A multi-component active play intervention to enhance 24-h movement behaviours and FMS in Bangladeshi primary school children: study protocol for a cluster randomised trial

Background Children’s physical activity (PA), sedentary behaviour (SB), and sleep are interdependent components of the 24-h movement cycle, yet adherence to integrated movement guidelines remains low worldwide. In Bangladesh, dense urban living, limited safe play spaces, academic pressure, and parental safety concerns restrict children’s movement opportunities, contributing to low PA and high sedentary time. Active play (AP) is a low-cost, feasible approach to improve movement behaviours and fundamental movement skills (FMS), with evidence showing consistent improvements in FMS and modest gains in PA. Objective To evaluate the effectiveness of a school-based AP intervention on PA, SB, sleep, and FMS among Bangladeshi primary school children. Methods A two-arm cluster randomised-controlled trial will be conducted with 1:1 allocation to intervention or waitlist control. Primary school children will participate in a 12-week AP programme with two 60-min sessions per week, combining guided and free play. PA, SB, and sleep will be measured using ActiGraph wGT3X-BT accelerometers and validated questionnaires, while FMS will be assessed using the TGMD-3. Outcomes will be analysed using linear mixed-effects models. Compositional data analysis with isometric log-ratio transformations will examine 24-h movement behaviours. Analyses will follow an intention-to-treat approach. Expected outcomes The intervention is expected to increase MVPA and LPA, reduce SB, extend sleep duration, improve FMS, and enhance adherence to 24-h movement guidelines. Conclusion This trial will provide rigorous, context-specific evidence on the effectiveness of a school-based AP intervention in Bangladesh.