The chest strap transmitter measures the number of times the users heart beats per minutes by monitoring voltages across the heart through electrodes which are in contact with the skin. As a heart beat is detected the transmitter sends a radio signal to the receiver which is used to determine the rate at which the heart beats. In higher end models this signal is coded in order to prevent "Cross Talk" between nearby monitors.

The first wireless EKG Heart rate monitor was invented in 1977 by Polar Electro. It was invented as a training aid for the Finnish National Cross Country Ski team. The concept of 'intensity training' infiltrated through the athletic world in the eighties and in 1983 the first wireless heart monitor was introduced. The portable Polar PE 2000 consisted of a transmitter and a receiver. The transmitter was attached to the chest by either disposable electrodes or an elastic electrode belt, whilst the receiver was a monitor worn as a watch on the wrist. By the 1990s individuals were not only looking at heart rate monitors for performance training needs, but also for their individual everyday fitness requirements.

The wireless Polar heart rate monitoring method was developed at the University of Oulu's department of electronics, and was originally aimed at coaches and sportsmen to help raise the quality and efficiency of their training. Exercise scientists also used them in their work after researching them.

The selection of monitors available today includes easy-to-use products for everyone with a keen interest in their physical health. There are also a wide number of receiver designs that have many different advanced features. These include, average heart rate over exercise period, time in a specific heart rate zone, calories burned during exercise period, along with detailed logging that can be downloaded to a computer.

In December 2005, Textronics Inc. introduced the first garment with integrated heart sensors in the form of a sports bra. Special materials in the sports bra sense the number of beats of the heart from the body and transmit it to a wrist receiver. The garment provides a comfortable alternative to the chest strap.

Modern receiver designs are wide ranging and can perform many advanced functions including average rate, calories burned & stride length. The data can then be logged by downloading it onto a computer.