Kathryn L. Dannecker, Nadezhda A. Sazonova, Edward L. Melanson, Edward S. Sazonov, Raymond C. Browning, accepted to Med Sci Sports Exerc. 2013.

Accurately estimating free-living energy expenditure (EE) is important for monitoring energy balance and quantifying physical activity. Recently, single and multi-sensor devices have been developed that can classify physical activities and these devices may result in improved estimates of EE. PURPOSE: To determine the accuracy of EE estimation of a footwear-based physical activity monitor and to compare this accuracy against a variety of research and consumer physical activity monitors. METHODS: Nineteen healthy young adults (10 male, 9 female), completed a four-hour stay in a room calorimeter. Participants wore a footwear-based physical activity monitor, as well as Actical, Actigraph, IDEEA, DirectLife and Fitbit devices. Each individual performed a series of postures/activities. We developed models to estimate EE from the footwear-based device, and we used the manufacturer’s software to estimate EE for all other devices. RESULTS: The shoe-based device was not significantly different than the mean measured EE (476(20) vs. 478(18) kcal) (Mean (SE)), respectively, and had a root mean square error (RMSE) of (29.6 kcal (6.19%)). The IDEEA and DirectLlife estimates of EE were not significantly different than the measured EE but the Actigraph, Actical and Fitbit devices significantly underestimated EE. Root mean square errors were 62.1 kcal (14%), 88.2 kcal(18%), 122.2 kcal (27%), 130.1 kcal (26%), and 143.2 kcal (28%) for DirectLife, IDEEA, Actigraph, Actical and Fitbit respectively. CONCLUSIONS: The shoe based physical activity monitor was able to accurately estimate EE while the research and consumer physical activity monitors tested have a wide range of accuracy when estimating EE. These results support the need to develop devices that can accurately classify and use activity specific algorithms to estimate EE.