Target Heart Rate Calculations

Maximal Heart-rate is the highest rate a person can attain during exercise. While an electrocardiogram test would provide the most accurate MHR, for practical application an age-predicted heart-rate formula was developed.

Maximal heart-rate = 220 - age

This formula is based on the assumption that one's heart rate at birth is 220 and decreases by one every year. The accuracy of determining maximal heart-rate based on this formula can vary at any given age by + 10 beats per minute.

Resting Heart-rate is the rate at which your heart beats at full rest. It is recommended that this rate be taken before getting out of bed, counting the pulse for a full 60 seconds, 3 mornings in a row and averaging the counts.

Determining the target heart-rate ranges:

Karvonen Formula

Using the Karvonen formula, the generally accepted heart-rate ranges are between 60% to 80% of maximal heart-rate reserve.

Target heart-rate = % intensity X heart-rate reserve + resting heart-rate

Here's how it would be calculated for a 45 year old with a resting heart-rate of 80 and an age-predicted maximal heart-rate of 175 at an 80% intensity level of maximum heart-rate reserve:

175 (age predicted MHR)
- 80 (resting heart-rate)
95 (heart rate reserve)
X.80 (intensity level)
76.00
+80.00 (resting heart-rate)
156.00 (target heart rate)

It is recommended that the formula be applied to both ends of the range, 60% and 80%, to determine the target heart-rate training zone.

The Karvonen formula is considered more accurate than the Maximal heart-rate formula, because the resting heart-rate is used in the calculation. From a practical standpoint, few people actually figure out an average for their true resting heart-rate.

Maximal Heart-Rate Formula

Therefore the simplified Maximal heart-rate formula is the standard that was used in most group exercise settings:

target heart-rate = maximal heart-rate (mhr) X % intensity

For the same 45 year old, here's how the range would be figured:

At 60 % Intensity -

175 (mhr: 220 - age)
X.60 (percent intensity)
105 (target Heart-rate)

At 80% Intensity -

175 (mhr: 220 - age)
X.80 (percent intensity)
140 (target heart-rate)