Population-level trajectories and social determinants of physical activity among older adults in China and South Korea

Given rapid population aging and the high prevalence of insufficient physical activity (PA) in East Asian societies, population-level studies of PA trends among older adults provide an opportunity to promote healthy aging and health equity. This study examines temporal trends in PA compliance and compares the localized social determinants of health (SDoH) driving specific patterns of health inequality among Chinese and South Korean older adults. Using the China Health and Retirement Longitudinal Study (2011/2018, N = 13,534) and the Korean Longitudinal Study of Aging (2010/2018, N = 10,622), Average Partial Effects models investigated the associations of rural-urban structural position, socioeconomic status (SES), and demographic characteristics with PA compliance. A triple interaction model tested cross-national heterogeneity in population-level inequality patterns. PA compliance among Chinese older adults increased from 16.0% (95% CI: 14.7–17.3) to 43.5% (95% CI: 42.5–44.4), whereas it remained stable in South Korea, from 25.4% (95% CI: 24.2–26.6) to 25.6% (95% CI: 24.5–26.8). The triple interaction models indicated that China exhibited an inverse SES gradient associated with rural informal networks, accompanied by expanding health disparities, whereas South Korea demonstrated a positive SES gradient associated with urban formalized leisure and persistent stratification. While gender and educational disparities narrowed in both cohorts, advanced age consistently restricted PA participation. The findings contribute to understanding population-level changes in PA shaped by distinct structural SDoH and support locally tailored interventions to promote health equity among older adults.