Exercise as a Medicine?

Being a physician-physiologist and lifelong sports and recreation enthusiast, it's not surprising that I'm an advocate of exercise as the most important medicine. But if we're going to think of exercise as a medicine, then we must scrutinize the therapeutic uses of exercise - know what health conditions it's good for and know how it can bring harm. This subject is the topic of the 4th edition of a textbook I've recently finished editing for the American College of Sports Medicine (ACSM).

Over twenty years ago, one of my mentors - Dr. Bill Haskell - gave the keynote presentation at the ACSM annual meeting and asked the question "If exercise were a drug, would it get FDA approval?". This lecture was formative in much of my thinking, in that I had already decided that I wanted to be known for having exercise as my (main) medicine, as an internist-physiologist specializing in mechanisms of exercise intolerance in patients who have a chronic condition. During my medical training, back in the late 1980s and early 1990s, it was common to describe patients with chronic disease as being deconditioned. While this is often the case, often this is an oversimplification of why patients with chronic conditions have difficulty doing physical activity.

The point Dr. Haskell was making in his keynote presentation is that we really need to know a lot about how exercise willl help a patient with a particular condition, how much exercise is necessary to achieve a training benefit, how much exercise is an "overdose" and what side-effects, risks and benefits come from exercise in that particular condition. In the two decades since his presentation, the exercise science community has learned quite a bit and today we have a much better notion of how to use exercise in patients who have chronic disease (with much more research needed).

In my opinion, the most important things we have learned are:

• Physical activity is essential in maintaining independence and quality-of-life,

• Physical activity is essential in preventing cardiovascular disease and type 2 diabetes in people who have chronic health conditions,

• There are very, very few chronic conditions for which exercise is not helpful, and

• Essentially all body tissues and physiological systems benefit from regular physical activity.

There is no medication a physician can prescribe that can match the breadth of benefits of exercise. Medications are more specific and usually have a greater therapeutic effect on their target cells, but exercise has beneficial effects on ALL cells and thus is unique among all the prescriptions a doctor can prescribe. Most important, there is no medication that can help someone maintain the robust hardiness to do things for himself or herself. For these reasons, I find exercise to be the most important medicine a doctor can prescribe.