title: Incidence of school failure according to baseline leisure-time physical activity practice: prospective study.
abstract: OBJECTIVE
  To evaluate the prospective association between leisure-time physical activity practice at 11 years of age and incidence of school failure from 11 to 15 years of age.
  
  
  METHODS
  The sample comprised >4,300 adolescents followed up from birth to 15 years of age participating in a birth cohort study in Pelotas, Brazil. The incidence of school failure from age 11 to 15 years was calculated by first excluding from the analyses all subjects who experienced a school failure before 11 years of age, and then categorizing as "positive" all those who reported repeating a grade at school from 11 to 15 years of age. Leisure-time physical activity was measured using a validated questionnaire.
  
  
  RESULTS
  The incidence of school failure was 47.9% among boys and 38.2% among girls. Adolescents in the top quartile of leisure-time physical activity practice at 11 years of age had a higher likelihood of school failure (OR: 1.36; 95% CI: 1.06, 1.75) compared with the least active adolescents. In adjusted analyses stratified by sex, boys in the top quartile of leisure-time physical activity practice at 11 years of age were also more likely to have failed at school from age 11 to 15 years (OR: 1.60; 95% CI: 1.09, 2.33).
  
  
  CONCLUSIONS
  Adolescents allocating >1,000 min/wk to leisure-time physical activity were more likely to experience a school failure from 11 to 15 years of age. Although this finding does not advocate against physical activity promotion, it indicates that excess time allocated to physical activity may jeopardize school performance among adolescents.
authors.affiliation: Postgraduate Program in Epidemiology, Universidade Federal de Pelotas, Pelotas, Brazil. rombaldi@brturbo.com.br
authors.forename: Airton J
authors.initials: AJ
authors.lastname: Rombaldi
authors.forename: Valerie L
authors.initials: VL
authors.lastname: Clark
authors.forename: Felipe F
authors.initials: FF
authors.lastname: Reichert
authors.forename: Cora L P
authors.initials: CL
authors.lastname: Araújo
authors.forename: Maria C
authors.initials: MC
authors.lastname: Assunção
authors.forename: Ana M B
authors.initials: AM
authors.lastname: Menezes
authors.forename: Bernardo L
authors.initials: BL
authors.lastname: Horta
authors.forename: Pedro C
authors.initials: PC
authors.lastname: Hallal
mesh_terms: D000293:Adolescent; D001938:Brazil / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D004522:Educational Status; D015444:Exercise; D005260:Female; D006801:Humans; D015994:Incidence; D007899:Leisure Activities; D008297:Male; D011446:Prospective Studies; D013332:Student Dropouts / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires