According to Wikipedia a heart rate monitor is a personal monitoring device that allows a subject to measure their heart rate in real time or record their heart rate for later study. Early models consisted of a monitoring box with a set of electrode leads that 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. ‘Intensity training’ became a popular concept in athletic circles in the mid-80s and retail sales of wireless personal heart monitors started from 1983.
Modern heart rate monitors usually comprise two elements: a chest strap transmitter and a wrist receiver or mobile phone (which usually doubles as a watch or phone). In early plastic straps water or liquid was required to get good performance. Later units have used conductive smart fabric with built in microprocessors that analyze the EKG signal to determine heart rate.
Strapless heart rate monitors now allow the user to just touch two sensors on a wristwatch display for a few seconds to view their heart rate. These are popular for their comfort and ease of use though they don’t give as much detail as monitors which use a chest strap.
More advanced models will offer measurements of heart rate variability, activity, and breathing rate to assess parameters relating to a subject’s fitness.
Another style of heart rate monitor replaces the plastic round-the-chest strap with fabric sensors – the most common of these is a sports bra for women which 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 Blue-tooth, 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 that is continuously monitoring the EKG and calculating the heart rate, and other parameters. These can include accelerometers that can detect speed and distance eliminating the need for foot 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.
Popular models are produced with a variety of features so you can choose a basic model to an advanced model. Prices will vary depending on the number of features that are included in the model.
The benefit of heart rate models are; They provide real time feedback to help you stay in the target heart rate zone for your training, plus information can be downloaded from your model to a computer and you can record your progress.