Abstract:
Validity of hip-mounted uniaxial accelerometrywith heart-rate monitoring vs. triaxial accelerometry in the assessment offree-living energy expenditure in young children: the IDEFICS Valida-tion Study.J Appl Physiol113: 1530–1536, 2012. First publishedSeptember 20, 2012; doi:10.1152/japplphysiol.01290.2011.—One of theaims of Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants (IDEFICS) validationstudy is to validate field measures of physical activity (PA) and energyexpenditure (EE) in young children. This study compared the validityof uniaxial accelerometry with heart-rate (HR) monitoring vs. triaxialaccelerometry against doubly labeled water (DLW) criterion methodfor assessment of free-living EE in young children. Forty-nine Euro-pean children (25 female, 24 male) aged 4–10 yr (mean age: 6.9 1.5yr) were assessed by uniaxial ActiTrainer with HR, uniaxial 3DNX,and triaxial 3DNX accelerometry. Total energy expenditure (TEE)was estimated using DLW over a 1-wk period. The longitudinal axisof both devices and triaxial 3DNX counts per minute (CPM) weresignificantly (P 0.05) associated with physical activity level (PAL;r 0.51 ActiTrainer,r 0.49 uniaxial-3DNX, andr 0.42 triaxial 3DNX). Eight-six percent of the variance in TEE could be predictedby a model combining body mass (partialr2 71%;P 0.05),CPM-ActiTrainer (partialr2 11%;P 0.05), and differencebetween HR at moderate and sedentary activities (ModHR SedHR)(partialr2 4%;P 0.05). The SE of TEE estimate for ActiTrainerand 3DNX models ranged from 0.44 to 0.74 MJ/days or 7–11% ofthe average TEE. The SE of activity-induced energy expenditure(AEE) model estimates ranged from 0.38 to 0.57 MJ/day or 24–26%of the average AEE. It is concluded that the comparative validity ofhip-mounted uniaxial and triaxial accelerometers for assessing PA andEE is similar.accelerometers; validity; young children; obesity; doubly labeledwater.