A sedentary lifestyle is a common cause of obesity, and excessive body weight in turn is considered a catalyst for diabetes, high blood pressure, joint damage, and other serious health problems.

But what if lack of exercise itself were treated as a medical condition? Mayo Clinic physiologist Dr. Michael Joyner argues that it should be. His commentary was published this month in The Journal of Physiology.

Physical inactivity affects the health not only of many obese patients, but also people of normal weight, such as workers with desk jobs, patients immobilized for long periods after injuries or surgery, and women on extended bed rest during pregnancies, among others, Joyner says.

Prolonged lack of exercise can cause the body to become deconditioned, with wide-ranging structural and metabolic changes: The heart rate may rise excessively during physical activity, bones and muscles atrophy, physical endurance wanes, and blood volume declines.

When deconditioned people try to exercise, they may tire quickly and experience dizziness or other discomfort, then give up trying to exercise and find the problem gets worse rather than better.

"I would argue that physical inactivity is the root cause of many of the common problems that we have," Joyner says. "If we were to medicalize it, we could then develop a way, just like we've done for addiction, cigarettes, and other things, to give people treatments—and lifelong treatments—that focus on behavioral modifications and physical activity."

Several chronic medical conditions are associated with poor capacity to exercise, including fibromyalgia, chronic fatigue syndrome, and postural orthostatic tachycardia syndrome, better known as POTS, a syndrome marked by an excessive heart rate and flu-like symptoms when standing or at a given level of exercise. Too often, medication rather than progressive exercise is prescribed, Joyner says.

Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center researchers found that three months of exercise training can reverse or improve many POTS symptoms, Joyner says. That study offers hope for such patients and shows that physicians should consider prescribing carefully monitored exercise before medication, he says.