To get the most out of your exercise, you should reach your target heart rate, sustaining it for 20 to 30 minutes. As conditioning improves, you can increase the time you exercise at your target rate.

  1. It is important to stay within the target heart rate for your age for the safest workout. Beginners should try to achieve a heart rate at the lower end of the age-specific range. And generally, pregnant women should not exceed 80% of their maximum heart rate.You can calculate your target heart rate by following these steps or by using the table below:
  2. Subtract your age from 220.
  3. Multiply that number by 0.6 to 0.8 (60 or 80% of your maximum rate) to get the range of suggested heart rates.

To use the table, go to your age, then find your target rate at either 60 or 80% of your maximum heart rate.

During exercise, you should check your heart rate by taking your pulse to make sure you are staying within your maximum range:

1. Feel your pulse on the inside of your wrist or at your neck just below the angle of your jaw (on the carotid artery).

2. Count the number of beats for 10 seconds.

3. Multiply that number by 6. That is your pulse rate.

Age60% of Max Rate80% of Max Rate

By maintaining your target heart rate, you are performing aerobic exercise-or exercise that allows the heart and cardiovascular system to fuel the muscles with oxygen. As a muscle, the heart benefits from this activity and can work more efficiently. However, exercising too fast, too intensely, or at too high a heart rate can have the opposite effect- creating an environment without oxygen (anaerobic exercise). In anaerobic exercise, muscles provide a source of energy without involving oxygen. Pregnant women should avoid anaerobic exercise because depriving the fetus of sufficient oxygen can be harmful.