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# What is the Karvonen Formula?

James Franklin
James Franklin

The Karvonen Formula is a series of simple equations intended to help exercisers safely improve their cardiovascular health. The formula uses the exerciser’s heart rates — at rest and while active — and plugs the differences between those numbers into two simple calculations. The Karvonen Formula is a rough guide and is not as accurate as a test conducted by a physician, who can consider other health factors before recommending an exercise program.

To use the Karvonen Formula, subtract your age from the number 220. Some experts recommend that women subtract their age from 226 instead of 220. That sum is considered your maximum heart rate (MHR), the most beats per minute your heart can make before you theoretically are in danger. For example, if you are a 40-year-old man, you would have a maximum heart rate of 180.

To get resting heart rate (RHR), take your pulse while you’re relaxed. Place a finger against an artery in your wrist or neck and count the number of beats for 10 seconds. Multiply that number by six to determine the number of heartbeats per minute. The sum should give you a general idea of your resting heart rate. For comparison’s sake, the average person’s resting heart rate is about 70 beats per minute.

Another number that’s required is called the heart rate reserve (HRR). Subtract your resting heart rate from your maximum heart rate to get the heart rate reserve. The heart rate reserve is then multiplied by two different percentages — 60 percent and 80 percent — to get your target heart rate zone. This zone indicates the ideal number of beats per minute your heart can safely make while exercising to allow you to better your aerobic health.

For simplicity’s sake, the equations in the Karvonen Formula are listed below:

(220 or 226) – age = maximum heart rate (MHR)

MHR – resting heart rate (RHR) = heart rate reserve (HRR)

HRR x .60 = lower limit of target heart rate zone

HRR x .80 = upper limit of target heart rate zone

The Karvonen Formula was developed by Dr. Martti Karvonen, a Finnish physician and researcher long associated with Helsinki’s Institute of Occupational Health. During his career, Karvonen investigated the role that nutrition plays in overall health, finding that people in countries with high-calorie diets generally performed more efficiently than those from nations with lower caloric intakes. He also explored the links between heart attacks, culture and individual lifestyles, research that eventually led to the formula that bears his name.