title: "For whom was it effective?" Moderators of the effect of a school-based intervention on potential physical activity determinants among Brazilian students.
abstract: Knowledge about the effects of school-based interventions on modifiable physical activity (PA) determinants (e.g., social support), and whether the intervention effect differs according to students' characteristics (e.g., age and gender) are relevant PA promotion topics. This study aims to answer these topics among Brazilian students. This cluster-randomized controlled trial was conducted with 548 students in the intervention group and 537 in the control group (51.5% of boys; aged 11-18years). The four-month intervention included strategies focused on training teachers, opportunities for PA in the school environment, and health education. Potential PA determinants (attitude, self-efficacy, support of friends, parents, and teachers, perceived neighborhood environment and PA facilities in school) and moderators (gender, age, socioeconomic status (SES), and PA level at baseline) were assessed using self-reported instrument. Height and weight were measured to estimate the students' body mass index (BMI) status. Generalized linear models were used. In general, there was a significant and positive intervention effect for attitude, support of friends and teachers for PA, as well as PA facilities in school; effect size was 0.29, 0.24, 0.34, and 0.29, respectively (P<0.05). Age (support of friends, parents and teachers, and PA facilities in school), SES (support of friends and PA facilities in school), and BMI status (support of friends) were moderators of the intervention effect on some outcomes. In conclusion, the intervention improved potential PA determinants, but some changes occurred differently according to students' characteristics. These findings should be considered in PA policies in the school context.
  
  
  BACKGROUND
  This study is registered at Clinicaltrials.govNCT02439827.
authors.affiliation: Research Centre in Physical Activity and Health, Department of Physical Education, Federal University of Santa Catarina, Florianópolis, Brazil; Research Centre in Physical Activity and Health in School, Institute of Physical Education and Sports, Federal University of Ceará, Fortaleza, Brazil; Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal. Electronic address: valtercbf@gmail.com.
authors.forename: Valter Cordeiro
authors.initials: VC
authors.lastname: Barbosa Filho
authors.affiliation: Research Centre in Physical Activity and Health, Department of Physical Education, Federal University of Santa Catarina, Florianópolis, Brazil.
authors.forename: Kelly Samara
authors.initials: KS
authors.lastname: da Silva
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.affiliation: Research Centre in Physical Activity and Health in School, Institute of Physical Education and Sports, Federal University of Ceará, Fortaleza, Brazil; Aids Project: Education and Prevention, Department of Nursing, Federal University of Ceara, Fortaleza, Brazil.
authors.forename: Neiva Francenely Cunha
authors.initials: NFC
authors.lastname: Vieira
authors.affiliation: Research Centre in Physical Activity and Health in School, Institute of Physical Education and Sports, Federal University of Ceará, Fortaleza, Brazil; Aids Project: Education and Prevention, Department of Nursing, Federal University of Ceara, Fortaleza, Brazil.
authors.forename: Fabiane do Amaral
authors.initials: FDA
authors.lastname: Gubert
authors.affiliation: Research Centre in Physical Activity and Health, Department of Physical Education, Federal University of Santa Catarina, Florianópolis, Brazil.
authors.forename: Adair da Silva
authors.initials: ADS
authors.lastname: Lopes
mesh_terms: D000293:Adolescent; D001938:Brazil; D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D009765:Obesity; D012574:Schools; D012923:Social Class; D012944:Social Support; D011795:Surveys and Questionnaires
keywords: Associated factors; Clinical trial; Health and environment; Motor activity; Obesity; Socioecological theory; Socioeconomic factors; Vulnerable populations