Enlarge By Frank Pompa  BLUES BUSTERS Can you walk away the blues? Quite possibly. Or you could try: • Biking • Jogging • Swimming • Tennis • Basketball • Dancing • Inline skating • Whatever form of moderate to vigorous exercise you like.  HEALTH COLUMNIST TWEETS  HAVE A HEALTH OR MEDICAL QUESTION? E-mail kpainter@usatoday.com. Please include your name, city and daytime phone number. Selected questions will be answered in the paper and online.

The treatment: exercise.

"It's become clear that this is a good intervention, particularly for mild to moderate depression," says Jasper Smits, a psychologist at Southern Methodist University in Dallas. Exercise as an anxiety treatment is less well-studied but looks helpful, he says.

It's no secret that exercise often boosts mood: The runner's high is legendary, and walkers, bikers, dancers and swimmers report their share of bliss.

Now, data pooled from many small studies suggest that in people diagnosed with depression or anxiety, the immediate mood boost is followed by longer-term relief, similar to that offered by medication and talk therapy, says Daniel Landers, a professor emeritus in the department of kinesiology at Arizona State University.

And exercise seems to work better than relaxation, meditation, stress education and music therapy, Landers says.

"Most physicians and therapists are aware of the effects," says Chad Rethorst, a researcher at the University of Texas Southwestern Medical Center in Dallas. "But they may not be comfortable prescribing it."

Smits and another researcher, Michael Otto of Boston University, are on a mission to change that. The two have written a guidebook for mental-health professionals and are working on guides for primary care physicians and consumers.

Ideally, Smits says, depressed or anxious people would get written exercise prescriptions, complete with suggested "doses" and strategies for getting started and sticking with the program.

One thing that helps people keep up this therapy, he says, is the immediate boost that many report. The same can't be said of taking pills, he says.

Questions still to be answered

But Smits and other exercise-as-treatment enthusiasts are quick to say that medications and psychotherapy are good treatments, too, and can be combined with exercise. "They work well," Smits says. "But too few people get them, and few get them in the doses that are needed."

Many people who start talk therapy or medications soon stop using them because of costs, side effects, inconvenience or other factors. In short-term studies, at least as many people stick with exercise as with drugs, Rethorst says. Not known, he says, is "how this will translate into the real world."

Other remaining questions:

•What kind of exercise works? Most studies have focused on aerobic exercise, such as running and walking, but have not ruled out strength training or other regimens.

•How much is needed? At least one study shows results from the amount recommended for physical health: 150 minutes of moderate exercise (such as brisk walking) or 75 minutes of vigorous exercise (such as running) each week.

•How does it help? Does it boost certain brain chemicals? Induce deeper sleep? Give patients a sense of action and accomplishment?

•Can it prevent initial bouts or recurrences of depression and anxiety?

That seems likely, says Michelle Riba, a psychiatrist who works with cancer patients and others at the University of Michigan. She prescribes exercise to depressed patients as part of a long-term plan for healthier living that includes sleep, eating and, in many cases, weight loss. Exercise can be especially important, she says, for patients taking antidepressant medications that cause weight gain.

"I don't' think exercise will ever be the only treatment, but it may be a major part of preventing recurrences," she says. "It should be part of everybody's plan of health."