Postexercise fat intake repletes intramyocellular lipids but no faster in trained than in sedentary subjects.
The hypotheses that postexercise replenishment of intramyocellular lipids (IMCL) is enhanced by endurance training and that it depends on fat intake were tested. Trained and untrained subjects exercised on a treadmill for 2 h at 50% peak oxygen consumption, reducing IMCL by 26-22%. During recovery, they were fed 55% (high fat) or 15% (low fat) lipid energy diets. Muscle substrate stores were estimated by (1)H (IMCL)- and (13)C (glycogen)-magnetic resonance spectroscopy in tibialis anterior muscle before and after exercise. Resting IMCL content was 71% higher in trained than untrained subjects and correlated significantly with glycogen content. Both correlated positively with indexes of insulin sensitivity. After 30 h on the high-fat diet, IMCL concentration was 30-45% higher than preexercise, whereas it remained 5-17% lower on the low-fat diet. Training status had no significant influence on IMCL replenishment. Glycogen was restored within a day with both diets. We conclude that fat intake postexercise strongly promotes IMCL repletion independently of training status. Furthermore, replenishment of IMCL can be completed within a day when fat intake is sufficient.
Décombaz
J
J
Nestlé Research Center, Nestec Ltd., PO Box 44, CH-1000 Lausanne 26, Switzerland. jacques.decombaz@rdls.nestle.com
Schmitt
B
B
Ith
M
M
Decarli
B
B
Diem
P
P
Kreis
R
R
Hoppeler
H
H
Boesch
C
C
D000328:Adult; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002247:Carbon Isotopes; D004041:Dietary Fats / Q000378:metabolism*; D005080:Exercise Test; D006003:Glycogen / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D019344:Lactic Acid / Q000097:blood; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D013997:Time Factors
D002247:Carbon Isotopes; D004041:Dietary Fats; D008055:Lipids; D019344:Lactic Acid; D006003:Glycogen