If you made a list of the health hazards that plague you, you probably wouldn’t think to add this one. But chances are, you’re sitting in one right now—a chair!

A slew of evidence shows that it’s dangerous to spend too much time on your derriere—in fact, researchers found a correlation between hours spent sitting and early death. On average, American adults spend more than half of their waking hours sitting. Can something so simple and commonplace really be so deadly?

Yes—but the reason why isn’t as simple as you might think. To explain more about the dangers of sitting, our editors turned to James A. Levine, MD, PhD, professor of medicine at the Mayo Clinic in Rochester, Minnesota, and coauthor of Move a Little, Lose a Lot. He said that doctors are now more aware of “the magnitude of the health consequences of prolonged sitting, including not only the obvious—obesity—but also high cholesterol, diabetes, cardiovascular disease and even cancer.”

DON’T SIT STILL!

Put simply, the danger in prolonged sitting is that it “stalls the metabolic machinery,” as Dr. Levine explained. “The body has an exquisitely designed system for trafficking fuels such as carbohydrates and fats. Serious consequences result when the muscular engine sits on idle.”

According to Dr. Levine, this “physiology of inactivity” results in a variety of immediate, undesirable effects. For instance, inactivity impedes the ability to metabolize fat and sugar and it also elevates triglycerides, potentially raising the risk for cardiovascular disease. Prolonged sitting weakens muscles, which can lead to back pain, arthritis and joint problems. Previous research has demonstrated that sitting for long periods suppresses lipase, an enzyme involved in fat metabolism that is produced only when leg muscles flex—low levels are associated with heart disease and other illnesses. Sex hormones, including estrogen and testosterone metabolism, also are affected, Dr. Levine noted, adding that “these impact all aspects of physical and emotional states.”

The good news here is that just a little movement can accomplish a lot for your health. Even if you must sit for certain parts of your day, modest efforts to move your muscles—such as taking the stairs instead of the elevator…rocking in a rocking chair when you read or watch TV…standing up and moving around while talking on the phone—are meaningful. Studies have shown that even fidgeting while sitting is good for you—anything to get the blood moving! One study showed that fidgeting increased energy expenditure by 10% compared with just sitting motionless.

A simple way to be sure that you don’t do damage to your body by sitting too long: For every hour you sit, get up and move around for 10 minutes—stretch, pace, do some jumping jacks. While you are seated, flex and contract your muscles from time to time…stretch…and even just shift your weight from side to side.

Also good: Turn movie and TV time into “moving” time—you can walk on a treadmill during your favorite show…sit on an exercise ball and rock back and forth…or make a habit of standing up and sitting down 10 times in a row every half hour.

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