### Calculation heart rate reserve

The heart rate reserve is a percentage that gives an indication of the perceived load. The hart rate in rest is set at 0% and the peak heart rate at 100%. The resting pulse can easily be determined by measuring the pulse in bed in the morning, immediately after waking up. The maximum heart rate is the highest measured heart rate. This heart rate differs per sport and will therefore have to be determined by rowing.

It is best to combine the exertion test with sports medical examination, because the maximum heart rate is also determined in this examination. Determining this maximum heart rate is not entirely without risk: the heart is heavily loaded. A sports medical examination is therefor mandatory before the before maximum heart rate is determined.

One method to determine the maximum heart rate is the following. Use a rowing ergometer and heart rate monitor for this with the option to read back the highest measured heart rate afterwards. Start with a warm up of about 10 minutes. Set the units on the display to watts. Start rowing with a power of 70 watts. Then increase the wattage by 20 watts every minute. If that power can no longer be held, squeeze out a 1 minute final sprint. The highest heart rate measured during this Rowing machine session is then the maximum heart rate.

A calculation example of the heart rate reserve. Assume that the resting pulse is 50 beats per minute and the maximum heart rate is 200 beats per minute. The heart rate reserve is then calculated using the following formula:

heart rate reserve = resting pulse + (exercise percentage * (maximum heart rate – resting pulse)).

A demanded effort of 80% then gives: 50 bpm + (80% * (200 bpm – 50 bpm)) = 50 bpm + 120 bpm = 170 bpm.