Muscle fatty acid oxidative capacity is a determinant of whole body fat oxidation in elderly people.
In sedentary elderly people, a reduced muscle fatty acid oxidative capacity (MFOC) may explain a decrease in whole body fat oxidation. Eleven sedentary and seven regularly exercising subjects (65.6 +/- 4. 5 yr) were characterized for their aerobic fitness [maximal O(2) uptake (VO(2 max))/kg fat free mass (FFM)] and their habitual daily physical activity level [free-living daily energy expenditure divided by sleeping metabolic rate (DEE(FLC)/SMR)]. MFOC was determined by incubating homogenates of vastus lateralis muscle with [1-(14)C]palmitate. Whole body fat oxidation was measured by indirect calorimetry over 24 h. MFOC was 40.4 +/- 14.7 and 44.3 +/- 16.3 nmol palmitate. g wet tissue(-1). min(-1) in the sedentary and regularly exercising individuals, respectively (P = nonsignificant). MFOC was positively correlated with DEE(FLC)/SMR (r = 0.58, P < 0. 05) but not with VO(2 max)/kg FFM (r = 0.35, P = nonsignificant). MFOC was the main determinant of fat oxidation during all time periods including physical activity. Indeed, MFOC explained 19.7 and 30.5% of the variance in fat oxidation during walking and during the alert period, respectively (P < 0.05). Furthermore, MFOC explained 23.0% of the variance in fat oxidation over 24 h (P < 0.05). It was concluded that, in elderly people, MFOC may be influenced more by overall daily physical activity than by regular exercising. MFOC is a major determinant of whole body fat oxidation during physical activities and, consequently, over 24 h.
Morio
B
B
Laboratoire de Nutrition Humaine, Université d'Auvergne, Centre de Recherche en Nutrition Humaine d'Auvergne, 63009 Clermont-Ferrand, France. morio@clermont.inra.edu
Hocquette
J F
JF
Montaurier
C
C
Boirie
Y
Y
Bouteloup-Demange
C
C
McCormack
C
C
Fellmann
N
N
Beaufrère
B
B
Ritz
P
P
D000368:Aged; D000375:Aging / Q000378:metabolism*; D001823:Body Composition; D002153:Calorimetry, Indirect; D003576:Electron Transport Complex IV / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000201:enzymology*; D010084:Oxidation-Reduction; D010168:Palmitates / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology
D005227:Fatty Acids; D010168:Palmitates; D003576:Electron Transport Complex IV