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Leucine partially protects muscle mass and function during bed rest in middle-aged adults,

English, K. L. ; Mettler, J. A. ; Ellison, J. B. ; Mamerow, M. M. ; Arentson-Lantz, E. ; Pattarini, J. M. ; Ploutz-Snyder, R. ; Sheffield-Moore, M. ; Paddon-Jones, D.

American Journal of Clinical Nutrition, 02/01/2016, Vol.103(2), pp.465-473 [Peer Reviewed Journal]

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  • Title:
    Leucine partially protects muscle mass and function during bed rest in middle-aged adults,
  • Author: English, K. L. ; Mettler, J. A. ; Ellison, J. B. ; Mamerow, M. M. ; Arentson-Lantz, E. ; Pattarini, J. M. ; Ploutz-Snyder, R. ; Sheffield-Moore, M. ; Paddon-Jones, D.
  • Subjects: Medicine ; Diet & Clinical Nutrition
  • Is Part Of: American Journal of Clinical Nutrition, 02/01/2016, Vol.103(2), pp.465-473
  • Description: BACKGROUND: Physical inactivity triggers a rapid loss of muscle mass and function in older adults. Middle-aged adults show few phenotypic signs of aging yet may be more susceptible to inactivity than younger adults.OBJECTIVE: The aim was to determine whether leucine, a stimulator of translation initiation and skeletal muscle protein synthesis (MPS), can protect skeletal muscle health during bed rest.DESIGN: We used a randomized, double-blind, placebo-controlled trial to assess changes in skeletal MPS, cellular signaling, body composition, and skeletal muscle function in middle-aged adults (n = 19; age ± SEM: 52 ± 1 y) in response to leucine supplementation (LEU group: 0.06 g ∙ kg(-1) ∙ meal(-1)) or an alanine control (CON group) during 14 d of bed rest.RESULTS: Bed rest decreased postabsorptive MPS by 30% ± 9% (CON group) and by 10% ± 10% (LEU group) (main effect for time, P < 0.05), but no differences between groups with respect to pre-post changes (group × time interactions) were detected for MPS or cell signaling. Leucine protected knee extensor peak torque (CON compared with LEU group: -15% ± 2% and -7% ± 3%; group × time interaction, P < 0.05) and endurance (CON compared with LEU: -14% ± 3% and -2% ± 4%; group × time interaction, P < 0.05), prevented an increase in body fat percentage (group × time interaction, P < 0.05), and reduced whole-body lean mass loss after 7 d (CON compared with LEU: -1.5 ± 0.3 and -0.8 ± 0.3 kg; group × time interaction, P < 0.05) but not 14 d (CON compared with LEU: -1.5 ± 0.3 and -1.0 ± 0.3 kg) of bed rest. Leucine also maintained muscle quality (peak torque/kg leg lean mass) after 14 d of bed-rest inactivity (CON compared with LEU: -9% ± 2% and +1% ± 3%; group × time interaction, P < 0.05).CONCLUSIONS: Bed rest has a profoundly negative effect on muscle metabolism, mass, and function in middle-aged adults. Leucine supplementation may partially protect muscle health during relatively brief periods of physical inactivity. This trial was registered at clinicaltrials.gov as NCT00968344.
  • Language: English
  • Identifier: ISSN: 0002-9165 ; E-ISSN: 1938-3207 ; DOI: http://dx.doi.org/10.3945/ajcn.115.112359

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