Development and validation of a measurement system for assessment of energy expenditure and physical activity in Prader-Willi syndrome

Objective: The morbid obesity associated with Prader-Willi syndrome (PWS) m ay result from either excessive energy intake or reduced energy expenditure (EE). In this report, we describe the development and validation of an Act ivity-Energy Measurement System (AEMS) to measure EE and physical activity components in an environment approximating free-living conditions. Research Methods and Procedures: The AEMS consists of a live-in, whole-room indirect calorimeter equipped with a novel force platform floor system to enable simultaneous measurements of EE, physical activity, and work efficie ncy during spontaneous activities and standardized exercises. Free-living p hysical activity and estimated free-living EE are measured using portable t riaxial accelerometers individually calibrated in each subject during their stay in the AEMS. Results: Representative data from two PWS patients and two matched control (CTR) subjects displayed EE during their inactive lifestyles. Discussion: This combination of methods will allow the quantification of da ily EE and its components, the amount and energy cost of physical activity, and the relationships between body composition and EE, in order to determi ne their roles in the development and maintenance of the morbid obesity in PWS.