Muscle protein synthesis and gene expression during recovery from aerobic exercise in the fasted and fed states

Matthew P. Harber, Adam R. Konopka, Bozena Jemiolo, Scott W. Trappe, Todd A. Trappe, Paul T. Reidy

Research output: Contribution to journalArticlepeer-review


The purpose of this investigation was to assess mixed-muscle fractional synthesis rate (FSR) and the expression of genes involved in skeletal muscle remodeling after aerobic exercise in the fasted and fed states. Eight recreationally active males (25 ± 1 yr; V̇O2 max: 52 ± 2 ml·kg-1·min-1) performed 60-min of cycle ergometry at 72 ± 1% V̇O2 max on two occasions in a counter-balanced design. Subjects ingested a noncaloric placebo (EX-FAST) or a beverage containing (per kg body wt): 5 kcal, 0.83 g carbohydrate, 0.37 g protein, and 0.03 g fat (EX-FED) immediately and 1 h after exercise. FSR was assessed at rest and following exercise with the use of a L-[ring 2H5]-phenylalanine infusion combined with muscle biopsies at 2 and 6 h postexercise. mRNA expression was assessed at 2 and 6 h postexercise via real-time RT-PCR. FSR was higher (P < 0.05) after exercise in both EX-FAST (0.112 ± 0.010%·h-1) and EX-FED (0.129 ± 0.014%·h-1) compared with rest (0.071 ± 0.005%·h-1). Feeding attenuated the mRNA expression (P < 0.05) of proteolytic factors MuRF-1 (6 h) and calpain-2 (2 and 6 h) postexercise but did not alter FOXO3A, calpain-1, caspase3, or myostatin mRNA expression compared with EX-FAST. Myogenic regulatory factor (MRF4) mRNA was also attenuated (P < 0.05) at 2 and 6 h postexercise in EX-FED compared with EX-FAST. These data demonstrate that a nonexhaustive bout of aerobic exercise stimulates skeletal muscle FSR in the fasted state and that feeding does not measurably enhance FSR between 2 and 6 h after aerobic exercise. Additionally, postexercise nutrient intake attenuates the expression of factors involved in the ubiquitin-proteosome and Ca2+-dependent protein degradation pathways. These data provide insight into the role of feeding on muscle protein metabolism during recovery from aerobic exercise.

Original languageEnglish (US)
Pages (from-to)R1254-R1262
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number5
StatePublished - Nov 2010


  • Calpain
  • Endurance
  • Muscle-specific RING finger protein-1
  • Protein turnover
  • Proteolysis

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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