REVISTA
PAULISTA
DE
PEDIATRIA
www.rpped.com.br
ORIGINAL
ARTICLE
Association
between
cardiorespiratory
fitness
and
body
fat
in
girls
Giseli
Minatto
a,∗,
Thiago
Ferreira
de
Sousa
b,
Wellington
Roberto
Gomes
de
Carvalho
c,
Roberto
Régis
Ribeiro
d,
Keila
Donassolo
Santos
d,
Edio
Luiz
Petroski
aaCentrodeDesportos,NúcleodePesquisaemCineantropometriaeDesempenhoHumano,UniversidadeFederaldeSanta
Catarina(UFSC/CDS/NuCiDH),Florianópolis,SC,Brazil
bUniversidadeFederaldoTriânguloMineiro,Uberaba,MG,Brazil
cLaboratóriodeEstudosePesquisasEpidemiológicasemAtividadeFísica,ExercícioeEsporte(LAPAES),Departamento
deEducac¸ãoFísica,UniversidadeFederaldoMaranhão,SãoLuís,MA,Brazil
dFaculdadeAssisGurgacz,Cascavel,PR,Brazil
Received10September2015;accepted2February2016 Availableonline14July2016
KEYWORDS
Adolescent; Physicalfitness; Bodycomposition
Abstract
Objective: Toestimatetheprevalenceoflowcardiorespiratoryfitnessanditsassociationwith excessbodyfat,consideringthesexualmaturationandeconomiclevelinfemaleadolescents. Methods: Cross-sectional,epidemiologicalstudyof1223adolescents(10---17years)fromthe publicschool systemofCascavel,PR, Brazil,in2006.We analyzed theself-assessed sexual maturationlevel(prepubertal,pubertalandpost-pubertal),theeconomiclevel(highandlow) throughaquestionnaireandbodyfat(normalandhigh)throughtricepsandsubscapular skin-folds.The20-meterback-and-forthtestwasappliedtoestimatemaximumoxygenconsumption. Cardiorespiratoryfitnesswasassessedaccordingtoreferencecriteriaandconsideredlowwhen theminimumhealthcriterionforageandsexwasnotmet.Chi-squaretestandlogisticregression wereapplied,withasignificancelevelof5%.
Results: Theprevalenceoflowcardiorespiratoryfitnesswas51.3%,beingassociatedwithall studyvariables(p<0.001).Atthecrudeanalysis,adolescentswithhighbodyfatwereassociated withlowcardiorespiratoryfitness,when comparedtothosewithnormalbodyfat (OR=2.76; 95%CI:2.17---3.52).Afteradjustmentbysexualmaturation,thisassociationremainedvalidand showedaneffectthatwas1.8-foldhigher(95%CI:1.39---2.46)andafteradjustingbyeconomic level,theeffectwas1.9-foldhigher(95%CI:1.45---2.61).
Conclusions: Approximatelyhalfoftheassessedgirlsshowedunsatisfactorylevelsof cardio-respiratory fitnessfor health,whichwasassociated withhighbodyfat,regardlessofsexual
∗Correspondingauthor.
E-mail:gminatto@gmail.com(G.Minatto).
http://dx.doi.org/10.1016/j.rppede.2016.02.014
maturationlevelandeconomiclevel.Effectivepublichealthmeasuresareneeded,with par-ticularattentiontohigh-riskgroups.
©2016SociedadedePediatriadeS˜aoPaulo.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).
PALAVRAS-CHAVE
Adolescente; Aptidãofísica; Composic¸ãocorporal
Relac¸ãoentreaptidãocardiorrespiratóriaeadiposidadecorporalemmeninas
Resumo
Objetivo: Estimar aprevalência de aptidão cardiorrespiratória baixa e suaassociac¸ão com excessodeadiposidadecorporal,considerandoamaturac¸ãosexualeoníveleconômico,em adolescentesdosexofeminino.
Métodos: Estudo epidemiológico transversal com 1.223 adolescentes (10-17 anos) da rede públicadeensinodeCascavel,PR,Brasil,em2006.Analisou-seamaturac¸ãosexual(pré-púbere, púberee pós-púbere) autoavaliada, onível econômico(NE) (alto ebaixo) porquestionário eaadiposidadecorporal(normaleelevada)pordobrascutâneasdotríceps esubescapular. Aplicou-seoteste devaivémde 20metros para estimaroconsumo máximodeoxigênio. A aptidãocardiorrespiratóriafoiavaliadaporcritériosreferenciadoseconsideradabaixaquando nãoatingidoocritériomínimoparaasaúdesegundoidadeesexo.Foramaplicadosotestede qui-quadradoearegressãologística,comníveldesignificânciade5%.
Resultados: A prevalênciadeaptidãocardiorrespiratóriabaixa foide51,3%quese associou atodasasvariáveisdoestudo(p<0,001).Naanálisebruta,asadolescentescomadiposidade corporal elevadaassociaram-se àaptidãocardiorrespiratóriabaixa,quandocomparadacom aquelascomadiposidadenormal(RC=2,76;IC95%2,17-3,52).Apósajustepelamaturac¸ão sex-ual,essaassociac¸ãosemanteveemostrouefeito1,8vezmaior(IC95%1,39-2,46)e,apósajuste peloNE,oefeitofoi1,9vezesmaior(IC95%1,45-2,61).
Conclusões: Aproximadamente metade dos avaliados apresentou níveis insatisfatórios de aptidãocardiorrespiratóriaparaasaúde,oqueseassociouàadiposidadecorporalelevada, inde-pendentementedamaturac¸ãosexualeNE.Medidasefetivasdesaúdepúblicasãonecessárias, comespecialatenc¸ãoparagruposdemaiorrisco.
©2016SociedadedePediatriadeS˜aoPaulo.PublicadoporElsevierEditoraLtda.Este ´eum artigoOpenAccesssobumalicenc¸aCCBY(http://creativecommons.org/licenses/by/4.0/).
Introduction
Cardiorespiratoryfitnessisconsideredanimportantmarker ofhealthsincechildhoodandadolescence.1Itisdefinedas
thecapacityof thecirculatory andrespiratory systemsto supplyoxygentothemusclesduringexerciseofmoderate tohighintensityandinvolveslarge musclegroups forlong periodsoftime.2
Studies indicate that cardiorespiratory fitness in chil-dren and adolescentshas decreased in recent decades in 27countries(reductionof0.46%)3 andin Brazil(reduction
of0.51%).4Theproportionofadolescentsthatdonotreach
acceptablelevelsofthiscomponentofphysicalfitnessfor healthvariesfrom37.8%5inFlorianopolisto60%6inParana.
The low level of cardiorespiratory fitnessis associated with increased cardiovascular risk factors and metabolic syndromeinyoungindividuals,7aswellastoincreased
car-diovascularriskinadulthood.8Ameta-analysisshowedthat
theoverallriskofdeathfromallcausesorfrom cardiovas-cular disease was two-fold higher in individuals with low cardiorespiratoryfitnesslevels,comparedtothosewithhigh levels.8 AccordingtoAzambujaetal.,9in2004theannual
costtopublicfundsforthetreatmentofcardiovascular dis-easewasR$30.8billion(36.4%for health,8.4%for social securityand reimbursementby employersand 55.2% asa resultoflostproductivity).
Anotheraggravatingfactoroflowfitnesslevelsisexcess bodyfatevenatearlyages.Adolescents withexcessbody fathavelowercardiorespiratoryfitness,6,10,11predominantly
girls.10 The increased gain in adiposity in adolescence is
associatedwiththeonsetofpuberty,at whichstagegirls, throughaction ofthehormoneestrogen,tend to accumu-latehigheramountsofbodyfat.12However,thereisastudy
thatreportsanegativeassociation between cardiorespira-tory fitness and sexual maturation, which controlled the percentageofbodyfatingirls10andmayindicatechangesin
cardiorespiratoryfitnessduringthematurationaland physi-caldevelopment.
Althoughtheassociation between cardiorespiratory fit-nessandbodyadiposityhasbeenexploredinadolescents,6,13
thereisagapintheliteratureontheassociationbetween thesevariableswhileconsideringtheeconomiclevel.In ado-lescents of high economic level, better cardiorespiratory fitnesswasfound inadolescentswithlessaccumulationof bodyfat.6
Whenonlytheboysareassessed,theassociationbetween body fat and other physical fitness components is also inverse,butseemstodifferbetweensocialstrata.13 Other
authors, in a study involving both genders, reported no association between cardiorespiratory fitness and eco-nomiclevel.5Theseconflictingresultsemphasizetheneed
cardiorespiratoryfitnessandbodyfatindifferenteconomic strata, aspreventive actionsmight considersuchaspects. Therefore,thisstudyaimedtoestimatetheprevalenceof lowcardiorespiratoryfitnessanditsassociationwithexcess bodyfat,whileconsideringsexualmaturationandthe eco-nomiclevelinfemaleadolescents(aged10---17years)from thecityofCascavel,Paranástate,Brazil.
Method
This is a school-basedepidemiological andcross-sectional study carriedout in 2006in Cascavel city,West regionof Paranástate,SouthernBrazil.Theestimatedpopulationof themunicipality in 2006 wasof 245,369inhabitants, with themajority(93.2%)livingintheurbanarea.14TheHuman
DevelopmentIndex(HDI)ofthemunicipalityis0.810(high humandevelopment).15
This article is part of a larger epidemiological, cross-sectionalstudy,called‘‘Anthropometry,bodycomposition, motorperformanceandsexualmaturationofstudentsfrom different socioeconomic levels in Cascavel city, Paraná’’. The target population of the largest study consisted of femalestudentsaged8---17years,livingintheurbanarea.
AccordingtothereportoftheRegionalEducationCenter andtheMunicipalEducationSecretariatofCascavel,in2006 the municipality had 39,830 students enrolledin elemen-taryandhighschools.GiventhattheMunicipalSecretariat of Education does not provide thenumber of studentsby gender,adistributionof50%wasconsidered,totalinga pop-ulationof19,915femalestudents.The samplecalculation followed theproceduressuggested byBarbetta,16 withan
expectedprevalenceof50%fortheoutcome,sampleerror of2percentagepointsand95%confidenceinterval,resulting inasampleof2221girls.
Thesamplingprocedureconsistedofathree-stage con-glomerate,withthefirstbeingtheeducationaldistrict,the secondbeingtheschoolandthethirdtheclasses, respect-ing the proportionality. Three educational districts were formedaccordingtothedistributionofstudentsindifferent geographicregions of themunicipality in orderto ensure better representativeness, according to the geographical divisionproposedbytheRegionalEducationCenterof Cas-cavel, PR. Student distribution showed a ratio of 35.8% at district I; 33.1% in district II and 31.2% in district III.
Atthefirststage,fourschoolswerechosenfromeach dis-trictbydrawinglots,twomunicipalandtwostateschools. Inthesecond stage,theschools thatwould participatein thestudywerechosen froma listprovidedbythe institu-tionsthemselves,whichcontainedtothestudents’ages,by drawinglots.Atthethirdstage,wecarriedoutasimple ran-domselectionofclasses,consideringtheproportionalityin relationtothetargetpopulation.
Forthisstudy,thecalculationofthesample’sstatistical power wascarriedout retrospectively. Totest the associ-ation between body fat (exposure) and cardiorespiratory fitness(outcome),aprevalenceofexposureof38%,a preva-lenceofoutcomeintheunexposedof42%andaconfidence level of 95% were considered with the analyzed sample (n=1223). Thestudy had100%power tofindan oddsratio of1.6orhigherassignificant.
Forthepresentstudy,onlytheadolescents(10---17years) enrolledin municipalor state publicschools who werein theclassroom onthe day ofdata collectionweredefined aseligible.Schoolsunabletoperformthecardiorespiratory fitnesstest andstudentsaged<10yearswereexcluded, as theaforementioned physical test is not indicated for this agerange.17
The evaluation team consisted of 3 teachers and 12 students of Physical Education. They underwent previous trainingtostandardizetheanthropometricassessmentand apilotstudyaimedtotestthemeasuringtoolsusedinthe study. The intra- and inter-rater technical error of mea-surement(TEM)waspreviouslycalculatedinasampleof19 studentsthatdidnotparticipateinthestudy.Theintra-rater TEMlimitwas3%forskinfoldsand1%forother measures. ForinterraterTEM,anerrorlimitof7%wasconsideredfor skinfoldsand1%forothermeasures.
DatacollectionwascarriedoutinAugust2006atschool duringthe classperiod.Anthropometric measurementsof bodyweight,heightandskinfoldstocharacterizethe sam-ple,nutritionalstatusandbodyfatevaluationwereobtained inapreviouslypreparedroom.Theself-assessmentofsexual maturationwascarriedoutinadifferentroom.
Demographicinformationongender,ageandskin color was self-reported in a questionnaire. Specifically, skin colorwasobtained basedonself-report, accordingtothe definitionsofInstitutoNacionaldeEstudosePesquisas Edu-cacionaisAnísioTeixeira(INEP).18
Cardiorespiratory fitnesswas obtained throughthe 20-meter shuttle run test proposed by Leger et al.19 and
validated for Brazilian samples.20 To determine whether
cardiorespiratoryfitness waslow,thecriteriareportedby Fitnessgramwereused.17
Body mass was measured in a bioimpedance scale (Tanita®)(TBF305model),withaprecisionof0.1kg.Height
was obtained with stadiometer (Seca®) and precision of
0.1cm. Both measurements were obtained by following standardprocedures.21
The sexual maturation stage was obtained by self-assessment of breast development,22 which is indicated
for the diagnosis of sexual maturation in children and adolescents.23Thestudentsreceivedrecommendations
indi-viduallyregardingthepurposeoftheassessmentandwere informedabout theself-assessmentproceduresand recor-dingthestageatwhichtheywereonaform.Thestudents wereasked to carefully observe each of the photographs andtoidentifythe oneonthe formthat mostresembled theirbreastsatthattime.Thevolunteersweredividedinto threegroups:prepubertal(stageI),pubertal(stagesII---IV) andpost-pubertal(stageV).12
Socialclasswasidentifiedthroughaquestionnaireofthe BrazilianAssociation ofSurveyCompanies(Abep),24 which
estimatesthefamilies’purchasingpowerbasedonthe accu-mulationofmaterialgoods,housingconditions,numberof domesticemployeesandeducationallevelofthehousehold head.The questionnaireclassifies,in descendingorder,in fiveclasses:A1,A2,B1,B2,CandD.Forthepresentstudy, thevolunteerswereclassifiedashigh(A+B)andlow eco-nomiclevel (C +D + E),due tothe lowfrequency of the categories.
(SS)skinfoldthicknesswasmeasuredintherighthemibody and in duplicate using a caliper (Cescorf®
Equipamen-tosAntropométricosLtda,PortoAlegre,Brazil).Themean valueofeachskinfoldwascalculatedandthesumofboth employedintheequationsofSlaughteretal.25:
BF%=0.546(TR+SS)+9.7(sumofTRandSSskinfolds>35mm);
BF%=1.33(TR+SS)−0.013(TR+SE)2
−2.5(sumofTRandSSskinfolds<35mm).
Basedonthevalueobtainedintheequations,thesample wasclassifiedaswithandwithoutexcessbodyfat,according tothecutoffsproposedbyFitnessgram.26
Descriptivestatisticswereusedtocharacterizethe sam-ple. The normality of maximum oxygen consumption and thepercentageof bodyfat wereverifiedthroughthe his-togram.The differencein mean valuesof thesevariables betweenagegroupswastestedbyanalysisofvariance (one-wayANOVA)followedbyBonferroniposthoc.Theproportion ofstudentsthathadlowcardiorespiratoryfitness(outcome) wasreported as prevalence in relation to the number of assessedstudents,althoughtheoutcomeofinterestisnota disease.Theassociationoflowcardiorespiratoryfitnesswith thestudyvariableswastestedusingtheChi-squaretest.
Theinteractionoftheeconomiclevelintheassociation betweencardiorespiratoryfitnessandbodyfatwasalso pre-viouslytested (p=0.149). Forthis reason,abinarylogistic regressionwasperformed totest theassociation between theoutcomeandexcessbodyfat,controlledbysexual mat-urationandeconomiclevel.Thevariableswereincludedin themodelonebyoneandremainedforadjustmentwiththe followingvariablewhenp<0.20.Theoddsratiosand confi-denceintervalswereestimated. Thesignificancelevel for allanalyseswas5%andtheStatasoftware(StataCorpLP, CollegeStation,USA)version12.0wasusedintheanalyses. ThestudywasapprovedbytheInstitutionalReviewBoard of Universidade Federal de Santa Catarina (UFSC), under Opinionn.131/2006.TheguidelinesofResolution196/96of theNationalHealthCouncilwerefollowedandaninformed consentformwassenttoallresearchparticipantstoinform themaboutthestudyobjectives.
Table 1 Comparisons ofloss of cardiorespiratoryfitness (CRF)accordingtothesamplecharacteristics.
Variables WithCRF (n=1223)
WithoutCRF (n=417)
% % p-Value
Agerange(years) 0.003
10---12 74.0 26.0
13---15 78.0 22.0
16---17 66.5 33.5
Schoolshift <0.001
Morning 67.7 32.3
Afternoon 83.7 16.3
Ethnicity 0.462
Caucasian 74.1 25.9
Another 76.0 24.0
Chi-square.
Results
Ofthe1910assessedstudents(86%oftheestimatedsample) seven adolescentswere excluded fromthe study because there was no information onage, 269 for being aged<10 years (n=268) or>17 years (n=1). Of the eligible ones (n=1634)itwasalsonecessarytoexclude417fornot under-goingthecardiorespiratoryfitnesstest.Therefore,atotalof 1223adolescentsinthisagegroup(75%oftheeligibleones) participatedinthestudy.Table1showsthatthelosseswere higher amongolder adolescents(16---17 years) andamong thestudentsfromthemorningshift,buttherewereno dif-ferencesregardingskincolor.
Themeanageoftheadolescentswas13±2years.Body fatpercentageshowedasignificantincreasewithageamong the adolescents, while this association was reversed for VO2max(Table2).
Theprevalenceoflowcardiorespiratoryfitnesswas51.3% (95%CI:48.5---54.1).Table3showstheadolescentswithhigh body fat,at the post-pubertalstage ofsexual maturation andhigheconomiclevelhadahigherprevalenceofthe out-come. Thesample distributionshowedahigherfrequency ofadolescentsinthepubertalstage,withnormalbodyfat, whichbelongedtoloweconomiclevel.
Table2 Samplecharacterizationpermeanvaluesandstandarddeviation(SD)ofexposure(bodyfat)andoutcome(VO2max)
accordingtotheagerange.
Variables Bodyfat(%) VO2max(mLkg−1min−1)
n Mean SD n Mean SD
Overall 1.221 26.5 6.9 1.223 39.0 4.7
Agerange(years)
10---12 559 24.2 6.7 559 42.4 2.9
13---15 494 27.9 6.4 496 37.2 3.5
16---17 168 29.8 6.2 168 32.8 3.2
p-Valuea <0.001 <0.001
Table3 Distributionoftheoverallsampleandwithlowcardiorespiratoryfitnessaccordingtothestudyvariables.
Variables Total(n=1223) LowCRF
n % % p-Value
Sexualmaturation <0,001
Pre-pubertal 50 4.1 8.0
Pubertal 1.009 82.8 47.4
Post-pubertal 160 13.1 88.0
Economiclevel <0.001
High 385 32.6 59.0
Low 796 67.4 48.0
Bodyfat <0.001
Normal 762 62.4 42.0
Elevated 549 37.6 66.7
CRF,lowcardiorespiratoryfitness;Chi-squaretest.
At the unadjusted analysis (Table 4),adolescents with high bodyfatwere 2.76-foldmorelikelytohavelow car-diorespiratoryfitnesswhencomparedtothosewithnormal bodyfat.Theassociationremainedafteradjustmentfor sex-ualmaturationand economiclevel.The chanceof female adolescentswithexcessbodyfatofhavinginadequatelevels ofcardiorespiratoryfitnessforhealthwas85%higherwhen controllingforsexualmaturationand94%higherwhenthe economiclevelwasincludedinthemodel.
Discussion
Themainfindingsofthisstudyshowthatapproximatelyhalf oftheassessedadolescentshadlowlevelsof cardiorespira-tory fitnessforhealth. The highestprevalence rates were foundamongadolescentswithhighbodyfat,post-pubertal maturationstage and thosebelonging tohighereconomic classes.Adolescentswithhighbodyfatweremoreexposed tolowcardiorespiratoryfitness,irrespectiveofsexual mat-urationandeconomiclevel.
The prevalence of low cardiorespiratory fitness in the presentstudywashigherthanthatfoundinfemale adoles-centsaged10---15 yearsfromFlorianópolis,Brazil (37.8%); inarepresentativeschool-basedsample,publicandprivate schoolswereconsidered.5Itwaslowerthantheproportion
foundinalongitudinalstudyofadolescentsofhigheconomic levelinLondrina,Paraná,fromacentralschoolinthe munic-ipality (60%).6 In a school-based longitudinal study with
adolescents (10---11 years) carried out in Ilhabela, Brazil,
between1978 and2010,therewasan annual decreasein cardiorespiratoryfitnessof0.51%inthelastthreedecades.4
Inananalysisofstudieswithchildrenandadolescents(6---19 years)from27countries,thisannualdecreasewas0.46%.3
Considering only the female gender (6---19 years), the decreasein cardiorespiratoryfitnessinstudiescarriedout in11countrieswas0.41%ayear.27 The proportionof
ado-lescents in this study with low cardiorespiratory fitness maybeareflectionoflowercardiorespiratoryfitnesslevels observedworldwide. These dataare alarming considering theexposureofyoungindividualstocardiovascularrisk fac-torsduringadolescence7andadulthood.8
Theproportionofadolescentswithlowcardiorespiratory fitnessdiffers according tosexual maturation stages. The adolescentsinthepost-pubertalstageweremorelikelyto havelowlevelsofcardiorespiratoryfitness.Thesefindings corroborateother school-basedstudies carried outwitha representativesample of girls in Brazil28 andin Europe.10
WhenassessinggirlsfromthestateofSergipe(9---14years),28
the influence of sexual maturation on cardiorespiratory fitnessshowed a significant (p<0.0001) and medium-sized effect (Eta2=0.069, power=1) on the VO
2max. In Spanish
and Swedish girls (13---18.5 years),10 cardiorespiratory
fit-nesswasnegativelyassociatedwithsexualmaturation,even aftercontrollingforbodyfat.Thissuggeststhatbodyfatisa modifyingfactorofcardiorespiratoryfitness.Thesefindings showthat the sexual maturationis an important variable tobeconsideredwhenassessingcardiorespiratoryfitnessin adolescents,especially due tothe body fat increase that occursinthisphaseofadolescence.
Table4 Crude andadjustedanalysisoftheassociationbetweenlowcardiorespiratoryfitness(CRF)andbodyfatinfemale adolescents.
Models LowCRF
OR 95%CI p-Valuea
Elevatedbodyfat 2.76 2.17---3.52 <0.001
ElevatedbodyfatadjustedbySM 1.85 1.39---2.46 <0.001 ElevatedbodyfatadjustedbySMandEL 1.94 1.45---2.61 <0.001
Another finding of this study showed that adolescents fromthehighersocioeconomic stratahad ahigher preva-lenceof low levelsof cardiorespiratoryfitnessin relation to their less favored peers. In adolescents (10---15 years) fromFlorianópolis,stateofSantaCatarina,theassociation wasfoundtobeinverse.Lowcardiorespiratoryfitnesswas moreprevalentin those fromthepoorer economic strata anddidnotdifferbetweengenders.5Itisnoteworthythat
the study carried out in Florianópolis5 included a sample
ofadolescentsfrompublicandprivateschools,whichmay explainthedifferencebetweenfindings.Theinverse associ-ationbetweencardiorespiratoryfitnessandeconomiclevel hasalsobeenreportedbyotherresearchers.29These
diver-gentresultsontheassociationbetweeneconomicleveland low cardiorespiratory fitness levels require more compa-rable studies to further elucidate this association and to contributetothediscussionsabout theinfluence ofsocial characteristicsonbiologicalvariables.
Increasedexposuretolowcardiorespiratoryfitness lev-elsalso occurredin adolescents withhigh body fat, even afteradjustingfor sexualmaturationandeconomic level. TheseresultscorroboratethestudiescarriedoutinBrazil, inwhichadolescentswithhigherlevelsofbodyfatshowed lowervaluesofmaximumoxygenconsumption.6,30
Interna-tionally,thisinverseassociationbetweencardiorespiratory fitness and body fat is also confirmed after adjustment for sexual maturation.11 The decrease in
cardiorespira-toryfitnessduringadolescenceisusuallyattributedtothe accumulation of adiposity related to sexual maturation; however, if the decrease persists even after controlling forbodyfat, thecausecanbeattributedtootherfactors ratherthan biological ones, such as the physical activity level.
It is noteworthy that the students’ motivation at the physical test was not controlled, which makes it impos-sible toknow whether they didtheir best. Moreover,the observeddifferentiallossesmayhavegeneratedsomebias andthus, cautionisrequiredininterpretingtheseresults. Oneof the main reasons for these losses wasthe impos-sibility of applying the cardiorespiratory fitness test due to bad weather, since sports courts were not covered in most schools. Another important limitation concerns the factthat the study wasperformed 10years ago, andthe observed scenario might have undergone changes, which requiresattentionininterpretingtheresults.Thisstudyis limitedtothepopulationofgirlsenrolledinpublicschools andresidentsinurbanareasandcannotbeextrapolatedto otherstudentsaged<10and>17years,fromprivateschools, fromtheruralareaandwithdifferentHDI.
Despitethelimitationsinherenttotheentirestudy,some strongpointsdeservetobehighlighted.First,thecontrolof confoundingfactors(sexualmaturationandeconomiclevel) allowedabetterdepictionoftheassociationbetween car-diorespiratoryfitnessandbodyfat.Althoughfurtherstudies areneededtobetterelucidatetheassociationbetweenlow cardiorespiratoryfitnessandeconomiclevel,thisstudy pro-motesthesearchforevidenceaboutthefactorsthataffect theassociationbetweencardiorespiratoryfitnessandbody fat. Second, we highlight the use of the most adequate fieldtesttomeasurecardiorespiratoryfitness.1Finally,the
resultsobservedinarepresentativesampleofchildrenare relevantforthepreparationofeffectivehealthpromotion
measures aimedatreducing bodyfatandimprovement in cardiorespiratoryfitnesslevelsinfemaleadolescents.
In conclusion, approximately half of the female ado-lescents showed unsatisfactory levelsof cardiorespiratory fitnessforhealthandpoorfitnessisassociatedwithexcess bodyfat,regardlessofeconomicstatusandsexual matura-tion.Newstudiesshouldbeperformed,aimingtointervene inthehighprevalenceoflowcardiorespiratoryfitnessfound, consideringtheexcessadiposity,identifiedasanassociated variableregardlessofeconomicandbiological characteris-tics. Suchstrategiescouldbeappliedinthepublichealth fieldtoreachteensintheir entiretyandpay attentionto thehigherriskgroups.
Funding
Thisstudydidnotreceivefunding.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgement
To Coordenac¸ão de Aperfeic¸oamento de Pessoal de Nível Superior (Capes) for the Doctoral Grant provided to GM, processn.006674/2015-01.
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