It's not news that exercise can boost mood. But as far as helping with actual depression, exercise might not work as well as other methods to ease symptoms.
A recent review found that exercise only minimally lowered depressive symptoms compared to having no treatment at all. And compared to antidepressants and psychological treatments, exercise didn't work any better.
According to the researchers of this review, previous studies that looked at how exercise affected depression were small and low in quality.
Gary Cooney, from the Division of Psychiatry at Royal Edinburgh Hospital in the UK, led this study that aimed to see whether exercise could reduce depression in adults over 18 years of age compared to using other treatment methods.
The researchers reviewed 37 studies, involving more than 2,300 participants, that had been published up until March 2013, as well as ongoing studies to March 2013.
The studies compared exercise to several other treatments, including antidepressant medications, psychological treatments, other treatments involving physical activity and no treatment at all or placebo (fake medicine).
In this review, exercise was defined by the American College of Sports Medicine as "planned, structured and repetitive bodily movement done to improve or maintain one or more components of physical fitness."
Studies excluded from the current investigation included those that involved patients who did not have depression and treatments that combined exercise with another activity or treatment.
Two independent reviewers tracked the participants' depression symptoms and mood after being treated.
The researchers also assessed participants' quality of life, cost of the treatments, any adverse side effects and how well participants accepted the treatment, as measured by attendance at exercise classes and the number of people who completed the treatments.
Attendance rates for the exercise treatments ranged from 50 to 100 percent from study to study.
According to the researchers, exercise was no more effective at reducing depression symptoms than antidepressants or psychological therapies.
In addition, exercise was only moderately more effective at reducing symptoms than having no therapy at all.
When the researchers only took high-quality studies into account, the difference between exercise and no therapy was less conclusive.
Overall, the researchers found that current research cannot fully confirm whether exercise aimed at helping depression can improve quality of life.
"Our review suggested that exercise might have a moderate effect on depression,” Gillian Mead, MD, co-author of the study and professor of stroke and elderly care medicine at the University of Edinburgh in the UK, said in a press release. “We can’t tell from currently available evidence which kinds of exercise regimes are most effective or whether the benefits continue after a patient stops their exercise program."
Exercise does help some to improve mood and energy, according to Rusty Gregory, a fitness trainer and dailyRx Contributing Expert.
"Regular exercise boosts serotonin levels in the brain which leads to an improvement in mood and an overall sense of well-being," Gregory said. "In addition, as serotonin levels rise, sleep is enhanced providing more energy to exercise. In turn, this helps defeat the ill-effects of depression."
The researchers noted that the studies they looked at were small, and many had weaknesses with their methodology.
The researchers said that future reviews should look at large-scale high-quality studies involving participants who were actually clinically diagnosed with depression.
They also noted that further research should look at what kinds of exercise could most benefit people with depression, as well as how often and how long exercise sessions should last to provide the most benefit.
This study, which was supported by the UK's National Institute for Health Research, was published online September 12 in The Cochrane Library.