Effects of forest bathing versus indoor gym exercise on exercise-related boredom: a randomized crossover trial with repeated measures

Objective Exercise boredom is a pervasive barrier to physical activity adherence; however, no study has examined it as a primary outcome using a multidimensional boredom measure with temporal tracking across exercise settings. This study compared forest bathing and indoor gym exercise on exercise-related boredom, affective responses, perceived restorativeness, and adherence intention. Design This is a randomized, counterbalanced crossover trial with repeated measures at four time points. Methods A total of 34 healthy university students (21 male and 13 female students; mean age = 21.3 years) completed two intensity-matched, 30-min walking sessions (forest-path and indoor treadmill conditions) in a counterbalanced order, separated by a washout period of 7- to 10-days between them. The primary outcome was exercise boredom, assessed using an 8-item adapted Multidimensional State Boredom Scale (MSBS; Cronbach’s α = 0.87–0.89). Data were analyzed using a 2 (condition) × 4 (time) repeated-measures analysis of variance (ANOVA) with Greenhouse–Geisser correction. Results A significant condition × time interaction emerged for boredom [ F (1.75, 57.62) = 7.17, p = 0.003, partial η 2 = 0.179]. Post-exercise boredom was lower after forest bathing compared to gym exercise [mean difference = 0.60, 95% confidence interval (0.17, 1.03), d = 0.49]. Boredom decreased during forest walking but increased during treadmill walking ( p < 0.001). Forest bathing resulted in higher affective valence ( d = 0.43), greater perceived restorativeness ( d = 1.84), and stronger adherence intention ( d = 0.37). Ratings of perceived exertion confirmed equivalent exercise intensity. Conclusion Exercise boredom is not merely an individual disposition but a context-sensitive response that is environmentally modifiable. Nature-based exercise warrants further investigation as a strategy for sustaining physical activity engagement.