Abstract / Summary
Abstract Background Physical activity is reliably linked to lower depression, yet the affective mechanism carrying this benefit and the individual differences deciding who benefits most remain unclear. This study tested whether exercise enjoyment mediates the association between physical activity and subclinical depressive symptoms, and whether reward sensitivity moderates the path from activity to enjoyment. Methods A three-wave longitudinal survey followed 1,235 Chinese undergraduates across one semester, with 973 completing all waves (retention 78.8%). Physical activity and exercise enjoyment were assessed with the PARS-3 and PACES, and depressive symptoms and reward sensitivity with the CES-D and TEPS. A moderated mediation model, controlling for sex and baseline enjoyment and depression, was tested with percentile bootstrapping (5,000 resamples). Results T1 physical activity predicted greater T2 exercise enjoyment (a₁ = .22, p < .001), and enjoyment predicted fewer T3 depressive symptoms (b = − .28, p < .001), with a significant direct effect (c′ = −.07, p = .010) indicating partial mediation. The physical activity by reward sensitivity interaction on enjoyment was significant (a₃ = .11, p < .001). The indirect effect was significant (ab = − .06, 95% CI [− .08, − .04]), as was the index of moderated mediation (a₃b = − .03, 95% CI [− .05, − .02]), and it was about three times larger among students high (− .09) than low (− .03) in reward sensitivity. Conclusion Exercise enjoyment is a proximal affective pathway linking physical activity to lower subclinical depression, and reward sensitivity governs its strength. Because the pathway is weakest among more anhedonic students, who may carry greater risk, physical-activity promotion may be strengthened by maximizing enjoyment and adding reward-focused components for students lower in reward sensitivity.