Do you want to live longer and in better health? A program of regular aerobic exercise can help you avoid chronic diseases such as heart disease, hypertension, stroke, diabetes, and some cancers.

It can also lower blood pressure, build stronger bones, improve muscle strength and flexibility, lessen depression and help control your weight.

Aerobic exercise includes walking, running, hiking, bicycling, swimming, cross-country skiing, stair climbing, rowing, aerobic dance, and many other activities.

Aerobic exercises use continuous, rhythmic activity of large muscles in the legs and buttocks to strengthen your heart and lungs (cardiovascular system). When you exercise, the muscles demand more oxygen-rich blood and give off more carbon dioxide and other waste. This makes your heart beat faster to keep up.

When you follow a program of regular aerobic exercise, over time your heart grows stronger and can meet the muscles' demands without as much effort. Both men and women can benefit from cardiovascular fitness. Check with your doctor first if you have a chronic condition or are overweight, a smoker or middle aged or older and have never exercised.

To strengthen your heart, you should do aerobic exercise intensely enough to reach your target heart rate. This is 60-80 percent of your maximum heart rate - which is 220 minus your age. (Example: if you're 50 years old, your maximum heart rate is 170; your target heart rate is 102-136.)

Safe and effective aerobic training guidelines include frequency, intensity, and time (FIT):

• Frequency: Exercise at least three times a week.
• Intensity: Exercise hard enough to reach your target heart rate. (Take your pulse immediately when you stop exercising, count the beats for 15 seconds and multiply the number by four.)
• Time: Include at least 20 minutes of aerobic exercise in each session.

If you are beginning an aerobic training program, start with:

• Five minutes of warm up.
• Five minutes of aerobic training activity.
• Five minutes of cool down.

Repeat the routine three or four times a week. Gradually add time to the aerobic training portion, working up to at least 20 minutes of aerobic exercise in each session.