Aims: We investigated the effect of a school-based physical-activity intervention on children's health-related quality of life (HRQoL) and the potential influence of moderate to vigorous physical activity (MVPA). Methods: A randomised, controlled trial (Active School) involving fifth-grade children was conducted during the 2014/15 school year. The sample included 435 children (10-11 years old) at five intervention schools and four control schools. The weekly interventions concerned two 45 min of physically active lessons, five 10 min of physically active breaks and five 10 min of physically active homework. The children's HRQoL was measured using KIDSCREEN-27 and a self-report questionnaire, while physical activity was measured using accelerometers. Results: The results of multilevel analysis showed a significant effect on psychological wellbeing (p = 0.005), social support and peers (p = 0.005) and school environment (p = 0.013). No gender differences were observed. Children's MVPA did not influence their KIDSCREEN-27 score. Conclusions: The school-based physical-activity intervention (Active School) shows positive effects on children's self-reported psychological wellbeing, social support and peers, and school environment.
Keywords: Physical activity; multilevel analysis; social interactions; wellbeing.