AHA Scientific Position

Physical inactivity is a major risk factor for developing coronary artery disease. Coronary artery disease is characterized by deposits of fatty substances, cholesterol, calcium and other substances in the inner lining of arteries that supply blood to the heart muscle. It also contributes to other risk factors, including obesity, high blood pressure, high triglycerides, a low level of HDL ("good") cholesterol and diabetes. Even moderately intense physical activity such as brisk walking is beneficial when done regularly for a total of 30 minutes or longer on most days.

Why is exercise or physical activity important?
Regular aerobic physical activity increases your capacity for exercise. It also plays a role in both primary and secondary prevention of cardiovascular disease. Physical inactivity is a major risk factor for heart disease and stroke and is linked to cardiovascular mortality.

Exercise can help control blood lipid abnormalities, diabetes and obesity. Aerobic exercise also has an independent, modest blood-pressure-lowering effect for certain groups of people with high blood pressure.

The results of pooled studies show that people who modify their behavior and start regular exercise after heart attack have better rates of survival and better quality of life. Healthy people -- as well as many patients with cardiovascular disease -- can improve their exercise performance with training.

How can physical activity or exercise help condition my body?

• Some activities improve flexibility, some build muscular strength and some increase endurance.
• Some forms of continuous activities involve using the large muscles in your arms or legs. These are called endurance or aerobic exercises. They help the heart by making it work more efficiently during exercise and at rest.
• Brisk walking, jumping rope, jogging, bicycling, cross-country skiing and dancing are examples of aerobic exercises that increase endurance.

For most healthy people:

For health benefits to the heart, lungs and circulation, perform any vigorous activity for at least 30 minutes on most days of the week at 50-75 percent of your maximum heart rate. Physical activity need not be strenuous to bring health benefits. Moderate-intensity physical activities for 30 minutes or longer on most days provide some benefits. What's important is to include activity as part of a regular routine.

These activities are especially beneficial when done regularly:

• brisk walking, hiking, stair-climbing, aerobic exercise
• jogging, running, bicycling, rowing and swimming
• activities such as soccer and basketball that include continuous running

For people who can't exercise vigorously or who are sedentary:

Even moderate-intensity activities, when performed daily, can have some long-term health benefits. They help lower the risk of cardiovascular diseases. Here are some examples:

• walking for pleasure, gardening and yard work
• housework, dancing and prescribed home exercise
• recreational activities such as tennis, racquetball, soccer, basketball and touch football

What risk factors are reduced?

Exercise can also help reduce or eliminate some of these risk factors:

• High blood pressure -- Regular exercise is associated with lower blood pressure.
• Cigarette smoking -- Smokers who exercise vigorously and regularly are more likely to cut down or stop smoking.
• Diabetes -- People at their ideal weight are much less likely to develop diabetes. Exercise may also decrease a diabetic's insulin requirements.
• Obesity and overweight -- Exercise can help people lose excess fat or stay at a reasonable weight.
• High levels of triglycerides -- Physical activity helps reduce triglyceride levels. High triglycerides are linked to developing coronary artery disease in some people.
• Low levels of HDL -- Low levels of HDL ("good") cholesterol (less than 40 mg/dL) have been linked to a higher risk of coronary artery disease. Recent studies show that regular physical activity significantly increases HDL cholesterol levels and thus reduces your risk.

What are other benefits of exercise?

• Physical activity builds healthy bones, muscles and joints, and reduces the risk of colon cancer. Millions of Americans suffer from illnesses that can be prevented or improved through regular physical activity.
• Physical activity also helps psychologically. It reduces feelings of depression and anxiety, improves mood and promotes a sense of well-being.
• The 1996 Surgeon General's Report on Physical Activity also suggests that active people have a lower risk for stroke.

When should I consult my doctor?

Some people should consult their doctor before they start a vigorous exercise program. See your doctor or other healthcare provider if any of these apply to you:

• You have a heart condition or you've had a stroke, and your doctor recommended only medically supervised physical activity.
• During or right after you exercise, you often have pains or pressure in the left or mid-chest area, left neck, shoulder or arm.
• You've developed chest pain or discomfort within the last month.
• You tend to lose consciousness or fall due to dizziness.
• You feel extremely breathless after mild exertion.
• Your doctor recommended you take medicine for your blood pressure, a heart condition or a stroke.
• Your doctor said you have bone, joint or muscle problems that could be made worse by the proposed physical activity.
• You have a medical condition or other physical reason not mentioned here that might need special attention in an exercise program (for example, insulin-dependent diabetes).
• You're middle-aged or older, haven't been physically active, and plan a relatively vigorous exercise program.

If none of these is true for you, you can start on a gradual, sensible program of increased activity tailored to your needs. If you feel any of the physical symptoms listed above when you start your exercise program, contact your doctor right away. If one or more of the above is true for you, an exercise-stress test may be used to help plan an exercise program.