Activity energy expenditure (AEE) during free-living conditions can be assessed using devices based on different principles. To make proper comparisons of different devices' capacities to assess AEE, they should be evaluated in the same population. Thus, in the present study we evaluated, in the same group of subjects, the ability of three devices to assess AEE in groups and individuals during free-living conditions. In twenty women, AEE was assessed using RT3 (three-axial accelerometry) (AEERT3), Actiheart (a combination of heart rate and accelerometry) (AEEActi) and IDEEA (a multi-accelerometer system) (AEEIDEEA). Reference AEE (AEEref) was assessed using the doubly labelled water method and indirect calorimetry. Average AEEActi was 5760 kJ per 24 h and not significantly different from AEEref (5020 kJ per 24 h). On average, AEERT3 and AEEIDEEA were 2010 and 1750 kJ per 24 h lower than AEEref, respectively (P < 0·001). The limits of agreement (± 2 sd) were 2940 (Actiheart), 1820 (RT3) and 2650 (IDEEA) kJ per 24 h. The variance for AEERT3 was lower than for AEEActi (P = 0·006). The RT3 classified 60 % of the women in the correct activity category while the corresponding value for IDEEA and Actiheart was 30 %. In conclusion, the Actiheart may be useful for groups and the RT3 for individuals while the IDEEA requires further development. The results are likely to be relevant for a large proportion of Western women of reproductive age and demonstrate that the procedure selected to assess physical activity can greatly influence the possibilities to uncover important aspects regarding interactions between physical activity, diet and health.
Keywords: AEE, activity energy expenditure; AEE5dresult, total energy expenditure, measured using the doubly labelled water method during days 1–5 minus BMR measured using indirect calorimetry; AEEActi, activity energy expenditure assessed using Actiheart; AEEIDEEA, activity energy expenditure assessed using IDEEA; AEERT3, activity energy expenditure assessed using RT3; AEEref, activity energy expenditure assessed using the doubly labelled water method and indirect calorimetry; Accuracy; Activity energy expenditure; Activity monitors; CountsActi, counts using Actiheart; CountsIDEEA, counts using IDEEA; CountsRT3, counts using RT3; DIT, dietary induced thermogenesis; Doubly labelled water; HRaR, heart rate above resting heart rate; MET, metabolic equivalent; TEE, total energy expenditure; TEE5dresult, TEE during days 1–5; TEEIDEEA, total energy expenditure measured using IDEEA; TEEref, total energy expenditure measured using the doubly labelled water method.