title: Determination of energy expenditure during heavy exercise, normal daily activity, and sleep using the doubly-labelled-water (2H2 18O) method.
abstract: Energy expenditure of four subjects was measured by the doubly-labelled-water (2H2 18O) method to determine if energy expenditure could be determined over short periods. Three subjects were studied while they performed 8 h of heavy exercise in a laboratory environment. Urine and blood samples were taken before and after exercise. Estimated energy expended during 8 h of high-intensity exercise (55% VO2 max) for three subjects was 757 +/- 118 kcal/h by the doubly-labelled-water method using urine and a two-point calculation, which compared favorably with 735 +/- 82 kcal/h obtained by respiratory gas exchange. For the fourth subject, daytime, nighttime, and daily energy expenditure was calculated by both the two-pair method and decay-curve analysis of urine and saliva samples collected in the morning and at night. Daytime and nighttime energy expenditures differed significantly (p less than 0.05).
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D001834:Body Water / Q000032:analysis; D002940:Circadian Rhythm; D003903:Deuterium; D004734:Energy Metabolism; D006801:Humans; D008297:Male; D010103:Oxygen Isotopes; D005082:Physical Exertion; D012890:Sleep / Q000502:physiology*
chemical_list: D010103:Oxygen Isotopes; D003903:Deuterium