Doctors are where the sick go to get medicine; gyms are where the healthy go to get exercise. At least that's how it used to work. Doctors and insurance companies are leading a growing movement to ask about exercise during medical appointments and prescribe exercise in place of medicine, where appropriate.

Nonprofit health insurer Kaiser Permanente began asking its member physicians to record exercise information in Southern California in 2008 and has since expanded to include other doctors in its network, and other insurance networks across the country are adopting similar programs. Such programs are one of the goals of Exercise Is Medicine™, an initiative launched by the American College of Sports Medicine in partnership with the American Medical Association in 2007 with the overall aim of making exercise a standard part of medical care. "There is no better indicator of a person's health and longevity than the minutes per week of activity a patient engages in," says Robert E. Sallis, chairman of EIM and a doctor in the Kaiser network. "When incorporated in a healthcare setting, the exercise vital sign can be an important tool for prevention and management of disease."

Now, along with a check of their blood pressure, temperature and pulse, patients are also asked about their exercise habits, which are recorded during exams along with other stats. Doctors can take that information into account when deciding to prescribe medications, recommending exercise for high blood pressure before writing a prescription, for example.

It should be common sense, but only one-third of respondents in last year's National Health Interview Survey by the Centers for Disease Control and Prevention said their doctor asked about their exercise habits. Maybe doctors are afraid of the answers. Results from a survey of the first year of Kaiser's Southern California initiative published in the American College of Sports Medicine's Medicine & Science in Sports & Exercise found that more than a third of patients never exercised. While the findings were worse than national statistics, the study's authors think it may be because patients are more honest with their doctor that with surveyors.

Adding exercise to the list of important vital signs also gives it more credence as a medical issue, pushing more patients to take exercise more seriously as a factor in improving their health. Moreover, bringing up the subject during medical appointments opens the door to better education on the health consequences of an inactive lifestyle.

Says Sallis, "All we ask our physicians to do is to make a comment on it, like, 'Hey, good job,' or 'I noticed today that your blood pressure is too high and you're not doing any exercise. There's a connection there. We really need to start you walking 30 minutes a day.' "