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Re: Evidence for benefit of resistance training on mtDNA [was: Re: Association between muscular strength and mortality]

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  • Paul Wakfer
    ... It is important to point out that even if fully verified to be true, this reduction of the proportion of mutant (incorrectly functioning) mtDNA would only
    Message 1 of 2 , May 27, 2009
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      On 05/21/2009 10:08 PM, Steve C. Floyd Jr. wrote:
      > Meta
      > Erich and Paul's discussion on Erich's reference to the study below, as
      > well as the coincidence that I happened across a study that I will refer
      > to, together, motivated me to send this message. I am working on several
      > other projects at this time, so I am not prepared to fully comment on
      > Paul's comments to Erich, so I will not do so at this time. However, I
      > wanted to bring this to Paul and Erich's (and the group's) attention,
      > since it is a recent topic of interest at this group. Also, I leave
      > Paul's comments below because they are related to the topic of this
      > message: possible salubrious effect of strength/resistance training.
      > /Meta
      >
      > Hello everyone,
      >
      > I ran across a study, referred to at fightaging.org, that discusses the
      > possibility of resistance training improving mitochondrial DNA (mtDNA).
      > More specifically, the paper discusses the possibility that satellite
      > cells (a type of adult stem cell related to muscle cells) are induced to
      > repair a muscle cell in the even that the muscle cell is damaged (i.e.
      > through resistance training). It is postulated that during this repair
      > process, the proportion of mutant mtDNA to wild-type mtDNA is improved
      > (made smaller).
      >
      > [For those who do not know - "wild-type" is a biological term
      > essentially meaning "normal", in the sense of non-mutated and
      > non-dysfunctional. --Paul]
      >
      > This article also states that this positive effect is
      > expected to be of the most benefit to older individuals whom have
      > accumulated a large proportion of mutant mtDNA than younger individuals.

      It is important to point out that even if fully verified to be true,
      this reduction of the proportion of mutant (incorrectly functioning)
      mtDNA would only occur in muscle cells and would only indirectly help
      the human body. However, this would be an argument against my suggestion
      that more muscle tissue is simply more tissue that could become
      cancerous, and would be reason why it seems that cancer rarely if ever
      occurs in the muscles. OTOH, my argument about the excess workload on
      the rest of the body tissues to support these large muscles would still
      apply.

      > Here is the link to the full-text paper:
      >
      > "Mitochondrial DNA shifting in older adults following resistance
      > exercise training": http://tinyurl.com/ojsots
      >
      > After reading this paper, the first question I had was: "is there a
      > limit to the number of satellite cells?" I would be concerned with this
      > because I understand some adult stem cells to come from a limited pool.
      > If satellite cells were to also be naturally limited over one's
      > lifetime, it would be wise to wait until one is older to engage in a
      > resistance training regiment designed to reduce mutant mtDNA
      > populations. To help answer this question I found the following
      > literature review: "Satellite Cell Self-Renewal". I do not know if this
      > is publicly-accessible or not, so I uploaded the full-text .pdf file to
      > this group. Note that this article has the name
      > "SatelliteCellSelfRenewal2006.pdf".
      >
      > After considering this article, it seems that satellite cells are *not*
      > limited, in that they renew their population during the repair process
      > initiated by resistance exercise. I will be further considering this point.

      All stem cells, by definition, renew themselves by an asymmetric
      division process in which one daughter cell is again a stem cell and the
      other is at least a little specialized toward the kind of tissue that
      the stem cell is supplying. However, the term "limited" is only
      relative. Even stem cells are not going to be able to divide in any
      truly unlimited extent. Errors in DNA replication and other types of
      dysfunction will necessarily occur over time even in the daughter stem
      cells.

      Meta
      I decided to remove the rest so that this becomes a different branch of
      the thread.
      My original response is still open for response directly to it.
      /Meta

      --Paul
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