Employing the X-Learner Algorithm to Evaluate the Intervention Effects of Physical Activity on Determinants of Elderly Mental Health.

(1) Objectives: This study aimed to investigate the intervention effects of physical activity and sedentary behavior on the relationship between various influencing factors and mental health outcomes in the elderly. (2) Methods: Complied data collected from a nationwide survey conducted between 2013 and 2022 were analyzed using the X-Learner algorithm to explore these relationships. (3) Results: The findings indicate that engagement in both high- and moderate-intensity physical activities leads to statistically significant improvements in depression, suicidal ideation, and stress levels compared to non-participation. (4) Conclusions: The study emphasizes the essential role of physical activity in enhancing the mental health of the elderly in South Korea, demonstrating that high- and moderate-intensity exercise can effectively reduce depression, suicidal thoughts, and perceived stress. It also highlights the detrimental effects of prolonged sedentary behavior on the mental health of older adults.