Dose-Related Associations Between Physical Activity and Multimorbidity Among Middle-Aged and Older Adults

The burden that multimorbidity places on people, families, and society as a whole has made it a global public health concern. While physical activity (PA) is supported by the World Health Organization (WHO) as a crucial approach for avoiding chronic diseases, there is minimal data to support its link with multimorbidity, especially among populations of middle-aged and elderly in China. Derived from the China Health and Retirement Longitudinal Study (CHARLS) conducted in 2018, a cross-sectional data was employed in this study. To analyze the linear connection between multimorbidity and PA, Restricted Cubic Spline (RCS) and Binary logistic regression were applied. The heterogeneity of this association across other groups was investigated using subgroup and interaction analysis. Three sensitivity analyses validated the results' robustness. Among 19,453 participants, 25.24% of middle-aged and older individuals actively engaged in moderate vigorous PA, 58.40% often participated in vigorous PA, and the prevalence of multimorbidity was 40.18%. After adjusting for all confounding factors, compared with low-intensity PA, moderate vigorous PA (OR = 0.889, 95% CI: 0.810-0.976) and vigorous PA (OR = 0.731, 95% CI: 0.673-0.794) demonstrated a significantly attenuated risk of multimorbidity. Multimorbidity and PA did not significantly correlate linearly, according to the RCS result. Age, residence, social activities and drinking were found to have substantial modifying effects on the relationship between PA and multimorbidity, according to the subgroup and interaction analyses. The outcomes of this research underline the the association between physical activity and a reduced risk of multimorbidity. This suggests that under the premise of ensuring safety, higher levels of physical activity among middle-aged and older adults may be linked to later onset of chronic disease.