Aerobic exercise promotes physical fitness by strengthening the heart and increasing lung capacity. Jogging and running are the most popular aerobics, but any activity that is rhythmic and sustained and uses the body’s large muscles qualifies. This includes walking, swimming, crosscountry skiing, jumping rope, climbing stairs, bicycling, and even vigorous dancing. To get the full benefit of aerobic exercise, you must do it for a minimum of 20 minutes at least three times a week.
The word aerobic means “occurring in the presence of oxygen.” All forms of aerobic exercise stimulate more rapid and efficient transport of oxygen through the bloodstream. Oxygen is needed to burn the fuel (calories) that provides the energy for the exercise. In essence, the blood flow to the heart increases, requiring the heart to pump harder. Since the heart is a muscle, the harder it pumps, the stronger it becomes. Calculating your training level The object of all aerobics is to increase your heart rate to what is called a training level and to maintain that level for at least 20 minutes. Your training level depends on your age. The maximum human heart rate is 220 beats per minute, but the rate declines by one beat for each year of life. The maximum heart rate for a 20 year-old, therefore, is 200 beats; for a 40-year-old, 180 beats.
Your training level is between 70 and 85 percent of your maximum heart rate. For a 20-year-old, this would be between 140 and 170 beats per minute; for a 40-year-old, between 126 and 153. To determine whether your heart rate has reached training level, take your pulse for 10 seconds immediately after exercising hard for several minutes. Then multiply by 6. Work up gradually to your training level. Anyone over 35 should check with a doctor before embarking on an exercise program.