Family socioeconomic status and moderate to vigorous physical activity among Chinese adults: the chain mediating roles of exercise environment and exercise motivation

Objective This study aimed to examine the relationship between family socioeconomic status (SES) and moderate to vigorous physical activity (MVPA) among adults aged 20–59 years, as well as the chain-mediating effects of exercise environment (EE) and exercise motivation (EM) in this association. Methods: Using data from the 2020 National Fitness Survey, a total of 55,804 adults aged 20–59 years were included in the analysis. Multiple linear regression, chain-mediation modeling, and subgroup analyses were performed using SPSS 30.0. Results (1) Family SES was positively associated with MVPA ( r = 0.053, p < 0.01). (2) EE and EM mediated the relationship between family SES and MVPA through three distinct pathways: the independent mediation of EE (effect size = 0.439, 95%CI = 0.387 ~ 0.494), the independent mediation of EM (effect size = 0.168, 95%CI = 0.141 ~ 0.195), and the chain mediation of EE and EM (effect size = 0.170, 95%CI = 0.128 ~ 0.151), accounting for 48.67, 18.63, and 15.52% of the total effect, respectively. (3) The direct effect of family SES on MVPA exhibited differential trends across age (20–29, β = 0.090, 95%CI = 1.139 ~ 1.726, p < 0.01, 30–39, β = 0.076, 95%CI = 0.854 ~ 1.311, p < 0.01, 40–49, β = 0.059, 95%CI = 0.731 ~ 1.282, p < 0.01, 50–59, β = 0.081, 95%CI = 1.410 ~ 2.101, p < 0.01), sex (male, β = 0.089, 95%CI = 1.315 ~ 1.709, p < 0.01, female, β = 0.014, 95%CI = 0.033 ~ 0.430, p < 0.05), and urban–rural subgroups(urban, β = 0.038, 95%CI = 0.469 ~ 0.814, p < 0.01, rural, β = 0.043, 95%CI = 0.592 ~ 1.160, p < 0.01), with significant interaction effects observed. Conclusion This study reveals that family SES influences MVPA among adults through three pathways: EE alone, EM alone, and the chain-mediation of EE and EM. These findings suggest potential entry points for strengthening family level support for physical activity and may inform strategies aimed at improving adults’ exercise participation.