The influence of physical exercise on the loneliness of the older adults: the mediating role of frailty and depression

Background Frailty, depression, and loneliness are risk factors for successful aging. Physical exercise is an important method to promote the physical and mental health of the older adults. Guided by the integral conceptual model of frailty, this study constructed a mediating model to examine the influence of physical exercise on the loneliness of the older adults, as well as determine the mediating role of frailty and depression between them. Methods In this descriptive and cross-sectional study, a questionnaire survey was conducted on 505 older adults individuals aged 60 and above in China from February to July 2023. The data were collected using the Physical Activity Rating Scale (PARS-3), the UCLA Loneliness Scale (ULS-8), the Tilburg Frailty Indicator (TFI) and the Patient Health Questionnaire-9 (PHQ-9). The collected data was analyzed for mediating effects using the SPSS macro program PROCESS v4.0, Model 6. Results Physical exercise negatively predicted frailty, depression, and loneliness in the older adults (β = -0.414, P < 0.01; β = -0.248, P < 0.01; and β = -0.194, P < 0.01, respectively). Physical exercise affects loneliness through four paths: direct effect, the mediating effect of frailty, the mediating effect of depression, and serial multiple mediating effect of frailty and depression. The mediating effect model explained 58.55% of the variation in loneliness. Conclusions Physical exercise can not only improve the frailty of the older adults but also alleviate the depression caused by the decline in their physiological and social functions, thereby comprehensively improving their loneliness. From the perspective of frailty, we could identify high-risk groups for depression and loneliness and find targeted interventions based on the type of frailty (social, psychological, and physiological), such as participating in collective physical exercise and combining physical exercise interventions with antidepressant medication or nutrition interventions. The results of this study can help older adults people manage their health and improve their physical and mental state.