The correct assessment of individual energy requirements of athletes remains a challenge. Available literature indicates that accelerometry-based sensors underestimated energy expenditure in athletes, especially during high-intensity exercise. The goal of our study was to evaluate two commercially available devices (Actiheart; SenseWear Pro3) during high-intensity running and to identify potential sources of error.
Twenty-nine male endurance- and strength-trained athletes participated in an incremental running exercise, which started at 2.8 m · s−1. Running speed was increased by 0.4 m · s−1 every 5 minutes until 4.8 m · s−1 or individual exhaustion were reached. Energy expenditure was measured with indirect calorimetry (IC) and both sensors were worn according to the manufacturers’ instructions. Twelve participants also conducted a step test in order to individually recalibrate the Actiheart data.
The Actiheart monitor underestimated energy expenditure (EE) for all speeds by 1.1 to 8.3 kcal · min−1 and showed a weak correlation with IC (r=0.61). Following individual recalibration there were no significant differences to IC but validity correlation did not improve (r=0.56). Heart rate was assessed correctly with the Actiheart when compared to a Polar 610 recorder. Activity counts increased only between 2.8 and 3.6 m · s−1 but plateaued thereafter. SenseWear significantly underestimated EE for all speeds by 1.0 to 9.5 kcal min−1 and was moderately correlated with IC (r=0.66). Longitudinal and transversal acceleration increased significantly between 2.8 and 4.4 m · s−1 and were correlated with running speed (0.63 < r<0.69).
Our results show that both devices underestimate EE during high-intensity running. For Actiheart, individual calibration is recommended in order to obtain sufficiently accurate results. For SenseWear, acceleration data could be used to improve EE prediction during high-intensity running. Further research is necessary to validate these portable devices in other groups, in field settings and during other exercise types
NOTE: The Bodymedia Sensewear Armband has been discontinued since the sale of Bodymedia to the consumer company ‘Jawbone’ in 2013. Jawbone subsequently went into liquidation in 2017 and all product support was discontinued. This illustrates the danger of choosing consumer focussed products for scientific research. Our professional, research grade Actiheart device has been available since 2003 and has hundreds of peer-reviewed publications.