Global positioning system watches for estimating energy expenditure

Area of Science:

• Exercise Physiology
• Sports Technology
• Biomechanical Engineering

Background:

• Commercial global positioning system (GPS) watches estimate energy expenditure (EE) using time, location, speed, and elevation data.
• The accuracy of these EE estimates is crucial for effective athletic training and field-based testing.

Purpose of the Study:

• To compare the energy expenditure (EE) estimates from four different GPS watches against a reference triaxial accelerometer (RT3).
• To evaluate the reliability and accuracy of commercial GPS watches in estimating EE across various walking speeds.

Main Methods:

• Sixteen healthy adults participated in the study.
• Participants wore four distinct GPS watches and one RT3 accelerometer.
• Walking trials were conducted on an outdoor track at three speeds: 3, 5, and 7 km/hr.

Main Results:

• GPS watches exhibited lower reliability across trials compared to the RT3 accelerometer, particularly at 7 km/hr.
• Three GPS watches (Forerunner, Polar, Suunto) significantly underestimated EE compared to the RT3 reference.
• Average mean differences in EE were -50.5% (Garmin), -41.7% (Polar), and -41.7% (Suunto), all statistically significant (p < 0.001).

Conclusions:

• Commercial GPS watches may not provide accurate energy expenditure (EE) estimates for athletes during field activities.
• Caution is advised when utilizing GPS watches for EE estimations in athletic training and testing.
• Further research is needed to improve the accuracy of GPS-based EE calculations in diverse athletic populations and conditions.