title: Effect of exercise intensity on 24-h energy expenditure and nutrient oxidation.
abstract: The aim of this study was to determine the effects of exercise at different intensities on 24-h energy expenditure (EE) and substrate oxidation. Sixteen adults (8 men and 8 women) were studied on three occasions [sedentary day (Con), a low-intensity exercise day (LI; 400 kcal at 40% of maximal oxygen consumption) and a high-intensity exercise day (HI; 400 kcal at 70% of maximal oxygen consumption)] by using whole room indirect calorimetry. Both 24-h EE and carbohydrate oxidation were significantly elevated on the exercise days (Con < LI = HI), but 24-h fat oxidation was not different across conditions. Muscle enzymatic profile was not consistently related to 24-h fat or carbohydrate oxidation. With further analysis, it was found that, compared with men, women sustained slightly higher rates of 24-h fat oxidation (mg x kg FFM(-1) x min(-1)) and had a muscle enzymatic profile favoring fat oxidation. It is concluded that exercise intensity has no effect on 24-h EE or nutrient oxidation. Additionally, it appears that women may sustain slightly greater 24-h fat oxidation rates during waking and active periods of the day.
authors.affiliation: Center for Human Nutrition, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. Ed.melanson@uchsc.edu
authors.forename: Edward L
authors.initials: EL
authors.lastname: Melanson
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Sharp
authors.forename: Helen M
authors.initials: HM
authors.lastname: Seagle
authors.forename: Tracy J
authors.initials: TJ
authors.lastname: Horton
authors.forename: William T
authors.initials: WT
authors.lastname: Donahoo
authors.forename: Gary K
authors.initials: GK
authors.lastname: Grunwald
authors.forename: Jere T
authors.initials: JT
authors.lastname: Hamilton
authors.forename: James O
authors.initials: JO
authors.lastname: Hill
mesh_terms: D000328:Adult; D002153:Calorimetry, Indirect; D050260:Carbohydrate Metabolism; D002940:Circadian Rhythm; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005223:Fats / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology; D010084:Oxidation-Reduction; D010807:Physical Endurance / Q000502:physiology*; D012727:Sex Characteristics
chemical_list: D005223:Fats