10 Reasons

To Work Your Body*

The numbers are shocking. Just 3 out of 10 American adults are active enough to stay healthy and fit. Nearly 4 out of 10 admit they aren't active at all, despite reams of research proving that exercise is a powerful preventive, and sometimes an antidote, for disability and illness. Which side of this divide are you standing on and why?

Regular physical activity makes an enormous difference to the quality and length of your life, a fact underscored by hundreds of solid studies. In a nutshell, exercise does the following:

1. Lessens the likelihood of getting heart disease, the No.1 killer of Americans. How? Exercising regularly may bump up the number of blood vessels feeding the heart, help prevent plaque buildup by striking a healthier balance of blood lipids (HDL, LDL, and triglycerides), and help arteries retain resilience despite the effects of aging. Even if you already have heart disease, exercise lowers your chances of dying from it.

2. Lowers blood pressure, a boon for many body systems. Long-term hypertension (high blood pressure) doubles or triples the odds of developing heart failure and helps pave the path to other kinds of heart disease, stroke, aortic aneurysm, and kidney disease or failure.

3. Helps prevent diabetes by paring off excess weight, modestly lowering blood sugar levels, and boosting sensitivity to insulin so that your body needs less of it. If you have diabetes, exercise helps control blood sugar.

4. Reduces risk for developing cancers of the colon, breast, endometrium (uterine lining), and prostate. By helping you attain a healthy weight, exercise also lessens your risk for other cancers in which obesity is a factor.

5. Helps shore up bones, which reach peak density and strength during the first three decades of life. Over time, bones become lacier and weaker as density slips away. When combined with calcium, vitamin D, and bone-saving medications if necessary, weight-bearing exercise like walking, running, and strength training helps ward off bone loss. And balance-enhancing activities, including tai chi and yoga, help prevent falls that may end in fractures.

6. Helps protect joints by easing swelling, pain, and fatigue and by keeping cartilage healthy. Strong muscles support joints and lighten the load upon them. Activities that boost flexibility, such as stretching, yoga, and tai chi, extend range of motion.

7. May limit and even reverse knee problems by helping to control weight--a big deal, since for every step taken, each additional pound of body weight translates to four additional pounds of load on the knee, according to the Arthritis Foundation.

8. Lifts spirits by releasing mood-elevating hormones, relieving stress, and promoting a sense of well-being. In some studies, exercising regularly has helped ease mild to moderate depression as effectively as medications; combining exercise with medications, therapy, and social engagement is even better.

9. May boost your ability to fend off infection, as shown in three randomized trials of women who walked briskly 35 to 45 minutes a day, five days a week for 12 to 15 weeks, and experienced half the cold symptoms of a sedentary group. Additional research shows exercise prompts a modest, short-term upswing in natural killer cells and white blood cells, which helps squelch infection.

10. Adds years to your life. In the long-running Framingham Heart Study, moderate activity tacked on 1.3 years of life for men and 1.5 years of life for women versus low activity. Raising the bar to high activity added 3.7 years for men and 3.5 for women. Even current couch potatoes can't wiggle out of this. A separate long-term study of 10,000 men ages 20 to 82, who were examined and given two fitness tests at five-year intervals, found those who made the effort to shift status from unfit to fit cut their likelihood of dying by 44 percent compared with those who stayed sedentary.

*Harvard Health Publications, February 24, 2009