The effect of school-based functional training for physical fitness and postural health among children: a school-based cluster intervention trial

School-aged children globally face declining physical fitness and postural health, yet evidence-based, scalable interventions within physical education (PE) curricula are limited. This school-based cluster intervention trial was conducted over a semester in Beijing, China. Two primary schools, matched for demographics and resources, were allocated to the intervention or control groups. The intervention group received functional training integrated into school PE, whereas the control group continued the usual PE. Improvements in physical fitness and postural health (including forward head posture [FHP] and uneven shoulders) were the primary outcomes of this study. In total, 1,286 participants were allocated to the intervention group (n = 601) and control group (n = 685). The baseline characteristics of the participants were similar. At 16 weeks, the intervention group demonstrated greater improvements in physical fitness (mean difference 0.77 [95% CI: 0.48-1.05], Cohen's d = 0.28, P < 0.001). Postural health improved, with the FHP prevalence reduced by 12.6% (risk ratio [RR], 0.65 [95% CI: 0.54-0.78]; P < 0.001), and uneven shoulders prevalence decreased by 23.3% (RR, 0.51 [95% CI: 0.42-0.65]; P < 0.001). Integrating functional training into school PE significantly improved physical fitness and postural health. These findings support its use as a scalable public health intervention to address declining physical fitness and postural health in school-aged children.Trial Registration: This trial was registered at the Chinese Clinical Trial Registry (ChiCTR-2500104984, 26/06/2025).