Changes in physical fitness in Chinese primary schools following the “double reduction” policy based on Policy Instrument Theory

This study examines the association and explores potential mechanisms of the “Double Reduction” Policy on primary school students’ physical fitness in China, using the Policy Instrument Theory framework. It analyzed 581,433 students (313,681 boys and 267,752 girls) from 156 schools in a central Chinese province from 2020 to 2024. A 5 × 2 factorial ANOVA compared five physical fitness indicators: body mass index (BMI; body shape), vital capacity (cardiopulmonary function), 50-meter run (speed and explosive power), sit-and-reach test (flexibility), and 1-minute rope skipping (motor ability). Findings indicated no significant gender-year interaction effect. The main effect of gender was statistically significant but practically negligible. The main effect of year was significant, with vital capacity, 50-meter run, sit-and-reach, and rope skipping in 2024 outperforming 2020, showing consistent improvement. BMI rose annually but stayed within normal ranges, though obesity risk warrants attention. The “Double Reduction” Policy, integrating “mandatory instruments,” “mixed instruments,” and “voluntary instruments,” forms a “time-space-resource” action chain, consistent with a proposed “time-space-resource” theoretical mechanism. However, the absence of nutritional intervention instruments represents a potential area for future policy development; energy balance considerations were not directly addressed in this study. These findings suggest a temporal association between the policy implementation period and improvements in primary school students’ physical fitness indicators; however, the integration of nutritional intervention instruments may warrant consideration in future policy design.