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New York Times Julie Macur doesn't seem like a fangirl to me

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buckwheat

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Le breton said:
Quote:
Originally Posted by Le breton
You lost me again.
Where did I do that analysis of physiology?
I know I have irritated some people sometimes with my simplistic views of physiology, but you were not around at the time.



Of course not.
I just calculated how much power is needed to do the climb under the stated conditions.

I said NOTHING about where the power came from. It could as well be from an electrical motor + battery hidden in the frame, would not change the result.

I also added that I might do some physiological interpretation later if I feel like it and at a considerably greater risk of making mistakes.

Oh ok, I was responding very generally to the back and forth here so I may have gotten crossed up.
 
Mar 18, 2009
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buckwheat said:
"Efficiency" is used as a catch all for things that are not very well understood.

Perhaps to a non-scientist such as yourself, but those who deal with energetics (engineers, physicists, physiologists, etc.) define, and have always defined efficiency in the thermodynamic sense, i.e., as energy out/energy in x 100%.
 
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Tubeless said:
Ok, using the "Peronnet et al" table, at 7,300 feet you'll have 91.75% of the sea-level equivalent aerobic power available. Hence Merckx's 6.2 W/kg at sea level would equate to 5.69 W/kg at that altitude. Not quite the 5.9 you referred to. Close enough for you?

It is certainly a more reasonable estimate than what you initially came up with by ignoring the curvilinear nature of oxyhemoglobin dissociation curve. Whether it is very close, though, is impossible to really say, as different individuals are impacted differently by altitude (which likely explains the difference between Bassett et al.'s and Peronnet et al.'s equations).

Tubeless said:
Using the same table to traspose Mercx's sea level performance to Alpe d'Huez altitude (using an altitude average of 4,200 feet - 95.6% of sea level aerobic power available), would yield 5.93 W/kg. Compare that to Armstrong's 6.75 W/kg - is Armstrong able to produce 14% more power than the greatest (clean) cyclist ever? Plausible? Or errors in the math somewhere along the line?

You left out the possiblity of errors in the initial assumptions.
 

buckwheat

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acoggan said:
Perhaps to a non-scientist such as yourself, but those who deal with energetics (engineers, physicists, physiologists, etc.) define, and have always defined efficiency in the thermodynamic sense, i.e., as energy out/energy in x 100%.



1)Conservation of energy is not a description of a mechanism.

http://jap.physiology.org/cgi/content/full/105/3/1021

Gore et al. (4) concluded that "there exists no credible evidence to support Coyle's conclusion that Armstrong's muscle efficiency improved." This is based erroneously on their argument that the calculation used for delta efficiency is without merit. It also assumes, incorrectly, that gross mechanical efficiency provides no information related to muscle function. Granted, delta efficiency has conceptual advantages over gross efficiency, which is the main theoretical point made by Gaesser and Brooks in 1975 (3). However, Gaesser and Brooks (3) did not provide data indicating that gross efficiency provides no information about muscle efficiency but instead indicate that much variability is experienced, given their low work rates. More recently, we directly measured muscle fiber composition in cyclists and reported that the percentage of type I fibers was significantly correlated with "both" gross and delta efficiency (2, 6). This provides evidence, which has been verified by others (5, 7), that gross efficiency is indeed related to muscle fiber composition and mechanical properties.

I don't know that Gore et. al. were making the assumptions Coyle says they're making. I also don't think improved muscular efficiency, is as intuitive after years of training as some would have us believe. I think it's actually more, wishful thinking.

a)It is a mathematical principal.

b)Energy is an abstract numerical quantity.
 

buckwheat

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http://jap.physiology.org/cgi/content/full/105/3/1020

Using the correct equation, we recalculated Armstrong's DE as 23.55% in January 1993 (23.02% if the 2-min stage is included), which exceeds the 23.12% value for the final test in November 1999. This is 8% higher than the reported value of 21.75%. The magnitude of this error warrants recalculation of the entire data set, but raw data from the remaining test sessions are not available from the author.

In conclusion, all of the published delta efficiency values are wrong. Thus there exists no credible evidence to support Coyle's conclusion that Armstrong's muscle efficiency improved.
 
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acoggan said:
Well there you go.



I'd do what any non-suicidal person would do: I'd lie and claim to be absolutely certain that he either did or did not, depending on my best guess as to what the person wanted to hear.

Short of that scenario, I am complete agnostic on the issue.

Andy, while I`ve absalutly no doupt you would tottaly lose me on the science what I find intersting is that on the subjective " best guess" question you refuse to be drawn citing "its not important to me personaly" .
If its not important then theres no harm in saying what you think to what you consider a hypothetical question anyway.
As a scientist its part of your duty to speculate cus if you didnt then your view of science is that of a been counter and not a discoverer.
More accountant than adventurer eh?
 
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buckwheat said:
http://jap.physiology.org/cgi/content/full/105/3/1020

Using the correct equation, we recalculated Armstrong's DE as 23.55% in January 1993 (23.02% if the 2-min stage is included), which exceeds the 23.12% value for the final test in November 1999. This is 8% higher than the reported value of 21.75%. The magnitude of this error warrants recalculation of the entire data set, but raw data from the remaining test sessions are not available from the author.

To reiterate: it is incorrect to compare, as Ashenden et al., did, delta efficiency values calculated using two different (but equally valid) approachs. Dave Martin, a coauthor on that letter, has admitted this to be true.

buckwheat said:
http://jap.physiology.org/cgi/content/full/105/3/1020In conclusion, all of the published delta efficiency values are wrong. Thus there exists no credible evidence to support Coyle's conclusion that Armstrong's muscle efficiency improved.

The "credible evidence" is that VO2 at a given power decreased over time, and the magnitude of the change is such that it can only be explained by a reduction in O2 uptake by exercising muscle. Ergo, as along as the raw data - i.e., VO2 and power measurements - are correct, so, too, is Coyle's conclusion that Armstrong's muscle efficiency improved - the fact that Coyle did not calculate delta efficiency exactly as described in the paper he cited, but used an alternative, but nonetheless equally valid, approach is irrelevant in this regard.
 
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buckwheat said:
1)Conservation of energy is not a description of a mechanism.

No one said that it was. I was merely pointing out to you the proper definition of efficiency to use in this context, since you didn't appear to know it.

http://jap.physiology.org/cgi/content/full/105/3/1021

buckwheat said:
Gore et al. (4) concluded that "there exists no credible evidence to support Coyle's conclusion that Armstrong's muscle efficiency improved." This is based erroneously on their argument that the calculation used for delta efficiency is without merit. It also assumes, incorrectly, that gross mechanical efficiency provides no information related to muscle function. Granted, delta efficiency has conceptual advantages over gross efficiency, which is the main theoretical point made by Gaesser and Brooks in 1975 (3). However, Gaesser and Brooks (3) did not provide data indicating that gross efficiency provides no information about muscle efficiency but instead indicate that much variability is experienced, given their low work rates. More recently, we directly measured muscle fiber composition in cyclists and reported that the percentage of type I fibers was significantly correlated with "both" gross and delta efficiency (2, 6). This provides evidence, which has been verified by others (5, 7), that gross efficiency is indeed related to muscle fiber composition and mechanical properties.

I don't know that Gore et. al. were making the assumptions Coyle says they're making.

Said assumption is implicit in the fact that they focussed on the calculation of delta efficiency, and completely ignored the fact that VO2 at a given power decreased over time, and by too large of an extent to be explained by anything other than a reduction in muscle O2 uptake, i.e., an increase in muscle efficiency (or experimental error, of course).

buckwheat said:
I also don't think improved muscular efficiency, is as intuitive after years of training as some would have us believe.

I suggest that you go educate yourself on changes in motor unit organization/myosin expression as a function of development/aging and also training, as then perhaps you will understand why changes in muscle efficiency are in fact to be expected.
 

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