WASHINGTON (Cox News Service) -- A program launched Wednesday seeks to encourage U.S. physicians to prescribe exercise to their patients as a way to treat and prevent illness.

"Exercise is Medicine" is a joint project created by the American College of Sports Medicine (ACSM) and the American Medical Association. Its mission is to promote exercise as a "free medication" and encourage physicians to monitor physical activity as a vital sign.

"Physical activity is one of the best indicators of a person's longevity," Dr. Ronald Davis, president of the American Medical Association, told a news conference here.

With an estimated 65 percent of Americans overweight or obese, and one in five adults acknowledging they have had no significant physical activity in the past month, Davis said it is a critical time to launch the program.

An estimated 250,000 premature deaths occur in this country each year due to a lack of physical activity, he said.

"This could be the greatest public health problem of our time," said Dr. Robert Sallis, president of the ACSM.

Both physicians said that a brisk 30-minute walk, five times a week, can be highly beneficial and may lower high blood pressure, cholesterol, hypertension, and the risk of type 2 diabetes.

Moderate exercise has also been shown as effective in treating depression and anxiety.

"If we had a pill that contained all of the benefits of exercise, it would be the most widely prescribed drug in the world," said Davis.

Nearly two-thirds of patients say they would be more interested in exercising to improve their health if advised by a doctor, a recent study by the ACSM found.

Sallis said that "Exercise is Medicine" wants doctors to prescribe exercise not only to their patients, but also to themselves.

If they "practice what they preach," Sallis said, physicians "will be more educated and better trained" to suggest exercise plans for their patients.

Fitness celebrity Jake Steinfeld, who chairs the California Governor's Council on Physical Fitness and Sports, said that exercise as a form of medicine is about more than just losing weight.

"It's about building confidence and self-esteem," Steinfeld told the news conference. "'Exercise is Medicine' takes that to the next level."

Sallis said the program hopes to "merge the fitness industry with the health care industry," and encourage doctors to refer patients to fitness experts in the same way they refer them to specialists.

Copyright 2007 The Cox News Service. All rights reserved.