Respiration data is not uniformly reported and there is still doubt regarding its validity. BG breathing measurements will be compared to gold standard measurement techniques of gas exchange using a mouthpiece connected to flow and gas analyzer. Activity data is reported but the investigators do not know how the value translates into clinically used objective parameters of activity e.g. METS. BG activity measurements will be compared to the gold standard activity measurements using metabolic rate (indirect calorimetry)