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Wednesday, January 16, 2008

Oscar Pistorius: The "missing" variables?

Pistorius to seek "independent" tests - the debate continues

On Monday this week, we did a double post, looking first at the report issued by the IAAF on the results of their testing of Oscar Pistorius, the "blade runner". This was followed by a post looking into the immediate response by Pistorius, where he declared that he would challenge any ban and ruling from the IAAF.

Well, Wednesday is as long as it took to hear more on that "challenge", though at this stage, the specific details are still very sketchy.

But in this news report, Pistorius was quoted as having said the following in an interview with Associated Press Television News:

"I was pretty surprised by the outcome...We have given the results to some university professors of biokinetics in the U.S. and they strongly believe I do not have an advantage," Pistorius said. "We are hoping to redo the tests at an independent level."

Pistorius was further reported as saying that the experts he'd consulted with had told him that the testing was not comprehensive enough, hence the need for more testing.

What might the IAAF have missed?

Now, this report is nothing especially new. But conspicuous by its absence is any detail on the testing, which has yet to emerge. That is perhaps understandable, as at this stage, there is no point in revealing everything.

But it is still enticing to debate just what these "missing tests" might be, and whether there might be any more to this (protracted) story.

The debate has gone on for some time now, which is why this concept of more testing is intriguing - there is either something everyone has missed, or this is a play to remain in the public eye as long as possible. Certainly, there is nothing that has been reported in the media, nothing that has been covered in this blog, and nothing else that I am aware of in the scientific literature that could possibly still be examined. I believe that the IAAF testing was in fact TOO broad and probably looked at too many variables. But that's not the main issue here. Rather, there are a couple of things things that Pistorius must account for in his "independent" testing.

We're back on the conflict of interests again

First things first though, it's hardly appropriate to call it "independent" testing! Regular readers of our blog will know that one of the biggest 'influencers' of scientific research is the conflict of interests that arises whenever a commercial company funds research on its own products. Think of the Gatorade Sports Science Institute doing research into sports drinks - they're hardly going to conclude that the benefits are insignificant. And here we have a case of an athlete/his team who are going to seek testing to find what exactly? That he has no advantage? It seems to us rather that Pistorius is seeking an alternative analysis in the hopes of the results being in his favour. It will be most interesting if this second analysis also shows he has an advantage. Then what? A third opinion?

That is not science, it's marketing and this whole scientific debate is in danger of degenerating into something of a protracted, drawn out affair, with farcical processes. It would seem that the only satisfactory conclusion will be when the science concludes there is no advantage and the IAAF allows Pistorius to run.

Two strikes so far - third time lucky

Going back to last year in July, when the story first broke, Pistorius was allowed to run in Rome and Sheffield, where the IAAF performed research on him during his races. Once the findings suggested some "unusual" pacing, Pistorius blasted the IAAF as "pathetic and incompetent" and accused them of spying on him. So that was strike 1, if you like.

Subsequently, the IAAF spent 50,000 Euros on a research study to establish the facts. When it was announced, Pistorius praised the opportunity and declared that the testing would clear up any doubt. But those results, which suggest a massive advantage, have similarly been dismissed as "incomplete" and inappropriate, despite the fact that Pistorius was given opportunity to choose representatives to oversee the testing to ensure its fairness. Strike 2, in effect.

So it would then seem that the only course of action that will satisfy Pistorius is when HIS OWN nominated scientists find no advantage, much as they suggested a 240% energy return.

The independent testing has already been done, and it found differences of 25% in energy consumption and never seen before energy return compared to the human limb. So to refer to further testing as "independent" is probably best forgotten - you KNOW that there's only one outcome possible from this "independent" testing, before it's even done. In fact, one statement from Ossur, who make the blades, would have us believe there "is no advantage". They swear there's no advantage, so it must be true...?

But, it 's still worth considering what possible variables might be considered - this is speculation of course, and we wait to hear exactly what it is. But given how this story has progressed, it seems prudent to anticipate what will happen - Pistorius might well have been the only one "surprised" by the IAAF result.

What variables still need to be considered?

All we can go on here is past stories and reports, because there has been a noticeable lack of real science originating the Pistorius camp since last July 2007. The only theory they did propose in support of Pistorius was the absolutely shocking, shameless scientific equivalent of "jock-sniffing," where they found scientists willing to say that the human tendon returns 240% of the energy it stores. This is at least three times higher than the reality, but it does give an indication as to how science can be made up when the need arises.

Are we destined to see more of the same now? I suspect so. I think that what will happen in the coming months is that scientific experts from the USA will be called upon to interpret results in a manner that supports the absence of an advantage. Quite how you erode a 25% advantage will be interesting to see...

The size of the differences - too large and too significant to be overturned

For the biggest challenge facing Pistorius is to overcome the sheer size of the difference - the IAAF found absolutely enormous differences. When we talk about elite athletes, 25% is a lifetime. In fact, if we took Kenenisa Bekele (who has a 10km PB of 26:17) and tested him in a laboratory to compare him to 5 other athletes who ran times of between 28 and 29 minutes for 10000m (this is a good two minutes slower than Bekele, bear in mind), I can assure you that we would find differences of no more than 5%.

The same goes for Jeremy Wariner - in a laboratory, I would be willing to bet that the difference between Wariner, the World's best 400m athlete, and an athlete who runs a 46 second time and can't even make the second round at the World Champs is not more than a few percentage points, if that. The fact of the matter is that in the laboratory, you simply struggle to find differences that are so huge between athletes who have huge gaps in their performance ability.

Yet here we have differences of 25 to 30%! That is astonishing, and even Prof Brueggemann admitted that he was taken aback by the margin. How many seconds does this equate to? That's difficult, if not impossible to say - but it's certainly not milliseconds.

So if Pistorius and the experts have some tests in mind, they have to find a disadvantage that outweighs this 25 to 30% advantage. Otherwise, the net conclusion must still be advantage.

So what might those tests be - lack of ankles, increased work for balance?

Turning now to what those tests might be, the only two things that have been mentioned in the media previously by the Pistorius camp (and their scientific team who would have us believe that the human ankle is capable of creating energy - is there not a million dollar reward for creating perpetual motion?) are the following:

  1. Pistorius does not have an ankle, so to run at the same speed, his other muscles must work harder
  2. Pistorius must work harder to keep his balance and so his overall energy cost would be higher.
Is it possible that these two things, neither of which Pistorius might believe are measured by the IAAF testing, are the "missing variables?" There was one other theory, which was put to us on this blog by a scientist in Canada, and this is that the limb moves around in the carbon fibre blade - that is, the "fit" is not ideal and so Pistorius would need extra energy because of the loss of energy through this inefficient attachment.

So those are the three possible arguments, as near as I can tell. But here's the catch...the IAAF have already measured all three, as implicit in their result.

In otherwords, when the IAAF measured how much energy Pistorius used during sprinting, they found that it was 25% LESS than other runners at the same speed. This energy use is measured in Pistorius, not in the limbs by themselves, and so it already includes:

1. The extra work his muscles might be doing to make up for no ankle
2. The extra work that he might have to do to stablize the body during sprinting
3. The loss of energy through the inefficient attachment

The point is, Pistorius is running using 25% less energy despite these differences - that's the advantage of the blades.

So, those three possibilities are out. Which leaves us with....? Any takers? If there are any experts out there who do have something to contribute to this one, we'd love to hear from you.

And then what of the Paralympic athletes?

The other group of people we would really love to hear from is the Paralympic community. Pistorius has openly declared that he is fighting out of obligation to the Paralympic community. Yet they have remained silent on the issue. We had a great couple of comments from one such athlete, Kara (USA Swimmer), and her views on the subject are very interesting - you can read them in the "Comments" section of this post. And I've seen some interviews where athletes have expressed lukewarm feelings, but other than this, no one has really asked - and a simple Google search reveals that.

What I suspect is happening though, is that Pistorius has consulted people who have expertise in prosthetics, but not in the physiology of performance. It must be emphasized that this specific case is very much about performance physiology. Sure, the prosthetics are important, but so unique is the situation that the answer will not come from a prosthetics textbook. The answer, I feel, came from Prof Brueggemann and a team of 10 scientists, who did EVERY POSSIBLE test and found an advantage that is probably comparable to the advantage in physiology that Jeremy Wariner enjoys overa typical high school or club athlete.

The debate continues...

Ross

2 Comments:

Jangir said...

What does the 25% mechanical advantage actually refer to? Is it based on VO2 measurement or some other formula? In another blog there's a reference to achilles heel returning up to 70% of energy. Do you have the name of the paper that states that? Also, you state that the ankle collapses. What does that mean exactly?

Ross Tucker and Jonathan Dugas said...

Hi Jangir

The IAAF testing showed two particularly large advantages. The first was an energetic advantage of 25%- this is measured using VO2 as a means of obtaining the energy cost for running at any given speed. For sprinting, this introduces a couple of theoretical arguments, but the end result is that at running speeds similar to those of a 400m race, Pistorius is using 25% less energy than an able bodied runner - this is exactly what the theory would predict, if you go back to the very first couple of posts we did on this subject. The theory, then, is that his energy cost would be lower, and the testing proved this, to the tune of 25%.

The second difference is the mechanical advantage you refer to. Here, the IAAF actually tested the mechanical properties of the limb using a special device known as the material testing machine T1-FR020TN.A50. That's a mouthful, but what the testing involves is actually taking the limb and exposing it to mechanical forces and then measuring the deformation, the hysteresis and energy dissipation were measured.

The measured energy return of about 95% using these methods, which is substantially higher than that of the ankle joint. The study also looked at the energy that was stored and then re-utilized by the blade compared to the human leg. The blade re-uses about 92% of the energy, compared to only about 55% by the human leg. This adds up to the mechanicl advantage reported of around 30%.

As for the ankle "collapsing", I'm not sure which post I used it in, but what I meant by that is that during sprinting, the athlete will land on the ball of the foot, and the ankle will then flex as the heel drops down and possibly makes contact with the ground - there is a difference in height of about 5cm between contact point and push-off, thanks to the movement of the ankle joint - this is what I was referring to as "collapsing". If you jump off a chair and land on your toes with straight legs, you'll see what that means at the extreme of the spectrum.

Regards
Ross