ABC | Volume 112, Nº6, June 2019

Original Article Scheer et al Exercise at school and cardiovascular risk factors Arq Bras Cardiol. 2019; 112(6):775-781 Table 2 – Comparison of demographic characteristics, anthropometric data and cardiovascular risk factors between students from RSch and OEG schools, stratified by sex Variable Girls Boys OEG RSch p value OEG RSch p value Students 354 (49.4%) 252 (64.0%) < 0.001 362 (50.6%) 142 (36.0%) < 0.001 Age (years) 12.6 ± 1.2 (n = 354) 13.4 ± 1.4 (n = 252) < 0.001 12.6 ± 1.1 (n = 362) 13.2 ± 1.6 (n = 142) < 0.001 BMI (kg/m 2 ) 20.6 ± 4.3 (n = 354) 21.9 ± 4.5 (n = 252) 0.001 20.3 ± 4.2 (n = 362) 20.6 ± 3.9 (n = 142) 0.56 Overweight 86/354 (24.3%) 90/252 (35.7%) 0.002 105/362 (29.0%) 43/142 (30.3%) 0.78 Altered glycemia 1/348 (0.3%) 0/252 (0.0%) NA 0/352 (0.0%) 0/141 (0.0%) NA Altered total cholesterol 146/355 (41.1%) 107/252 (42.5%) 0.74 124/359 (34.5%) 45/141 (31.9%) 0.56 Altered triglycerides 226/321 (70.4%) 162/247 (65.6%) 0.22 177/303 (58.4%) 91/140 (65.0%) 0.19 Pre-hypertension/ hypertension 61/352 (17.3%) 67/251 (26.7%) 0.006 55/360 (15.3%) 45/142 (31.7%) < 0.001 Data are reported as mean ± standard deviation or absolute number (percentage). OEG: Olympic Experimental Gymnasium project; RSch: regular schools; BMI: body mass index; NA: not applicable; p-value obtained by chi-square test or Student’s t test. Table 3 – Binary logistic regression models using cardiovascular risk factors as independent variables, adjusted for age and sex Overweight Pre/Hyp Altered TC Altered TGL Overall a,b (n = 1010) (n = 1105) (n = 1104) (n = 1010) RSch 1.49 [1.13 – 1.98] § 1.86 [1.36 – 2.54] § 1.01 [0.77 – 1.31] 0.88 [0.66 – 1.16] Girls a (n = 606) (n = 603) (n = 606) (n = 567) RSch 1.89 [1.30 – 2.75] § 1.66 [1.10 – 2.51] § 1.03 [0.73 – 1.45] 0.69 [0.48 – 1.01] Boys a (n = 404) (n = 502) (n = 498) (n = 443) RSch 1.09 [0.71 – 1.69] 2.20 [1.37 – 3.54] § 0.95 [0.62 – 1.46] 1.19 [0.78 – 1.82] Data are reported as odds ratio and 95% confidence interval: OR [95%: lower – upper limit]. Pre/Hyp: pre-hypertensive/hypertensive; TC: total cholesterol; TGL: triglycerides; RSch: regular schools. a adjusted for age, b adjusted for sex, § = p < 0.05. reasonable to hypothesize that the differences in health status between OEG and RSch students can result from the PA policy implemented in the OEG. The time course for weight changes and BP control by non-pharmacological intervention, 19 and the association between school PA policy and CVD risk factors 20,21 could support our hypothesis. As for lipid profile, the absence of differences was not a surprise, once PA is known to have only a slight effect on lipid content. 22 However, the high prevalence of dyslipidemia needs to be addressed. In the whole sample, the prevalence of dyslipidemia was almost two times greater in RSch than OEG (38.1% vs 64.9%). In the ERICA study, 23 the frequency of hypercholesterolemia and hypertriglyceridemia was 20.1% and 7.8%, respectively, in a sample of 38,069 adolescents aged 12-17 years. A possible explanation for the discrepancy between our data and that of literature is that the age of 12-13 years corresponds to the pubertal spurt period in boys and girls, and hormonal and other biological interactions may influence biological markers, making it difficult to correctly quantify them. 24 It is also important to point out the association between obesity and hypertension. Bloch et al. 12 reported a higher prevalence of hypertension in obese adolescents (28.4%) than in overweight (15.4%) and eutrophic (6.3%) adolescents. The fraction of hypertension attributable to obesity was 17.8%, which raises the hypothesis that about one-fifth of hypertensive patients would not have high BP if they were not obese. This seems important and could serve as a basis for decision-makers of the potential benefits of increasing school-based PA interventions, including intermediate outcomes as control of hypertension, a major cause of cardiovascular mortality in later life. 25 Interestingly, while both boys and girls attending RSch were less physically active and had a higher frequency of pre-hypertension/hypertension, only girls appeared to benefit more from attending OEG schools when the goal was control of body weight. A possible explanation for this finding is that boys are usually more active than girls and more frequently engaged in non-scheduled PA. 26 Regarding our exploratory binomial logistic regression analysis, after adjusting for age and sex, RSch students had higher odds to be overweight and to have pre-hypertension/ hypertension than OEG students, supporting the rationale and results described above. 19 Actually, no differences were found for altered glycemia or lipid profile. The results of the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE), a largemulticenter cross-sectional study, demonstrated a positive association between sedentary behavior and obesity, even in the cluster analysis of 6,000 students from12 countries 27 and in the evaluation of those meeting the recommendations for 24-hour movement guidelines. 28 778