Classic1,2 and recent3,4 studies present evidence

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1 Correltes of Crdiorespirtory nd Musculr Fitness mong Brzilin Adolescents Vlter Cordeiro Brbos Filho, MS; Adir d Silv Lopes, PhD, MS; Rodrigo Bozz, MS; Cssino Ricrdo Rech, MS; Wgner de Cmpos, PhD, MS Objective: To nlyze socioeconomic indictors, physicl ctivity (PA) opportunities, nd behviorl correltes of crdiorespirtory nd musculr fitness mong Brzilin boys nd girls. Methods: A smple of 1555 dolescents ws rndomly selected. Age- nd sex-specific stndrd scores were clculted for ech fitness component. Results: Among boys, hed of household s schooling, involvement in orgnized PA, meeting the PA recommendtions, nd computer/gmes use were ssocited with crdiorespirtory fitness. Involvement in orgnized PA nd ctive time in Physicl Eduction (PE) clsses were predictors of musculr fitness. Among girls, ctive time in PE clsses nd TV wtching were predictors of crdiorespirtory fitness. Meeting the PA recommendtions ws ssocited with musculr fitness. Conclusion: PA vribles nd sedentry behviors should be independently considered for physicl fitness promotion in youth. Key words: dolescent behvior, erobic fitness, socioeconomic sttus, helth promotion, cross-sectionl study, Brzilin dolescents Am J Helth Behv. 2014;38(1):42-52 DOI: Clssic1,2 nd recent3,4 studies present evidence reveling tht crdiorespirtory fitness is n importnt indictor of n individul s helth. These studies suggest tht crdiorespirtory fitness is inversely ssocited with morbidity nd mortlity from crdiovsculr diseses in dults (eg, hypertension or stroke). Among children nd dolescents, crdiorespirtory fitness hs been n importnt predictor of severl crdiovsculr risk fctors, including obesity, 5 insulin resistnce, 5,6 nd metbolic syndrome. 7 The continuity of crdiorespirtory fitness from youth to dulthood reinforces the importnce of this component in determining the present nd future helth of young people. 8 Evidence hs shown tht musculr fitness is nother determinnt of individul helth sttus. 9 Musculr fitness ws inversely nd independently Vlter C. Brbos Filho, Reserch Center for Physicl Activity nd Helth, Federl University of Snt Ctrin, Florinópolis, Brzil. Adir S. Lopes, Deprtment of Physicl Eduction, Federl University of Snt Ctrin, Florinopolis, Brzil. Rodrigo Bozz, Reserch Center for Sports nd Exercise, Federl University of Prn, Curitib, Brzil. Cssino Ricrdo Rech, Undergrdute Progrm of Physicl Eduction, Federl University of Prn, Curitib, Brzil. Wgner de Cmpos, Deprtment of Physicl Eduction, Federl University of Prn, Curitib, Brzil. Contct Ms Vlter Brbos Filho; vltercbf@gmil.com ssocited with leding cuses of deth in dults nd the elderly (eg, dibetes nd hypertension). 10 Low musculr fitness lso ws ssocited with the development of risk fctors for crdiovsculr diseses mong dolescents, regrdless of crdiorespirtory fitness nd body composition. 11,12 Considering this evidence, the literture hs stimulted interest in evluting crdiorespirtory nd musculr fitness nd their potentil correltes mong young people. 9 Previous studies highlighted some demogrphic vribles (eg, sex, ge nd rce/ethnicity) s correltes of physicl fitness mong dolescents However, the ssocitions between socioeconomic indictors (eg, socioeconomic sttus, prentl eduction, nd employment sttus) nd crdiorespirtory nd musculr fitness re uncler. Additionlly, behviorl vribles during dolescence, especilly PA prctices (eg, chieving recommended levels of PA for helth) nd sedentry behviors (eg, wtching TV or using computers/gmes excessively), re strongly ssocited with crdiorespirtory fitness. 13,16-18 However, little evidence is vilble tht ssocites PA prctices or sedentry behviors with musculr fitness. 16,19 Finlly, PA opportunities (eg, weekly physicl eduction [PE] clsses nd orgnized PA) cn be criticl for the promotion of physicl fitness, 20,21 but studies evluting the reltionship between these vribles nd physicl fitness re 42

2 Brbos Filho et l still needed, especilly studies including musculr fitness components. 19 Studies filling these gps ply fundmentl role in the intervention designed to promote physicl fitness mong young people. Indeed, ctions trgeting groups t risk for low crdiorespirtory nd musculr fitness cn be more effective for helth promotion in youth. The present study imed to nlyze potentil socioeconomic indictors, PA opportunities, nd behviorl correltes of crdiorespirtory nd musculr fitness mong boys nd girls from Curitib, southern Brzil. We tested if the correltes of crdiorespirtory nd musculr fitness re different for boys thn girls. Thus, ll nlyses were strtified by sex. METHODS Smpling Procedures We performed representtive cross-sectionl survey, including dolescents enrolled in clsses from the 6 th grde of elementry school to the 2 nd grde of secondry school (5 school grdes) in public schools in the metropolitn re of Curitib, southern Brzil (Humn Development Index of this municiplity = 0.856). Curitib hs pproximtely 370 public schools tht serve 80% of ll dolescents cross the municiplity. The smple size for this study ws clculted using the following prmeters: (1) popultion of 115,524 dolescents, (2) confidence level of 95%, (3) smpling error of 3%, (4) prevlence of low physicl fitness estimted t 50%, nd (5) (Luiz, 2000)[11]design effect of Thus, the minimum smple size ws estimted to be 1480 dolescents. Considering mrgin of 30% for possible losses nd refusls, the study ws designed to include 1800 dolescents. The smple ws selected using 2-stge cluster smpling process. In the first stge, 5 schools (primry smpling unit) were rndomly selected in ech of the 9 microregions of Curitib. Thus, the smpling ws strtified by microregion, nd ech school represented one grde for its respective microregion. In the second stge, one to 3 clsses (secondry smpling unit) were rndomly selected ccording to the number of dolescents in the respective microregion. The forementioned selection process generted smple of 1812 students. All of these dolescents were evluted (100% of invited dolescents) fter obtining written informed consent from their prents/gurdins. During dt nlysis, we found tht 31 dolescents (1.7%) were outside the ge rnge of interest (18 yers nd older), 153 dolescents (8.4%) did not complete ll of the questionnire items, nd 73 dolescents (4.0%) did not complete ll motor tests. These dolescents were excluded from the smple. Therefore, the finl smple consisted of 1555 dolescents enrolled in 44 public schools in Curitib, Brzil. The clcultion of the smple sttisticl power ws performed posteriori, considering confidence level of 95% (α =.05) nd power of 80% (β =.20). The smple of 1555 dolescents cn identify odds rtios bove 1.34 s risk for low crdiorespirtory nd musculr fitness, considering prevlence rte bove 40% in the unexposed group. Mesures nd Dt Collection Procedures Dt were collected between Februry nd June Adolescents completed questionnires in the clssroom to identify the potentil correltes nlyzed in the study. The physicl fitness tests were performed in the gymnsium of ech school. The completion of the questionnires nd the performnce of the physicl fitness tests were supervised by 2 investigtors with support from previously trined PE professionls nd cdemics. Crdiorespirtory nd Musculr Fitness Crdiorespirtory fitness ws estimted using the 20-meter shuttle run test, s described by Léger et l. 23 Prticipnts were required to run between 2 lines 20 meters prt in time with n udio signl. The initil speed of the signl ws 8.5 km/h nd ws incresed by 0.5 km/h per minute (1 minute equl to 1 stge). The test ws concluded when the prticipnt filed to rech the end lines concurrent with the udio signls on 2 consecutive occsions. Otherwise, the test ended when the prticipnt stopped becuse of ftigue. The velocity in the lst stge completed by ech prticipnt ws recorded nd used to clculte the VO 2mx (ml/kg/ min) ccording to the eqution vlidted by Léger et l, 23 s follows: VO 2mx = *velocity *ge *velocity*ge. The study found Person s correltion coefficient between estimted nd mesured VO 2mx of 0.84 nd testretest relibility of Musculr fitness ws ssessed by combintion of 3 different musculr-relted tests (hndgrip strength, 60-second bdominl, nd stnding brod jump tests). These musculr tests followed the protocols proposed by Eurofit. 24 Upper body strength ws ssessed by the hndgrip strength test. The hndgrip strength test ws performed using digitl device with optiml grip spn (TKK 5101 Grip D; Tkey, Tokyo, Jpn). Ech dolescent rted mximum performnce with the right nd left hnd, nd n verge ws clculted between the 2 executions. Centrl body strength ws evluted using the 60-second bdominl test. Ech dolescent performed the mximum number of bdominl contrctions in 60 seconds, nd the performnce ws expressed in repetitions completed during this period. Lower body musculr strength ws mesured with the stnding brod jump. To perform the brod jump, ech dolescent stood with feed pproximtely shoulder width prt behind the strting line nd then jumped s fr s possible. Ech prticipnt performed the jump twice, nd the higher performnce ws recorded in centimeters. The combintion of different tests for musculr fitness determintion hs been used in dults 10 nd youth. 11,19 Am J Helth Behv. 2014;38(1):42-52 DOI: 43

3 Correltes of Crdiorespirtory nd Musculr Fitness mong Brzilin Adolescents We chose to estimte the crdiorespirtory nd musculr fitness by sex nd ge (11, 12, 13, 14, 15, 16, nd 17 yers) stndrd scores. We combined 3 different musculr fitness tests iming to crete helth-relted indictor of globl musculr fitness. Additionlly, cutoff points for crdiorespirtory fitness bsed on other popultions hve limited use mong Brzilin dolescents. 25 Considering these fctors, we chose to clssify crdiorespirtory nd musculr fitness bsed on ptterns in the smple itself. Similr procedures were performed elsewhere. 19 Sex- nd ge-specific z-scores were clculted considering the estimted VO 2mx. A sex- nd ge-specific z-score ws lso clculted for ech musculr fitness test nd the men of the 3 musculr test z-scores were clculted to crete single musculr fitness indictor. For nlysis purposes, we chose to dichotomize crdiorespirtory nd musculr fitness considering the stndrd scores. Adolescents with negtive z-scores for the estimted VO 2mx (ie, VO 2mx lower thn the medin for individuls from sme sex nd ge) were considered to hve low crdiorespirtory fitness. The verge of 3 musculr fitness z-scores were used to clssify musculr fitness. A similr procedure lso ws dopted in previous study tht used nonliner sttisticl resources to verify correltes of dolescents physicl fitness. 26 Potentil Correltes of Crdiorespirtory nd Musculr Fitness Three socioeconomic indictors (socioeconomic sttus, employment sttus, nd hed of household s schooling) were nlyzed in this study. Socioeconomic sttus nd the hed of household s schooling were evluted with the questionnire of the Brzilin Assocition of Reserch Compnies. 27 This instrument groups people into socioeconomic clsses (A1 [richest], A2, B1, B2, C1, C2, D, nd E [poorest]) bsed on score combining ownership of ssets, schooling of hed of household, nd number of employees in the household. For the purposes of nlysis, the socioeconomic clsses were grouped into 2 ctegories: A+B (best condition) nd C+D+E (worst condition). The hed of the household s schooling (prent or gurdin who is the chief finncil officer nd hs the highest eductionl level of the household) ws clssified into 3 ctegories: 8 yers, 9-11 yers, nd 12 yers. Finlly, the employment sttus (employed or not employed) of ech dolescent lso ws evluted. Adolescents were considered to be employed if they performed ny ctivity tht contributed to the production of goods or services, including unpid ctivities, but excluding household chores in the dolescent s own residence. Two environmentl vribles were studied bsed on previous instrument. 28 Ech dolescent reported the number of PE clsses in typicl week, nd the nswers were clssified into 3 ctegories (no clss/dispensed, 1-2 clsses, or 3 clsses). The dolescents responded to one dichotomous question (yes or no) bout the prticiption in orgnized PA (eg, swimming, volleybll, indoor soccer), excluding the PE clsses. The PE clsses nd orgnized PA items were previously tested nd they hd good test-retest relibility (Kpp s greement index of nd 0.595, respectively). 28 Four behviorl vribles were considered. The dolescents nswered question bout the time spent in PA during PE clss (in Brzil, ech PE clss hs men time of pproximtely 50 minutes). 28 The nswers were clssified into 2 ctegories: (1) < 30 minutes, nd (2) 30 minutes. PA level ws ssessed using self-report questionnire tht ws developed by Bouchrd et l 29 hving questions pertining to 3 dys in typicl week (2 weekdys nd one weekend dy). The questionnire determined n estimtion of the time involved in moderte to vigorous physicl ctivities (ctivities with scores from 6 to 9, s proposed in the originl instrument) during typicl week. 29 The count of scores from 6 to 9 estimted by dolescents hd high correltion with physicl working cpcity (intr-clss correltion = 0.80). 29 Bsed on the current physicl ctivity guidelines, teengers were considered insufficiently ctive when they reported less thn 420 minutes of physicl ctivity per week. 30 Adolescents who met the current physicl ctivity guidelines were considered sufficiently ctive. The mount of time spent wtching TV or using computers/gmes ws evluted by selfreport questionnire tht ws previously dpted nd vlidted for the young Brzilin popultion. 28 A good test-retest relibility (Kpp s greement index of nd for TV wtching nd computer/gmes use, respectively) ws observed for the sedentry behviors items. 28 We evluted the mount of time spent wtching TV on weekdys nd on weekend dys in 2 seprte items. Two dditionl questions were used to nlyze the mount of time using computers/gmes on weekdys nd on weekend dys. Items bout prticiption in these sedentry ctivities on weekdys nd on weekend dys were merged to crete vrible of 4 ctegories: (1) < 3 hours every dy (2) 3 hours on weekend dys only (3) 3 on weekdys only (4) 3 hours every dy. Sttisticl Anlysis The bsolute nd reltive frequencies were used for description of ctegoricl vribles. Mens, stndrd devitions, nd 95% confidence intervls were used for description of the continuous vribles. We performed the Kolmogorov-Smirnov test for normlity of the physicl fitness dt, nd noted tht no vrible hd norml distribution. The Kruskl-Wllis test ws used to nlyze differences mong ges for the 4 physicl fitness tests for ech sex. The chi-squre test for liner trends ws used in the bivrite ssocition between ctegoricl vribles. We used logistic regression nlysis s mesure of ssocition. All nlyses were strtified by sex. The dependent vrible included in the re- 44

4 Brbos Filho et l Tble 1 Prticipnt Chrcteristics of the Totl Smple nd by Sex, Curitib, Brzil (2011) Vribles All prticipnts (N = 1555) Boys (N = 737) Girls (N = 818) p-vlue Age in yers, M (SD) (1.60) (1.62) (1.59).093* Socioeconomic Vribles, % (N) Socioeconomic sttus.060** A+B (best) 67.9 (1,056) 71.0 (523) 65.2 (533) C+D+E (worst) 32.1 (499) 29.0 (214) 34.8 (285) Hed of household s schooling.632*** 8 yers 36.2 (563) 35.5 (262) 36.8 (301) 9-11 yers 40.0 (622) 41.2 (304) 38.9 (318) 12 yers 23.8 (370) 23.2 (171) 24.3 (199) Employment sttus.052** No 83.0 (1,290) 81.0 (597) 84.7 (693) Yes 17.0 (265) 19.0 (140) 15.3 (125) PA opportunities, % (N) Weekly PE clss 3 clsses 54.6 (849) 56.6 (417) 52.8 (432) 1-2 clsses 33.6 (523) 31.9 (235) 35.2 (288) No clss/dispensed 11.8 (183) 11.5 (85) 12.0 (98).231*** Involvement in orgnized PA <.001** Yes 34.5 (537) 48.4 (357) 22.0 (180) No 65.5 (1,018) 51.6 (380) 78.0 (638) Behviorl Vribles, % (N) Active time during PE clss <.001** 30 or more minutes 43.9 (683) 55.1 (406) 33.9 (277) Less thn 30 minutes 56.1 (872) 44.9 (331) 66.1 (541) PA level <.001** Sufficiently ctive (420+ min/wk of MVPA) 48.6 (756) 65.5 (483) 33.4 (273) Insufficiently ctive (< 420 min/wk of MVPA) 51.4 (799) 34.5 (254) 66.6 (545) Dily computer/video gme use <.001*** < 3 hours every dy 22.0 (342) 17.9 (132) 25.7 (210) 3+ hours on weekend dys only 26.4 (410) 22.7 (167) 29.7 (243) 3+ hours on week dys only 15.9 (248) 17.4 (128) 14.7 (120) 3+ hours every dy 35.7 (555) 42.1 (310) 30.0 (245) Dily TV wtching.001*** < 3 hours every dy 23.5 (366) 22.4 (165) 24.6 (201) 3+ hours on weekend dy only 29.3 (455) 25.2 (186) 32.9 (269) 3+ hours on week dys only 18.0 (280) 20.1 (148) 16.1 (132) 3+ hours every dy 29.2 (454) 32.3 (238) 26.4 (216) * p-vlues obtined using the Mnn-Whitney U-test. ** p-vlues obtined using the chi-squre test for heterogeneity. *** p-vlues obtined using the chi-squre test for liner trends. Note. PA: physicl ctivity; PE: physicl eduction; MVPA: moderte to vigorous physicl ctivity; M (SD): men (stndrd devition). Am J Helth Behv. 2014;38(1):42-52 DOI: 45

5 Correltes of Crdiorespirtory nd Musculr Fitness mong Brzilin Adolescents Figure 1 Mens nd 95% Confidence Intervls (Error Brs) of Physicl Fitness Tests in Adolescents by Sex nd Age Boys Girls () (b) 51 ) in 48 k g / m 45 l/ (m 42 x O 2m 39 V d te 36 E s tim 33 Estimted VO 2mx p =.286 p < ) 170 m (c p m156 ju d 142 ro b g in 128 d n S t 114 Stnding brod jump p <.001 p = Age (yers) Age (yers) (c) g ) (k 32 g th n28 s tre 24 g rip d n20 H Hndgrip strength p <.001 p < Age (yers) (d) 45 s ) n 40 e titio p 35 (re s t 30 l te in m o25 d b - s s bdominl test p <.001 p = Age (yers) Note. All p-vlues obtined using the Kruskl-Wllis test. gression model ws crdiorespirtory or musculr fitness, dichotomized bsed on the stndrdized scores (0: positive fitness scores; 1: negtive fitness scores) for ech component. The hierrchicl pproch ws dopted for inclusion of independent vribles in the regression model, 31 considering 3 levels. In the first, socioeconomic vribles were included. In the second, PA opportunities were included. In the lst level, we included the behviorl vribles. We initilly used the djustment of the first-level vribles. Anlyses of subsequent levels were controlled for the vribles from the sme level nd those from the previous level. The results were considered significntly ssocited with the outcome under review when the p-vlue ws <.05 for 2-tiled tests. There were no high levels of multicollinerity between independent vribles, llowing the inclusion of ll vribles in the multivrite model, when necessry. Additionlly, the z-scores of crdiorespirtory nd musculr fitness were significntly correlted (Person s correltion coefficient = 0.511; p <.001). Therefore, fitness index ws not included s confounder vrible in the multivrible model for the other type of fitness, s performed in previous studies. 13,20,32,33 Sttisticl nlyses were performed using Stt 11.1 (Stt Corp., College Sttion, USA), nd ll nlyses were incorported procedures for studies with complex methodologies (ie, dding the prefix svyset to incorporte strt, conglomertes, nd smple weight). RESULTS This smple of 1555 dolescents (737 boys nd 818 girls) hd men ge of yers (SD = 1.6 yers). The smple hd more prticiption from dolescents with higher socioeconomic sttuses (A+B; 67.9%), dolescents who were not employed 46

6 Brbos Filho et l Tble 2 Correltes (Socioeconomic Indictors, PA Opportunities nd Behviorl Vribles) of Crdiorespirtory nd Musculr Fitness mong Boys, Curitib, Brzil (2011) Low crdiorespirtory fitness Low musculr fitness Vribles % (N) OR (95% CI) % (N) OR (95% CI) First Level (socioeconomic vribles)*** Socioeconomic sttus A+B (best) 54.3 (284)* (263) 1.00 C+D+E (worst) 45.8 (98) 0.82 ( ) 49.1 (105) 0.97 ( ) Hed of household s schooling 8 yers 48.1 (126)** (130) yers 48.4 (147) 1.17 ( ) 49.0 (149) 0.97 ( ) 12 yers 63.7 (109) 1.73 ( )* 52.0 (89) 1.06 ( ) Employment sttus No 52.6 (314) (306) 1.00 Yes 48.6 (68) 0.90 ( ) 44.3 (62) 0.76 ( ) Second Level (PA opportunities)*** Weekly PE clss 3 clsses 50.8 (212) (202) clsses 56.2 (132) 1.22 ( ) 53.6 (126) 1.21 ( ) No clss/dispensed 44.7 (38) 0.73 ( ) 47.1 (40) 0.73 ( ) Involvement in orgnized PA Yes 42.3 (151)** (165)* 1.00 No 60.8 (231) 2.24 ( )** 53.4 (203) 2.24 ( )** Third Level (behviorl vribles)*** Active time during PE clss 30 or more minutes 48.0 (195)* (188)* 1.00 Less thn 30 minutes 56.5 (187) 1.40 ( ) 54.4 (180) 1.48 ( )* PA level Sufficiently ctive (420+ min/wk of MVPA) 45.1 (252)** (228)* 1.00 Insufficiently ctive (< 420 min/wk of MVPA) 64.2 (130) 1.61 ( )* 55.1 (140) 1.27 ( ) Dily computer/gmes use < 3 hours every dy 41.7 (55)* (61) hours on weekend dys only 50.9 (85) 1.46 ( ) 53.9 (90) 1.36 ( ) 3+ hours on week dys only 57.8 (74) 1.93 ( )* 49.2 (63) 1.12 ( ) 3+ hours every dy 54.2 (168) 1.61 ( )* 49.7 (154) 1.21 ( ) Dily TV wtching < 3 hours every dy 49.7 (82) (81) hours on weekend dys only 51.6 (96) 0.96 ( ) 51.6 (96) 1.03 ( ) 3+ hours on week dys only 50.0 (74) 0.74 ( ) 49.3 (73) 1.08 ( ) 3+ hours every dy 54.6 (130) 1.14 ( ) 49.6 (11)* 1.06 ( ) * p <.05 obtined using the chi-squre test (percentge comprisons) nd the logistic regression (OR estimte). ** p <.01 obtined using the chi-squre test (percentge comprisons) nd the logistic regression (OR estimte). *** OR nd 95% CI djusted for ll other vribles contined in the sme level nd other vribles contined in the previous level. Note. PA: physicl ctivity; PE: physicl eduction; MVPA: moderte to vigorous physicl ctivity; (95% CI): odds rtio nd 95% confidence intervl. Am J Helth Behv. 2014;38(1):42-52 DOI: 47

7 Correltes of Crdiorespirtory nd Musculr Fitness mong Brzilin Adolescents Tble 3 Correltes (Socioeconomic Indictors, PA Opportunities nd Behviorl Vribles) of Crdiorespirtory nd Musculr Fitness mong Girls, Curitib, Brzil (2011) Low crdiorespirtory fitness Low musculr fitness Vribles % (N) OR (95% CI) % (N) OR (95% CI) First Level (socioeconomic vribles)*** Socioeconomic sttus A+B (best) 56.1 (299) (265) 1.00 C+D+E (worst) 50.2 (143) 0.85 ( ) 49.8 (142) 0.96 ( ) Hed of household s schooling 8 yers 50.5 (152) (158) yers 55.0 (175) 1.17 ( ) 46.2 (147) 0.78 ( ) 12 yers 57.8 (115) 1.26 ( ) 51.3 (102) 0.95 ( ) Employment sttus No 53.1 (368) (339) 1.00 Yes 59.2 (74) 1.31 ( ) 54.4 (68) 1.22 ( ) Second Level (PA opportunities)*** Weekly PE clss 3 clsses 52.5 (227) (214) clsses 54.5 (157) 1.08 ( ) 48.3 (139) 0.95 ( ) No clss/dispensed 59.2 (58) 1.24 ( ) 55.1 (54) 1.19 ( ) Involvement in orgnized PA Yes 47.8(86) (79) 1.00 No 55.8 (356) 1.39 ( ) 51.4 (328) 1.33 ( ) Third Level (behviorl vribles)*** Active time during PE clss 30 or more minutes 45.8 (127)** (126) 1.00 Less thn 30 minutes 58.2 (315) 1.54 ( )* 51.9 (281) 1.24 ( ) PA level Sufficiently ctive (420+ min/wk of MVPA) 50.2 (137) (118)** 1.00 Insufficiently ctive (< 420 min/wk of MVPA) 56.0 (305) 1.19 ( ) 53.0 (289) 1.41 ( )* Dily computer/video gme use < 3 hours every dy 51.0 (107) (100) hours on weekend dys only 51.4 (125) 0.94 ( ) 45.7 (111) 0.90 ( ) 3+ hours on week dys only 64.2 (77) 1.11 ( ) 50.8 (61) 1.04 ( ) 3+ hours every dy 54.3 (133) 0.83 ( ) 55.1 (135) 1.26 ( ) Dily TV wtching < 3 hours every dy 43.8 (88)** (92) hours on weekend dys only 53.2 (143) 1.62 ( )* 48.3 (130) 1.23 ( ) 3+ hours on week dys only 62.1 (82) 1.79 ( )* 51.5 (68) 1.17 ( ) 3+ hours every dy 59.7 (129) 2.04 ( )** 54.2 (117) 1.29 ( ) * p <.05 obtined using the chi-squre test (percentge comprisons) nd the logistic regression (OR estimte). ** p <.01 obtined using the chi-squre test (percentge comprisons) nd the logistic regression (OR estimte). *** OR nd 95% CI djusted for ll other vribles contined in the sme level nd other vribles contined in the previous level. Note. PA: physicl ctivity; PE: physicl eduction; MVPA: moderte to vigorous physicl ctivity; OR (95% CI): odds rtio nd 95% confidence intervl. 48

8 Brbos Filho et l (83.0%) nd whose hed of household hd 9-11 yers of eduction (40.0%). Additionlly, over hlf of the dolescents were involved in 3 PE clsses per week (54.6%), nd did not prticipte in orgnized PA (65.5%). Considering the behviorl vribles, greter proportion of dolescents reported spending 30 minutes in ctive time during PE clss (56.1%). Most dolescents were clssified s insufficiently ctive (51.4%). Finlly, lrge proportion of dolescents reported wtching TV (29.2%) nd using computers/gmes (35.7%) for 3 hours every dy. There were no sex differences in the socioeconomic vribles. However, more boys thn girls (ll p <.001) reported prticipting in orgnized PA (48.4% vs 22.0%), being sufficiently ctive (65.5% vs 33.4%), nd being ctive for 30 minutes during PE clss (55.1% vs 33.9%). More boys thn girls lso reported wtching TV (32.3% vs 26.4%) or using computers/gmes (42.1% vs 30.0%) for 3 hours every dy (p <.001 for both; Tble 1). Figure 1 presents the men nd 95% confidence intervls for ech physicl fitness test ccording to sex nd ge. Boys hd tendency to increse in musculr fitness with ge (horizontl jump, hndgrip strength, nd 60-second bdominl test (ll p <.001). There were no differences mong ges for VO 2mx (p =.286). Among girls, significnt reduction trend in VO 2mx with dvncing ge ws observed (p <.001). Inversely, significnt increse with ge ws observed for the hndgrip strength test (p <.001). There were no significnt differences mong ges for the horizontl jump nd 60-second bdominl test in girls (p >.05). The chi-squres test (Tble 2) showed tht there ws bivrite ssocition between crdiorespirtory fitness nd the following vribles in boys: socioeconomic sttus, hed of household s schooling, orgnized PA, ctive time in PE clss, PA level, nd dily time spent using computers/gmes. Involvement in orgnized PA, ctive time in PE clss, nd the PA level were ssocited with musculr fitness in boys. In the djusted nlysis (Tble 2), the hed of household s schooling ws ssocited with crdiorespirtory fitness in boys. Boys whose hed of household hd 12 yers of eduction were 73% more likely to exhibit low crdiorespirtory fitness, compred to peers whose hed of household hd less schooling. Boys who did not prticipte in orgnized PA hd pproximtely twice the odds of hving low crdiorespirtory fitness. Boys who did not meet the current PA recommendtions (< 420 minutes per week) lso hd greter odds of hving low crdiorespirtory fitness. Finlly, the excessive use of computers/gmes ( 3 hours) during weekdys only or dily ws ssocited with greter odds of hving low crdiorespirtory fitness. Socioeconomic sttus, employment sttus, weekly PE clsses, ctive time in PE clss, nd dily time spent wtching TV were not ssocited with crdiorespirtory fitness in boys. In the djusted nlysis, involvement in orgnized PA nd ctive time in PE clss remined ssocited with musculr fitness in boys (Tble 2). Boys who did not prticipte in orgnized PA hd twice the odds of hving low musculr fitness. Similrly, dolescents who reported < 30 minutes of ctive time in PE clss hd 48% greter odds of hving low musculr fitness. Other vribles were not ssocited with musculr fitness in boys (p >.05). The chi-squre test (Tble 3) showed tht the ctive time in PE clss nd dily time spent wtching TV hd bivrite ssocition with crdiorespirtory fitness in girls. Only the PA level ws ssocited with musculr fitness in girls. After djusting for confounders, girls who reported 30 minutes of ctive time during PE clss hd 54% greter odds of hving low crdiorespirtory fitness (Tble 3). A significnt inverse reltionship between dily time spent wtching TV nd crdiorespirtory fitness ws observed. Girls who reported wtching TV for 3 hours, even if they wtched tht on weekend dys only, hd greter odds of hving low crdiorespirtory fitness. Other independent vribles were not ssocited with crdiorespirtory fitness in girls (p >.05). After djustments for confounders, the PA level remined ssocited with musculr fitness in girls. Girls who did not meet the current PA recommendtions hd 41% greter odds of hving low musculr fitness, compred to insufficiently ctive girls (Tble 3). DISCUSSION This study identified severl potentil correltes of crdiorespirtory nd musculr fitness mong boys nd girls, including socioeconomic indictors, PA opportunities, nd behviorl vribles. We chose to perform ll dt nlyses strtified by sex, considering the biologicl nd behviorl differences between boys nd girls. As expected, these differences were found in this study (Tble 1 nd Figure 1). Moreover, sex ws n importnt modertor in the identifiction of correltes of crdiorespirtory nd musculr fitness in dolescents (Tble 2 nd 3). This study found tht hed of household s schooling ws negtively ssocited with crdiorespirtory fitness in boys. This result ws lso found in nother study with Brzilin dolescents. 13 However, study with Portuguese dolescents found positive ssocition between prentl eduction nd crdiorespirtory fitness in girls but not in boys. 15 A longitudinl study showed tht prentl schooling ws positively ssocited with improvements in physicl fitness from youth to dulthood. 8 The direction nd epidemiologicl significnce of the ssocition between these vribles remin uncertin nd it my chnge ccording to region/country. However, in the present study, Brzilin boys whose hed of household hs better eduction seemed to represent subgroup tht lso should be observed crefully within the school environment if crdiorespirtory fitness is to be improved. Am J Helth Behv. 2014;38(1):42-52 DOI: 49

9 Correltes of Crdiorespirtory nd Musculr Fitness mong Brzilin Adolescents Other socioeconomic indictors (ie, socioeconomic sttus nd employment sttus) were not ssocited with crdiorespirtory nd musculr fitness in boys nd girls. This result for crdiorespirtory fitness ws lso obtined elsewhere. 14,16 For musculr fitness, however, one study found n inverse nd significnt ssocition mong socioeconomic sttus, working condition, nd musculr fitness. 13 The severl definitions for fitness nd socioeconomic sttus my explin the different results between studies. Conversely, nother cross-sectionl study showed tht the ssocition between socioeconomic vribles (eg, prentl eduction nd fmily income) nd physicl fitness re medited by PA. 14 Thus, the inclusion of some socioeconomic vribles in the monitoring of physicl fitness during dolescence is minly justified by its significnt ssocition with PA, n importnt determinnt of crdiorespirtory nd musculr fitness in this popultion. 17,19 Boys who did not prticipte in orgnized PA were high-risk subgroup for low crdiorespirtory nd musculr fitness (Tble 2). Previous studies corroborte these findings for crdiorespirtory 16,20,21 nd musculr 19 fitness. Orgnized PA seems to be n importnt determinnt of fitness becuse the orgnized sessions often consist of specific exercises for physicl fitness improvement. 9 However, mong boys, it ws observed tht the current PA recommendtions were ssocited with crdiorespirtory fitness, but not with musculr fitness (Tble 2). There is evidence indicting tht orgnized PA (eg, resistnce exercises, sports, nd, specilly, vigorous PA) is essentil for musculr fitness in youth. 9,19,34 The mount of PA prescribed in globl recommendtions for helth my be sufficient for improving scores in crdiorespirtory fitness. 9,34 However, filure to meet the current PA recommendtions ws ssocited with low musculr fitness mong girls (Tble 3). Girls re less ctive thn boys, nd prticiption in generl PA t recommended levels for helth my be sufficient to promote musculr fitness mong girls but not in boys. Thus, 2 complementry but distinct gols should be considered: (1) stimulte the reliztion of PA t recommended levels for helth (ie, 60 minutes dily of moderte-to-vigorous PA); nd (2) stimulte PA sessions focused on musculr fitness, such s orgnized sports nd exercises. 7 Interventions with these perspectives re essentil for the continution of ctive behvior in future phses 35 nd the improvement of youth physicl fitness. 9 An importnt behviorl correlte of physicl fitness ws the ctive time in PE clsses. Studies hve showed n ssocition between involvement in PE clsses nd helthy behviors, 36,37 s well s components of physicl fitness. 20 Interventions to chnge PE clsses (eg, including PA of greter intensity) lso hve been effective in promoting physicl fitness in schools. 38 Wheres Brzilin studies showed PE clsses with little ctive time, 39 it is noted tht Brzilin government policies should encourge the reliztion of PA during PE clsses. This ction my hve gret impct on promoting behviors nd ttributes (eg, musculr nd crdiorespirtory fitness) relted to young people s helth, principlly mong dolescents who re not involved in extrcurriculr PA. Sedentry behviors were not ssocited with musculr fitness in boys nd girls, s noted previously. 19 However, dily computer/gmes use nd dily TV wtching ws inversely ssocited with crdiorespirtory fitness in boys nd girls, respectively. These results lso were obtined previously. 18,21 Previous studies showed tht TV wtching is the mjor sedentry behvior mong girls, wheres boys spend more time on computers/gmes. 33,40 This difference ws confirmed in this study nd it my explin the influence of sedentry behvior type on crdiorespirtory fitness in boys nd girls. Sedentry behviors mong Brzilin dolescents hve been close to or even higher thn the estimtes for high-income countries. 41 Reduction of sedentry behviors mong dolescents should be included in physicl fitness-promoting public policies trgeting Brzilin youth. Interventions should focus on different sedentry behviors, s well s sex-specific ctions directed to boys nd girls. Excessive time spent wtching TV, even if only on weekend dys, hs been ssocited with low crdiorespirtory fitness mong girls (Tble 3). It is common prctice to chnge fmily norms (ie, ccess to TV nd computer in the dolescent s room nd the limit time for the use of these medi) between weekdys nd weekend dys. 40,42 Therefore, it is essentil tht prents nd professionls involved with dolescents crefully observe the behviors dopted by dolescents, even if they re performed on dys without clss (weekend dys). Further investigtions testing this hypothesis should be conducted, including sedentry behviors, PA nd other helth-relted behviors, s well s observing the impct of these behviors on dolescents helth. The strength of this study ws the nlysis of 2 importnt components of helth (ie, crdiorespirtory nd musculr fitness) in representtive smple of dolescents from public schools in mjor Brzilin municiplity. The public schools serve pproximtely 80% of ll students cross Curitib nd they re the min focus of public helth promotion policies in Brzil. Additionlly, the study of severl potentil correltes of low crdiorespirtory nd musculr fitness mong dolescents, including socioeconomic indictors, PA opportunities, nd behviorl vribles, contributed to the identifiction of high-risk subgroups for these 2 helth mrkers. This nlysis cn guide the development of interventions tht im to promote helthy lifestyle mong dolescents. Limittions One limittion of this study is the use of indirect 50

10 Brbos Filho et l motor tests for identifiction of physicl fitness nd self-report instruments to identify behviorl vribles. A second limittion is the fct tht the smple ws extrcted only from dolescents from public schools, thereby limiting the extrpoltion of the results to other groups of dolescents. A third limittion is the use of cross-sectionl study design to indicte ssocitions mong the vribles. An inherent chrcteristic of the cross-sectionl design is the possibility of reverse cuslity. These limittions demonstrte the need for cution when interpreting results. Conclusions The hed of household s schooling ws the socioeconomic vrible tht ws significntly ssocited with crdiorespirtory fitness, but only in boys. In turn, PA opportunities (eg, involvement in orgnized PA) nd behviorl vribles (eg, PA level, ctive time in PE clss, nd sedentry behviors) were ssocited with physicl fitness mong dolescents. An ctive lifestyle, including performing PA t recommended levels or s involvement in orgnized PA, is fundmentl to the promotion of 2 importnt components of helth-relted physicl fitness mong youth. However, voiding sedentry time, even if it occurs only on weekends, my prevent low crdiorespirtory fitness, especilly mong girls. Public policies focused on physicl fitness mong dolescents should offer sex-specific ctivities for greter effectiveness becuse the correltes of physicl fitness re different for boys nd girls. Humn Subjects Sttement The Reserch Ethics Committee of the Federl University of Prn pproved this study (CAAE: ). Ech school gve forml permission for dt to be collected on ech cmpus. Ech dolescent s prent/gurdin provided written informed consent for prticiption in this study. Authors Contributions All uthors were involved in the conception nd design of the study. VCBF nd RB were involved in the dt collection. VBCF nd CRR conducted the dt nlysis, nd VCBF drfted the mnuscript. 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