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Wednesday, December 19, 2007

Oscar Pistorius banned - IAAF result


On January 14, the IAAF issued a report revealing the results of scientific testing done on Oscar Pistorius. If you would like to be redirected to a summary of those results, click on the links below:

  1. IAAF Announcement: Oscar Pistorius banned - IAAF report findings and analysis
  2. Oscar Pistorius to challenge ban - Insights and discussion on the results, the history of the debate and what the future may hold for the debate
Leaked reports that Pistorius' Carbon fibre prosthetic limbs provide a "considerable advantage"

The IAAF tests on Paralympic athlete Oscar Pistorius have now been handed to IAAF President Lamine Diack, and the early reports are that the tests have indeed confirmed that the carbon fibre prosthetic limbs, knowns as "Cheetahs", do in fact provide Pistorius with "considerable advantage" over other runners.

Unfortunately and frustratingly for us, the IAAF have issued a press release which states that "the IAAF does not plan to discuss the contents of the report, or make any public announcement about any decision related to the report, until 10 January 2008". Because of this, we don't have access to the specific results and so we cannot, unfortunately, bring you any more detailed insights or interpretation of the specific test results. But the lead researcher, biomechanics expert Prof Gert-Pieter Bruggemann was quoted in a German newspaper as saying that the advantage is considerable - several percentage points in size. Apparently Prof Bruggemann was himself surprised at the size of the difference.

To be quite honest, I'm also surprised at the apparently definitive result, but not because I don't think there is no advantage (I'm on record as suggesting about 5 seconds advantage, and only next year will the actual facts emerge), but rather because of my slight scepticism about the tests the IAAF eventually put him through. I think that the IAAF took on a brave, but essentially impossible question to answer by trying to find the mechanisms and underlying physiology for the potential advantage.

However, returning to the tests, the focus was clearly on the oxygen consumption and lactate accumulation during running. There was a very sound physiological basis for investigating oxygen consumption, but lactate was not quite as clear cut. There were also many potential pitfalls and possible problems with the measurement of these variables during a short duration sprint and sub-maximal exercise bout, so I'm not 100% convinced the issue is resolved - in my opinion, it has been for a while, but whether this result will end it, I'm not sure.

But because the test results are not available yet, it would pure speculation as to what they found. I suspect that his oxygen consumption must have been radically lower than other athletes', but I would suspect even more strongly that the biomechanical assessment of the limbs (apart from the physiological data measured when he ran) were the clinchers in this argument.

The theoretical basis for an advantage

Now, it may seem radical to some of you that the prosthetic limbs actually provide an advantage. This is a case that has been absolutely gripping as far as sports science goes, and earlier this year, when we did a series on Pistorius and the possibility that he had an advantage, we tried to explain just what the basis of that advantage would be, and it produced some excellent debate and discussion (mostly, anyway!)

I think that in our 8 months of existence here at The Science of Sport, the longest post we ever did was one I wrote looking at all the available evidence and theories for Pistorius having an advantage. This was an epic post to write (and probably even more challenging to read!) so rather than rehash all the same old points, and put you through that test of endurance, I refer you onto the following post if you are interested in some of the relevant arguments:
The main point we were making in this post was that because the carbon fibre limbs are providing elastic energy return without any possibility for fatigue, Pistorius would have a substantial advantage that would be seen most in the second half of his races. The human tendon is also able to provide energy return, but it comes at a cost - this "cost", while difficult to quantify, results in what we recognize as fatigue, with the athlete slowing down progressively as the race develops.

The Cheetahs, however, provide "free energy" the whole way around. In addition, the far lighter limbs (carbon fibre vs. bone, muscle, fat and blood = major weight difference) would also provide an advantage. There was a bit more to it than just this, but it's covered in the above post for interested visitors. But basically, the hypothesis created based on this theory is that when everyone else was slowing down (despite the fact that they're sprinting maximally), he would be speeding up.

With this hypothesis in mind, we waited for his first European race in Rome, and analysed his pacing strategy during that race. Sure enough, Oscar Pistorius ran a 400m race that no athlete has ever done - even the great Michael Johnsons and Jeremy Wariners were running a race completely different to Pistorius. We covered this analysis in the following post:
Now this finding alone could well have been enough to conclude that the advantage existed. In trying to find the mechanisms, the IAAF were really taking a chance, because mechanistic physiological studies are really very difficult to do. This one was particularly challenging, partly because of the fact that he is a sprinter (it's far more tricky to interpret VO2 data in sprinting than long distance running), but also because of the emotional aspect of the issue.

An impossible question to answer

In fact, this is one of the most challenging scientific questions that I can think of, and if we had an award for "Stimulating science question of the year", this would be it. The main issue is that the study is impossible to do "properly". In other words, you cannot have a Control group, because you can't have other athletes run on carbon fibre blades, and you cannot measure Pistorius running on normal limbs! So to actually ask the question "Do the blades give Pistorius an advantage over other runners RIGHT NOW?" is an impossible one to answer with 100% certainty.

And this is where many of the problems developed, because people, understandably, want this question answered. One has to realise that no one can answer this question, though.

Instead, the real issue was never whether this particular model of limb on this particular athlete provide an advantage. The real question that should have been asked is "Is Pistorius different from able-bodied athletes in a PREDICTABLE, measurable manner?" Because IF you can find difference, and IF you had predicted those differences based on the theory and physiology explaining them, then you would know that something was at play with the prosthetic limbs. And the extension of this difference, is that regardless of whether he's better now, technological developments in the future would further improve the limb and eventually, this measured difference will become significant enough to see the athlete win. Now, the pacing data from Pistorius' race in Rome was highly suggestive of this difference, and it was definitely a favourable difference.

The crucial point made in the earlier series was that if Pistorius went away and spent 2008 training and working with the engineers who make these blades, would he come back in 2009 running 2 seconds faster? If so, was it his hard training, or was it the technology? Ultimately, you'd never know, and for that reason, preventing the use of the carbon fibre blades was the correct way to go.

The IAAF - substantial investment and accommodation

The IAAF have been exceedingly gracious and accommodating in this case. They have bent over backwards, forwards, sideways, and done handstands in order to accommodate Pistorius on this issue, even paying for the tests to be done (a figure that would be in the high five figures, for the advanced type of testing that was done). Not that it is wasted funding, because the question was so fascinating and relevant, but because I don't believe it was ever the responsibility of the governing body of the sport to prove the presence of an advantage, especially given that they have rules in place to regulate the equipment used by athletes.

Instead, I really do believe that it should have been up to the Pistorius team to prove that they did not have an advantage. That is, they were the ones requesting permission in a special case, so would have been well-advised to prove that the limbs were not advantageous themselves. Of course, the IAAF probably would have done their own testing, but had Pistorius and his team approached the IAAF with some data, their position would have been enormously strengthened.

One of the most telling indictments on the situation is that in 2005, I was called up by members of the Pistorius team who were looking for an "endorsement" that the limbs did not provide an advantage. I would not give that endorsement in the absence of test results and proof, and neither could Prof Tim Noakes, who I know was contacted as well. Both Tim Noakes and I advised them to get the scientific testing done before they even contemplated the bid to compete in Beijing. We both invited them to come down to meet with us in Cape Town and discuss the way forward, because it was quite clear that the science was the key and had to be negotiated eventually. Yet two years passed and nothing was done.

Now, the million dollar question - if it meant that much to you, and you were desperate to compete, and you KNEW that the scientific evidence was going to make or break your attempt, why would you not have had the testing done? So why not be proactive and make it even more difficult for the IAAF to prevent you from competing later on?

Instead, Pistorius and his team went on what the media called "PR and support generating tours" of the USA, drumming up support and funding for his effort - everything but the science. I was involved in a TV debate on the issue - the problem was that we never debated anything, because any science that was put forward was simply brushed aside and we were reminded that he is inspirational and a role-model. I agree on both points, but it definitely highlighted an aversion to proof, perhaps because that proof would should what that IAAF now have?

The focus on the support and PR was understandable though, I suspect most would do it, but it does highlight the difference in incentives between the groups. And ultimately, it was left to the IAAF to carry the can, and despite some debatable science tests, they carried the situation as well as I think anyone would ever expect.

What next for Pistorius?

As for Pistorius, there was a time earlier this year when the issue was topical and in the media every day, that he actually threatened at one point that if they banned him from running in the Olympics, he would quit the sport altogether and not even run at the Paralympics. This was an unfortunate comment, because he was effectively holding himself to ransom. Also, it didn't demonstrate much respect for the Paralympic movement, and for the enormous role he could play as a role-model for people everywhere. Make no mistake, Pistorius is an inspirational character - it's not for nothing that Tom Hanks has visions of a movie of his life! So I really do hope that he is able, assuming he accepts this decision, to move on and continue to inspire people with his determination and courage. The emotional issue should always be seen as distinct from the scientific one.

But for now, I feel the IAAF have made the right call - it's taken a long time, and it may not even be finished yet! But based on the theory and the limited results so far, it's a decision that is in the sport's best interests.

We'll do our best to bring you detailed reports and scientific interpretation as they come, if they come!



Andrew said...

The implications of this stretches into the saralympics, as he used to compete in both single and double amputee competitions. Surely he has a large advantage over single leg amputee?
Now that I think about it, weren't there complaints during the 2004 Paralympics?

Ross Tucker and Jonathan Dugas said...

Hey Andrew

Yes indeed. Now that is a can of worms that one might consider opening. There were some disgruntled competitors in the Paralympics, but no official protests, as I understand.

The advantage is even more pronounced in the Paralympics, incidentally, because Pistorius has balance, whereas a single leg amputee does not - the biggest problem for a single leg amputee is that one leg has a "fixed" length (apart from flex), whereas the other has joints that flex and extend, and the result is that they are very much off balance. So when you watch them run, they go sideways a lot more than a balanced runner.

So this fact, plus the fact that the blades give some advantage, does certainly suggest this. That is perhaps an even trickier argument than the one we've been having, for ethical/moral reasons. I'm interested to see how it develops!


Andrew said...

It's going to be very interesting, I'm looking forward to it.

Ryan said...

My take: he shouldn't be allowed to compete with regular athletes using these blades, theres too much possibility for a extraordinary mechanical and unnatural advantage. What is stopping him from having super-blades designed which make him leap 40 feet with each stride, and he'd run a 1 minute mile wearing them? If they would let him compete with his blades, Heck, let him wear a jetpack instead or even let him wear rollerskates. I even agree with the paraolympic protests.

Unknown said...

I think that the decision is the logically correct and fair response. Nevertheless, I cannot help but be disappointed for Oscar. To be prevented from achieving what you have worked hard for by a 3rd party, through no fault of your own, must be an awful feeling. Also, I very much enjoyed watching him race and was looking forward to seeing him smoke people in the 800 one day.

The rollerblade/jetpack etc. slippery slope argument comes up a lot with Oscar, but personally, I don't think it is entirely applicable. Running is unique in that it doesn't use a lot of technical equipment, so Oscar's advantage is 'more novel' in a sense. A runner with 1970s shoes may be able to run as fast as today's runners. However, apply that metric to a cycling time trialist with aerobars, an aero helmet, and an aero frame that is also stiffer and transfers more power. In this case using the 1970s equiptment would be a huge detriment. Same thing for clap skates in speed skating. In fact, I think more sports fall in the category of 1970s being a severe detriment in competition than not.

When it comes to technology that provides an advantage, sports organizations seem to apply two valid criteria:
1) does it change the sport so much as to no longer make it the sport we think of?
2) is it available to all?
The UCI does not allow recumbent bikes because they deemed that it changes the sport too much by having everyone pedaling while on their backs. In 1972 fiberglass poles were temporarily banned from the Olympics on the grounds that they had not been available to all competitors for 12 months (although this was very contentious).

Rollerblades or jet packs clearly violate the first question. In my opinion, Oscar's blades do not. To me, he is still running. I acknowledge that some may view this differently, but if he's not running, what is he doing.? What would he have to do differently for it to be running? In my opinion its a moot point because shy of intentionally amputating my legs, the technology is not available to me.

Ryan said...

If they let Oscar run with these blades, then logically they would have to allow regular athletes to attach these same blades to the bottom of their feet. You wouldn't need an amputation to use them. They would be fancy pogo shoes.

Ross Tucker and Jonathan Dugas said...

Hey everyone

Great debate - Phillipe, well put! I haven't seen such a logical and well thought out argument on the issue for a while.

When we debated this issue in June on the site, this came up - people wanted to know where the boundary would be drawn once you allowed this kind of technology? Of course, this is a valid question, but I share your view that it's quite easy to see where the use of technology becomes unreasonable for running.

The interesting thing about this case is that initially, the IAAF position was to attack the possible huge strides Pistorius would take, because he was running on springs. If you consider this, it was always quite logical that the effect would not be measured as an increase in stride length, because with the naked eye, that would be easy to pick up, because his stride rate would then be so low. It was clear that he was comparable, so whatever the advantage was, it was 'expressed' as a result of some other factor - of course, "springs" does come into it, but that report will reveal a more complex picture than simply enabling longer strides - the answer, I feel is in the energy saving, and the fact that Pistorius gets "free" energy when other runners are paying for theirs with muscle contraction. I tried to cover all this in a previous post (link below).

I made the point back then that if you want to know how technology influences performance, one way to test this is to compare Jeremy Wariner's times TODAY with his times running in the shoes that were available 30 years ago.

Then do the same with Oscar Pistorius. Of course, 30 years ago, this type of carbon fibre limb never existed, and so one would then argue that this is a silly concept. But to me, it illustrates perfectly the point that the technology of prosthetic limbs is developing so rapidly that we cannot possibly know where on "the curve" we are. In other words, if we compared the 2007 Prosthetics to the ones that will be developed in 2017, would they be different? The answer is almost certainly YES, and possibly by a large margin.

So therefore, in the interests of the sport, the ban was the right decision. Can you imagine if this level of technology was allowed into running? Instead of anti-doping controls, you would now suddenly have to create a new control body for "Anti-technology", because you know athletes would abuse it. So effectively, a track athlete would become like a Formula 1, which has to be examined by technical officials after every race to make sure it complies with specifications! How about a headline saying "Olympic 400m champion disqualified for improper legs/shoes"!

That quite clearly detracts from the sport.

Now, the question of whether Pistorius would have run sub 50-seconds as an able-bodied athlete is a hypothetical one - for sure, he's worked hard and inspired many, and for that reason, I hope he doesn't quit altogether, as he threatened to. That would not send a positive message to any other Paralympians (many of whom are already a bit disgruntled at this whole affair, I might add), and detracts from the true Olympic and Paralympic ideals. So let's hope that doesn't happen, but for the IAAF, they've done a good job, if a sligtly shaky one at times.

One last things - they already have a pair of feet that have been adapted for use in able-bodied athletes - if you check out the following post:


and scroll down to near the bottom, you'll see a description of how a journalist gets a pair of shoes with the feet on them - he says "they bounce of their own accord".

Imagine Jeremy Wariner with a pair of shoes that bounces of its own accord...

Ross Tucker and Jonathan Dugas said...

Sorry, that link again:

Oscar Pistorius debut: the scientific facts and implications

And then the other thing that is interesting is that Pistorius has made repeated claims in the media that the EXACT same prosthetic limbs have been available for 14 years, and no one has run the same times.

That is incorrect to begin with - the company that makes the blades actually commissioned a journalist to write an article on Pistorius and in this artile, the journalist writes about how Pistorius spent a day at the track testing out various prototypes of the new limbs!

So it's quite clear that the limbs are constantly modified, and then you have to ask: "For what reason?" The answer is pretty obvious, I think.


Unknown said...

Ryan - your comment about fancy pogo shoes reminded me that I think this product already exists! Although if I recall they're not cheap. Anyways, for some fun, check out this video of a guy jumping a car in power risers (fancy pogo shoes)


Once again, let me state that I agree that the Pistorius ban is justified. Playing devils advocate here: anti-technology controls might be new to running, but they are not new to sport. UCI weighs the bikes before mountain stages in the tour de France to ensure they are not too light. They reserve the right to weigh them afterwards as well to prevent riders from putting ice in the down tubes to meet the original weigh in, but melt before the climbs (or at least thats the rumor I heard).

This is theoretically so that riders don't descend on dangerously light bikes. However, with the advent of carbon fiber, the limit is now out-dated and now it serves to level the playing field. Do these 'technology police' detract from the sport? Not that I can tell. The only reason I even know about it is that every year certain bike companies make a big publicity stunt about how their product is so advanced they need to add weight back to it.

Anonymous said...

Has anyone ever heard of the conservation of energy? Using a pulley to lift a load does not reduce the amount of energy used to lift the load. Also, you need to consider the efficiency of the energy return. You can not, under any circumstance, achieve 100% efficiency on a passive piece of equipment. He is not racing in an electric powered wheelchair, he is inputting all energy into the cheetahs. There are LAWS of Thermodynamics.

The true test would be to give a non-handicap sprinter a pair of modified cheetahs and see if he can run. Oscar's cheetahs are built to take advantage of his disadvantages. Bilateral symes amputees do not have leg length discrepancies (with prosthetics), they have weight bearing stumps, and they're muscles have developed to maximize utilization of their quads and gleuts in the abscence of calves. Their entire day ambulating is like one long squat exercise.

This is a great discussion with a lot of variables. I am suprised by what is considered "conclusive" results. The picture is much bigger.

My son has bilateral fibular hemimelia (what Oscar has), so this discussion is near and dear.....

Ross Tucker and Jonathan Dugas said...

Hi Anonymous

Thanks for the comments.

I disagree on the test that is suggested for a number of reasons, all of which I have covered in the previous series on Pistorius - this may be worth reading. I've posted a link to the key article "Oscar Pistorius - Science and Engineering vs Training. An evaluation of ALL the evidence" about halfway up this post, which I would suggest you read.

I agree that there are laws of thermodynamics, but the point is that the Cheetahs are taking more advantage of those laws than the human limb. The energy return from the Cheetahs is higher than from normal legs, and also there is no fatigue component. Laws of Thermodynamics are only part of the picture - there are laws of fatigue and return on investment here, and that's the reason he has an advantage. He doesn't have the fatigue component as the race progresses, this is apart from the elastic energy return, which is greater than that of a human leg (according to the scientific literature - again, read the initial post).

So yes, you cannot achieve 100% energy return, but then nor do human legs. They are worse. The results of the IAAF testing haven't been released, but I strongly suspect that this will be their definitive test, because as I wrote in a post a few days before this one, I was sceptical of some of the IAAF tests. But the mechanical properties, that's going to clinch it.

To me, however, it's the fatigue issue that is most important and they could have banned him back in August based on his racing patterns.

The picture is far bigger than the latest round of tests, I agree, but I think you need to evaluate the other arguments, because there is a whole body of evidence that goes beyond "conservation of energy". That's one of many theoretical considerations. And like you, I don't think that the latest tests, by themselves, are conclusive. But the results from his race in Rome, that was conclusive, in my opinion. There's a link to that article on this post too, incidentally, which you might read.

Thanks for the comments!

Ross Tucker and Jonathan Dugas said...

One other thing - I don't believe with the contention that he is "putting all the energy into the prosthetics". Of course, he is forcing down and taking advantage of elastic recoil, but the fact of the matter is, an able-bodied athlete requires muscle contraction in the entire leg in order to store enough energy to recoil during the subsequent push-off phase of running. The Cheetahs are loaded primarily by gravity acting on body weight, which is then aided by active contraction in the thighs.

But that's the same for the able-bodied athletes, and the bottom line is that Pistorius and the Cheetahs will be getting energy return "for free" - recoil without cost of investment FROM MUSCLE ACTIVITY.

And the test that is needed, in contrast to what is suggested, is simply to see how performance is affected when Pistorius runs in the same limbs as someone from Barcelona's Olympics in 1992, and then let Jeremy Wariner run in the shoes worn in 1992. You'll see enormous differences in the times for Pistorius, whereas Wariner will run the same time (or very close).

And that would tell you that technology of prosthetic limbs is responsible for most of the improvement in time in the last 15 years. If that happens, then you cannot allow the technology, because in five years' time, there'd be no guarantee that the technology would not have continued to improve to the point where an athlete like Pistorius (I don't believe he is uniquely able to run this way, it's a matter of opportunity) runs 41 seconds for 400m. And then what do we do? Point is, the technology must either be outlawed or regulated. And this is not the same as just weighing a javelin or discus - it's enormously complex.

So this was the right decision, not because it discriminates against Pistorius, but because the introduction of the technology compromises the sport.


Anonymous said...

I think there is some confusion between kenetic and potential energy. Energy is not free. The cheetahs cannot run by themselves. Gravity is not free energy since what comes down, must first go up. The cheetahs store potential energy previously produced by the quads and gleuts and returns the energy in conjunction with the aforementioned muscles.

I agree, the energy returned by the cheetahs is much higher than normal lower legs. Normal lower legs do not convert kenetic energy to potential and back, however, they do convert chemical energy into kenetic energy. Oscars do not. This is apples and oranges, but the delta between these two values is very important and would provide insight into how Oscar performs.

Oscar does not have functional muscle structure in his lower legs, therefore, there are less muscles to fatigue. "He doesn't have the fatigue component" is an incorrect statement. The muscles in his upper legs and torsoe fatigue much more rapidly than an able bodied runner.

The so called "advantage" Oscar experiences with his cheetahs on straight-aways actually works against him in the corners. He does not have ankles, therefore he cannot corner like able-bodied runners. He is burning energy trying to prevent his legs from continuing in a straight line. Good ol' Newton's first law. He needs to back off in order to prevent himself from running into the wall or falling over.

As far as using older limbs, who is to say they would not put Oscar at a disadvantage?

Again, great discussion. I'm looking forward to the results next month.

Ross Tucker and Jonathan Dugas said...

Hi again

Everything you've argued is correct in theory, but it's been argued before. These points are the same ones that were being raised prior to Pistorius' first race in Rome back in the middle of the year.

There were a couple of other points, brought up by a remarkable young guy in Canada who had experience working with able-bodied and amputee sprinters, which were along the same lines.

The thing is, once you have these two conflicting theories, the way to evaluate them is through testing. And when Pistorius made his debut, we got a fascinating opportunity to evaluate the two opposing theories.

According to my theory, that that Pistorius doesn't have the same fatigue component (a theory which I do believe is true, and not incorrect), Pistorius would begin the race and then speed up progressively. He would not show the NORMAL slowing down of other athletes. The day before his IAAF race, I wrote in a post that this would happen - it was the prediction based on the theories that I had explained in the posts up to that point.

According to your theory, Pistorious would show the fatigue-related decline in running speed, probably even more, because his muscles are going to fatigue more rapidly than able bodied runners. The other thing you are predicting is that Pistorius would be slowest on the bends.

The results showed that neither of these two things happened. In fact, Pistorious ran a race that has never been seen before - he simply got faster and faster. Living in the same country as him, I've also been able to watch many of his races live and on television, and this is a common feature of his racing.

Now of course, one will argue that he is pacing himself this way on purpose, and perhaps all the other runners should do the same. But there is an enormous body of scientific evidence that tells us that the optimal way to run a 400m race is to start fast and slow down at the end as a result of fatigue. The same goes for 100m, 200m, 800m, and all the short distance cycling and sprinting events.

So now, the only conclusions we can make is that either Pistirous is running a good second SLOWER than he should be because of his unusual voluntary pacing strategy (in other words, he is choosing to under perform, in which case his coach should be fired), or the alternative is that the Cheetahs provide some advantage. An advantage that is manifest most towards the end of the race. This is precisely what had been predicted ahead of the race in Rome, based on the two possible models.

So given that, I consider that that IAAF could have issued the ban right there and then. The point here is that you are not looking for an advantage, but a DIFFERENCE. I have tried as much as possible to emphasize this point. This debate is not about whether there is an advantage or not, it should be about whether the Cheetahs create anything unusual. This is because over time, the magnitude of an advantage or disadvantage will change as a result of technological advancements, and so it cannot be controlled for. So it's far more important to look for anything different. In Rome, we saw a never seen before 400m race, and that was enough to issue the ban, in my opinion.

Now as it turns out, based on the IAAF testing, there is an advantage as well, so the sum of the results is pretty unequivocal to me.

Then to touch upon the energy issue, I think that what is missing from the argument is that the "Cheetahs bounce of their own accord". This is quote from a journalist employed by Ossur (the company that manufactures them) when he strapped a pair on at the laboratories while doing a story on Pistorius. If it is true that the Cheetahs are able to return more energy than the human leg, then you have a third energy component in elastic energy. This has always been the crux of the arguments suggesting he has an advantage, together with the chemical energy cost incurred by normal athletes.

Because what you have is a human leg, which requires in investment of energy to return energy - it costs the athlete and the result is fatigue. However, the Cheetahs are able to return kinetic energy both from gravity and elastic energy. Part of the propulsion during the push-off phase is elastic return without the expenditure of chemical energy. Able bodied athletes get less return, with more cost.

That's the big difference, and that's why I do believe there is an advantage. I don't believe that Pistorius fatigues as much or more than able-bodied athletes, based on the results from his first race in Rome - that is fatigue/pacing strategy physiology, which I don't think is well understood by physiologists yet, but I believe it's crystal clear.

And as for the final point about the legs from 15 years ago, that's a hypothesis that would need to be tested. But again, based on all that I have read, including the fact that Pistorius gets a prototype Cheetah designed specially for him every year, I believe it would be true that the technological advancements will make a significant difference to performance. It is the possibility of these same advances that lead to the point where you have to ban their use - I do not wish to watch an athlete in 2012 running 41 seconds for the 400m thanks to technology.

So the point is, if Pistorius goes away in 2007/2008, and emerges in July and suddenly runs 44 seconds, can you guarantee that this improvement is due to his hard work in training, or it is the fact that the team have developed new blades - Cheetahs Mach 3? You can't, and that's not good for the sport.