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What helps children to move more at school recess and lunchtime? Mid-intervention results from Transform-Us! cluster-randomised controlled trial
  1. Mine Yıldırım1,
  2. Lauren Arundell2,
  3. Ester Cerin2,3,
  4. Valerie Carson2,
  5. Helen Brown2,
  6. David Crawford2,
  7. Kylie D Hesketh2,
  8. Nicola D Ridgers2,
  9. Saskia J Te Velde4,
  10. Mai J M Chinapaw1,
  11. Jo Salmon2
  1. 1Department of Public and Occupational Health and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
  2. 2Faculty of Health, Centre for Physical Activity and Nutrition Research, Deakin University, Burwood, Victoria, Australia
  3. 3Institute of Human Performance, The University of Hong Kong, Hong Kong, China
  4. 4EMGO Institute for Health and Care Research and the Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands
  1. Correspondence to Dr Mai J M Chinapaw, EMGO Institute for Health Care Research, VU University Medical Center, van der Boechorststraat 7, Amsterdam 1081 BT, The Netherlands; m.chinapaw{at}


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.

  • Children
  • Intervention Effectiveness
  • Physical Activity Measurement

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