Validity of Apple Watch, Garmin Forerunner^® 935 and GENEActiv for estimating energy expenditure during close quarter battle training in Special Forces soldiers

Abstract

The purpose of this study was to investigate the validity of three wrist‐worn devices for estimating energy expenditure (EE) and heart rate (HR) during close “Close Quarter Battle” (CQB). Fifty male soldiers (mean ± SD: age 30.9 ± 4.6 years, height: 1.81 ± 0.64 m and body mass 87.3 ± 7.7 kg) wore three activity monitors (Apple Watch 5, Garmin Forerunner® 935 and GENEActiv accelerometer), a Metamax 3B metabolic cart and a Polar chest strap, whilst conducting a CQB training activity (duration: 26.6 ± 5.0 min). EE and HR data from each test device were compared against criterion measures using ordinary least products regression, 95% limits of agreement, equivalence testing and Mean Absolute Percentage Error (MAPE). Based upon the criterion measure the mean EE for the activity was 372.2 ± 57.6 kcal. All of the devices tested demonstrated fixed and/or proportional bias for EE and a MAPE of >10% (Apple 11.3%, Garmin 15.3%, GENEActiv 57.7%) and therefore did not agree with the criterion. The Apple Watch was a valid method for measuring HR, with a MAPE of 0.6%, and differences with the criterion falling within acceptable limits (≤1 bpm = 83.7%; ≤3 bpm = 97.5% and ≤5 bpm = 97.5%), whereas the Garmin Forerunner® 935 was not valid for measuring HR due to an unacceptable difference compared to the criterion (≤1 bpm = 19.1%; ≤3 bpm = 33.3% and ≤5 bpm = 45.2%). Overall, the Apple Watch 5 can be recommended for measuring HR, but none of the devices are recommended for estimating EE, during CQB.