The Relationship Between Physical Activity and Depression Among Middle-aged and Elderly Chinese: A Longitudinal Study

Objective: This study aims to discuss the association between physical activity and the risk of depression using cross-sectional and longitudinal data respectively, in order to determine whether physical activity serves as a protective or risk factor for depression. Methods: A total of 3,564 eligible middle-aged and elderly individuals from the China Health and Retirement Longitudinal Study (CHARLS) were included. Cross-sectional data from 2020 were analyzed to examine the dose-response relationship between physical activity and depression. Group-based trajectory model was used to identify trajectories of physical activity from 2011 to 2020, and multivariable logistic regression was employed to analyze the association between physical activity trajectories and depression symptoms in 2020. Results: 1) Cross-sectional analysis revealed a U-shaped relationship between physical activity level and depression risk. 2) Longitudinal analysis of physical activity demonstrated that compared to the low-stable group (Group A), the moderate-stable group (Group B) had the lowest risk of depression, with a 47% decrease in risk (odds ratio [OR] 0.53, 95% confidence interval [CI] 0.39-0.71, P < 0.001), while the highest-stable group (Group E) had the highest risk of depression, with a 37% increase in risk (OR 1.37, 95% CI 1.02-1.82, P = 0.033). 3) The protective effect of physical activity trajectories was significant in both male and female groups, while the harmful effect was only significant in the female group. Conclusion: Physical activity serves as both a protective factor and a risk factor for depression prevention in middle-aged and elderly Chinese populations. Both men and women can benefit from long-term moderate physical activity, but women are more susceptible to the harmful effects of excessive physical activity. Adequate physical activity is an effective measure for preventing depression, while early reduction of excessive physical activity may also be beneficial.