The Effect of Exercise on Depressive Symptoms in Unmedicated Patients

This trial investigates the biological effect of exercise training on depression. Participants will randomly be allocated to either a aerobic exercise group performing exercise on stationary bikes or a group performing low-impact exercise such as stretching exercises. Both groups will attend sessions three times per week for 3 months. Before and after the intervention the investigators will measure the severity of depression using the Hamilton depression rating scale (HAM-D17).