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Cited by 333Muscle metabolism and nutritionMuscle Physiology and DisordersRNA and protein synthesis mechanisms

Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after Exercise

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Norton, Layne E, Layman, Donald K·2006·The Journal of Nutrition
DOI 10.1093/jn/136.2.533s
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Abstract

High-performance physical activity and postexercise recovery lead to significant changes in amino acid and protein metabolism in skeletal muscle. Central to these changes is an increase in the metabolism of the BCAA leucine. During exercise, muscle protein synthesis decreases together with a net increase in protein degradation and stimulation of BCAA oxidation. The decrease in protein synthesis is associated with inhibition of translation initiation factors 4E and 4G and ribosomal protein S6 under regulatory controls of intracellular insulin signaling and leucine concentrations. BCAA oxidation increases through activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH). BCKDH activity increases with exercise, reducing plasma and intracellular leucine concentrations. After exercise, recovery of muscle protein synthesis requires dietary protein or BCAA to increase tissue levels of leucine in order to release the inhibition of the initiation factor 4 complex through activation of the protein kinase mammalian target of rapamycin (mTOR). Leucine's effect on mTOR is synergistic with insulin via the phosphoinositol 3-kinase signaling pathway. Together, insulin and leucine allow skeletal muscle to coordinate protein synthesis with physiological state and dietary intake.

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Crossref · 10.1093/jn/136.2.533s

Cites

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  • The three branched-chain amino acids (BCAAs), leucine, isoleucine, and valine are unique among the EAAs for their roles in protein metabolism, neural function, and blood glucose and insulin regulation.

    “The three branched-chain amino acids (BCAAs), leucine, isoleucine, and valine are unique among the EAAs for their roles in protein metabolism [150], neural function [151–153], and blood glucose and insulin regulation [154].”

    From International Society of Sports Nutrition Position Stand: protein and exercise (2017) · cites this paper as [150]

    Citation [150] is attached to the protein-metabolism portion of the sentence, not the claims about neural function or glucose and insulin regulation. In “Metabolic roles of leucine in skeletal muscle” (page not provided), the paper describes leucine’s distinctive role in regulating muscle protein synthesis, but it does not establish that all three BCAAs have that distinctive role among essential amino acids. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • Consumption of leucine could turn a negative protein balance to a positive balance following an intense exercise bout by prolonging the MPS response to feeding.

    “Norton and Layman [150] proposed that consumption of leucine, could turn a negative protein balance to a positive balance following an intense exercise bout by prolonging the MPS response to feeding.”

    From International Society of Sports Nutrition Position Stand: protein and exercise (2017) · cites this paper as [150]

    The 'Metabolic roles of leucine in skeletal muscle' section says net protein balance remains negative after resistance exercise until dietary protein or leucine is ingested. The 'Effect of exercise on translation initiation factors' section says supplemental leucine permits maximum protein synthesis and anabolic recovery. Neither passage says leucine works by prolonging the muscle-protein-synthesis response to feeding; the paper instead describes stimulation of translation initiation. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

  • The ingestion of a protein or essential amino acid complex that contains sufficient amounts of leucine has been shown to shift protein balance to a net positive state after intense exercise training.

    “the ingestion of a protein or essential amino acid complex that contains sufficient amounts of leucine has been shown to shift protein balance to a net positive state after intense exercise training [46, 150].”

    From International Society of Sports Nutrition Position Stand: protein and exercise (2017) · cites this paper as [150]

    The Metabolic roles of leucine in skeletal muscle section says net protein balance remains negative after resistance exercise until dietary protein or leucine is ingested. It also reports recovery of protein synthesis after a protein-containing meal or leucine following exhaustive exercise. It does not establish that ingestion shifts net protein balance to a positive state, or specify a sufficient leucine amount in a protein or essential-amino-acid complex. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Consumption of leucine can turn individuals from a negative to a positive whole body protein balance after intense resistance training exercise.

    “Similarly, Norton & Layman [14] found that the consumption of leucine, one of three BCAAs, can turn individuals from a negative to a positive whole body protein balance after intense resistance training exercise [14].”

    From In a single-blind, matched group design: Branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet (2016) · cites this paper as [14]

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Cites

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Research works printed but not linked: 4

  1. Rennie MJ, Tipton KD. Protein and amino acid metabolism during and after exercise and the effects of nutrition. Annu Rev Nutr. 2000;20:457-83.
  2. Phillips SM, Tipton KD, Aarsland A, Wolf SE, Wolfe RR. Mixed muscle protein synthesis and breakdown following resistance exercise in humans. Am J Physiol. 1997;273:E99-107.
  3. Biolo G, Tipton KD, Klein S, Wolfe RR. An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein synthesis. Am J Physiol. 1997;273:E122-9.
  4. Long X, Ortiz-Vega S, Lin Y, Avruch J. Rheb binding to mTOR is regulated by amino acid sufficiency. J Biol Chem. 2005;280:23433-6.

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Authors
Norton, L. E., & Layman, D. K.
Affiliations
University of Illinois Urbana-Champaign (US)
Corresponding author
Layman, Donald K
ORCID
Layman, Donald K
Venue
The Journal of Nutrition
Publisher
Elsevier BV
Published
2006-02
Volume
136
Issue
2
Pages
533S-537S
ISSN
0022-3166 (ISSN-L)
DOI
10.1093/jn/136.2.533s
OpenAlex
W2100833380
Cited by
333
References
41
Citations by year
2026: 15 · 2025: 23 · 2024: 13 · 2023: 20 · 2022: 11 · 2021: 17 · 2020: 14 · 2019: 21 · 2018: 20 · 2017: 22 · 2016: 20 · 2015: 21 · 2014: 20 · 2013: 19 · 2012: 11
FWCI
4.69
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Nutrition (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › RNA and protein synthesis mechanisms
Keywords
leucine, translation initiation, skeletal muscle, post-exercise recovery, muscle protein synthesis, branched-chain amino acids, branched-chain ketoacid dehydrogenase, mTOR, insulin signaling, phosphatidylinositol 3-kinase, ribosomal protein S6, protein degradation
MeSH terms
Animals, Exercise Test, Humans, Leucine, Muscle Proteins, Physical Conditioning, Animal, Protein Kinases, Protein Biosynthesis, Exercise, Muscle, Skeletal, Rats, TOR Serine-Threonine Kinases

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