http://scienceofsport.blogspot.com/2007/11/effect-of-epo-on-performance-who.htmlWednesday, November 07, 2007
The effect of EPO on performance: Who wouldn't want to use it?
It's been a busy time for running posts here at the Science of Sport, with first the marathon world record in Berlin, the heat of the Chicago marathon and then the drama of the New York Marathon dominating our recent postings. And as offshoots of these events, we've covered a variety of interesting, relevant (and somewhat controversial) topics in our "series" over the last 6 weeks. We'll return to that theme next week, when we'll look at muscle cramps and electrolytes in a little more detail.
But until then, we thought we'd do a more general week, posting on a variety of interesting articles related to sports. And to begin with, we thought we'd return to another controversial topic - drug use in sport (read cycling!) That's harsh on the sport, I admit, but I saw an interview with Pat McQuaide on BBC recently (HardTalk), where he denied that cycling had a problem with doping. Quite frankly, if that is their attitude, then they deserve to have all the sponsors withdraw and media coverage of their events pulled.
Around the time of the Tour de France this year, we featured a number of posts on drug use. We looked at the history of doping in the sport, evidence of the effectiveness of drugs, and then of course, the Tour came along and gave us plenty to write about! Rasmussen, Vinokourov, etc! Cycling seems to deliver on controversy without fail! (You can find the links to these articles below)
A clean winner vs. a dirty 'loser': Can an athlete win without doping?
It was pretty clear around that time that one of the main problems with the argument that doping was rife in the sport was the fact that very few studies have even evaluated the effect of drugs on performance. There is a remarkable scarcity of data around the effects of doping on performance. It has often been argued that if "one cyclist is using, then they must all be using". There are some flaws in that thinking, for sure, but it does raise the interesting question that if the guys who are finishing middle of the pack, and losing by minutes on a climb or time-trial, are found to be using drugs, then how does the athelte who WINS the race do so clean?
The answer must be that:
* Either the drugs are not that effective, and so the riders using them are gaining little or no benefit anyway (if this was true, then one has to wonder why drug use is still prevalent - you just KNOW it's not the case), or;
* The winner is so vastly physiologically superior without drugs that he overcomes whatever benefit the drug provides to his rivals. If this is the case, then the natural, physiological differences between a "clean winner" and "dirty loser" must be greater than the improvement provided by doping
Either way, we need to know just how much drugs improve performance. And that is what today's post is about...
Evidence for the effect of drugs on performance
In previous posts, we've looked at the data from the East German doping "machine" published by Franke & Berendonk in 1997 in Clinical Chemistry, looked at the effect of a steroid programme on performance. That paper showed a great example of how a 'mediocre' shot-put athlete became a world record holder, driven on by a 17% improvement in ONE season
But, that was steroids, not the most widely used drugs in cycling, though they are certainly used, if the tests and testimonies are believed. There are benefits to using steroids, for sure, in that they will assist in recovery. There is ample evidence of how testosterone levels fall progressively during a period of hard training or racing and so the correct use of steroids will improve recovery and thus performance in the longer races.
But we're more interested in EPO. There is plenty of evidence that shows indirect benefits, including Marco Pantani's remarkble hematocrit graph, which correlated precisely with his performance over the course of three seasons. But it's direct evidence we're after, and that's where we turn to a study published in August this year.
EPO improves performance by 54% in a laboratory trial
This great study, published in the European Journal of Applied Physiology earlier this year, evaluated the effects of EPO use on performance during cycling. We'll try to break the study down as simply and clearly as possible:
Who was tested?
They had 16 reasonably fit cyclists take part in the study. The pre-testing VO2max tests showed an average VO2 of about 3.90L/min and a Peak Power Output of 325 W. By no means world-class cyclists, but fit athletes. This does have some implications for the application of the data, which we'll get to later.
How were they tested?
The testing involved an 13-week period, where the 16 athletes were split into two groups. The control group received placebo injection, whereas the 8 cyclists in the EPO group received a dosage of EPO on a schedule worked out over the 13-week period. One potential problem with the study was that the EPO group could not be blinded that they were receiving EPO, for ethical reasons. What this means is that everyone receiving EPO KNEW that they were, and there's good reason to believe that simply knowing you're receiving a drug improves performance as well! The control subjects were blinded, so they did not know whether they were on EPO or not, which does partly offset this problem.
Measures of performance?
All the athletes were tested BEFORE and AFTER the injections doing two performance-trials:
* Peak Power Output testing - here, the subjects start off riding at a low power output and the workload increases every 90seconds until exhaustion. Basically, the cyclist has to go harder and harder until they cannot push anymore! The test is used to measure VO2max and also a Peak Power Output
* This was followed by a Trial to Exhaustion at 80% of the previously determined Peak Power Output. In this trial, the cyclist rides at ONE power output - 80% of their maximum, and they ride until exhaustion. This test is used as a measure of endurance performance. This trial was done after 4 weeks and again after 11 weeks of the trial.
The results: A 54% improvement in performance
We don't wish to go into all the blood analysis and DEXA work done - they measured all kinds of things, but this is a post about performance. And the main finding was that EPO use improved time to exhaustion by an enormous 54% within 4 weeks! Peak Power Output improved by 13% in the first four weeks of the trial. The graph below shows the results:
What are the implications?
The graph above clearly shows the benefits that can be gained through the use of EPO. At the intensity of cycling tested in this study, the improvement in time before exhaustion was roughly 11 minutes on a 22 minute trial. Of course, there are some (including us) who would debate the merits of a "ride to exhaustion" as a measure of performance. Normally, we prefer to see a Time-trial as a measure of performance, because the concept of riding to fatigue is not really an accurate or repeatable measure of performance.
However, when you consider the sport of cycling, the final climb of a big mountain day in the Tour is effectively just this - a ride to exhaustion. A group of riders will arrive at the bottom of a 10km climb together, and by the time they reach the summit, the winners are the ones who have managed to sustain a high power output without reaching exhaustion! Now, if you can improve your time to fatigue (that is, the point at which you crack and get dropped) by 11 minutes, that's clearly a massive improvement - it is the difference between making the summit and being dropped with 5km to go!
Another potential problem with the study is the extrapolation of the data to the elite. These subjects were fit, but clearly not elite. It's likely that in the elite, the improvement would be smaller. For example, you could hardly take an Alberto Contador, who might have a Peak Power Output of 500W and bump it up to 565 (13% increase, see graph above) in 4 weeks! Having said that, if you could take this figure and get it to 515W, that would be a very significant increase at the elite level. Similarly, if you could help an elite cyclist improve his average power output by only 5%, that would represent a major step forward. Whether or not EPO would do this is debatable, but given this study, it would seem that 5% is a pretty conservative guess for how much EPO would improve performance...
So can you win a cycling race clean?
So while the results still don't fully answer the question of "how much does EPO improve performance?", they do go a long way to showing us that the effect is potentially massive. Even a quarter of this improvement - 15%, would be the difference between a yellow jersey and the autobus during the Tour de France.
There is the slight problem that EPO is probably not the most widely used drug AT THE MOMENT - in the 1990's, certainly, its use was widespread, by admission and testing result. But in the current generation, it seems that more advanced chemical compounds, as well as blood doping are the choice of dopers. Is their effect the same? I'd lean towards saying, yes, they are, in which case you still have this potentially enormous increase in performance.
So can you win clean? As much as I'd like to think so, when you have this situation where a guy finishing in the top 10 is using drugs and being beaten by minutes on a mountain climb, I find it difficult to believe that physiologically, the margins can be that large. I believe that the NATURAL, physiological difference between riders is tiny - maybe 1% separates a champion from tenth place. So take a drug that improves performance by, let's be conservative and say 5%, and that mid-packer still can't win the race, then you have to wonder about the guy who is winning...?
This study clearly shows that EPO works. I'd extend that to say that any practice that increases the body's ability to carry O2 will work - so the same goes for blood doping. If they work, and work by the sort of margins we seem to be talking here - tens of percent, then can one gifted, unique individual dominate the sport? I think not.
Unless of course, he's genetically altered like a certain mouse was reported to have been last week...but yes, that's ridiculous, as we pointed out in our post on the "Mighty Mouse", and so I'm highly sceptical....
Ross
