The effects of an after-school intervention program on physical activity level, sedentary time, and cardiovascular risk factors in adolescents

Abstract Aim: To ascertain the effects of an after-school intervention on physical activity levels and cardiovascular risk factors in adolescents from Campinas, Brazil. Methods: This was an intervention study with 71 adolescents that was carried out in two schools, randomly assigned to a control group (CG:n=45) or an intervention group (IG:n=26). We performed evaluations of body composition, sexual maturation, blood pressure, level of physical activity, sedentary time (ST), and eating habits, as well as biochemical variables by a portable analyzer. The IG participated in two weekly sessions of physical activities and controlled physical exercises for 14 weeks. The sessions lasted 60’, and were divided into warm-up (5-10’), main part (40-50’), and recovery (5-10’). Results: 30.8% of the IG and 24.4% of the CG were classified as overweight/obese. Additionally, the IG showed significantly lower ST (total: p=0.037; daily: p=0.009) after the intervention, as well as in the post-period (total ST: p=0.043; daily ST: p=0.007). The IG showed a reduction in glycemia (p=0.025). Conclusion: The intervention program generated positive changes in glycemia levels and ST. These results suggest that interventions involving physical exercise should be promoted in the school environment, as physical activity is an important component of a healthy lifestyle.