Isolated & combined wearable technology underestimate the total energy expenditure of professional young rugby league players ; a doubly labelled water validation study

Accurately determining total energy expenditure enables the precise manipulation of energy balance within professional collision-based sports. Therefore, this study investigated the ability of isolated or combined wearable technology to determine the total energy expenditure of professional young rugby league players across a typical pre-season and in-season period. Total energy expenditure was measured via doubly labelled water, the criterion method, across a fourteen-day pre-season (n=6) and seven-day in-season (n=7) period. Practical measures of total energy expenditure included SenseWear Pro3 Armbands in isolation and combined with metabolic power derived from microtechnology units. SenseWear Pro3 Armbands significantly under-reported pre-season (5.00 (2.52) MJ.day-1; p = 0.002) and in-season (2.86 (1.15) MJ.day-1; p < 0.001) total energy expenditure, demonstrating a large and extremely large standardised mean bias, and a very large and large typical error, respectively. Combining metabolic power with SenseWear Pro3 Armbands almost certainly improved pre-season (0.95 (0.15) MJ.day-1; ES = 0.32 ±0.04; p < 0.001) and in-season (1.01 (0.15) MJ.day-1; ES = 0.88 ±1.05; p < 0.001) assessment. However, SenseWear Pro3 Armbands combined with metabolic power continued to significantly under-report pre-season (4.04 (2.38) MJ.day-1; p = 0.004) and in-season (2.18 (0.96) MJ.day-1; p = 0.002) expenditure, demonstrating a large and very large standardised mean bias, and a very large and large typical error, respectively. These findings demonstrate the limitations of utilising isolated or combined wearable technology to accurately determine the total energy expenditure of professional collision-based sport athletes across different stages of the season.