Karvonen heart rate calculation is a better way of determining your optimum heart rate for training.
Most people are familiar with the quick and easy way to determine your training heart rate, which is often stated as:
65-80% of (220 – your age in years)
The Karvonen formula however is a different way of calculating your training heart rate based not on a percentage of your absolute heart rate, but on your heart rate reserve – ie the amount of capacity your heart has to do work above and beyond its resting work rate. The formula is given as:
Target heart rate = [(max heart rate ? resting heart rate) × %intensity]
+ resting heart rate
To calculate your heart rate reserve, you need to know your age (you should know this!), and your resting heart rate. Suppose your resting heart rate is 60 beats per minute (bpm). Your maximum heart rate is still calculated as 220 – your age ie 184bpm. But your heart rate reserve is now given as the difference between resting and maximum heart rate, or 184 – 60bpm = 124bpm.
If you work at 75% of your heart rate reserve, you’ll be training at 75% of 124bpm over and above your resting heart rate ie 93bpm above 60bpm, which is 153bpm. At 80% of heart rate reserve, it’s 80% of 124bpm over and above resting heart rate, which is 99bpm above 60bpm or 159bpm. Your 75-80% training zone therefore is 153bpm – 159bpm.
Although it’s slightly more complex to apply, the Karvonen formula more accurately reflects the working % of your maximum oxygen uptake than does a simple % of max heart rate calculation, particularly for fitter people. So for example, you’re much more likely to be working at 75-80% of your maximum aerobic capacity at 153-159bpm than you are at 138-147bpm, which is the figure you get doing it the simple method based on maximum heart rate only described at the top of this page. This is why Karvonen calculated training heart rate zones are often preferred to simple max heart rate calculations in those who train regularly and who are seeking a more accurate estimation of their ideal training heart rate.