A heart rate monitor is a lightweight electronic device that allows a subject to measure and record his or her heart rate. Modern heart rate monitors generally consist of a chest strap and a wrist watch. These devices provide an easy and accurate way to measure heart rate while performing an exercise workout. This is vital for maintaining good cardiovascular fitness since a heart rate monitor will help monitor your target heart rate. The target heart rate refers to the heart rate one must maintain while exercising to achieve optimal cardio fitness. The target heart rate of a person is a percentage of their maximum heart rate. For moderate intensity physical activity the target heart rate should be between 50-75 percent of the maximum heart rate while for high intensity physical activity the figure should be between 70-85 percent. A waterproof heart rate monitor is built of durable materials and is designed to be water resistant. This is a useful device for swimmers and people who play other water sports. It is particularly important for professional divers, swimmers and sailors.

The chest strap of a heart rate monitor has electrodes that detect the electrical activity of the heart. The straps are made of a special conductive smart fabric with microprocessors embedded in it to analyze this activity and measure the heart rate. This information is then transmitted to a wristwatch which displays it. The chest monitor continuously measure the heart rate and relays it to the receiver which comes in various designs and contains additional features which include average heart rate over exercise period, time in a specific heart rate zone, calories burned, breathing rate, built in speed and distance calculator and detailed logging that can be downloaded to a computer. Modern heart rate monitors include GPS functionality as well and provide indications such as alarms when a person is outside his or her target range.

The type of waterproof heart rate monitor required depends on the individual's needs and fitness level. For weight loss a monitor that measures the time spent within your target heart rate as well as the calories burned during the exercise is most suitable. For athletes and professional swimmers a waterproof heart rate monitor that offers multi-sport support, workout feedback and advanced features such as GPS and data logging is recommended. Waterproof heart rate monitors only function above certain specified depths.

Waterproof heart rate monitors cost between $50- $500 depending on the brand and features. Inexpensive models are generally recommended for beginner and intermediate users who generally follow a moderate exercise workout. The more expensive models contain many additional features and are more accurate and durable and are more appropriate for professional athletes and advanced users who engage in vigorous physical activity and exercise. Brands like Polar and Timex are world renowned suppliers of waterproof heart rate monitors.

When using a waterproof heart rate monitor the user must first moisten the electrode pads on the underside of the chest strap with water before fastening the chest strap just below the pectoral muscles. The wristwatch will then indicate the current heart rate. The buttons on the wristwatch should not be pressed while immersed in water. If the waterproof heart rate monitor seems to be malfunctioning it should be brought closer to the chest strap. Electrical signals from other sources can also sometimes interfere with the readings. Saltwater and the underwire of some bathing suits may also give erroneous readings. All these facts should be taken into account when purchasing and using a waterproof heart rate monitor.