The Effect of Outdoor and Indoor Group Exercise Classes on Psychological Stress in College Students: A Pilot Study with Randomization.

Emerging evidence suggests that outdoor group exercise may reduce stress more than indoor group exercise because the outdoor environment provides unique mental health benefits. Stress leads to illnesses and diseases, but exercise mitigates harmful impacts. This study explored differences in perceived stress and outdoor physical activity participation among college students in an indoor or outdoor group exercise class. Data were collected pre-, mid- (after four sessions), and post-intervention (after eight sessions). Seventeen participants indicated an interest in the study, but 13 signed up. Participants completed a four-week group exercise intervention that met twice weekly in outdoor and indoor conditions. Mixed ANOVAs with Tukey post hoc tests determined between-group differences in perceived stress and outdoor physical activity levels. Partial eta-squared () estimated effect sizes. Significant differences in perceived stress scores existed across time for the whole sample [(2, 12) = 48.359, < 0.001, = 0.890] and for the interaction between time and condition [(2, 12) = 10.051, = 0.003, = 0.626]. Post hoc analysis revealed that the outdoor group's perceived stress ( < 0.001) was reduced more than the indoor group post-intervention ( = 0.028).