The Physical Activity Behaviors Outside School and BMI in Adolescents

Background: The aim of this study is to investigate the associations between active transport (AT), nonorganized out of school physical activity (NOPA) and organized out of school PA (OPA) with BMI in Portuguese adolescents. Methods: The sample comprised 1121 adolescents age 13 to 17 years-old, which were assigned to 1 of 4 PA groups according to the sum of participation in different physical activity behaviors outside of school [AT, OPA, and NOPA]. Results: In boys but not in girls, BMI was lower as the participation in more PA behaviors outside school increased. For those who only carry out 1 PA behavior, AT was the most common behavior (boys = 48.9%; girls = 55.1%). On the other hand, NOPA was the most common behavior for those engaged in 2 types of PA (girls = 51.6%; boys = 46%). For those that carried out all the PA behaviors outside school OPA was the most common choice in both girls (59.5%) and boys (54%). AT, NOPA and OPA are different sources of PA outside school that accrued in different ways to the increased level of PA. Conclusions: In boys but not in girls, BMI was lower as the participation in more PA behaviors outside school increased.