The impact of physical exercise on depression among college students: the mediating role of core self-evaluation and meaning in life

Objective In recent years, increasing attention has been paid to the effectiveness of physical exercise in alleviating depression. This has led to extensive research into its underlying mechanisms. College students are particularly vulnerable to mental health problems due to academic pressure, employment competition, complex interpersonal relationships, and external stress. Drawing on the framework of positive psychological capital, this study examines the role of physical exercise in promoting mental health among college students. It also explores the mechanisms through which such exercise is associated with depression symptoms. Methods A total of 1,100 university students were recruited through convenience sampling from universities in Shandong, Ningxia, Hainan, Zhejiang, Guangdong, Guangxi, and Jiangxi. Data were collected using the Physical Activity Level Scale, Self-Rating Depression Scale, Core Self-Evaluation Scale, and Meaning in Life Scale. Additionally, we conducted statistical analyses using SPSS 26.0 and applied Hayes’ PROCESS macro to test the hypothesized chain mediation model and applied bootstrap methods to assess the significance of the mediation paths. Results Significant gender differences were identified in physical exercise, core self-evaluation, and meaning in life. Grade-level differences were observed only for meaning in life. Physical exercise was significantly associated with depression, core self-evaluation, and meaning in life. Both core self-evaluation and meaning in life independently mediated the relationship between physical exercise and depression. In addition, a significant chain mediation effect was identified. Specifically, three indirect pathways were significant: (1) Physical exercise → core self-evaluation → depression (indirect effect = −0.047, 95% CI not including 0), accounting for 32.64% of the total effect; (2) Physical exercise → meaning in life → depression (indirect effect = −0.008, 95% CI not including 0), accounting for 5.56% of the total effect; (3) Physical exercise → core self-evaluation → meaning in life → depression (indirect effect = −0.008, 95% CI not including 0), accounting for 25.69% of the total effect. Conclusion Physical exercise, depression, core self-evaluation, and meaning in life are significantly associated among college students. Physical exercise is strongly associated with lower levels of depressive symptoms, and is indirectly related to these symptoms through both independent and sequential mediation by core self-evaluation and meaning in life.