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

Am J Physiol Regul Integr Comp Physiol. 2010 Nov;299(5):R1254-62. doi: 10.1152/ajpregu.00348.2010. Epub 2010 Aug 18.

Abstract

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; Vo(2 max): 52 ± 2 ml·kg(-1)·min(-1)) performed 60-min of cycle ergometry at 72 ± 1% Vo(2 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 (2)H(5)]-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 Ca(2+)-dependent protein degradation pathways. These data provide insight into the role of feeding on muscle protein metabolism during recovery from aerobic exercise.

Publication types

  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Beverages
  • Biopsy
  • Blood Glucose / metabolism
  • Dietary Carbohydrates / administration & dosage
  • Dietary Fats / administration & dosage
  • Dietary Proteins / administration & dosage
  • Eating*
  • Exercise*
  • Fasting*
  • Fatty Acids / blood
  • Gene Expression Regulation
  • Glycogen / metabolism
  • Humans
  • Infusions, Intravenous
  • Insulin / blood
  • Male
  • Muscle Contraction*
  • Muscle Proteins / biosynthesis*
  • Muscle Proteins / genetics
  • Muscle, Skeletal / metabolism*
  • Oxygen Consumption
  • Phenylalanine / administration & dosage
  • Phenylalanine / analogs & derivatives
  • RNA, Messenger / metabolism
  • Recovery of Function
  • Time Factors
  • Young Adult

Substances

  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats
  • Dietary Proteins
  • Fatty Acids
  • Insulin
  • Muscle Proteins
  • RNA, Messenger
  • Phenylalanine
  • Glycogen