title: Increased p70s6k phosphorylation during intake of a protein-carbohydrate drink following resistance exercise in the fasted state.
abstract: The present study aimed at comparing the responses of myogenic regulatory factors and signaling pathways involved in muscle protein synthesis after a resistance training session performed in either the fasted or fed state. According to a randomized crossover study design, six young male subjects participated in two experimental sessions separated by 3 weeks. In each session, they performed a standardized resistance training. After the sessions, they received during a 4-h recovery period 6 ml/kg b.w. h of a solution containing carbohydrates (50 g/l), protein hydrolysate (33 g/l), and leucine (16.6 g/l). On one occasion, the resistance exercise session was performed after the intake of a carbohydrate-rich breakfast (B), whereas in the other session they remained fasted (F). Needle biopsies from m. vastus lateralis were obtained before (Rest), and 1 h (+1h) and 4 h (+4h) after exercise. Myogenin, MRF4, and MyoD1 mRNA contents were determined by RT-PCR. Phosphorylation of PKB (protein kinase B), GSK3, p70(s6k) (p70 ribosomal S6 kinase), eIF2B, eEF2 (eukaryotic elongation factor 2), ERK1/2, and p38 was measured via western blotting. Compared with F, the pre-exercise phosphorylation states of PKB and p70(s6k) were higher in B, whereas those of eIF2B and eEF2 were lower. During recovery, the phosphorylation state of p70(s6k) was lower in B than in F (p = 0.02). There were no differences in basal mRNA contents between B and F. However, compared with F at +1h, MyoD1 and MRF4 mRNA contents were lower in B (p < 0.05). Our results indicate that prior fasting may stimulate the intramyocellular anabolic response to ingestion of a carbohydrate/protein/leucine mixture following a heavy resistance training session.
authors.affiliation: Department of Biomedical Kinesiology, Research Center for Exercise and Health, FABER, K.U.Leuven, Tervuursevest 101, 3001 Leuven (Heverlee), Belgium.
authors.forename: Louise
authors.initials: L
authors.lastname: Deldicque
authors.forename: Katrien
authors.initials: K
authors.lastname: De Bock
authors.forename: Michael
authors.initials: M
authors.lastname: Maris
authors.forename: Monique
authors.initials: M
authors.lastname: Ramaekers
authors.forename: Henri
authors.initials: H
authors.lastname: Nielens
authors.forename: Marc
authors.initials: M
authors.lastname: Francaux
authors.forename: Peter
authors.initials: P
authors.lastname: Hespel
mesh_terms: D000465:Algorithms; D001774:Blood Chemical Analysis; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000494:pharmacology; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000494:pharmacology; D004326:Drinking / Q000502:physiology; D005080:Exercise Test; D005215:Fasting / Q000502:physiology*; D005248:Feeding Methods; D006801:Humans; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism*; D055070:Resistance Training; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D011494:Protein Kinases; D038762:Ribosomal Protein S6 Kinases, 70-kDa