An important barrier for a nationwide implementation of a daily physical activity (PA) at primary schools is the lack of spatial and human resources. Therefore, we developed a PA intervention that can be implemented without additional spatial resources or changes in school curricula. In the intervention group, children received a daily PA unit consisting of physical education lessons and simultaneous academic content over a 9-month period. The control group received conventional (physical education) classes. Body weight, height, waist circumference and health-related fitness parameters were measured. Of 412 children (9.7 ± 0.5 years) included, 228 participated in the intervention group. In regression analysis adjusted for baseline, gender, school location, sports club membership (total only) with standardized outcome variables, the intervention group showed a reduction in waist-to-height ratio (B = 0.30, p < 0.001) and an increase in several fitness parameters (cardiorespiratory endurance: B = 0.20, p = 0.037; lower body muscle strength: B = 0.11, p = 0.041; lower body muscle endurance: B = 0.12, p = 0.027; flexibility: B = 0.19, p = 0.019) compared to the control group. Intervention effects for cardiorespiratory endurance and flexibility were more pronounced in the group of children without sports club membership. Thus, especially children with no sport club membership seem to benefit from daily PA in school (Trial registration: DRKS00025515).
Keywords: Physical activity; RCT; health-related fitness; physical education; school.