- Jul 1, 2009
- 320
- 0
- 0
acoggan said:You give up too easily.![]()
acoggan said:And as I have said before:
1) you can't claim that Coyle's conclusion that Armstrong's power-to-mass increased in season as a result of weight loss is incorrect, because you don't know that Armstrong's self-reported body mass data are incorrect.
2) neither the gross nor the delta efficiency data have been shown to be in error - the only issue there is that Coyle calculated delta efficiency using a different, but nonetheless widely-accepted, method than described in the paper he cited.
acoggan said:Think what you like, but ask yourself this: if individuals like Ashenden, the former head of the IOC, etc., comported themselves more like, say, President Obamathan Rush Limbaugh
, would there be nearly as many discussions on the web such as this one?
acoggan said:Because the particular issue at hand is, what was Armstrong's power-to-mass when he won his multiple Tours? Since he never weighed Armstrong during that time, all he could do was ask him what he weighed.
acoggan said:A better way to put it would be "which is more likely - a small but nonetheless significant (from a competition perspective, anyway) improvement in the efficiency of someone who was only 20 y at the time of the initial measurements, or something not being controlled properly in five measurements conducted over a 7 period?"
Even phrased that way, I'd say that there is good reason to be concerned about the accuracy of the data. As I have repeatedly pointed out, however, Coyle's observation that efficiency tends to improve over time in highly-trained cyclists has since been confirmed in several more carefully-controlled, prospective studies.
elapid said:Again, this is just BS science. Coyle could not calculate Armstrong's in-season power-to-mass ratio because he had neither his in-season weight nor steady-state power. Why use an out-of-season power that was measured four months after the TdF and an estimated racing weight? As a respectable scientist, he should have used paired power and weight measurements and recorded rather than estimated body weights. Furthermore, what is the point of comparing an in-season power-to-weight ratio, regardless of how flawed Coyle's calculation was in this regard, to preseason power-to-weight ratios? No conclusion can be drawn from such a comparison because of immediate biases introduced by differences in weight and power in and out of season.
keen_but_slow said:I'm being harsh. Coyle did some experiments and reported his results in good faith and I'm not having a go at him (more the people who read too much into one study). I'm not a professional scientist, but I do have a mathematics degree, and I'd like to take you up on your use of the word "significant".
keen_but_slow said:What if, for example, a tired rider is less efficient (maybe they "pedal in squares")? Do we know what the standard deviation of efficiency is, when taking into account all the small (but hopefully independent) error terms in nutrition, equipment, climate, fatigue, time of year, recent racing programme, state of mind etc?
ggusta said:Strike 3. 3rd unnecessary injection of politics in 24 hours in the forums i read.
Oh brother....as overheated as the actual subject of the discussion is....can you please try and stick to it ? And if you're going to ATTEMPT to draw parallels, please consider using individuals that might be a little less ... shall we say ....subjective.
In my few years of cycling, I have never seen a bunch of people so uniquely eager to self-identify their political views and almost always in a ' this is right, anyone who sees differently is an a-hole' manner. Tasteless, pointless, counter productive and utterly BORING. It undermines your own credibility.
Nothing like going on a 200km with an MD who keeps dancing around politics until you get to the rest stop. And then....he pounces. After all, he's a doctor! Guess what, doc, I've forgotten more cr@p than you'll ever know. I just don't bore you with it.
Please stick to the subject.
All right, I feel better.
In my experience, the greater depth one must have in their field, ie, doctors, scientists, the less breadth they have about the world beyond that discipline since staying current in their field is so time consuming.
acoggan said:I was referring to their demeanors, not their actual political views.
Digger said:Originally Posted by Digger
Shame MA and others couldn't get their hands on Coyle's data records. The dog ate it I guess.
A Coggan last night in his reply to my above comment:
"Unless Coyle simply made up all the numbers, it wouldn't have made any difference".
ggusta said:The Ashenden interview pretty much settled it for me.
acoggan said:So you admit that I never commented on Coyle's statement that he lost much of the original data?
acoggan said:Again, I'm not sure that I follow. The efficiency measurements were made in the laboratory under (hopefully) carefully-standardized conditions, and are (or should be) quite reproducible. The assumption is that changes in efficiency measured under such conditions translate into changes in efficiency in competition, but until someone measures both power and VO2 in a large number of cyclists during races we don't really know for sure.
Digger said:Are you illiterate?
acoggan said:You are overlooking a key point: with the exception of the immediate post-chemotherapy measurements, Armstrong's VO2 at LT remained essentially constant at 4.5-4.7 L/min - all that changed over the time was the power to which this corresponded. Coyle's assumption was therefore that his in-season LT was comparable, such that he was justified in dividing by reported in-season body mass to arrive at his in-season power:mass. Whether that assumption is correct or not cannot be said, so you can't argue that this is a clear-cut mistake on his part.
(BTW, on my way home yesterday I thought of an interesting scenario: pretend that you are a scientist and one of your colleagues died before they had the chance to finish some potentially very interesting experiments, such that the results were left with a lot of holes. Would you try to make the best out of the situation that you could just to get the data out there, or would you dump it all in the circular file without even trying to write it up? Assuming that you took the former route, how would you feel A) if the paper were accepted, and B) if the paper were rejected?)
keen_but_slow said:Let me tell it by analogy.
Three science fellows go on a train journey to scotland, and they see a black goat in a field. "That's interesting, said the statistician, "the goats in scotland are black". "Not so" said the pure mathematician, "all we know is that there exists a black goat in scotland". "You're quite mistaken", said the physicist, "all we know is that there exists a goat in scotland whose face is black on one side".
Coyle's paper, to me, tells me something about how efficient one guy was, as measured by equipment which may or may not have been the same (or repaired, or worn, or not set up properly by the lab assistant), whilst he was in states of training, hydration and muscle fatigue which may or not have been the same, on isolated occasions many years apart, at different times of day at different times of the year. It's interesting, but for my standards .... well ... that's all it is .... <adjusts spectacles>
Sorry, I should get out more.
elapid said:I am not overlooking any key point. In-season weight was not measured, in-season steady-state power was not measured. Assuming that you can use a power measurement four months after an estimated body weight, which is wrong on some many levels, comparing an in-season power-to-weight ratio to previous preseason power-to-weight ratios is invalid. There are two key points there which you seem to be either overlooking or ignoring.
elapid said:In regards to your situation, which bears no resemblance to this scenario, it would firstly depend on whether I was involved or not in the research. If I was not involved, which would be the implication considering that Coyle was the sole author, then I would let it die. If I was involved, then I would try to fill the holes in and publish. If I couldn't fill the holes in and the holes were as glaring as Coyle's flawed methods, then no I would not publish. This paper should not define Coyle's work which is obviously substantial and presumably more rigorous and scientifically sound than this paper, but this is the paper that is the most public representation of his work. Personally, I would have been happy submitting this paper for publication but letting it rest on its laurels. I would not have included the estimated racing weight because this is the sole data which is both not measured and not paired with other data. If Coyle had stuck to the recorded data sets then all calculations and comparisons would have been appropriate and valid.
ScienceIsCool said:http://www.ncbi.nlm.nih.gov/pubmed/1549019
So, the accuracy of VO2 measurements is apparently ~ +/- 0.3 l/min, which is +/- 5% at 6 l/min. That means there's a +/- 5% error rate attached to any efficiency calculations. Love how Coyle reports VO2max to two sig figs... Heh. Unbelievable.
http://www.find-health-articles.com/rec_pub_19177315-accuracy-velotron-ergometer-srm-power-meter.htm
http://cat.inist.fr/?aModele=afficheN&cpsidt=2418760
The accuracy between individual measurements is expected to be +/- 1-3% based on which ergometer is being used and how the ergometer is being used. Also, a total error of ~10% can be expected when using the ergometer across the range of power measurements (i.e., increasing or decreasing workloads). This changes the slope of VO2 vs workload, n'est pas? I'd assume it's consistent for the exact same ergometer used under the exact same conditions - so this might be moot in Coyle's case if he documented the ergometer model and serial number.
However, if you add the errors up (i.e., make a competent error analysis) there's no way in hell, absent some calibration data, that Coyle could make any claims based on the data as presented. Total error in muscle efficiency measurements looks to be in the range of +/- 8%.
I really can't believe the low standards for test, measurement, and analysis are in the world of physiology. His paper is cited!? My god...
John Swanson
http://www.bikephysics.com
ScienceIsCool said:I found this to be fascinating, too: http://www.sportsci.org/encyc/drafts/VO2max.doc
Expect 4-7% error between successive measurements, of which only 1-2% of that is expected to be expermental variation.
On this point, you have confirmed that "unnamed grad" students have stated that different ergometers were used. So it is basically Ed's word against theirs. One has to ask the question though, why would they lie about something such as this and possibly bring about a professional misconduct suit? What do they have to gain from it so many years later? If the same ergos were used then one also has to ask the question, why would Ed refuse to provide the calibration records to the Aussies but instead provide a photo which proves nothing?acoggan said:That's not a bad analogy, but your 2nd paragraph above contains some questionable assertions/allusions:
1) Coyle has stated that the equipment remained the same and was in good repair throughout the period during which Armstrong was tested. Absent definitive evidence to the contrary (and an isolated pic of Armstrong on another ergometer is hardly definitive, since we don't know if any data collected during that session made it into the paper), all one can do is accept this statement at face value.
Quite the opposite in fact. Ed Coyle did make some, but not all, data available, but it most certainly did not provide any confidence in the measurements.acoggan said:2) Coyle had provided data regarding the reproducibility of the efficiency measurements made in his lab, thus providing at least some measure of confidence that the measurements are indeed correct.
Delta efficiency calculation in Tour de France champion is wrong
TO THE EDITOR: We previously raised concerns (6) about the methodology used to assess Lance Armstrong's muscle efficiency in the popular Journal of Applied Physiology paper entitled "Improved muscle efficiency displayed as Tour de France champion matures" (1). Subsequently, Coyle made available raw data from the January 1993 test that revealed several additional deviations from the published methodology. Coyle used a 20-min ergometer protocol (not 25 min), including 2- and 3-min stages where respiratory exchange ratios (RER) exceeded 1.00. An RER >1.00 invalidates use of the Lusk equations (5) to estimate energy expenditure.
A review of the raw data established that the published delta efficiency (DE) values in the Armstrong paper were calculated using the wrong equation. Coyle's published methodology (1) and that used by his group on several previous occasions (2, 4, 7) stipulates that linear regression (y = mx + b) be used to calculate DE, as the reciprocal of the slope from the relationship between the energy equivalent of oxygen uptake and cycling power output. However, Coyle calculated DE using the general formula 100 x (X x Y)/(X2). This calculation is equivalent to linear regression using y = mx, which forces the regression line through the origin. Resting metabolic rate (RMR) as well as the cost of cycling without load (including the variable cost of ventilation and circulation) mandate that the regression line used to calculate DE cannot pass through the origin.
In their benchmark paper, Gaesser and Brooks (3) argue that DE, as the first derivative of the increase in caloric cost of exercise with respect to ordered increases in work, is a "floating base-line" method. Hence it is essential that the regression is not forced through zero when calculating DE. By employing y = mx for each of the four data sets used to calculate DE, Coyle has assumed that Armstrong's RMR and cost of cycling without a load was not influenced by orchiectomy and chemotherapy, plus well-publicized weight fluctuations during the 7-year study.
Gross efficiency values reported by Coyle, which demonstrate an r = 0.999 correlation with his DE data, have been cogently dismissed by Gaesser and Brooks (3) as being of little value in understanding muscular efficiency. This interpretation is recognized by Coyle who notes on p. 2194 of his publication (1), "delta efficiency ... provides the best reflection of power production ... as it eliminates or minimizes the influence of the energy cost of unloaded cycling, ventilatory work, and other metabolic processes not directly linked to muscle power production."
Using the correct equation, we recalculated Armstrong's DE as 23.55%]
Gore et al (2008). Delta efficiency calculation in Tour de france champion is wrong. JAP 105: 1020.
Krebs cycle said:On this point, you have confirmed that "unnamed grad" students have stated that different ergometers were used.
Krebs cycle said:So it is basically Ed's word against theirs. One has to ask the question though, why would they lie about something such as this and possibly bring about a professional misconduct suit?
Krebs cycle said:If the same ergos were used then one also has to ask the question, why would Ed refuse to provide the calibration records to the Aussies but instead provide a photo which proves nothing?
Krebs cycle said:Quite the opposite in fact. Ed Coyle did make some, but not all, data available, but it most certainly did not provide any confidence in the measurements.
Krebs cycle said:The WRONG equation was used
Krebs cycle said:According to Gore et al. when you use the correct one it changes the results dramatically, in fact the re-calculated economy is remarkably similar in 1993 to the values reported in 1999.
Krebs cycle said:This is a result which is remarkably consistent with hordes of data (published and unpublished) that demonstrates cycling efficiency does not change markedly, and is also very similar between recreational and pro riders.
Krebs cycle said:None of this ever had anything to do with LA or doping