Original Article

European Journal of Applied Physiology

, Volume 108, Issue 4, pp 791-800

First online:

Increased p70s6k phosphorylation during intake of a protein–carbohydrate drink following resistance exercise in the fasted state

  • Louise DeldicqueAffiliated withResearch Group in Muscle and Exercise Physiology, Institute of Neurosciences, UCLouvain
  • , Katrien De BockAffiliated withDepartment of Biomedical Kinesiology, Research Center for Exercise and Health, FABER, K.U.Leuven
  • , Michael MarisAffiliated withDepartment of Biomedical Kinesiology, Research Center for Exercise and Health, FABER, K.U.Leuven
  • , Monique RamaekersAffiliated withDepartment of Biomedical Kinesiology, Research Center for Exercise and Health, FABER, K.U.Leuven
  • , Henri NielensAffiliated withResearch Group in Muscle and Exercise Physiology, Institute of Neurosciences, UCLouvain
  • , Marc FrancauxAffiliated withResearch Group in Muscle and Exercise Physiology, Institute of Neurosciences, UCLouvain
  • , Peter HespelAffiliated withDepartment of Biomedical Kinesiology, Research Center for Exercise and Health, FABER, K.U.Leuven Email author 

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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, p70s6k (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 p70s6k were higher in B, whereas those of eIF2B and eEF2 were lower. During recovery, the phosphorylation state of p70s6k 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.

Keywords

Skeletal muscle Nutrition Amino acids Carbohydrates p70s6k MRF