Rapid down-regulation of mitochondrial fat metabolism in human muscle after training cessation is dissociated from changes in insulin sensitivity.
The association between impairment in mitochondrial muscle fat oxidative capacity (OX(FA)) and occurrence of insulin resistance was examined in 14 healthy trained men (age, 24+/-4 yr) submitted to 4 weeks of training cessation. Training stop induced a significant decrease in mRNA levels of proteins involved in muscle fat metabolism, particularly PPARalpha (-58%, P<0.01) and PGC-1alpha (-30%, P<0.05), a 21% reduction in OX(FA) (P<0.01), and reduced fat oxidation during moderately intense exercise (P<0.05). In contrast, there was no significant alteration in insulin sensitivity. In conclusion, decline in OX(FA) is a rapid metabolic event following training cessation. It is involved in the regulation of whole body fat balance but not in the deterioration of insulin sensitivity.
Rimbert
Virginie
V
INRA, UMR1019 Human Nutrition, F-63120 Saint-Genès-Champanelle, France.
Vidal
Hubert
H
Duché
Pascale
P
Debard
Cyrille
C
Giraudet
Christophe
C
Boirie
Yves
Y
Chardigny
Jean-Michel
JM
Morio
Béatrice
B
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D015536:Down-Regulation; D015444:Exercise; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D010084:Oxidation-Reduction; D055815:Young Adult
D001786:Blood Glucose; D007328:Insulin