Abstract
Physical exercise has consistently been shown to improve mood; however the mechanism through which exercise combats depression is relatively unknown. Improvements in depression may be partially due to the reduction in resting-state levels of inflammation through exercise training. This study examined the effects of high intensity interval training (HIIT) on depression and inflammation levels in sedentary university students across 10 weeks. Depression was assessed using the Beck-Depression Inventory-II and pro-inflammatory cytokine levels were assessed using blood samples before and immediately after exercise. Both measures were taken weekly across the intervention. Aerobic fitness (VO2 max) was measured pre, mid and post-intervention. It was hypothesized that HIIT training would reduce depressive symptoms and resting-state inflammation. Participants were randomized into two groups: 1) Exercise group, who completed HIIT training three times per week for nine weeks, and 2) Active control group, who remained sedentary for nine weeks except for the three maximal exercise tests done during pre, mid and post intervention. Critically, participants in the active control group were given a cover story that we were examining the impact of the three acute exercise tests on mood. Fitness levels significantly increased for the exercise group compared to controls post-intervention (p = 0.05). Depression decreased significantly across the intervention for both groups (p < 0.01). Although this was hypothesized for the exercise group, the mood of active control group may have been affected by our cover story. These results raise interesting question regarding potential placebo effects in the effect of physical exercise on mood.Acknowledgments: Natural Sciences and Engineering Research Council of Canada (NSERC)