Oscar Pistorius: My Views......

There is something twisted in the logic that a runner has an advantage because his missing limbs don't fatigue. Runners who have to contend with fatigue in their lower legs only care because they rely on their lower legs to give them power when they run. Pistorius gets power from other muscles in his body, all of which fatigue normally.

Do you have a theory about how one speeds up due to non-fatigue of the lower leg? It seems like AC's theory about having to run more slowly on the curve is more realistic.

I don't know enough to have an opinion about whether his legs provide some kind of advantage -- but surely the fact that metal doesn't get tired can't be the rationale for excluding him.

I say let him race. Could he have an advantage, maybe, but if he doesn't fatigue then he should run the 800 and up. If he is continually getting faster then he could run world records based on his negative 400 splits. His heart is still pumping blood,my arms get tired sometimes in a 400. He didn't choose (no philosophical argument) to have prosthetics, and how many others with artificial limbs have made it to this level? When he busts out a 39, yea, we should challenge his eligiblity.

Hi webby

He doesn't slow down on the bend - as I said, that's data that won't be released for a while yet, so it's kind of a blind faith thing, but I can assure you that he doesn't slow down on the bend - it's the fastest part of the race. Apologies for not being more open than this, but I can't comment on their results. And his peak speed is achieved as he enters the back straight and then he doesn't slow down. So it's not that he speeds up, it's just that he doesn't slow down.

Your points are valid that he doesn't have the muscle to propel him forward but I would disagree with you that all his other muscles fatigue normally. There is a physiological reason to suggest that they don't, which is covered in various arguments. The main point is that the Cheetahs are designed to take loading force and store energy and then translate this energy into linear motion (you'll see this if you read the Ossur specs, they make the Cheetahs). Now a human limb can't do this - it doesn't take force in one direction and change it into another, UNLESS there is muscle contraction. And muscle contractions are not free. They cost energy, and the energy has implications - depletion of ATP, buildup of phosphates, fall in pH etc. All these peripheral changes are the problem for sprinters - that's why they slow down. So it's not simply that metal does not fatigue - there are other factors too. The mass of the limb is another critical factor.

Of course, I must acknowledge the other side of the debate, that running on prosthetics can have increased energy costs. A study that was presented at the recent ACSM sports medicine and science conference showed that running-specific prosthetics (like the Cheetah) are able to reduce the cost of running and make it similar to running on legs AT SLOW RUNNING SPEEDS. Quite what happens at high speeds is debatable, acknowledged.

MAYEROFF wrote:

The most important concern here is the ethical one. Mr. Pistorius has a right to compete in the able-bodied events if he makes the qualifying standard.

Jason

Exactly where is this "right" stated?

give me some carbon fiber fins after I cut off my legs and I'll crush Michael Phelps...

Well presented and for Letsrun.com a suprisingly mature and non-confrontational invitation to a discussion of an interesting and difficult issue.

I haven't decided one way or the other but I am concerned about what used to be called the slippery slope. I say used to be called the slippery slope because today precendent almost immediately invites legal challenges.

If Pistorius is permitted to run, the governing bodies will have a difficult time refusing the next level of para-assistance or will be chilled from refusing by the threat of expensive litigation or yellow journalism from self-styled civil rights groups.

With increased levels of disability will come greater usage of technology. Does a person born blind, without arms and legs merit a scooter and a driver/navigator.

Don't laugh. I know attorneys that could make 60% of the viewing audience say, "He might have a good point there."

Thanks, Ross. You've obviously done a lot of research on the subject. It's been an engaging and educational thread. From what you say about storing energy and translating it to horizontal motion, it sounds as though there is a spring effect -- which would seem clearly beneficial, and "unfair" if it were a substantial effect. I would have thought that spring action would have been outlawed early on without much debate. Is that the issue? If not, how does it store energy?

I do wonder if your portrayal of the human leg as unable to store energy is entirely accurate. I would think that the elastic properties of ligaments and tendons would have a similar spring effect -- although I have no idea how its magnitude would compare to that of the cheetahs.

The issue of leg mass seems minor and easily rectifiable if the goal is to make it possible for amputees to compete with too much technological "advantage." For that matter, it shouldn't be too hard to design a prosthesis that behaves like a live leg in terms of energy storage. I hope that this kind of constructive approach to the disagreement is the goal of IAAF, rather than simply handing down a broad exclusion of all prosthetics.

I feel that he has worked very hard over his career and was born at a disadvantage having no bone in his lower legs (not to say he still has a disadvantage when running). I think the IAAF should let him walk in with his country, and run the first round of the 400m and DQ him no matter what he runs. This hurts no one and gives Oscar a chance to run at the Olympics and honor his country which he deserves. Even the IAAF would be fine with this. This is the best Oscar has to hope for. Anything more would be unfair to the other athletes.

A very thoughtful piece of writing, Jason.

Although I agree with you on so many of your points, I would ask the question about how might allowing Oscar compete alongside abled bodies competitors open the door for other disabled athletes from seeking the same opportunities.

For example a wheelchair athlete, who is in that condition much in the same way that Oscar has, might have also broken the qualifying standard for a given event. could this athlete make the same argument that Oscar is? Wouldn't a chair athlete have a significant advantage over an abled bodied athelte?

Towson Exile wrote:

When he busts out a 39, yea, we should challenge his eligiblity.

A lot of people seem to be advancing this argument -- that, as long as he's not breaking records, he should be allowed to compete. But surely we don't decide whether it's right or wrong based on how much innate ability he has! That's like saying steroids are only wrong if they make you fast enough to break a world record. You can't say that super-legs are okay for Pistorius because he only runs 46s, but they'd be illegal for the next superstar amputee who comes along and runs 43. They're either legal or illegal, whether you're running 65 or 45.

And the fact that Pistorius is by far the fastest ever double amputee by no means indicates that he represents the ultimate limit of performance. There have probably been fewer serious double-amputee sprinters in history than there are at the California state high school championships in any given year.

webby wrote:

The issue of leg mass seems minor and easily rectifiable if the goal is to make it possible for amputees to compete with too much technological "advantage." For that matter, it shouldn't be too hard to design a prosthesis that behaves like a live leg in terms of energy storage.

In my mind, the significant disadvantage of the prosthesis is that it makes no active contribution to propelling the athlete. This may be balanced (not to imply equally balanced) by the fact that the prosthesis is more efficient at energy storage and return, that is, it can be tuned to be a better spring than the human leg.

The issue of leg mass is easily rectifiable, but I strongly disagree that it is minor. From the video clips I've seen, Oscar has a very high stride rate at top velocity and adding significant weight to the prosthesis would either slow his stride rate or require a higher level of energy to maintain it. If you've taken physics, remember how a pendulum works, move the (center of leg) mass higher and the natural frequency increases. The IAAF spokesman that stated the other day that Oscar's high stride rate was due to lower aerodynamic drag is, in my opinion, missing this more significant factor.

As for building a prosthesis that behaves like a human leg, that's a noble goal and one that I'm sure people are working on. For competition purposes though, do we give him legs like mine (unspectacular everywhere, more so at 400 m) or like Michael Johnson?

Hello again Webby

Thank you for the follow up questions. I have done a fair amount on it - perhaps I should explain the origins of my involvement. I am a South African, a sports scientist and running coach. And I coached a couple of the SA athletes from Athens. And so when Oscar Pistorius burst onto the scene, a journalist came across my name and in 2004, I was asked whether I thought he would ever be able to compete in the able bodied Olympic Games.

I said back then that the IAAF/IOC would probably have to make a difficult decision at some stage in the future, but that no research existed to answer the question one way or the other.

Then, in 2005, I was contacted by Pistorius' agent to 'endorse' the fact that the legs did not give him advantage. For about a month, we had email contact, and my position was that research needed to be done before the statement could be made or refuted. Then the next I heard, they had contacted Tim Noakes (my direct boss here in SA) and asked for the same. He says his view was the same - let us do research to prove it or disprove. And so that was the origin of my involvement. The research was never really followed up on, which I actually think is quite telling...

Anyway, jump ahead to 2007, the debate was on again, but our media down here in SA is what I would call "immature" with facts - they report stories, but often without insight. And so what happening was they were commenting on the story and only really giving one side of the argument. So for example, Pistoris was talking about lactic acid making his back sore, and a lot of other incorrect statements that could be (but were not) scientifically challenged. At about the same time, i started that blog for science in sport, where I was going to give scientific insights into sports news. This was an obvious one, because of how close it was to home, and because my PhD work was pretty close to a lot of the theories - fatigue, energy use, performance. And because I coach, so that's the background to the research (not that you asked!)

Just to add one thing - you're quite right, I didn't portray the human leg as completely as I might have. The human leg does store energy. BUT (and this is crucial), in order to store the energy, the human leg needs a muscle contraction. Then to release the energy, it needs another muscle contraction. So two contractions are required, both have a cost. The Cheetah, in contrast, is passive - there is no cost to storing energy. The energy is stored through compression, which causes deformation. now if the object is stiff, then a great deal of energy can be stored and return. But vitally, there is no energy cost to (at least not directly), whereas the human limb requires two energy inputs. So yes, you're right, the human limb does the same job, but at a price. So the irony is that Pistorius has said many times in the media that his legs are "passive", but that's part of the potential theory against.

I must point out that I have received a good deal of emails from people questioning, in a very constructive way, the points I have made. And they are valid points. So there are two models - one that the prosthetics use MORE energy, and then the one I've described, where they use LESS. The theoretical arguments are complex, and probably never ending and that's why the data from the IAAF are so telling. In my opinion, they evaluate the two models and show which is more likely to be correct.

Lastly, you raise a very interesting option - can the IAAF monitor the limbs to ensure that they are not unfair? This may be possible, but would obviously be very difficult to implement. The larger problem of course is that then the IAAF would have to adopt the role of a 'watchdog', basically checking the equipment. It would become like motor car racing, where a technical team has to weigh, measure and assess the cars after every race. But that may be the way to go...

A very interesting and well reasoned debate. Here's another thought...

Are the prosthetic legs Oscar wears when racing the same legs he uses for general purpose. E.g. Walking up and down stairs, riding a bike, or all the other activities he does every day? If not, presumably they have been optimized in some manner for this particular activity. Is that not providing him with an unfair technical advantage? An advantage that others are not able to benefit from.

Sure, we can train our bodies to be runners, jumpers or throwers. And we can change shoes to help our performance. But changing the base of our shoes (feet) is about the limit to which technology is allowed to assist us. If Oscar is only adding spikes to the base of his regular, everyday prosthetics, that is one thing. If the prosthetics he is using are used solely for racing and training purposes, that is another.

Wheelchair racers use specially engineered chairs for racing, different from their non-racing chairs. Over the years such chairs have developed into highly specialized pieces of equipment, and have their own classes of competition distinct from able-bodied competition (though it's not uncommon for road races to include wheelchair categories).

To my thinking, prosthetics are little different from wheelchairs. They have their own class of competition, making for fair head-to-head racing. This does not exclude such athletes from competing alongside able-bodied athletes in competition, they are simply classified differently. When it comes to world championships, there are distinct championships for the different classifications.

I agree 100%. The issue is not Oscar Pistorius and his times, it's whether the technology provides an advantage. And you can't ban an athlete because he's fast. The whole point is that the legs might make him fast between now and 2009 (or whenever it is) that he gets to the level. And I'd like to know that the sprinter I'm watching has achieved is times because of training, not the creation of a new ultra light and ultra stiff carbon titanium alloy, and the allignment of the legs. If I want that, I'll watch Formula 1, where the race is won in the pit lane!

And the other thing that is EXACTLY right is that there are so few double amputees out there that the argument that he's the first is a weak one. I mean, think about what it takes - you have to learn to walk on prosthetics, which eliminates about half the population of amputees), then you have to receive therapy when you are still learning to walk (knock off maybe another 90%), then you have to be seriously rich - the legs cost $25 000! So those three things alone mean that there are fewer double amputee runners than in a high school meeting. And then to that, you have to add athletic talent, and it's no wonder. And the other thing - every interview I've seen with pistorius, he says how he's the first guy in 14 years to do this. Isn't that an argument FOR technology making a difference? No one thought the landspeed record would ever exceed the speed of sound. But guess what? Technology made it happen. And if you really believe they're running on the same legs as 14 years ago, think again! Of course they redesign it. That's like saying we've been driving cars for 100years, because the Model T Ford is that old!

Good points!

The leg mass issue is possibly quite significant. You go out and run with 6 kg extra tied to each leg. Now I've heard the argument that the extra cost of balance (which has been called the "mental cost" of running on prosthetics) offsets this, so that there is no difference. of course, we could debate that all night (and probably will). But the point is the hip flexor muscles (quads especially) are accelerating a lower mass and also a centre of mass that is closer to the point of rotation on each stride and that means the same force or a similar force will produce faster acceleration - hence the very quick movements you see, and that Citizen Runner has mentioned. So I agree, one prediction made by the mass-reduction theory is that his limb will move through very rapidly. That seems to be borne out. And the aerodynamic theory is probably part of it, but not the main component.

In terms of energy return, the prosthesis is reported to return about 80 to 85% of the energy. This depends on the mass of the runner and the velocity of the limb at footstrike, presumably. The human tendon is reported to return about 75%, and this decreased with fatigue. It's difficult to measure that though, because you have to either insert pins into the tendon, or take the tendon out or base it on estimates and mechanical models. But it's about there. And the prosthesis is also designed in the shape that it is (that funny S-shape) so that it does actively propel the athlete forward. In fact, the company that make it even have a name for it - Active Tibial Progression. It's designed to absorb impact energy, and the recoil in the FORWARD direction.

Final one - design a limb that functions as a human one. Challenging, but implementing that might be well near impossible. Imagine reading the next day that the Olympic 400m champ has been stripped of gold and his world record because his legs/shoes did not conform to standards!

The we would have the formation of WADADA - the World Anti Doping and Assistive Devices Agency!

ross, i just wanted to thank you for spearheading probably the most informative, professional and well-thought out thread i ever have seen on here. your posts are extremely enlightening. however, i have not seen any information regarding what kind of aerobic engine OP has, if there is some minimal baseline for world class 400m runners and if he differs from that. for example, if he were a 5000m runner and his vo2max was 50 but he was running 13:20s, then i think that it would be safe to conclude that his legs were aiding him much more than normal legs (because no able-bodied runner with a vo2max of 50 could run anywhere near a 13:30).

Citizen Runner wrote:The issue of leg mass is easily rectifiable, but I strongly disagree that it is minor . . . do we give him legs like mine (unspectacular everywhere, more so at 400 m) or like Michael Johnson?

CR, I'm convinced by your argument about how significant a difference the weight of the legs can make. I guess if I were charged with finding a fair and reasonable solution to competitive prosthetic design, I would create a table based on the average characteristics of elite runners in the event (in this case 400m).

Just the fact that his best 400m times are run with negative splits tells me that it is a different sport.

It is fine for him to race able bodied athletes for competition but I don't think the times should be IAAF ratified.

MAYEROFF wrote:

We have a tradition in the USA, a tradition of Civil Rights that is central to our identity as AMERICANS: The legal bedrock of this tradition is the US Supreme Courts ruling on Brown Vs. Board of Education. Brown vs. Board of Education said that the "Separate but Equal" system of segregation was bogus, and there was no equality. Does this legal standard apply to Track and Field? I say HELL YES IT DOES.

If only the Olympics were USA only events...