Tara

ps418- Thanks for the great post.

I do understand that a whole slew of factors contribute to the level of performance an athlete realizes, genetics being only part of the equation. But as I see it, genetics are the limiting factor; they set the upper limit for performance potential. Of course, most of us never come close to realizing all of our genetic potential. But the fact remains that despite how hard and smart we train, some of us are just far better suited for running, for example, than others. It becomes apparent within a few years of training certainly, whether a runner has any potential to turn out “competitive” times and this would be mainly because of genetics I'd think. http://www.drlenkravitz.com/Articles/genetics.html

Another quote same source, backing the limiting role of genes...
http://www.drlenkravitz.com/Articles/genetics.html

But of course, from the same source, the fact that training is essential to “unlock” potential is not denied:

I see how Greg Ward’s "beyond endowment" stance could be interpreted as only poor wording from some of his writings, but I believe he gradually lessened his stance to the more reasonable. He was also very wrongly, for reasons unbeknownst to me, assuming, that I was of the position that genetics are everything, and environment/training plays no role. I know far better than that, I assure! I made statements recognizing that a person with the genetic potential to be an Olympian, who only trains half-heartedly or not at all, will obviously realize very little of his potential.

An early quote of Greg’s:
I agree with some of his writing above, that genetics are a framework and a critical component (indeed, they’re a limiting component) but I certainly don't agree with the notion of it being possible to go beyond genetics. As Ps148, makes clear that is obviously NOT possible and it does seem to me this was what he was espousing. It also seems silly to me to say genetics are “half or slightly more of the equation”; it can hardly be quantified like that, can it?

Whatever, I'm not convinced he really knows that well what he's talking about. Which is a little scary noting his Princeton alumni email address and knowledge that he has a masters in exercise phys. But maybe he knows his stuff more than I give him credit for.

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On a last note, back to muscle fibres. I’m a little confused about muscle fiber type proportions and to what extent they are genetically determined. From that same article, this is the simplistic explanation I understood:

But in the first of Psi’s references and from an actual scientific journal (!) which is undoubtedly a better source than my article (is non-journal quoting even permited on this board?):

40% phenotype variance due to environmental factors? I thought type I to type II muscle fiber proportion was genetically dictated, hence why some athletes are clearly sprinters and others are more endurance/distance runners and it is only possible to make both fast twitch and slow twitch fibers more oxidative; the proportion, save some of that hybridization of fast twitch to slower fast twitch (but still fast twitch nonetheless), is genetically endowed. I understand the size of fibers is changed by training it that what accounts for the environmental influence on fiber type proportion?

I’m a little confused…

ps418

As best as I can tell, the article's statement that "Strength or endurance training can not change these proportions (of fast to slow twitch muscle)", is incorrect. The Pette (2002) review article states:

Pette is the same author whose earlier work (1990) is cited in the "Genetics" article to the effect that the proportions of fast twitch/slow twitch are not influenced by training.

So, some fast-slow fiber transitions seem to occur, though the total number of muscle fibers is probably set at birth. Also, just because a portion of variance in a trait is environmental in origin doesn't necessarily mean that it is altered by training. For instance, a feature could be subject to environmental influences prenatally, but not postnatally. For such a feature, there could be substantial environmental variance yet little or no response to training. I dont know if thats the case with muscle fiber type, though.

Patrick

Tara

Okay thanks, pretty clear now.

It seems like I've heard this view: "Strength or endurance training can not change these proportions (of fast to slow twitch muscle)" numerous times. But I guess it's really not accurate.

Science.... always changing

Wounded King

Dear Godot,

I suppose it depends how specific you feel fields are in research. I have worked on the development of muscle but I wouldn't consider that the topic under discussion was my field of research.

Perhaps you are a biochemist and make the assumption that exercise biochemistry should subsume any exercise related area of biology (damned boichemists, mutter, mutter). I would tend to draw a distinction between exercise biochemistry and differential gene expression induced by exercise/electrical stimulation.

TTFN,

Wounded

Tara

I was going to try to get him (or her) to expand on this... anyone interested in mitochondrial biogenesis? I wouldn't expect anyone to be keen on giving up their anonymity on that message board, it's hardly a civil atmosphere.

What fields are you (any of you) in, if you don't mind me asking?

Godot

Tara,
I too would be interested in learning more about mitochondrial biogenesis. We only covered it *very* briefly in my undergrad. I, for one, am a nutritionist presently working on a masters degree at the University of Canberra while my undergrad was in kinesiology at the University of Calgary.

Wounded King,
biochemistry and I don't have the greatest of relationships. I was more into the exercise physiology (at somewhat of a more macro level) and am moving towards epidemiology/population health. I would assume, however, a certain degree of generalist knowledge regardless of the specificity of your professed field.

Wounded King

All well and good, but why do you assume a highwire or pubmed search for the posters supervisor would turn up relevant papers, if the poster doesnt work in the relevant field?

And whats wrong with anonymity on the internet?

Tara

http://www.letsrun.com/forum/flat_re...&thread=117514mitochondrial biogenesis

All I have to say re: mitochondrial biogenesis as of now is: ?

Tara

hrm... you wouldn't think HTML would prove such a challenge.

mitochondrial biogenesis

Godot

To the former: it's a shot in the dark. Whatever papers that turned up may have shed a bit more light on this issue, that's all. The poster included the tidbit about his qualification and supervisor to lend credence to his argument (not that it really needed it). What need was there to include this information if it wasn't somehow relevant (even tangentially)?
To the latter: generally speaking, nothing. The biggest knock against it is simply that things may not be as they appear. Most everything we know about netfriends is taken on faith and cannot be substantiated without a great deal of effort.