Background-Several reports indicate that physical activity can reduce the severity of symptoms in depressed patients. Some data suggest that even a single exercise bout may result in a substantial mood improvement. Objective-To evaluate the short term eVects of a training programme on patients with moderate to severe major depression. Conclusions-Aerobic exercise can produce substantial improvement in mood in patients with major depressive disorders in a short time. (Br J Sports Med 2001;35:114-117) Methods-Twelve patients (mean (SD