A recent review of controlled studies looking at the effect of exercise on clinically depressed adults showed that exercise has a small benefit in relieving symptoms of depression with clinically diagnosed depression in the short term. The effect did not last beyond the duration of the exercise program.
The number and quality of the studies available to analyze were disappointing with only 3 high quality studies cited in the article. With only 3 trials it was impossible to look at the effect of different types of exercise or at the duration of exercise intervention.
The authors conclude that at this time exercise shouldn't be the only intervention "prescribed" for a patient with clinical depression. Large, high quality trials, with long term follow-up are needed to determine whether exercise has an important antidepressant effect.
Krough J, Nordentoft M, Sterne J, Lawlor D. The Effect of Exercise in Clinically Depressed Adults: Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Clin Psychiatry Apr 2011 529-538.
