Effect of exercise intensity on 24-h energy expenditure and nutrient oxidation.
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.
Melanson
Edward L
EL
Center for Human Nutrition, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. Ed.melanson@uchsc.edu
Sharp
Teresa A
TA
Seagle
Helen M
HM
Horton
Tracy J
TJ
Donahoo
William T
WT
Grunwald
Gary K
GK
Hamilton
Jere T
JT
Hill
James O
JO
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
D005223:Fats