Metabolic rate monitoring and energy expenditure prediction using a novel actigraphy method.

BACKGROUND A novel actigraphy method, the proportional integral mode, was used for monitoring metabolic rate and energy expenditure during different levels of exercise intensity. MATERIAL/METHODS 13 young (24+/-3 yrs) male subjects, clothed in T-shirts, shorts and athletic shoes, ran/walked for 30 min on a level treadmill at different speeds (3, 5, 2, 6, 4, and 7 mph), 5 min at each speed. The following variables were continuously measured: Actigraphy (PCD, USA) data at three different modes (proportional integral mode, zero crossing, and time above threshold) from the wrist; oxygen consumption (Sensor Medics, USA), and heart rate (Polar, Finland). RESULTS Analysis of the measured data revealed with low correlation between oxygen consumption and zero crossing or time above threshold (R=0.364 and 0.384, respectively), but with high correlation between oxygen consumption and proportional integral mode (R=0.843). CONCLUSIONS The proportional integral mode, which is unlike the other modes, followed the oxygen consumption and the heart rate curves, showing a potential unique method to predict oxygen consumption and energy expenditure.