Improving energy expenditure estimation for physical activity.

Purpose: The purpose of this study was to validate the Intelligent Device for Energy Expenditure and Activity (IDEEA) for estimation of energy expenditure during a variety of activities. An additional aim was to improve the accuracy of the estimation of energy expenditure of physical activity based on second-by-second information of type, onset, and duration of activity.

Methods: This study included two tests: a mask calorimetry test with 27 subjects [age = 33.7 +/- 13.8 (mean +/- SD) yr; BMI = 24.8 +/- 4.8 kg x m] and a respiratory chamber calorimetry test with 10 subjects (age = 32.9 +/- 12.4 yr; BMI = 26.1 +/- 5.6 kg x m). In the mask test, the subjects performed activities (sitting, standing, lying down, level treadmill walking, and running at different speeds) for 50-min durations. For the chamber test, subjects lived in the metabolic chamber for 23 h and performed three exercise sessions to compensate for the confined environment.

Results: The results showed significant correlations (P < 0.0001) between energy expenditure estimated by IDEEA and energy expenditure measured by the calorimeters with an accuracy >95%. After corrections for the decrease in sleeping metabolic rate, the estimation accuracy for the chamber test was increased by 1-96.2%, whereas the estimation accuracy for nighttime activity was significantly improved by 4-99%.

Conclusion: IDEEA provides a suitable method for estimating the energy expenditure of physical activity. It provides both instantaneous and cumulative estimates of energy expenditure over a given period.