title: The physical activity behaviors outside school and BMI in adolescents.
abstract: 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.
authors.affiliation: Research Centre in Physical Activity, Health, and Leisure, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Mota
authors.forename: Jose Carlos
authors.initials: JC
authors.lastname: Ribeiro
authors.forename: Joana
authors.initials: J
authors.lastname: Carvalho
authors.forename: Maria Paula
authors.initials: MP
authors.lastname: Santos
mesh_terms: D000293:Adolescent; D000367:Age Factors; D015992:Body Mass Index; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D012574:Schools / Q000706:statistics & numerical data*; D012737:Sex Factors; D014186:Transportation