The Accuracy Of Heart Rate Monitors For Calories

The advancement of technology in training watches has led to the development of heart rate monitors with the ability to track calories. These watches provide a resource for tracking caloric expenditure during exercise or daily activities and are commonly used by athletes, fitness enthusiasts, rehab patients or people looking for weight loss. Several factors, however, need to be taken into account regarding calories, resulting in a debate on the accuracy of heart rate monitors for calories.

Function

Caloric expenditure -- commonly referred to as energy expenditure -- is traditionally measured in a laboratory by calculating the correlation between oxygen consumed and carbon dioxide produced. Heart rate monitors, however, predict the caloric expenditure with software that estimates maximum oxygen consumption by measuring the length of time between heart beats. Along with estimating caloric expenditure, heart rate monitors can measure recovery times, maximum heart rate and resting heart rate.

Features

Most heart rate monitors will use a flexible chest strap that communicates heart rate data wirelessly with a watch. The chest strap features electrodes that detect electrical information during each heartbeat and continuously sends the information to the watch. After the watch collects the heart rate data, the information can be downloaded to a computer for reference and data collection.

Effects

Despite the continuous transfer of heart rate data, several factors can affect heart rate, resulting in a change in the estimated caloric expenditure. Most heart rate monitor watches take into account your gender and body weight, but your heart rate can change due to external factors such as caffeine or stimulants. World-class athletes, for example, typically have lower than average heart rates, which could adjust the estimated caloric expenditure.

Benefits

Even with external factors potentially changing the caloric results, heart rate monitors provide a reference tool for tracking workout intensity over a period of time. For example, heart rate zones are designed for maximizing weight loss or cardiovascular benefits, and the heart rate monitors can accurately keep you within those recommended zones during a workout. As a general rule, as the intensity of the workout increases, so does the caloric expenditure. Rehab patients recovering from surgeries can also use the heart rate monitors to track calories and find the appropriate training zone.

Results

A 2009 research study in the "Journal of Strength and Conditioning Research" compared a heart rate monitor and a laboratory-based calorie measurement. The test had subjects perform submaximal and maximal intensity treadmill running with the results showing a variation of about 6 percent to 13 percent for estimated caloric expenditure.