Exercise seems to be particularly important for some people. In a 2007 study in the journal Psychosomatic Medicine, depressed people who were engaged in an exercise program recovered about as well as people who took medication. Both groups did better than a third group that got only a placebo.
While regular exercise may be as effective for mild or moderate depression as antidepressants, there is a big catch, one that triathlete Peatick has figured out: It has to be intense, for at least 30 minutes, according to Madhukar Trivedi, MD, professor of psychiatry and head of the Mood Disorders Research Program and Clinic at University of Texas Southwestern Medical Center in Dallas. He has authored several studies that show regular exercise can reduce depressive symptomsin one case by up to 47%.
Theories as to how exercise works abound. Dr. Trivedi has suggested that it may change levels of chemicals in the brain (such as serotonin), just as antidepressants might.