IntroductionThe aim of this study was to investigate the simultaneous presence of risk factors for non-communicable diseases and the association of these risk factors with demographic and economic factors among adolescents from southern Brazil.MethodsThe study included 916 students (14–19 years old) enrolled in the 2014 school year at state schools in São José, Santa Catarina, Brazil. Risk factors related to lifestyle (i.e., physical inactivity, excessive alcohol consumption, smoking, sedentary behaviour and unhealthy diet), demographic variables (sex, age and skin colour) and economic variables (school shift and economic level) were assessed through a questionnaire. Simultaneous behaviours were assessed by the ratio between observed and expected prevalences of risk factors for non-communicable diseases. The clustering of risk factors was analysed by multinomial logistic regression. The clusters of risk factors that showed a higher prevalence were analysed by binary logistic regression.ResultsThe clustering of two, three, four, and five risk factors were found in 22.2%, 49.3%, 21.7% and 3.1% of adolescents, respectively. Subgroups that were more likely to have both behaviours of physical inactivity and unhealthy diet simultaneously were mostly composed of girls (OR = 3.03, 95% CI = 1.57–5.85) and those with lower socioeconomic status (OR = 1.83, 95% CI = 1.05–3.21); simultaneous physical inactivity, excessive alcohol consumption, sedentary behaviour and unhealthy diet were mainly observed among older adolescents (OR = 1.49, 95% CI = 1.05–2.12). Subgroups less likely to have both behaviours of sedentary behaviour and unhealthy diet were mostly composed of girls (OR = 0.58, 95% CI = 0.38–0.89); simultaneous physical inactivity, sedentary behaviour and unhealthy diet were mainly observed among older individuals (OR = 0.66, 95% CI = 0.49–0.87) and those of the night shift (OR = 0.59, 95% CI = 0.43–0.82).ConclusionAdolescents had a high prevalence of simultaneous risk factors for NCDs. Demographic (gender and age) and economic (school shift) variables were associated with the most prevalent simultaneous behaviours among adolescents.

The aim of this study was to verify the effectiveness of a multicomponent, school-based intervention in reducing screentime in adolescents according to sex. Methods: This is a non-randomized controlled intervention study focusing on cardiorespiratory fitness, body image, nutrition and physical activity. Screentime (television, computer/ video game) was the secondary outcome of the intervention and was addressed using educational strategies (folders, posters, educational sessions and group discussions). Screen time was measured using a structured questionnaire validated in Brazilian adolescents and the excess time spent on-screen was defined as two hours or more daily. The effect of the intervention was analyzed by the McNemar test and logistic regression. Results: Intervention effectively reduced the proportion of adolescents exposed to more than two hours a day of computer/videogame in males from 71.7% to 57.5% (p= 0.002) and excessive time of television in females from 81.5% to 72.6% (p = 0.024), from the beginning to the end of the study in the group receiving intervention. However, no effect of intervention was found in the comparison between intervention and control groups for computer/video game time (OR = 0.822; p = 0.504) and television time (OR = 0.667; p = 0.252). Conclusion: The intervention was not effective in reducing screen time in the comparison between intervention and control groups, but it reduced the screen time of adolescents in the intervention group.

BACKGROUND: Sedentary behavior (SB) is related to unhealthy outcomes and is performed in many contexts, including school. The aim of this study was to identify sociodemographic, biological, and psychosocial correlates of SB performed at school in a sample of adolescents. METHODS:Adolescents provided information regarding sex, age, socioeconomic status, and psychosocial variables related to physical activity (self-efficacy, attitudes, perception of school environment, peer and parental support). Body fat was estimated using skinfolds, and maximum aerobic capacity with a 20 m shuttle run. Adolescents wore accelerometers and SB performed during class time, physical education (PE) classes, and recesses was estimated. RESULTS:Adolescents (N = 567, 53% female, 12.9 ± 5.3 years old) spent 67% of class time, 41% of PE classes, and 41% of recesses in SB. Girls spent more time in SB, and age was negatively associated with SB. Body fat was positively associated with SB in class time and PE classes. Peer support for physical activity was negatively associated with SB in class time, whereas attitudes related to physical activity were negatively associated with SB during PE classes and recesses. CONCLUSION:Adolescents spend long periods in SB at school, even during opportunities to be active like PE classes and recesses.Keywords: child and adolescent health; physical fitness and sport; public health.Citation: da Costa BGG, da Silva KS, Bandeira AS, Martins CR, Vieira JAJ, Petroski EL. Pattern of sedentary behavior in different periods of school time of Brazilian adolescents.