In this study we propose 1) to develop a new multisensor monitoring system associating a tri-axial accelerometer and a magnetometer to measure physical activity in free-living adults, 2) to perform its calibration and assess its validity in a series of activity tasks in comparison with the measure of energy expenditure by indirect calorimetry as the criterion measure, and with existing physical activity monitors (cardiofrequencemetry and accelerometers used either alone or in combination). Briefly the subjects will perform a series of standardized activity tasks of different intensities and a 30-min free physical activity period while wearing 6 MOTIONPOD(TM) and different commercial activity monitors. Physical activity energy expenditure will be measured using a metabolic gas analyser.

Data of the 30 first subjects will be used to develop new algorithms to identify the different activity tasks and to estimate the related energy expenditures. Data of the following 30 subjects will be used to validate the MotionPOD(TM) against indirect calorimetry and existing physical activity monitors

Inclusion Criteria:

• Normal-weight, overweight or obesity according to body mass index
• Low,moderate or high level of physical activity as estimated by questionnaire
• No angina and/or peripheral arterial disease symptoms or medical history

Exclusion Criteria:

• Subjects with cardiac implants
• Claustrophobic subjects
• Drug use that could affect energy expenditure
• Medical history or evolving disease which are a contra-indication for moderate physical exercise