The two methods of calculating target heart rate zones are very similar to one another, with one distinct difference. The first method is known as the percent of APMHR--age-predicted maximum heart rate--and simply involves determining your maximum heart rate from a formula based on age and multiplying the result by assigned percentages to determine training zones. The Karvonen formula also uses the APMHR to determine max heart rate, but it factors in an individual's resting heart rate to make the zone more specific to each person. The Karvoven formula is the more accurate measurement of caloric expenditure through heart rate training zones.
Step 1
Determine your true resting heart rate (RHR). Measure your heart rate first thing upon waking up on three consecutive days. Take your radial pulse--on the thumb-side of the wrist--or your carotid pulse--beneath your jawline, on the side of the neck. Count the number of beats in one minute and record. Calculate the average of the three measurements and document it as your resting heart rate.
Step 2
Calculate your age-predicted maximum heart rate (APMHR). Subtract your age from 220. This number will represent roughly the most your heart can beat per minute during exercise. This estimation has a margin of error of plus or minus 10 to 15 beats, yet it should suffice in assisting you to determine your training zone.
Step 3
Subtract your RHR from your APMHR to determine your working heart rate or your heart rate reserve (HRR). This number will indicate how many beats per minute your heart rate will need to increase in order to reach your max heart rate from a resting starting point.
Step 4
Calculate your heart rate training zone by factoring in exercise intensity. Multiply your HRR by an upper and lower limit percentage. Begin conservatively if you are a sedentary, or inactive, individual. Multiply by 50 percent to determine your lower limit zone. A good upper level limit for most individuals is 75 percent. The formula looks like this: (220 - age) - RHR x percent + RHR = target heart rate zone.
For example, if you are 40, your APMHR would be 180. If your RHR is 72, subtract 72 from 180 to get a heart rate reserve (HRR) of 108. Find your lower and upper limit training zones by multiplying the HRR by desired exercise intensity in the form of percentages. In this case, use 50 percent as your low end intensity, so 108 x 0.50 = 54. Then add the RHR back to that result: 54 + 72 = 126 bpm. This would be the low end of your training zone. For the higher intensity, multiply your HRR by 75 percent, or 0.75, which yields a result of 81. Add your RHR of 72 back into the equation: 81 + 72 = 153 bpm, which represents the upper level of your training zone. Thus, your target heart rate training zone is between 126 to 153 bpm.
Tips and Warnings
- If you manually measure your pulse to gauge your heart rate during exercise, take a final reading within five seconds of finishing because the heart rate begins to drop dramatically at the end of a workout.
References
- "NSCA's Essentials of Personal Training"; National Strength and Conditioning Association; 2004
- "Sports and Fitness Nutrition"; R. Wildman and B. Miller; 2004
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