A heart rate monitor is an electronic device that allows a user to monitor heart rate while engage in sports like swimming, or running and exercising. It normally has two parts a chest strap and a wrist receiver. Wrist receiver has a watch. Strapless heart rate monitors are available in market, but lack some of the functionality of the original design. New models with additional facilities measure heart rate variability to assess a trainee's fitness. Heart rate monitor specially built for contest and altitude need special features like:

1. displaying altitude;
2. display atmospheric pressure;
3. displaying environmental temperature;
4. measuring speed and distance,
5. saving training session information for improvements;
6. Help in programming exercise or session for user.
7. keeping record of heart rate with  time and exercise routine,
8. Analyzing sessions.

Many products are available in market a description of popular heart rate monitor with special features is listed:

The polar s720i includes: manufactured primarily for cyclists, mountaineers and skiers
1. measures speed and distance,
2. precision performance software: training sessions can be saved, analyzed in detail and emailed,
3. built in altimeter to check altitude,
4. Built in thermometer to check environmental temperature.
5. Can pre- program exercise schedule.
6. Exercise profiles can be programmed as per use's choice.

Ciclosport hac4 hrm: designed primarily for cyclists, mountaineers and skiers: the special features are:

1. Altitude,
2. Rate of accent and decent,
3. Temperature and heart rate information is provided.

Suunto 51-advizor altimeter, barometer, heart rate monitor, compass.

1. altimeter,
2. barometer,
3. ascent/descent rate for every hour,
4. time spent in, above and below target heart rate zone;
5. Stores total training time.

Acumen tz-max 100 heart rate monitor w/usb connection

1. 2-way pc communication included software and connector,
2. heart rate with target zone alarms,
3. a recovery heart rate timer,
4. 9 interval timers,
5. A stopwatch feature.

Ultimo cardio sport heart rate monitor: designed for personal trainers, coaches, competitive athletes, and multi-sport athletes.

1. 80 hours of heart rate recording during exercise,
2. playback of single recording session data,
3. up to 6 files available at selectable intervals,
4. files can be uploaded to pc,
5. it has a high /low limit heart zone alarm,
6. time in zone display,
7. displays time in, above, and below zones.

For more advice for maintening a healthy heart visit:
http://www.restheartrate.com