Translational signalling correlates to Hypertrophy

Discussion in 'Hypertrophy Research' started by dkm1987, Jul 9, 2009.

  1. dkm1987

    dkm1987 New Member

    Hot off the press

    David L Mayhew, Jeong-su Kim, James M Cross, Arny A Ferrando, and Marcas M Bamman

    Medical Scientist Training Program, and Departments of Physiology and Biophysics and Surgery,
    University of Alabama at Birmingham, Birmingham, Alabama

    Articles in PresS. J Appl Physiol (July 9, 2009). doi:10.1152/japplphysiol.91234.2008
    Copyright © 2009 by the American Physiological Society.

    Translational signaling and myofiber hypertrophy
    While skeletal muscle protein accretion during resistance training (RT)-mediated myofiber
    hypertrophy is thought to result from up-regulated translation initiation signaling, this concept is based
    on responses to a single bout of unaccustomed resistance exercise (RE) with no measure of
    hypertrophy across RT. Further, aging appears to affect acute responses to RE but whether age
    differences in responsiveness persist during RT leading to impaired RT adaptation is unclear. We
    therefore tested whether muscle protein fractional synthesis rate (FSR) and Akt/mTOR signaling in
    response to unaccustomed RE differed in old vs. young, and whether age differences in acute
    responsiveness were associated with differences in muscle hypertrophy after 16 wk of RT. Fifteen old
    and 21 young completed the 16 wk study. The phosphorylation states of Akt, S6K1, RPS6, 4EBP1,
    eIF4E, and eIF4G were all elevated (23-199%) 24 h after a bout of unaccustomed RE. A concomitant
    62% increase in FSR was found in a subset (6 old, 8 young). Age x time interaction was found only
    for RPS6 phosphorylation (+335% in old only), while there was an interaction trend (P=0.084) for FSR
    (+96% in young only). After 16 wk of RT, gains in muscle mass, type II myofiber size, and voluntary
    strength were similar in young and old. In conclusion, at the level of translational signaling we found
    no evidence of impaired responsiveness among old and, <u>for the first time, we show that changes in
    translational signaling after unaccustomed RE were associated with substantial muscle protein
    accretion (hypertrophy) during continued RT.</u>
  2. Lol

    Lol Super Moderator Staff Member

    Excellent! Any idea how old the 'old' folks were?
  3. dkm1987

    dkm1987 New Member

    average was 64 for old versus 27 for young
  4. Lol

    Lol Super Moderator Staff Member

    When I get older, losing my hair,
    Many years from now,
    I could still be packing on the pounds of beef,
    Which, I can tell you, is a relief!

    If I'm still training down at the gym,
    You can blame it on Mr. Moore!
    Will you still need me, will you still feed me,
    When I'm sixty-four?

  5. dkm1987

    dkm1987 New Member

    (Lol @ Jul. 10 2009,12:21)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">When I'm sixty-four?

    Too funny

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