Evaluation of Actiheart and a 7d activity diary for estimating free-living total and activity energy expenditure using criterion methods in 1•5- and 3-year-old children

Accurate and easy-to-use methods to assess free-living energy expenditure in response to physical activity in young children are scarce. In the present study, we evaluated the capacity of (1) 4d recordings obtained using the Actiheart (mean heart rate (mHR) and mean activity counts (mAC)) to provide assessments of total energy expenditure (TEE) and activity energy expenditure (AEE) and (2) a 7d activity diary to provide assessments of physical activity levels (PAL) using three sets of metabolic equivalent (MET) values (PAL(Torun), PAL(Adolph) and PAL(Ainsworth)) in forty-four and thirty-one healthy Swedish children aged 1 center dot 5 and 3 years, respectively. Reference TEE, PAL(ref) and AEE were measured using criterion methods, i.e. the doubly labelled water method and indirect calorimetry. At 1 center dot 5 years of age, mHR explained 8% (P=0 center dot 006) of the variation in TEE above that explained by fat mass and fat-free mass. At 3 years of age, mHR and mAC explained 8 (P=0 center dot 004) and 6 (P=0 center dot 03)% of the variation in TEE and AEE, respectively, above that explained by fat mass and fat-free mass. At 1 center dot 5 and 3 years of age, average PAL(Ainsworth) values were 1 center dot 44 and 1 center dot 59, respectively, and not significantly different from PAL(ref) values (1 center dot 39 and 1 center dot 61, respectively). By contrast, average PAL(Torun) (1 center dot 5 and 3 years) and PAL(Adolph) (3 years) values were lower (P<0 center dot 05) than the corresponding PAL(ref) values. In conclusion, at both ages, Actiheart recordings explained a small but significant fraction of free-living energy expenditure above that explained by body composition variables, and our activity diary produced mean PAL values in agreement with reference values when using MET values published by Ainsworth.