Postexercise high-fat feeding suppresses p70s6k1 activity in human skeletal muscle

• Autores: Kelly M. Hammond, Samuel G. Impey, Kevin Currell
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 48, Nº. 11, 2016, págs. 2108-2117
• Idioma: inglés
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• Resumen

  • AB Purpose: 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. Methods: Ten males completed a twice per day exercise model (3.5 h between sessions) comprising morning high-intensity interval training (8 x 5 min at 85% V[spacing dot above]O2peak) and afternoon steady-state (SS) running (60 min at 70% V[spacing dot above]O2peak). In a repeated-measures design, runners exercised under different isoenergetic dietary conditions consisting of high-CHO (HCHO: 10 g[middle dot]kg-1 CHO, 2.5 g[middle dot]kg-1 protein, and 0.8 g[middle dot]kg-1 fat for the entire trial period) or reduced-CHO but high-fat availability in the postexercise recovery periods (HFAT: 2.5 g[middle dot]kg-1 CHO, 2.5 g[middle dot]kg-1 protein, and 3.5 g[middle dot]kg-1 fat for the entire trial period). Results: Muscle glycogen was lower (P < 0.05) at 3 h (251 vs 301 mmol[middle dot]kg-1 dry weight) and 15 h (182 vs 312 mmol[middle dot]kg-1 dry weight) post-SS exercise in HFAT compared with HCHO. Adenosine monophosphate-activated protein kinase [alpha]2 activity was not increased post-SS in either condition (P = 0.41), although comparable increases (all P < 0.05) in PGC-1[alpha], p53, citrate synthase, Tfam, peroxisome proliferator-activated receptor, and estrogen-related receptor [alpha] 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[middle dot]min-1[middle dot]mg-1). Conclusion: 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. (C) 2016 American College of Sports Medicine