Gauging intensity using your heart rate

Another way to gauge your exercise intensity is to see how fast your heart is beating on average during physical activity. To use this method, you first have to figure out your maximum heart rate. The maximum heart rate is the upper limit of what your heart and blood vessel system, called the cardiovascular system, can handle during physical activity.

If you're healthy, you can figure out your approximate maximum heart rate by multiplying your age by 0.7 and subtracting the total from 208. For example, if you're 45 years old, multiply 45 by 0.7 to get 31.5, and subtract 31.5 from 208 to get a maximum heart rate of 176.5. This is the average maximum number of times the heart should beat each minute during exercise in this example.

Once you know your maximum heart rate, you can find out your desired target heart rate zone. The target heart rate zone is the level at which you're exercising and conditioning the heart but not overworking it.

The American Heart Association generally recommends these heart rate targets:

• Moderate exercise intensity: 50% to about 70% of your maximum heart rate.
• Vigorous exercise intensity: 70% to about 85% of your maximum heart rate.

If you're not fit or you're just beginning an exercise program, aim for the lower end of your target heart rate zone. Then, slowly build up the intensity. If you're healthy and want to exercise at a vigorous intensity, opt for the higher end of the zone.