J Physiol. 2008 Jun 12.

Discussion in 'Hypertrophy Research' started by dkm1987, Jun 26, 2008.

  1. dkm1987

    dkm1987 New Member

    Differential effects of resistance and endurance exercise in the fed state on signaling molecule phosphorylation and protein synthesis in human muscle.Wilkinson SB, Phillips SM, Atherton PJ, Patel R, Yarasheski KE, Tarnopolsky MA, Rennie MJ.
    McMaster University.

    Resistance (RE) and endurance (EE) exercise stimulate mixed skeletal muscle protein synthesis. The phenotypes induced by RE (myofibrillar protein accretion) and EE (mitochondrial expansion) training must result from differential stimulation of myofibrillar and mitochondrial protein synthesis. We measured the synthetic rates of myofibrillar and mitochondrial proteins and the activation of signaling proteins (Akt-mTOR-p70S6K) at rest and after an acute bout of RE or EE in the untrained state and after 10 wk of RE or EE training in young healthy men. While untrained, RE stimulated both myofibrillar and mitochondrial protein synthesis, 67% and 69% (P<0.02), respectively. After training, only myofibrillar protein synthesis increased with RE (36%, P= 0.05). EE stimulated mitochondrial protein synthesis in both the untrained, 154%, and trained, 105%, (both P<0.05) but not myofibrillar protein synthesis. Acute RE and EE increased the phosphorylation of proteins in the Akt-mTOR-p70S6K pathway with comparatively minor differences between two exercise stimuli. Phosphorylation of Akt-mTOR-p70S6K proteins was increased after 10 wk of RE training but not by EE training. Chronic RE or EE training modifies the protein synthetic response of functional protein fractions, with a shift toward exercise phenotype-specific responses, without an obvious explanatory change in the phosphorylation of regulatory signaling pathway proteins.
     
  2. dkm1987

    dkm1987 New Member

    Some excerpts from the paper mentioned

    Resistance exercise training stimulates mixed MPS at rest and after an acute bout of resistance exercise (Phillips et al., 1999; Phillips et al., 2002; Kim et al., 2005). Those studies have also shown that resistance training attenuates the acute post exercise increase of mixed MPS to the same relative exercise intensity (Phillips et al., 1999; Phillips et al., 2002; Kim et al., 2005). We did not find an attenuation of myofibrillar protein synthesis after 10 wk of resistance exercise training. (there goes that theory out the window)



    The differing response of mixed and myofibrillar protein synthesis could be due to dampening of the synthetic response of non-myofibrillar proteins while maintaining the synthesis of myofibrillar proteins after training. (this is the same result found recently by another researcher, I need to find that study again in my papers)
    In support of this we observed that the increase in mitochondrial protein synthesis seen after resistance exercise in the untrained state was absent after 10 wk
    of resistance training. This response does not appear to be mediated by changes in the phosphorylation status of known regulatory signaling proteins; however it is possible that increased specific gene transcripts for myofibrillar proteins remain elevated after resistance training, promoting production of myofibrillar proteins, whereas those for mitochondrial/sarcoplasmic proteins are not.



    Our results are similar in that AMPK phosphorylation was elevated immediately after exercise, but returned to baseline within 4 h post exercise. In contrast to previous reports (Coffey et al., 2006), we found that 10 wk of training was insufficient to blunt the exercise stimulation of AMPK activity seen in athletes who had trained in their respective disciplines for years.
     
  3. FullDeplex

    FullDeplex New Member

    <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Resistance exercise training stimulates mixed MPS at rest and after an acute bout of resistance exercise (Phillips et al., 1999; Phillips et al., 2002; Kim et al., 2005). Those studies have also shown that resistance training attenuates the acute post exercise increase of mixed MPS to the same relative exercise intensity (Phillips et al., 1999; Phillips et al., 2002; Kim et al., 2005). We did not find an attenuation of myofibrillar protein synthesis after 10 wk of resistance exercise training. (there goes that theory out the window)</div>
    Call me stupid, but exactly which theory goes out of the window and why. I have an idea about which theory you mean, but I am not sure.
    Please explain...
     

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