Effects of ActTeens intervention on physical activity and health indicators in Brazilian adolescents: a pilot study

Objective: To evaluate the effect of 12 weeks of the ActTeens program on physical activity (PA) practice at different intensities, health-related physical fitness, and cardiometabolic indicators in Brazilian adolescents. Methods: The sample comprised 55 adolescents (37.5% female; mean age 13.84 [0.62]years) from two secondary private schools were included and divided by simple randon allocation into intervention (IG = 31 students) or control group (CG = 24 students). This pilot study of the ActTeens Program was conducted during the COVID-19 pandemic restrictions and included three components: (1) structured PA sessions delivered within Physical Education, (2) self monitoring plus goal setting by a pedometer, and (3) healthy lifestyle guidance (mHealth). PA was assessed using Actigraph hip-worn accelerometer (model GT3X+), muscular fitness was mensured by 90-pushup, sit-to-stand, and Cardiorespiratory fitness was assessed using the 20-m PACER shuttle run test, following standardized procedures, as well as cardiometabolic profile indicators (glucose; blood pressure and waist circumference). Intragroup analyzes were performed using generalized estimating equations, and intergroup by ANCOVA using the intention-to-treat principle with adjustment for the covariates of age, maturation, sex, and baseline values. Results: Adolescents in the IG showed significant increase for moderate (mean difference: 11.2 minutes/day; 95% CI: 2.9; 21.0) and moderate-to-vigorous (mean difference: 18.9 minutes/day, 95% CI: 5.9; 32.1) PA in comparison to the CG. No effect of the intervention was observed in sencondary outcomes (physical fitness and cardiometabolic indicators). The IG presented a significant increase in muscular and cardiorespiratory fitness, and decreased blood pressure after 12 weeks of the intervention. Conclusion: The strategies used in the ActTeens intervention were effective to promote the increase in PA and improve physical fitness in these adolescents during the COVID-19 pandemic.