| Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state. | |
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MedLine Citation:
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PMID: 22383503 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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We made sex-based comparisons of rates of myofibrillar protein synthesis (MPS) and anabolic signalling after a single bout of high-intensity resistance exercise. Eight men (20 ± 10 y, BMI = 24.3 ± 2.4) and eight women (22 ± 1.8 y, BMI = 23.0 ± 1.9) underwent primed constant infusions of L-[ring-(13)C(6)]phenylalanine on consecutive days with serial muscle biopsies. Biopsies were taken from the vastus lateralis at rest, and 1, 3, 5, 24, 26 and 28 h after exercise. 25 g of whey protein was ingested immediately and 26 h after exercise. We also measured exercise-induced serum testosterone since it is purported to contribute to increases in MPS post-exercise and its absence has been hypothesized to attenuate adaptative responses to resistance exercise in women. The exercise-induced area under the testosterone curve was 45-fold greater in men than women in the early (1 h) recovery period following exercise (P < 0.001). MPS was elevated similarly in men and women (2.3- and 2.7- fold, respectively) 1-5 h post-exercise and after protein ingestion following 24 h recovery. Phosphorylation of mTOR(Ser2448) was elevated to a greater extent in men than women acutely after exercise (P = 0.003), whereas increased phosphorylation of p70S6K1(Thr389) was not different between sexes. Androgen receptor content was greater in men (main effect for sex, P = 0.049). Atrogin-1 mRNA abundance was decreased after 5 h recovery in both men and women (P < 0.001) and MuRF-1 expression was elevated in men after protein ingestion following 24 h recovery (P = 0.003). These results demonstrate minor sex-based differences in signalling responses and no difference in the MPS response to resistance exercise in the fed state. Interestingly, our data demonstrate that exercise-induced increases in MPS are dissociated from post-exercise testosteronemia and that stimulation of MPS occurs effectively with low systemic testosterone concentrations in women. |
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Authors:
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Daniel W D West; Nicholas A Burd; Tyler A Churchward-Venne; Donny M Camera; Cameron J Mitchell; Steven K Baker; John A Hawley; Vernon G Coffey; Stuart M Phillips |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-3-1 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2012 Mar |
Date Detail:
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Created Date: 2012-3-2 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1McMaster University. |
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