title: Empowering adolescents to be physically active: three-year results of the Sigue la Huella intervention.
abstract: OBJECTIVE
  To examine the effects of a school-based intervention called Sigue la Huella (Follow the Footstep) on adolescents' daily moderate-to-vigorous physical activity (MVPA).
  
  
  METHODS
  This quasi-experimental, cohort study took place in four secondary schools in Huesca (Spain) during the 2009-2010, 2010-2011, and 2011-2012 academic years (students aged 12-15 years). Two schools were assigned to the experimental condition (n=368) and two schools to the control condition (n=314). Sigue la Huella was based on the social ecological model and self-determination theory. MVPA was measured for 7 days on 4 occasions using accelerometers. Data were analyzed with individual growth curve models.
  
  
  RESULTS
  There was a significant difference in linear growth rate of daily MVPA between the experimental and the control group, independent of study wave, type of school (public vs. private), grade level and gender (p<0.001). Specifically, MVPA increased in the experimental group (β=7.02, 95% confidence interval (CI)=1.27 to 12.78, p=0.017) and tended to decrease in the control group (β=-5.26, 95% CI=-11.17 to 0.65, p<0.081). The observed increase was larger in boys than in girls (p=0.003).
  
  
  CONCLUSIONS
  Sigue la Huella had a positive effect on adolescents' daily MVPA over three school years. Both genders benefited from the intervention, although boys to a greater extent.
authors.affiliation: Departamento de Expresión Musical, Plástica y Corporal, Universidad de Zaragoza, Huesca C.P. 22002, Spain. Electronic address: bmurillo@unizar.es.
authors.forename: Berta Murillo
authors.initials: BM
authors.lastname: Pardo
authors.affiliation: Department of Kinesiology and Physical Education, McGill University, Montreal H2W 1S4, Canada. Electronic address: enrique.garcia@mcgill.ca.
authors.forename: Enrique García
authors.initials: EG
authors.lastname: Bengoechea
authors.affiliation: Departamento de Expresión Musical, Plástica y Corporal, Universidad de Zaragoza, Huesca C.P. 22002, Spain. Electronic address: jajulian@unizar.es.
authors.forename: José A
authors.initials: JA
authors.lastname: Julián Clemente
authors.affiliation: Departamento de Expresión Musical, Plástica y Corporal, Universidad de Zaragoza, Huesca C.P. 22002, Spain. Electronic address: generelo@unizar.es.
authors.forename: Eduardo Generelo
authors.initials: EG
authors.lastname: Lanaspa
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D015444:Exercise / Q000523:psychology; D005260:Female; D015438:Health Behavior; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D009042:Motivation; D011209:Power, Psychological; D012572:School Health Services; D013030:Spain
keywords: Adolescents; Moderate-to-vigorous physical activity; School-based intervention; Self-determination theory; Social ecology