Background: Understanding the longitudinal interplay between psychological well-being and health-related behaviours, such as physical activity, is critical for promoting sustainable mental and physical health in adults. This study examined the bidirectional associations between general mental health, assessed using the Psychological Well-being Index (PWI-SF), and physical activity through cross-lagged panel modeling. Methods: Data were drawn from the Health Examinees (HEXA) study, a large-scale genomic cohort that recruited Korean adults aged 40–69 years. Psychological well-being was assessed using the 18-item PWI-SF, with each item rated on a 4-point Likert scale; item scores were summed to derive a total PWI score, where higher scores indicated greater psychological stress. Exercise was quantified as the total physical activity time per week, calculated by multiplying the reported number of sessions by the average duration of each session across various physical activity domains, including leisure-time and household exercise. Baseline and follow-up PWI and exercise data were standardised by converting scores into z-scores. Cross-lagged panel models were fitted to evaluate temporal stability and directional relationships between these domains, adjusting for age and sex. Parameter estimates and p-values were reported. Results: PWI demonstrated strong temporal stability (β = 0.17–0.34, p < .001), whereas exercise behaviour showed weak longitudinal stability (β = 0.003, p = .50). Baseline PWI predicted exercise engagement at follow-up (β = –0.052, p = .017), but cross-lagged paths from exercise to PWI were non-significant. Age was negatively associated with exercise, and females reported slightly higher PWI (high stress) scores with lower exercise levels. Conclusions: Psychological well-being showed strong temporal stability and modestly predicted future physical activity, whereas exercise behaviour did not influence subsequent mental health. These results highlight the importance of supporting psychological well-being to foster sustained engagement in physical activity, especially in middle-aged adults, and suggest that interventions targeting mental health may indirectly benefit physical health behaviours.
Noh et al. (Tue,) studied this question.