Aerobic exercise training has positive effects on depression severity and mood in individuals with depression. The effects of single sessions of aerobic exercise may also provide some short-term benefits in depression. It is believed that a reduction in depression severity may be facilitated by changes in the nervous system, however this has yet to be examined. Although aerobic exercise has beneficial effects for those with depression it is unclear as to why this may occur. Therefore the goal of our project is to better understand the effect of a single session of aerobic exercise on the nervous system, physiology, and mood in depression.