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Age‐related anabolic resistance after endurance type exercise in humans
Author(s) -
Durham William,
Casperson Sha,
Dillon Edgar Lichar,
Keske Michelle A,
PaddonJones Douglas,
Sanford Arthur,
Lakshman Kishore M,
Hickner Robert C,
Hong Chuan,
Grady James,
SheffieldMoore Melinda
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.997.14
Subject(s) - anabolism , skeletal muscle , medicine , amino acid , endocrinology , catabolism , sarcopenia , microdialysis , phenylalanine , biology , metabolism , biochemistry , central nervous system
Age‐related skeletal muscle loss is thought to stem from suboptimal nutrition and resistance to anabolic stimuli. Impaired microcirculatory (nutritive) blood flow may contribute to anabolic resistance by reducing delivery of amino acids to skeletal muscle. In this study, we employed contrast‐enhanced ultrasound and microdialysis sampling of skeletal muscle interstitium, along with stable isotope methodology, to assess hemodynamic and metabolic responses of older individuals to endurance type (walking) exercise during controlled amino acid provision. We hypothesized older individuals would exhibit reduced microcirculatory blood flow, interstitial amino acid concentrations, and amino acid transport when compared with young controls. We report for the first time that aging induces anabolic resistance following endurance exercise, manifested as reduced (by ~40%) efficiency of muscle protein synthesis. Despite suggesting reduced nutritive flow in the old, our findings comprehensively refute our hypothesis that amino acid availability limits post‐exercise anabolism in older individuals, as circulating and interstitial amino acid concentrations and phenylalanine transport into skeletal muscle were all equal or higher in older individuals than in the young. Our data point to alternative mediators of age‐related anabolic resistance and importantly suggest correction of these impairments may reduce requirements for and increase the efficacy of dietary protein in the old.