Nationwide evidence from China on the dose-response between environmental fitness support and physical activity.

This study aims to investigate the relationship between Environmental Fitness Support (EFS) scores and physical activity (PA), analyzing the non-linear and dose-response relationships between fitness environment support and different intensities of PA, as well as the impact of various environmental dimensions on PA intensity. Using data from the 2020 China National Fitness Activity Status Survey, a multi-stage stratified random sampling method was employed to select 5,760 village (resident) committees from 31 provinces, yielding 58,844 valid samples. The survey collected demographic information and environmental support factors (EFS scores), and used the International Physical Activity Questionnaire to measure PA intensity. Statistical analyses were conducted using R software, including multiple linear regression and Generalized Additive Models. The EFS scores are significantly associated with PA intensity. MVPA demonstrated a negative association at low EFS scores, turning positive near the threshold of 35.06 (95% CI: 32.50, 37.80) points. In the adjusted model, traffic safety was negatively associated with VPA (β = -0.13, p < 0.001), while fitness facility support and aesthetics were positively associated with VPA (β = 0.15, p < 0.001 and β = 0.05, p = 0.021). MPA was also positively influenced by fitness facility support and aesthetics (β = 0.42, p < 0.001 and β = 0.63, p < 0.001), with traffic safety positively associated with MPA (β = 0.24, p < 0.001), but accessibility showed a negative correlation with MPA (β = -0.07, p = 0.014). Environmental fitness support was associated with VPA significantly and moderately with MPA, while fitness facility aesthetics benefit both; however, traffic safety and infrastructure were negatively associated with VPA.