This article refers to a device used by non-scientists. For the article on the medical device performing a similar function, see Electrocardiography.

A heart rate monitor is a personal monitoring device which allows a subject to measure his or her heart rate

Heart rate

Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....

 in real time or record his or her heart rate for later study. Early models consisted of a monitoring box with a set of electrode leads which attached to the chest.

The first wireless EKG Heart rate monitor was invented in 1977 as a training aid for the Finnish National Cross Country Ski team and as 'intensity training' became a popular concept in athletic circles in the mid-80s, retail sales of wireless personal heart monitors started from 1983.