To investigate the relationship between muscle strength and the risk of depression in the middle-aged and elderly, and to provide reference for the prevention and treatment of depression in the middle-aged and elderly in China.

Based on the data of China Health and Retirement Longitudinal Study (CHARLS), the middle-aged and elderly people who participated in the survey in 2015 and 2018 were selected. Firstly, restricted cubic splines (RCS) were used to analyze whether there was a dose-response relationship between upper limb strength (standardized grip strength) and lower limb strength (time to stand up from a chair) and the risk of depression in the middle-aged and elderly. Secondly, the upper and lower limb strength were divided into three groups, and Logistic regression model was used to evaluate the correlation between upper and lower limb strength, overall muscle strength and depression risk in the middle-aged and elderly.

A total of 6 245 subjects were enrolled in this study. During the 3-year follow-up period, a total of 2 095 (33.5%) subjects had depressive symptoms.There was a dose-response relationship between upper and lower limb strength and the risk of depression in the middle-aged and elderly. Logistic regression model showed that after adjusting the confounding factors such as sex, age and marital status, stronger upper and lower limb strength could reduce the risk of depression by 24% and 28%, respectively. Compared with the weakest overall muscle strength group, the strongest muscle strength group had a 48% lower risk of depression (OR=0.52,95%CI: 0.41-0.67).

Strong muscle strength can reduce the risk of depression in the middle-aged and elderly.