Validity of a combined heart rate and motion sensor for the measurement of free-living energy expenditure in very active individuals

Objectives: The correct assessment of energy expenditure in very active individuals is important to ensure that dietary energy intake is sufficient. We aimed to validate a combined heart rate (HR) and motion sensor in estimating total (TEE) and activity energy expenditure (AEE) in males and females with high physical activity levels. Design: Cross-sectional. Methods: Doubly-labelled water (DLW) was used to assess 7-day TEE in 12 male and female elite junior basketball players, aged 16-17 years. Resting energy expenditure (REE) was assessed with indirect calorimetry and AEE was calculated (AEE = TEE-RMR-0.1 x TEE). Simultaneously, TEE and AEE were measured by combined HR and motion sensing. Individual HR calibration was performed with step-test. TEE and AEE were estimated from accelerometry and HR with individual (ACC + HRstep) and group calibration (ACC + HRgroup). Results: No mean differences were found between TEE and AEE from the ACC + HRstep and ACC + HRgroup with DLW. TEE values (kJ/day) from ACC + HRgroup and ACC + HRstep explained TEE from DLW by similar to 60% and 53%, respectively whereas AEE (kJ/day) estimated by ACC + HRgroup and ACC + HRstep explained 53% and 41% of the variability of AEE from the reference method. Concordance correlation coefficients for TEE and AEE using ACC + HRgroup were 0.74 and 0.69, correspondingly while for ACC + HRstep values of 0.69 and 0.45 were found. Large limits of agreement were found for TEE and AEE using both ACC + HRgroup and ACC + HRstep. Conclusions: ACC + HR models are a valid alternative to estimate TEE but not AEE in a group of highly active individuals however the considerable rate of equipment failure (similar to 50%) limits its usefulness. (C) 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.