title: What helps children to move more at school recess and lunchtime? Mid-intervention results from Transform-Us! cluster-randomised controlled trial.
abstract: BACKGROUND
  To investigate the interpersonal and physical environment mediators of the Transform-Us! mid-intervention effects on physical activity (PA) during recess and lunchtime.
  
  
  METHODS
  Transform-Us! is a clustered randomised school-based intervention with four groups: sedentary behaviour intervention (SB-I), PA intervention (PA-I), combined PA+SB-I and control group. All children in grade 3 from 20 participating primary schools in Melbourne, Australia were eligible to complete annual evaluation assessments. The outcomes were the proportion of time spent in moderate-to-vigorous PA (MVPA) and light PA (LPA) during recess and lunchtime assessed by accelerometers. Potential mediators included: perceived social support from teachers; perceived availability of line markings; perceived accessibility of sports equipment; and perceived school play environment. Generalised linear models were used and mediation effects were estimated by product-of-coefficients (a·b) approach.
  
  
  RESULTS
  268 children (8.2 years, 57% girls at baseline) provided complete data at both time points. A significant intervention effect on MVPA during recess in the SB-I and PA-I groups compared with the control group (proportional difference in MVPA time; 38% (95% CI 21% to 57%) and 40% (95% CI 20% to 62%), respectively) was found. The perceived school play environment was significantly positively associated with MVPA at recess among girls. An increase in perceived social support from teachers suppressed the PA+SB-I effect on light PA during recess (a·b= -0.03, 95% CI -0.06 to -0.00). No significant mediating effects on PA during recess and lunchtime were observed.
  
  
  CONCLUSIONS
  A positive perception of the school play environment was associated with higher MVPA during recess among girls. Future studies should conduct mediation analyses to explore underlying mechanisms of PA interventions.
authors.affiliation: Department of Public and Occupational Health and the EMGO Institute for Health and Care Research, VU University Medical Center, , Amsterdam, The Netherlands.
authors.forename: Mine
authors.initials: M
authors.lastname: Yildirim
authors.forename: Lauren
authors.initials: L
authors.lastname: Arundell
authors.forename: Ester
authors.initials: E
authors.lastname: Cerin
authors.forename: Valerie
authors.initials: V
authors.lastname: Carson
authors.forename: Helen
authors.initials: H
authors.lastname: Brown
authors.forename: David
authors.initials: D
authors.lastname: Crawford
authors.forename: Kylie D
authors.initials: KD
authors.lastname: Hesketh
authors.forename: Nicola D
authors.initials: ND
authors.lastname: Ridgers
authors.forename: Saskia J
authors.initials: SJ
authors.lastname: Te Velde
authors.forename: Mai J M
authors.initials: MJ
authors.lastname: Chinapaw
authors.forename: Jo
authors.initials: J
authors.lastname: Salmon
mesh_terms: D001835:Body Weight; D002648:Child; D016000:Cluster Analysis; D004777:Environment; D004779:Environment Design; D015444:Exercise / Q000502:physiology*; D005260:Female; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D007398:Interpersonal Relations; D062409:Lunch; D008297:Male; D009042:Motivation; D009765:Obesity / Q000517:prevention & control; D012572:School Health Services; D057185:Sedentary Behavior; D012944:Social Support
keywords: Children; Intervention Effectiveness; Physical Activity Measurement