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The Tour on the horizon
The Tour de France - three weeks of drama awaits
Despite all the focus on the World Cup, it has not escaped our attention that one of the highlights of the sports year starts in a matter of days. On Saturday, 20 teams of 9 riders each will start a three-week tour around Holland and then France in what is usually described as one of the most difficult tests of sporting performance in the world.
This year's Tour has been designed to be filled with drama. Every stage is always vital, but with the cobbles of Arenberg awaiting on only the third stage, plus two trips up the Col du Tormalet, numerous mountain top finishes, only one individual time-trial (excluding Saturday's 8.9km prologue in Rotterdam), and numerous other challenges, 2010 should produce GC drama throughout. Check out Cyclingnews.com for an overview of the Tour stages.
Scientific analysis of the race
The other reason why the Tour is so great to follow is that it lends itself to science and analysis. Of strategy, of physiology, of performance. In the last two years, we've tried to add some insight into the race here at The Science of Sport, and we'll certainly aim to do the same in 2010. The measurement of power output opens up a world of discussion, comparison and prediction that inspired some great debate last year.
To refresh your memory, last year there was some great discussion over analysis that was done on the climbing performances on the Verbier, where Alberto Contador laid the foundations for his overall victory. We first analysed the climb, then compared Contador's performance (in vertical ascending meters or VAMs - admittedly, an imprecise measure) to other climbs in Tour history.
And then, Antoine Vayer was quoted as having calculated that Contador's performance predicted a VO2max of 99.5ml/kg/min, which is of course very unlikely, and led to debates around whether it was an "unphysiological" performance. That formed the basis for another lively discussion.
So the Tour equals analysis, and analysis always leads to discussion. This year should be no different, and we're looking forward to having you along for the next three weeks.
Performance as a means to identify doping
It's early days yet, and who knows where the race will go. But the analysis of performance lends itself to a very interesting discussion around whether a cyclist is doping or not.
And so to get the ball rolling, here is an interesting article that came out in New Scientist today, called "Superhuman performance could betray sport drug cheats". I know it because I'm quoted in it and helped with some of the analysis. The basic premise is this - in order to produce a certain power output on a climb, you have to have a certain capacity to use oxygen. The work done has an oxygen cost, and this cost tells you a good deal about the "ceiling". If the climbing power output predicts a ludicrously high oxygen consumption, then you have a waving red flag.
It's not proof, but a very suspicious question mark. And I can assure you, the Tour is littered with question marks, from the 1990s up to perhaps last year. This year's Giro d'Italia, many of you have already noticed, has seen a substantial drop in power outputs on the climbs, and they are now "physiological" again.
If you read the New Scientist article, and feel a little under-informed and needing more detail, don't despair! I will definitely be covering this topic in much more detail in the coming weeks, explaining the method, the assumptions, the limitations and the implications. Analysing performance, and predicting physiology based on what we see!
However, I'm going to be as direct as possible right now and say the following:
A sustained (over 40 minutes) power output of greater than 6.2 W/kg at the end of a Tour stage is simply not physiologically believable, and is strongly suggestive of doping. In fact, anything above 6.0 W/kg is very, very suspect. Those are power outputs that are produced by riders who are doping, because the physiology required to drive that kind of performance, well, it just doesn't exist.
For the basis of that position, join us over the next few weeks!
Your input welcome
As always, we welcome any ideas, any questions, any data (if you have power output data for Tour riders, please send it). I know many reading this are close to the sport, and you will have insights that all of us will enjoy, so please, don't hold back!
Other than this, I'll do my best to keep the Science of Sport Twitter account going during the Tour - not to overwhelm you with tweets, but for those who can't watch, I'll try to give the crucial updates, and a few snippets of information. So please check us out on Twitter!
Who knows where the next three weeks will take us? But wherever it is, we'll try to cover it for you!
Ross
12 Comments:
looking forward to an explanation on the power output assumption and also examples of performances that are known to exceed it!
What would be the basis for saying, for example, that guys like Phelps and Bolt aren't doping, but a guy like Armstrong or Contador is? It seems they're all subjected to the same testing, so where do we draw the line between amazing performance and impossible performance if they all have clean tests?
A better discussion of this topic located here:
http://forum.cyclingnews.com/showthread.php?t=8395&page=2
9 watts per kilogram is possible!
To the last anonymous poster (7:58):
I'm afraid I looked for this "better discussion", but I just didn't find it. All I found were the occasional insult and bald assertions without reasonable backing.
For example, a paper on Marathon runners by Joyner is supposed to highlight the problems. It doesn't. All it does is repeat the very factors that I have already taken into account to draw my conclusions. SO nothing new there.
Then second issue around this 9W/kg is a great statement, very intriguing, but without any evidence at all. Coggan writes "based on what has been published in the scientific literature I can make the argument that an "hour power" of nearly 9 W/kg is physiologically plausible"
Well, where is this published literature? What studies support this?
It's simply not possible,unless the person has a cycling efficiency of about 35%, and is capable of cycling at their VO2max power for over an hour. Let me assure you, neither of those is possible. So 9W/kg is not possible.
If Coggan has this evidence, then I would love to discuss it, rather than have to deflect insults, destructive criticism and dismissals.
Ross
And then just further to my previous point, I would like to point out that I am not alone in this 6.2W/kg position:
http://www.cyclingnews.com/news/sassi-talks-about-basso-evans-and-the-zoncolan
To quote from the piece: "In the past Sassi has said that any value over 6.2w/kg for a long effort on a major climb at the end of a stage race could be an indication of doping."
And also, I believe Allan Lim has gone on record saying 6W/kg is a limit.
9W/kg - the stuff of Pixar movies.
Ross
I'm looking forward to future Tour posts. You guys do great work.
~Amanda
Ross,
I don't know why you feel that I insulted you by saying that I did not find the logic of the New Scientist article particularly impressive, but be that as it may:
over 9 W/kg is what you get when you combine the highest reported values for VO2max, % of VO2max sustained for 1 h, and efficiency. IOW, said estimate is directly comparable to the 1:5X marathon time that Mike calculated in his article. As I said at the outset when I put forth the figure, I don't really believe it - rather, my point in mentioning it was to emphasize just how much uncertainty there exists in such calculations (to the point that I think they are essentially irrelevant to any anti-doping efforts, especially since power is rarely directly measured).
Andy
Hello !
Thanks Ross for the always accurate and complete discussion of the topic. I think we should not forget what we are using the information for that we are modelling here: To TARGET athletes with other doping tests. And acknowledging a certain degree of uncertainty (a major factor being certainly the wind and/or the drag from cars and motorcycles in the climb), we can still get valuable information out of what we see. Especially if we compare the modelled data with "field data" from SRM measurements. I am sure we will get some SRM data during this years Tour on the Team Websites. So I am looking forward to see this comparison!!
Y.O. Schumacher
Hi Yorck
Thanks for the post! Great to hear from you - for those who don't know, Yorck is a good friend of the site and one of the key players in the biological passport in cycling. You can read an interview with him here:
http://www.sportsscientists.com/2009/08/doping-control-interview-with-prof.html
And to respond, yes, absolutely. This exercise, and the one in the next post, is never intended to catch anyone, or prove anything, only to identify "flags", precisely because of the error, which we must always acknowledge!
I certainly hope that we see plenty of SRM data during the Tour, and we'll certainly do our best to give some thoughts on it!
Regards
Ross
the big problem with all these type of debates is that even if the calculations used are reasonably accurate models of the physiological processes and forces involved. They are still estimates for the large part, compounded by complete estimates/guesses to do with terrain, weather, actual rider and bike weight , tire pressure rolling resistance, draft from other riders...... so while its all fun n all, and kicks up debates. it does end up in lots of pointed fingers based on really shakey back-of-napkin style maths. Not facts. Not science.
As always it comes down to if you dont have the actual data, you're just having an intellectual game. Not contributing anything to the fight (or even debate) against dope.
To Anonymous
I disagree - you're being too binary, too 'black and white'
First off, I only said about five times in the post that this does not constitute proof. And if you read the follow-up, then you will see that again, I emphasize this point over and over. I acknowledge the sources of error repeatedly.
As for shaky assumptions, they're not. Read the post after this and you'll realize that all the assumptions can be made to give every possible benefit to the rider, much like you would if you opened a business and had to assumed sales projections. You don't just suck it out of the air - you control the assumptions in order to limit the potential for false conclusions.
And that's done here. The estimation of power output is actually quite accurate - an error of 2.4% for this method, validated against SRM devices. So even with that size of error, the physiological implications of the performances are sometimes so outrageous that the difference between them and what is realistic is much higher than the error. Do you understand the implications of that?
There is a scientist by the name of Hans Rosling, and I guess he has probably had to deal with your kinds of accusations about 'back of napkin' science his whole career, but he does population studies and collects data from everywhere. He's always accused of having too much error in the data. But he understands the value of the data and that the size of the differences is larger than the size of the error, and therefore it's still valuable.
I believe this to be the same. As I have said (this is the tenth time at least), I agree that there is error and I agree that it is never proof. But if you control the assumptions and you are cautious with what you estimate, then you produce valuable science.
Please read the next post after this for more on that.
Ross
"The estimation of power output is actually quite accurate - an error of 2.4% for this method, validated against SRM devices."
Where does this accuracy level come from? A reference would be really helpful to me, or even a brief explanation of the unpublished source? I haven't seen anything (apart from one internet source with a single participant which was given to me by someone else) which compares power meter data with estimates, but this is not my area so I may be looking in the wrong places.
Have you covered this elsewhere?
Thanks!
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