What is heart rate

Heart rate is a measure of the number of contractions the heart makes per minute. It is measured in beats per minute (bpm). To effectively use this target heart rate calculator, it is important to understand the concepts of resting heart rate, maximum heart rate, and heart rate reserve.

Maximum heart rate

Maximum heart rate is a measure of the highest number of beats per minute the heart reaches during intense exercise. It is most accurately measured through a cardiac stress test, which typically involves exercising on a treadmill while being monitored by an electrocardiogram (ECG). As the subject walks/runs on the treadmill, the intensity is periodically increased until certain changes in heart function indicating maximum heart rate are detected. The theoretical maximum human heart rate is 300 bpm.

More commonly, maximum heart rate is estimated using various formulas. It is worth noting that maximum heart rate formulas have been criticized as inaccurate as they output generalized population averages and estimates can vary significantly from an individual's maximum heart rate. Maximum heart rate is largely correlated with age, and most formulas are primarily based on this. Thus, while they are generally useful for estimating the average maximum heart rate for a given age group, the heart rate of an individual within the age group can differ significantly. One interesting observation made by Dr. Fritz Hagerman was that the maximum heart rates of a group of men in their 20s who were on Olympic rowing teams varied between 160 and 220 beats per minute, so even at the elite level, there is significant variability.

The following are some formulas used to estimate maximum heart rate.

Haskell & Fox Formula (1971):

maximum heart rate = 220 - age

Tanaka, Monahan, & Seals Formula (2001):

maximum heart rate = 208 - 0.7 × age

Nes, Janszky, Wisloff, Stoylen, Karlsen Formula (2013):

maximum heart rate = 211 - 0.64 × age

Resting heart rate

Resting heart rate is a measure of a person's heart rate at rest, where rest is defined as when a person is awake in a neutral environment that is neither too hot nor cold, and the person is not subject to stress or surprise. It can be measured using a variety of devices or just by counting your pulse over a minute (or extrapolating it based on a shorter period, though this is less accurate).

A typical resting heart rate (RHR) for an adult ranges between 50-90 bpm. Some sources state this range as 60-100 bpm, but this range is slightly dated. A resting heart rate above the upper range is referred to as tachycardia while one below the lower range is referred to as bradycardia. A RHR in the 50-60 range in some cases may be considered bradycardia, but very fit athletes often have RHRs in this range, and sometimes even below.

Heart rate reserve

A person's heart rate reserve (HRreserve) is the difference between their maximum heart rate (MHR) and their resting heart rate (RHR):

HRreserve = MHR - RHR

For example, given a person has a maximum heart rate of 180 bpm and a resting heart rate of 68, their heart rate reserves is:

HRreserve = 180 - 68 = 112