Exercise does more than improve the body. It lifts the spirits, researchers say.
Exercise can help to fight depression, according to an article in the Physician and Sportsmedicine medical journal. Many doctors prescribe exercise along with drug treatment and psychotherapy, the report said.
But a separate researcher cautions that not everyone can expect benefits, and he says the idea that exercise causes the improvement is not proved.
"Many physicians have started to use exercise as an important adjunct treatment," said the article's authors, Drs. George Nicoloff of St. Mary's Hospital in Grand Rapids, Mich., and Thomas L. Schwenk of the University of Michigan Medical School, Ann Arbor.
Previous studies have found that clinically depressed patients who start exercising have improved moods, the article said. One study of nine patients in psychotherapy and nine other patients who started to run found that running improved mental health scores as much as therapy did, the article said. Other researchers who reviewed data from many studies found that exercise combined with therapy was better than therapy alone, it said.
But the benefits don't show up in all forms of depression, said researcher Bill Morgan, director of the Sport Psychology Laboratory at the University of Wisconsin. They seem not to apply to bipolar depression, where periods of depression are offset with periods of intense excitement, he said.
"I am unaware of any compelling, systematic evidence" that physical activity affects bipolar depression, Morgan said.
And the journal article reported that exercise does not work better than tricyclics, a common form of anti-depression drug.
To make exercise work, the program has to be one that the exerciser can stick with, so Nicoloff and Schwenk advised other doctors against ordering a tough regimen. Mild to moderately depressed people may benefit from only a little exercise, they said.
The type of exercise can vary, because research has not found a specific regime that's psychologically best, the article said. But the same amount of aerobic activity that works for the non-depressed seems to help the depressed, it said. For example, one set of guidelines for psychological benefit calls for two to five workouts a week for 30 to 40 minutes each at 60% to 70% of maximum heart rate, plus five to 10 minutes each of warm-up and cooldown, it said.
Patients with depression probably are more easily discouraged by exercise, so doctors should keep close track of how their patients are doing with the exercise program and keep them motivated, the article said.
Researchers don't know why exercise can fight depression, but they have some ideas, Nicoloff and Schwenk said. One idea is that exercise gives the patient something to think about besides his or her problems. Another is that exercise is something of a triumph, offering a way to gain control over part of a person's life. Exercise may also cause physiological changes in chemicals that affect the brain, producing a feeling of euphoria, the article said.
Exercise not only helps to improve the moods of the depressed, it also seems to help ward off depression, the report said. One group of researchers found that exercise reduced depression ratings in the depressed and in the healthy, it said.
Morgan, however, argues that there is no cause-and-effect proof that exercise battles depression. Patients may improve simply because they are being offered exercise as therapy and therefore believe they should improve, he said. Researchers have difficulty factoring out this possibility from their studies, and doctors face a similar problem in therapy, he said.
Morgan also does not think much of the idea that exercise must work or physicians wouldn't prescribe it. That's not proof, either, he said. And conventional medical belief isn't necessarily right, he added: Physicians once prescribed bloodletting.