Research published in Family Practice News (May 2006) examined how different amounts of exercise affected adults with mild to moderate depression. The study included 80 participants who were not taking antidepressant medication and were randomly assigned to one of five groups.
Two groups performed low levels of aerobic exercise totaling 7 kcal/kg/week. One of these groups exercised three days per week, and the other exercised five days per week. Two additional groups performed higher levels of aerobic exercise, totaling 17.5 kcal/kg/week—more than twice the amount of the low-exercise groups. Again, one group exercised three days per week and the other five days per week. A fifth group served as the control and performed stretching only, without aerobic exercise.
The study lasted 12 weeks. Depression severity was measured using the Hamilton Rating Scale for Depression (HAM-D). At the end of the study, depression scores had dropped by an average of 47% in the groups performing higher levels of exercise, compared with a 30% reduction in the low-exercise groups. The control group showed a 29% reduction, although this group had a higher dropout rate than all four exercise groups combined.
A positive treatment response was defined as a reduction in HAM-D score of 50% or more. This level of improvement occurred in 46% of participants in the higher-exercise groups, compared with 26% in the low-exercise groups and 15% in the control group.
Remission was defined as a HAM-D score of seven or lower. At the end of the study, 42% of participants in the higher-exercise groups met criteria for remission, compared with 26% of those in the low-exercise groups and 11% of the control group.
The authors concluded that higher levels of aerobic exercise were associated with greater reductions in depressive symptoms and remission rates that were comparable to other established treatments for depression.
