Lead author Matthew Herring, a research associate in the UAB's School of Public Health's department of epidemiology, said it is known that exercise can decrease depressive symptoms.
Herring and colleagues reviewed 90 previous studies of more than 10,500 sedentary patients with a chronic illness who were randomly assigned to exercise training or a non-exercise comparison. Trials had to measure depression before and after exercise training, Herring said.
The study, published in the Archives of Internal Medicine, found among patients with a chronic illness, exercise training -- including aerobic exercise like jogging, cycling and resistance exercise -- reduced depressive symptoms by 22 percent overall. More improvement was seen in participants who met physical activity recommendations of at least 150 minutes of moderate intensity exercise per week or at least 75 minutes of vigorous intensity exercise, the study said.
"This suggests that it is plausible that exercise-induced depressive symptom reductions are explained in part by improvements in function among patients," Herring said in a statement.