Re: Re:
acoggan said:
VT is determined based on measuring respiratory gas exchange, not by obtaining blood and measuring lactate concentrations. In a heterogeneous sample, it would be correlated with OBLA, but on an individual basis, could be higher or lower by 5% or even more.
I understand that, but it still refers to a point on the lactate curve. It's one of several methods for estimating or defining sustained power or oxygen utilization.
Can you provide a link to a study in which power at VT was 5% higher than at OBLA for some individual? In a study of 28 "elite cyclists" (about half of them pros, including some who had won races), no significant difference between power at VT2 (which I assume is the VT referred to in the 2007 report) and OBLA was found, but the mean power associated with the OBLA values was actually about 7% higher than the mean for VT2. Again, not familiar with all the literature here, and this is only one study, but it suggests to me that it would be relatively rare to find an individual elite cyclist with sustained power at VT2 5% higher than that as determined at OBLA. Based on this study, at least, it would seem that the 2007 reported power would more likely to be underestimated, not overestimated, relative to the 2015 power.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1756168/pdf/v033p00178.pdf
Speaking specifically to Froome's data, based on the data reported it is unlikely that his sustainable power was higher that 420 W in 2007, whereas it possible it was higher than 419 W in 2015. This is because the true metabolic control limit is unlikely to be above VT, but in trained male cyclists is often above OBLA. Given the apples-to-oranges nature of such comparisons as well as the fact that both VT and OBLA are only predictors of performance, no real conclusions can be drawn.
This is very interesting and relevant to the discussion if true. I wish you had posted it before. But the article I cited seems to contradict this. The mean sustained power at OBLA was higher than the mean power at VT2. The difference was not significant, but the point is, if the mean for OBLA for the group was at all higher than the mean for VT, then some of the individual cyclists, most likely a majority, must have had a higher power at OBLA than at VT2.
I could understand saying it's possible Froome's sustained power, measured consistently in the two years, was actually significantly greater in 2015 than in 2007. It's not something that can be conclusively ruled out. But it seems more likely that if anything, the reverse would be the case. The fact that peak power was also higher also supports this, even if we don't know exactly how the latter was measured in 2007.
Well to start with you, just a few posts ago you seemed to be arguing that Froome's sustainable power was A) known, and B) hadn't increased, when in fact you seemed to be unaware of how VT was even determined.
This exchange started when I responded to your assertion that there was no direct measurement of sustained power in 2007. There clearly was. I am aware of the different ways that sustainability can be defined, I was not aware that the differences in power at these various levels were very significant, and as both you and the paper I cited above in this post indicate, they apparently aren't at a population level.
I can appreciate that they may differ significantly for any particular individual. But as I just pointed out, the evidence of at least one paper is in the opposite direction that you indicate. Moreover, given that 1) Swart himself never pointed out that VT2 and OBLA shouldn't be compared for a particular individual; 2) the entire thrust of the discussion following the study was that Froome's absolute power was just as great in 2007 as in 2015; and 3) AFAIK, you never publicly called him on that, I think I can be forgiven for that. I assumed that I could take Swart at his word, and that if you didn't challenge his word, you also wouldn't challenge my repeating his word.
I'm now frankly very surprised you haven't been more critical of Swart. In recent podcasts that were linked upthread, he now backs away from his original claim that it was mostly weight loss, and suggests multiple factors underlying Froome's improvement, including schisto, better technique, and being the team leader. Unless I missed it though, he never says that there could have been a 5% or more improvement in sustainable power, not even as a possibility that can't yet be ruled out. Or if I possibly did miss that, I'm really sure he didn't say that the VT method in 2007 is a good reason for believing this.
Then there's The Hog, who thinks that a patch used to collect sweat is an ECG electrode, and attempts to impugn Swart by implying that he was lying that maximum heart rate wasn't available due to problems with a Polar-like chest strap.
There's also sniper, who attempted to imply that A) I am somehow associated with Mark Burnley, and B) I/we had something to do with the acceptance of Coyle's paper on Armstrong by JAP, seemingly not knowing (or caring) about the actual timeline of events, or even the limited role that members of the editorial boards play at scientific journals.
But these have nothing at all to do with questions about interpretations of sustainable power. I was responding to this:
Now I have no idea of whether that happened [Froome's sustainable power increased from 2007-15], and if so, how he might have achieved it, but the point is that there is a lot of ill-informed speculation in this thread.
I still haven't seen any ill-informed speculation on a possible power increase, except that Swart apparently conflated VT with OBLA without cautioning anyone on this, and no one called him on this through all the subsequent media discussion until I took him at his word, and only then you brought up possible individual differences. But I'm also not convinced, based on the article above, that the conflation is such a serious one.