The High Cost of Inactivity

Author: Winston Craig, MPH, PhD, RD.

There is a high price tag to pay for being a couch potato. The lack of exercise can adversely affect the function of the brain, heart, blood vessels, bones, liver, and the intestinal tract. An inactive person is more likely to suffer from anxiety and depression, and find stress harder to manage.

Those who don't exercise lose fitness and often become overweight - adding up to 5 pounds a year. This is mostly abdominal fat, which increases the risk of heart disease and diabetes. On the other hand, one hour of brisk walking every day can cut the risk of obesity by 24 percent.

Muscles atrophy when not used. For every decade after age 50, you lose about 6 percent of muscle mass with a 10-15% loss of strength. To build muscle, it is important to do strength training exercises at least twice a week using weights that you lift 10 to 12 times. By gently overloading a muscle, one can make muscle fibers thicker and stronger. Strength training also helps prevent bone loss better than walking.

Inactivity also diminishes insulin sensitivity, leading to elevated blood sugar levels. Regular exercise can reverse these trends. In a large study of nurses, they found that for every 2 hours a day of watching TV the risk of diabetes increased 14 percent. On the other hand, every hour per day of brisk walking decreased the risk of diabetes 34 percent. Unfortunately, diabetes is no longer just a disease of middle age. Because of the sedentary lifestyle of American children we are increasingly seeing diabetes among the youth.

Inactivity also raises the risk of cancer. Men and women who are physically active can reduce their risk of colon cancer by 30 to 40 percent. Regular exercise also appears to lower the risk of breast cancer by about 20 percent. Regular exercise also boosts the immune system and reduces the risk of upper respiratory tract infections.

People who are not physically active are at a greater risk for cognitive decline and dementia. In animal studies, the brains of physically active mice have more nerve connections and a better oxygen flow. When mice are given more stimulating cages with exercise wheels they develop fewer amyloid deposits commonly seen in brains of Alzheimer's patients.

Inactivity increases the risk of cardiovascular disease. Women who did no regular walking were twice as likely to be diagnosed with heart disease as those who walked briskly for an hour per week. Exercise improves heart function and increases flexibility of blood vessel walls and decreases blood pressure and the risk of blood clots and hence the risk of stroke. Active persons are 25 percent less likely to have a stroke compared with their sedentary counterparts.

To achieve the best health benefits one needs at least 30 minutes a day of moderate-intensity exercise, such as brisk walking and cycling.

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