Resting heart rate. The average heart rate for a person at rest is 60 - 80 beats per minute. It is usually lower for people who are physically fit, and often rises as you get older. You can determine your resting heart rate by counting how many times your heart beats in one minute. The best time to do this is in the morning after a good night's sleep before you get out of bed. Maximum heart rate. To determine your own maximum heart rate per minute subtract your age from 220. For example, if you are 45, you would calculate your maximum heart rate as follows: 220 - 45 = 175. Target heart rate. Your target rate is 50 - 75% of your maximum heart rate. You should measure your pulse off and on while you exercise to make sure you stay within this range. After about 6 months of regular exercise, you may be able to increase your target heart rate to 85% (but only if you can comfortably do so). Certain heart medications may lower your maximum and target heart rates. Always check with your doctor before starting an exercise program. Note: Swimmers should use a heart rate target of 75% of the maximum and then subtract 12 beats per minute. The reason for this is that swimming will not raise the heart rate quite as much as other sports because of the so-called "diving reflex," which causes the heart to slow down automatically when the body is immersed in water. VO2 Max. Serious exercisers may use a VO2 max calculation, which measures the amount of oxygen consumed during intensive, all-out exercise. The most accurate testing method uses computers, but anyone can estimate V02 without instrumentation (with an accuracy of about 95%): After running at top pace for 15 minutes, round off the distance run to the nearest 25 meters. Divide that number by 15. Subtract 133. Multiply the total by 0.172, and then add 33.3. Olympic and professional athletes train for VO2 max levels above 80. A VO2 max equaling between 50 and 80 is considered an excellent score for overall fitness. For the average person exercising for fitness and health, this value is not necessary. To determine your maximum heart rate, subtract your age from 220. This number represents how many times your heart should beat per minute at its maximum rate. Multiply that number by 0.6 and 0.85 to determine the range of heart rate to strive for. Healthy people can build up gradually to sustain this heart rate for 30 to 45 minutes at least 3 times a week to build aerobic fitness. The health benefits of exercise depend more on regular activity than on pace, intensity, and heart rate.