The Accuracy of Calories Burned in Polar Heart Rate Monitors

Athletes and exercise enthusiasts looking to maximize their fitness efforts can utilize heart rate monitors to evaluate their energy expenditure. Among a crowded field of options, Polar heart rate monitors are often ranked at the top. Some of the monitors, which are typically worn on the wrist, allow you to create a custom training program and provide a guide to keep you in the ideal fat-burning range.

A woman is tracking progress on her smartphone. (Image: Ammentorp Photography/iStock/Getty Images)

Are They Accurate?

Various studies utilizing different Polar heart rate monitors have demonstrated that the monitors are highly accurate at estimating energy expenditure when compared to the actual energy expenditures evaluated by indirect calorimetry -- a lab-based test that is considered the gold standard measure of energy expenditure. The monitors appear to be the most accurate when measuring moderate-intensity exercise. Low-intensity and high-intensity exercise have produced less accurate measurements. You can also increase the monitor's accuracy by entering your individual VO2 max and maximum heart rate into the device. VO2 max is your maximum rate of oxygen consumption during exercise and will increase with physical fitness. Your maximum heart rate is usually 220 minus your age and a doctor can perform a supervised VO2 max test, but the average exercise enthusiast can use a Polar heart rate monitor to identify those values.

Big on Data Collection

Polar heart rate monitors allow you to collect a lot of data about your exercise program to help you adjust your routine to a desired level of intensity. The information can be used to prevent you from pushing too hard or exercising at a level that is too light to receive benefit. As a bonus, the monitors will give you detailed information about your training without interrupting your workout to stop and take your own pulse.

Margin for Error

There has been concern that heart rate monitors could become inaccurate when evaluating exercises that include arm movements, since heart rate increases disproportionately to the rise in VO2 when arm movements are added to exercise. Therefore, heart rate monitors could incorrectly estimate energy expenditure. Studies have shown, however, that there is not an increase in error in energy expenditure estimation when heart rate monitors evaluate combined arm and leg exercises. Still, there is always some error in estimation. Regardless of the type of movement involved, heart rate monitors may overestimate energy expenditure by as much as around 12 percent.

Most Accurate for Many If Not Most

For the average user, Polar heart rate monitors are among the most accurate monitors available. Individuals of normal weight and those who are overweight should be able to get an idea about how many calories they have burned during use, but they should also bear in mind that since heart rate is not always the best way to determine energy expenditure, the monitors have a tendency to slightly overestimate calories burned.