Postexercise High-Fat Feeding Suppresses p70S6K1 Activity in Human Skeletal Muscle.
This study aimed to examine the effects of reduced CHO but high postexercise fat availability on cell signaling and expression of genes with putative roles in regulation of mitochondrial biogenesis, lipid metabolism, and muscle protein synthesis.



Ten males completed a twice per day exercise model (3.5 h between sessions) comprising morning high-intensity interval training (8 × 5 min at 85% V˙O2peak) and afternoon steady-state (SS) running (60 min at 70% V˙O2peak). In a repeated-measures design, runners exercised under different isoenergetic dietary conditions consisting of high-CHO (HCHO: 10 g·kg CHO, 2.5 g·kg protein, and 0.8 g·kg fat for the entire trial period) or reduced-CHO but high-fat availability in the postexercise recovery periods (HFAT: 2.5 g·kg CHO, 2.5 g·kg protein, and 3.5 g·kg fat for the entire trial period).



Muscle glycogen was lower (P < 0.05) at 3 h (251 vs 301 mmol·kg dry weight) and 15 h (182 vs 312 mmol·kg dry weight) post-SS exercise in HFAT compared with HCHO. Adenosine monophosphate-activated protein kinase α2 activity was not increased post-SS in either condition (P = 0.41), although comparable increases (all P < 0.05) in PGC-1α, p53, citrate synthase, Tfam, peroxisome proliferator-activated receptor, and estrogen-related receptor α mRNA were observed in HCHO and HFAT. By contrast, PDK4 (P = 0.003), CD36 (P = 0.05), and carnitine palmitoyltransferase 1 (P = 0.03) mRNA were greater in HFAT in the recovery period from SS exercise compared with HCHO. Ribosomal protein S6 kinase activity was higher (P = 0.08) at 3 h post-SS exercise in HCHO versus HFAT (72.7 ± 51.9 vs 44.7 ± 27 fmol·min·mg).



Postexercise high-fat feeding does not augment the mRNA expression of genes associated with regulatory roles in mitochondrial biogenesis, although it does increase lipid gene expression. However, postexercise ribosomal protein S6 kinase 1 activity is reduced under conditions of high-fat feeding, thus potentially impairing skeletal muscle remodeling processes.
1Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM; 2English Institute of Sport, Loughborough University, Loughborough, UNITED KINGDOM; 3Health and Exercise Sciences Research Group, University of Stirling, Stirling, UNITED KINGDOM; and 4Centre for Exercise and Nutrition, Mary MacKillop Health Research Institute, Australian Catholic University, Victoria, AUSTRALIA.
Kelly M
KM
Hammond
Samuel G
SG
Impey
Kevin
K
Currell
Nigel
N
Mitchell
Sam O
SO
Shepherd
Stewart
S
Jeromson
John A
JA
Hawley
Graeme L
GL
Close
Lee D
LD
Hamilton
Adam P
AP
Sharples
James P
JP
Morton
D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D015870:Gene Expression; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism / Q000235:genetics; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics; D018482:Muscle, Skeletal / Q000201:enzymology*; D001678:Organelle Biogenesis; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D055815:Young Adult
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D009124:Muscle Proteins; D006003:Glycogen; D019893:Ribosomal Protein S6 Kinases