaying activevideo games mayeven havepositiveeffectsonoveralllevelsofchildren’sphysical activity.30

Goingtoschoolcanbephysicalactivity,sincesome chil-drenwalkorcycle,butinchildreninthepresentstudy,the carwasthemostcommontypeoftransportation.Younger childrenwalktoschoollessfrequentlythanolderchildren. Atyoungerages,parentsusuallytakechildrentoandfrom school,mostlybycar.Thecommonuseofmechanicalmeans oftransportationtogotoschoolisassociatedwithalower levelofenergyexpenditure,contributingtoincreased over-weightandobesityinchildren.However,theresultsofthis studydidnotshowasignificanteffectofthetypeof trans-portonoverweightorobesity.

The fact that TVPC and type of transportation used wereevaluatedthroughaquestionnaireandnotby direct observation is a limitation of this study that may influ-encetheresultsoftheassociationbetweenthesevariables and overweight/obesity. Children sometimes have diffi-cultyanswering questionnairescorrectly,astheir recallis limited.31 However, this study would have been virtually impossibletocarryoutbydirectobservation.

Inconclusion,theprevalenceofoverweightandobesity inchildrenfrom6to13yearsofageintheNortheastregion ofPortugal(Braganc¸aandMacedodeCavaleiros)was32%. Themajorityofchildrengotoschoolbycar,andonly12.2% spendlessthan1.5hourswatchingtelevisionand/orplaying videogames.Boyswhospendlessthan1.5hourswatching televisionand/orplayingvideogamesare75.4%lesslikely tobe overweight/obesethan thosewhospend more than 1.5hours.

Ethic

disclosures

Protection of human and animal subjects.The authors declarethatnoexperimentswereperformedonhumansor animalsforthisinvestigation

Confidentialityofdata.Theauthorsdeclarethattheyhave followedtheprotocolsoftheirworkcenteronthe publica-tionofpatientdataandthatallthepatientsincludedinthe

studyhave receivedsufficientinformationand havegiven theirinformedconsentinwritingtoparticipateinthestudy.

Right to privacy and informed consent.The authors declarethatnopatientdataappearsinthisarticle.

Conflicts

of

interest

Theauthorshavenoconflictsofinteresttodeclare.

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