I read this over on timetriallingforum.
Very entertaining. http://www.timetriallingforum.co.uk/....php?showtopic=98754
This is a cross-post from Wattage Groups by Nathan Townsend. I thought, in light of some postings on the forum thus far it would make for interesting reading:-
A 30min TT is closer to threshold than a 60min TT
Long winded rant here but with plenty of interesting up to date science. Continue only if you have an open mind and wish to learn and understand about how to train with power....
I'm not going to waste any time whatsoever arguing any of this with Andrew Coggan, but the evidence is clear, 60min for the average trained cyclist is too long and is thus an underestimate of the power at which a true non-steady state metabolism emerges (at a rate which is meaningful for training). Most people cannot maintain threshold power for that long. There is always human variability though so some of you will be able to maintain a true threshold for that long, but the average trained cyclist no.
So by all means do a 20min TT and then estimate your FTP which is itself is an underestimate of threshold and then pretend that when you do medium or long intervals slightly above this power that you are in fact depleting your "FRC". Whilst W' and W'balance are considered to be representative of mechanisms that contribute to peripheral muscle fatigue and there is plenty of evidence to support this, I don't know what FRC is supposed to represent because there is not a shred of science on this made up variable, but what the evidence does tell us is that it probably isn't related to peripheral muscle fatigue (see attached study by Thomas et al).
There are many studies using a wide variety of experimental techniques which lead to these conclusions. In particular, as mentioned in another thread, the fundamental nature of the VO2 slow component means that mammals cannot commence exercising at threshold power and expect to be able to maintain this power for 60min, because the VO2 slow component occurs earlier than this ie: you start to fatigue earlier. Thus, you must either commence at a power output BELOW threshold and then as you fatigue you reach a power which is sustainable for a longer duration, or you commence at threshold, then as you fatigue, you gradually drop the power so that you're always on your threshold. It should come as no surprise that this is exactly how both Brandle and Dennis paced their successful hour record attempts, and is a fairly typical power profile of 40km TTs.
Here are two very recent articles (ie: current April edition of ESSR) which provide commentary on the VO2sc and its relevance to human performance.....
The Critical Power Framework Provides Novel Insights Into Fatigue Mechanisms http://journals.lww....es_Novel.1.aspx
In particular note the following statement "for many years the VO2 slow component was ignored tacitly because it did not fit with muscle energetics models". It looks pretty obvious that the good Dr Coggan continues to ignore the relevance of the VO2sc and is thus leading all of you down the garden path with this "FRC" non-scientific garbage.
Skeletal Muscle Fatigue and Decreased Efficiency: Two Sides of the Same Coin? http://journals.lww....ciency__.3.aspx
Also, I've uploaded a very interesting study already known to this forum that contains strong evidence in favor of everything that I've written here on this topic over the past couple of years, yet nothing in favor of the broscience that Coggan continues to carry on with in his perpetual state of scientific denial and/or ignorance....
Central and Peripheral Fatigue in Male Cyclists after 4-, 20-, and 40-km Time Trials. http://www.ncbi.nlm....pubmed/25051388
Look at the results carefully:
-Average time for 20km TT = 31min, 40km TT = 65min
-Mean (SD) power for 20km TT = 279 (22); 40km TT = 255 (21) W.
So on average about 24W difference there. That isn't quite meaningless is it?
-In the 20km TT the average RER is 0.96. How is this possible if a 30min effort is above threshold? It is not possible. If you are above threshold then the RER must be above 1.0. (I conducted many 30min TTs on elite cyclists, including Cadel Evans when I was a grad student in the AIS physiology lab in Canberra. Using gold standard metcart equipment, usually these elite cyclists could hold right on 1.0, but not once did I see a cyclist hold a higher RER than 1.01-1.02 nor did I ever see that value steadily increasing until the last 5min or so. If FTP is closer to a 60min max effort, then 30min must be above threshold. So why doesn't RER keep increasing even for elite performers? The answer is simple. a 30min TT is not above threshold, therefore approx 60min is lower than threshold and so Coggan is wrong).
-In the 4km TT the subjects achieve a significantly greater level of peripheral fatigue than either the 20km or 40km TT but there is NO DIFFERENCE between the 20km and 40km TT. If a 20km TT is above threshold, then by definition you must be depleting "FRC". If FRC is supposed to be conceptually equivalent to W', which itself is closely related to the mechanisms which underpin peripheral muscle fatigue (see above review by Grassi et al), then what we should see is a difference in the level of peripheral fatigue between the 20km and 40km TT, but there isn't. Why? because the 20km TT is not being performed above threshold and there is little or no difference in depletion of FRC/W' between the two. Ergo FRC/W' is not depleting any faster in the 20km TT than it is for the 40km TT which is impossible in reality (but only possible in Coggan's alternate reality).
-Look at the lactate values (not including the final end spurt values). According to an arbitrary definition of MLSS in the 20km TT the average subject would be above MLSS. Can ANYONE honestly look at that figure and say that lactate has not attained a near steady state but instead is continuously increasing?
-In both the 20km and 40km TT the magnitude of central fatigue is about the same, and in both cases it is greater than for the 4km TT. What this tells us is that over these longer durations such as 30-60min, a contributing factor as to why an average trained cyclist adopts a lower power than their true threshold, is because we experience an additional component of central fatigue that has less effect over shorter durations.
Overall, this study is highly revealing and informative. If we could do a follow up study then a good option would be to repeat the experimental techniques and on separate days do TTs over the following durations 10min, 15min, 20min, 25min and 30min. We know that by the time you arrive at 30min, the level of peripheral fatigue has dropped and central has increased. Even in the 20km and 40km TTs I suspect the level of peripheral fatigue becomes magnified in the last 5min or so as subjects raise the power above threshold and properly start depleting W'. So for example this could be controlled for by simply instructing the subject to maintain the power constant (at whatever it is over the predecing 5min or so) until the end.
So there is a lot of criticism here, not of Andrew Coggan himself, but of his biased opinions and lack of scientific rigour. I do not have anything personal against him, but the fact is that the science does not agree with his belief that the original definition of FTP (as stated in his book TARWAPM ie: approx one hour max power) is equivalent to the true maximal intensity at which the physiological mechanisms underlying the threshold phenomenon occur at. The lay cycling world is being led astray due to an incorrect and corrupted presentation of the true science which continue to to be developed throughout the scientific literature. However since blogs and non-peer reviewed books such as TARWAPM are more easily accessible and understandable to the lay public than peer reviewed journals, the incorrect version becomes accepted as de facto evidence and people believe it.
Lastly, whether or not any of this makes a difference to the way people train is irrelevant. It might not make any difference whatsoever to many people, however it does make a difference to factual validity which some people might consider important. Personally I know that if I want to conduct intervals which develop a higher level of peripheral fatigue, then I cannot assume my FTP is the correct boundary. I choose a higher intensity and do my intervals above that. Numerous studies in the literature indicate somewhere in the range of a 20-30MMP is probably a good choice, longer if you are better trained.
Why people conduct a performance measure eg: a 20min TT, and then make some arbitrary correction factor which has an unknown level of error eg: 95% to estimate something which is an estimate of something else, none of which has a scrap of scientific scrutiny to validate the hypothesis, is beyond me. By all means, keep it for your PMC, but when it comes to planning interval training and knowing whether your threshold power has improved, throw that 95% correction factor out the window because you've already got the hard untouched raw data in your hands.
Don't expect me to reply to a continuous stream of ignorant denial because the science is there published in print. If people need further clarification then they should read the science because I'm too busy to spend all my days on this forum. Enjoy and good luck everyone with your training and racing.P