title: Effect of school-based interventions on physical activity and fitness in children and adolescents: a review of reviews and systematic update.
abstract: BACKGROUND
  School-based interventions are thought to be the most universally applicable and effective way to counteract low physical activity (PA) and fitness although there is controversy about the optimal strategy to intervene.
  
  
  OBJECTIVE
  The objective of this review was to summarise recent reviews that aimed to increase PA or fitness in youth and carry out a systematic review of new intervention studies.
  
  
  METHODS
  Relevant systematic reviews and original controlled and randomised controlled school-based trials with a PA or fitness outcome measure, a duration of ≥12 weeks, a sufficient quality and involvement of a healthy population aged 6-18 years that were published from 2007 to 2010 were included. Results In these reviews, 47-65% of trials were found to be effective. The effect was mostly seen in school-related PA while effects outside school were often not observed or assessed.
  
  
  CONCLUSIONS
  The school-based application of multicomponent intervention strategies was the most consistent, promising strategy, while controversy existed regarding the effectiveness of family involvement, focus on healthy populations at increased risk or duration and intensity of the intervention. All 20 trials in the review update showed a positive effect on in-school, out-of-school or overall PA, and 6 of 11 studies showed an increase in fitness. Taking into consideration both assessment quality and public health relevance, multicomponent approaches in children including family components showed the highest level of evidence for increasing overall PA. This review confirms the public health potential of high quality, school-based PA interventions for increasing PA and possibly fitness in healthy youth.
authors.affiliation: Swiss Tropical and Public Health Institute, University of Basel, Socinstr 59, 4002 Basel, Switzerland. susi.kriemler@unibas.ch
authors.forename: S
authors.initials: S
authors.lastname: Kriemler
authors.forename: U
authors.initials: U
authors.lastname: Meyer
authors.forename: E
authors.initials: E
authors.lastname: Martin
authors.forename: E M F
authors.initials: EM
authors.lastname: van Sluijs
authors.forename: L B
authors.initials: LB
authors.lastname: Andersen
authors.forename: B W
authors.initials: BW
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D002648:Child; D015444:Exercise / Q000502:physiology*; D006293:Health Promotion / Q000458:organization & administration; D006304:Health Status; D006801:Humans; D009048:Motor Skills / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D012572:School Health Services / Q000458:organization & administration*; D000078202:Systematic Reviews as Topic