Translational signalling correlates to Hypertrophy

dkm1987

New Member
Hot off the press

TRANSLATIONAL SIGNALING RESPONSES PRECEDING RESISTANCE TRAINING-MEDIATED MYOFIBER HYPERTROPHY IN YOUNG AND OLD HUMANS
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.
JAPPL-91234-2008.R2

Translational signaling and myofiber hypertrophy
ABSTRACT
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>
 
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?

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

biggrin.gif
</div>
Too funny
 
Back
Top