Effectiveness of a school-based intervention on physical activity and screen time among adolescents.

Objectives: To evaluate the effectiveness of a multi-component school-based intervention on physical activity (PA) and screen time (ST) among urban adolescents in Bangladesh.

Design: Cluster-randomised controlled trial.

Methods: Eight high schools were randomly assigned to either intervention group (IG) or control group (CG). Participants (n = 160 per group, 40 school) were in grades 8-9. A 12-week multi-component intervention was developed based on the WHO's Health-Promoting Schools framework. The IG received weekly supervised circuit exercise (30 min/week), health education session (10 min/week) with health educational materials, and lunchtime sports activities (20 min/week). The main outcome measures included self-reported PA, ST, knowledge on PA and SB, which were assessed at baseline, 8 and 12 weeks. Repeated measures ANCOVA was used to evaluate the intervention effects.

Results: Total PA (MET-min/week) was increased from baseline to 8 and 12 weeks in the IG (3%-5%) but decreased in the CG (5%-3%) and significantly improved in the IG compared to the CG (p < 0.001) over time. Average ST (min/day) reduced from baseline to 8 and 12 weeks in the IG (28%-35%), while remained unchanged in the CG (6%-5%). The IG had a significantly lower average ST than the CG at 12 weeks. The average knowledge scores on PA and SB were significantly higher in the IG than the CG at 12 weeks (p < 0.001).

Conclusions: Our intervention has demonstrated some promising effects on increasing PA, reducing ST, and improving PA and SB knowledge. This study underscores the need for a scaled-up evaluation in other locations including rural settings.