Depression

Exercise can prevent or treat mild to moderate cases of stress-induced depression, although the mechanisms weren’t known. We found one mechanism that protects the brain from changes elicited by unpredictable stress, which are associated with the development of depression. In brief, if you train your muscles (through aerobic exercise), they acquire the capacity to filter out of the blood a molecule called kynurenine. Kynurenine is known to increase in circulation under stress and to accumulate in the brain, where it correlates with the development of depression.