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X-ray image of a chest strap (left: frontal view; right: side view). Visible is the circuit board, the antenna for data transfer, the battery and the connections to the electrodes in the adjoining belt at picture top and bottom.
Photo of a strapless heart rate monitor
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 that allows one to measure one's heart rate in real time or record the heart rate for later study. It is largely used by performers of various types of "physical exercise.



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 by "Polar Electro (Seppo Säynäjäkangas), as a training aid for the Finnish National Cross Country Ski team. As 'intensity training' becameales of wireless personal heart monitors started from 1983.[1]


Modern heart rate monitors usually comprise two elements: a chest strap transmitter ["needs update] and a wrist receiver (which usually is a "smartwatch). In early plastic straps, water or liquid was required to get good performance. Early units have used conductive smart fabric with built-in microprocessors that analyze the electrical activity to determine the heart rate similar to an "EKG. More recent devices use optics to measure heart rate by which measures changes in blood flow by shining a light from an "LED through the skin and measuring how it scatters off blood vessels.[2]["better source needed]

Strapless heart rate monitors (often referred to as "wearables") now allow the user to just touch two sensors on a smartwatch display for a few seconds to view heart rate data. These are popular for comfort and ease of use, though they don't give as much detail as monitors that use a chest strap. Some models of these variations of heart rate monitors use either "infrared light or red visible light to measure the heart rate, as opposed to two or more "electrodes. In addition to measuring the heart rate, devices using this technology are able to measure blood oxygen saturation ("SpO2)

More advanced models offer measurements of heart rate variability, activity, and breathing rate to assess parameters relating to a subject's fitness. Sensor fusion algorithms allow these monitors to detect core temperature and dehydration.

Another style of heart rate monitor replaces the plastic around-the-chest strap with fabric sensors - the most common of these is a "sports bra that includes sensors in the fabric.

In old versions, when a heart beat is detected a radio signal is transmitted, which the receiver uses to determine the current heart rate. This signal can be a simple radio pulse or a unique coded signal from the chest strap (such as "Bluetooth, "ANT, or other low-power radio link); the latter prevents one user's receiver from using signals from other nearby transmitters (known as cross-talk interference).

Newer versions include a microprocessor, which simultaneously monitors heart rate, "SpO2, and other parameters. These may include sensors such as accelerometers, gyroscopes, and GPS to detect speed, location and distance eliminating the need for ankle worn devices.

There are a wide number of receiver designs, with various features. These include average heart rate over exercise period, time in a specific heart rate zone, calories burned, breathing rate, built-in speed and distance, and detailed logging that can be downloaded to a computer. The receiver can be built into a "smartwatch or "smartphone. Bracelets with integrated sensors work optically, and have poor accuracy.

See also[edit]


  1. ^ Burke, E (ed) Precision Heart Rate Training
  2. ^ "Oxygen Saturation". Wikipedia.org. Retrieved February 16, 2018. 

External links[edit]

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