We may not know the specifics of how exercise impacts depression and other mental health conditions, but since numerous studies show it to be beneficial, there is little harm in participating in it for that purpose, according to Harvard mental health experts.

“Although it is no magic remedy, there is little to lose and everything to gain by trying to work off depression and anxiety, ” they write in the latest issue of the Harvard Mental Health Letter.

Dr. Michael Craig Miller, editor-in-chief of the letter, told Reuters Health: “It’s clear that exercise is beneficial for mental health. What’s not clear is how it works.”

For example, in one of the studies cited in the letter, researchers found that adults who participated in a three-month rigorous exercise program experienced a decline in depressive symptoms about as great as they would have experienced had they received standard depression treatment, such as antidepressant medication.

Even among middle-school children, higher levels of physical activity have been found to be associated with fewer depressive symptoms, according to a Reuters Health report. Other studies have found exercise to be similarly associated with improvements in panic disorder, post-traumatic stress and other anxiety disorders.

Researchers speculate that vigorous exercise may be associated with increased levels of “helpful chemicals in the brain,” such as endorphins, which are responsible for the euphoric feelings associated with exercise, said Miller, an assistant professor of psychiatry at Harvard Medical School, in Boston, Massachusetts.

Also, the support group provided by other exercisers, as well as the heightened sense of alertness and improved self-esteem often associated with regular physical activity, all contribute to an enhanced sense of well being, he said.

Still, an increased level of physical activity will affect different people in different ways, and it is not a proven cure for any mental illness, according to the health letter.

What’s more, some depressed individuals may simply not have the desire to exercise.

Citing the popular NIKE slogan, Miller said, “Most people cannot ‘just do it,’ particularly if they are depressed.”

He advises that people who fall in this category do as much as they can, even if it means exercising for a few minutes at a time.

“The advantage of doing a little bit is that sometimes a little bit leads to a little bit more,” he said.

“You don’t have to have a program that includes 45 minutes of sweating and grunting and moaning,” he added. “A 10-minute walk is as good a place to start as anything else.”

SOURCE: Harvard Mental Health Letter, December 2005.