Many people on antidepressants take more than one kind at a time. But for those who don't respond fully to one drug, aerobic exercise may work at least as well as adding another, says Madhukar Trivedi, a psychiatrist at the University of Texas Southwestern Medical Center in Dallas. In a study he led, sedentary people who were depressed despite medication tried a supervised exercise program as they kept taking their pills. Using treadmills or stationary bikes, they did the equivalent of walking four miles per hour for 210 minutes weekly (high intensity) or three miles per hour for 75 minutes weekly (moderate intensity). After 12 weeks, about 30 percent of the people in both groups were no longer depressed, and an additional 20 percent showed improvement. For women, the intense exercise appeared more effective if they had no family history of depression, while those who did were more likely to stick with the less-vigorous regimen.