Investigating the protective effects of high and moderate intensity cycling on psychological stress and depression in young adults


With mental illness affecting ~20% of Canadians, there is a need to understand the factors that reduce negative mood. Physical exercise is a powerful stimulus that may regulate mood; however, it is unclear what dose of exercise is needed to induce a positive change in mood. This study examined which psychological factors exercise targets to regulate mood and the optimal intensity of exercise for decreasing negative mood states. It was hypothesized that exercise would target both stress and depression to improve mood, and the high-intensity exercise would improve mood more than moderate-intensity exercise. Twenty-six participants were assigned to one of three groups: 1) High-intensity exercise, 2) Moderate-intensity exercise, and 3) Non-exercise control. The exercise groups underwent exercise training three times per week for six weeks. Aerobic fitness, depression, stress, and anxiety were measured before and after the 6-week intervention. It was found that exercise protected students against depression as indicated by a significant increase in depression for the control group (p< 0.01) that was not observed for either of the exercise groups. Stress and anxiety levels were positively correlated with depression (all correlations: r (55) >.36, p < .001) but were not impacted by the exercise intervention. The results suggest that exercise may help to mitigate depressed mood in young adults as a potential way to reduce their risk of mental illness.