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

ObjectivesThe 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.DesignCross-sectional.MethodsDoubly-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 × 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).ResultsNo 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 ∼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.ConclusionsACC + 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 (∼50%) limits its usefulness.