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Sunday, July 15, 2007

Oscar Pistorius - Science and Engineering vs Training. An evaluation of ALL the evidence

Welcome to the Science of Sport. If you are looking for the VERY LATEST discussion about the research on Oscar Pistorius' advantages ahead of the Daegu World Champs,  please read THESE ARTICLES:

  1. The first study - the IAAF find "bouncing locomotion at lower metabolic cost"
  2. The second study - how Herr selectively ignored data to make Pistorius look more similar when the evidence said massive differences and advantages existed
  3. The mechanical advantages that explain why Pistorius has a running advantage
The article below was written in 2007, but has been "dated" by the latest publications by Weyand and further debate on the issue.

Thanks for visiting!

    Evaluation of Science of Oscar Pistorius

    So over the last month or so, we've had quite a big response to some articles written about Paralympic sprinter Oscar Pistorius. He is bidding to be allowed to run in the Beijing Olympics in 2008 for able-bodied athletes. We've carried a series of articles looking at the scientific merits of the case - there is a possibility that the Cheetah prosthetic limb gives him an advantage, and we wanted to look at the possible basis for this.

    So last night, I was interviewed on an SABC show on the topic. It wasn't too bad, but I certainly felt that not all the cards were laid on the table. My perception of the media and this story so far is that it is actively being moved away from the science at every opportunity. And so hostile and aggressive responses are initiated every time anyone suggests that it may in fact be unfair to allow Pistorius to run. So what I realised last night is that no one is talking here. Science is saying one thing, but Pistorius is not directly addressing these concerns. Instead, he is actively engaging in a "smokescreens and mirrors" campaign to move the focus away from the science and onto the human element (which, by the way, is remarkable, no argument there). So what I then realised is that NO ONE has yet attempted to evaluate the evidence, both from the IAAF side and from the Pistorius side. So below is my attempt at this - it's a long article, I must warn you, but I do think it's complete and these points need to be heard. Thanks for reading!

    The following four key issues are what I would consider important to the argument on Oscar Pistorius’ desire to compete in the Olympic Games in 2008. I really do believe that each is critical to the argument and would respectfully suggest that no article is complete without sufficiently mentioning each one.

    1. Incentive clarification

    Before even beginning to discuss the science of running on the prosthetic limbs, you have to clarify people’s incentives. It is critical that anyone who expresses an “educated” or scientifically formulated opinion on the limbs and their possible performance enhancing effects or lack thereof is understood in terms of their interests in the affair.  We must remember that science and commerce/business are very uneasy bedfellows, and so the incentive gap between the search for truth and the desire for an outcome (in this case, competition in the Olympics) must be acknowledged as a key driver of how we interpret information that we have at our disposal.

    If anyone says that the limbs “definitely do not improve performance”, or confidently asserts that they are passive is lying. And what you will find is that this person has a reason, usually financial, to say so. Thus, the coach, the athlete, the sponsors, and anyone else with a vested interest in Pistorius must first clarify their position before expressing their “scientific” opinion. Again, science and commerce are uneasy bedfellows, and the perverse incentive created by the commercial pull is a bias that must be acknowledged.

    2. The role of the IAAF

    The IAAF, as the custodian of world athletics, must be cautious in how it approaches this particular situation. It is in a very difficult situation, but I must stress that I don’t believe that it will make a decision that is based on discrimination or bias in any way. We must try to return to the root question, and the issue here is not the discrimination of the IAAF vs. one person.

    An unfortunate development over the last few weeks has been what I can only describe as a very hostile and aggressive response to the IAAF (and to me) by those supporting the bid to run at the Olympics. I read recently that Pistorius had labelled the IAAF as “pathetic” and “discriminatory” and suggested that they “wake up”. These statements are inflammatory, and I would hope and encourage the whole group, from both sides, in fact, to avoid such personal inflammatory statements. I have actually taken heat in the last few weeks as well, and for no reason other than people are interpreting this situation as personal and discriminatory, when it is not. The only issue is the credibility of the sport.

    One has to realise that the IAAF must act now based on the possibility that in the future, the introduction of technology into the sport will be impossible to control. The possible implications of the technology are discussed below in Section 4, but briefly, the IAAF risk opening Pandora’s Box of technology in sport unless it can first be shown that the limbs do not confer an advantage to performance.

    3. Evaluation of the scientific arguments

    There are perhaps three key arguments for why the limbs would provide an advantage. What I will do is summarize each of these three arguments below, and this will be followed by my response to the arguments that have thus far been put forward by Oscar Pistorius and his team. I feel that it is critical to the issue that we discuss these theoretical concerns. To date, not a single one of the three main points I raise has been addressed by anyone. Rather, they are simply avoided and the focus is deliberately moved away from the science. So what I propose to do in the following pages is the first complete discussion and debate of the issues – I will first present why I believe the limbs confer an advantage and will then evaluate the counter-arguments, according to Pistorius.

    Key scientific argument 1

    Spring design of the legs and implications for running

    Firstly, there is the issue of the design of the limbs – the limb is specifically designed to store and then return as much energy as possible. In fact, if you go to the Ossur website (Ossur is the company which manufactures the limbs), you will see statements to this end. I quote verbatim one such statement below:

    “Vertical forces generated at heel contact are stored and translated into a linear motion described as Active Tibial Progression, from the foot-flat to toe-off phase. This action reduces the need to actively push the body forward using the contralateral foot as well as equalizing stride length”
    This statement is effectively saying that the prosthetic limb is able to take the forces that are generated DURING LANDING, store them and then translate this into FORWARD movement. In effect, the limb is able to propel the athlete forward. Now, a human limb is similar in respect to being able to store energy. However, there are two critical differences between the human limb and the Cheetah Prosthesis.
    1. Firstly, the human limb is unable to translate the energy into FORWARD MOTION. The Cheetahs, I gather can do this because they have their unique shape. A human limb cannot take a force in one direction and convert it to another without requiring muscle contraction.
    2. The human limb is not able to return energy PASSIVELY. In otherwords, if you jump off a box and land on the floor, you do not bounce up, and almost all the energy that might have been stored is lost. This means that if you want to use that energy, a human limb must ACTIVELY contract. There are many studies that have shown that if a landing phase is followed by an active contraction, then at most 70% of the energy can be recovered. Some studies have found energy return of only 30%, much less than the Cheetahs, and this is ACTIVE return. The point is that this recovery of energy is ACTIVE – it requires muscle contraction and therefore requires energy. Pistorius does not require energy, and so the metabolic cost of running will be lower and he has a potentially enormous advantage as a result.
    The implication of this physiological reality is that the energy cost of running may be reduced. During running, it is factors related to metabolism that are responsible for the fatigue experienced by athletes. These, and the oxygen demand from the muscles, will be reduced in Oscar Pistorius. This is, until proven otherwise, a clear advantage.

    Key scientific argument 2

    Reduced limb mass

    At its core, sprinting is about accelerating mass. In otherwords, the athlete uses muscle, which applies force to a mass to cause it to accelerate. It is well known in coaching and in science, that two factors can influence how much acceleration can be achieved. The first is the force that is applied by the muscles. This is the reason that the sprinters you see on television are so extremely well-built and defined – a great deal of power is required to sprint.

    The second factor is mass. A smaller mass is easier to accelerate. Now an athlete’s lower limb would usually weight between 5 and 8 kg. In Pistorius’ case, the limb is massively reduced by ultralight carbon fiber blades that weigh no more than 1kg. This means that he is saving approximately 6 kg on each leg when he runs. I would challenge anyone to go out and run with an extra 6 kg tied to each leg and see how far they get. The reduction in mass is thus a massive advantage.

    Now, the counter-argument to this is that Oscar does not have calf muscles to assist with this force generation. This is of course true, and so the scientific response is to look at just HOW MUCH DO CALF MUSCLES ACTUALLY CONTRIBUTE TO PROPULSION DURING RUNNING? And the answer is surprisingly little. In fact, studies have estimated that during walking, only 6% of the total energy comes from the Achilles tendon and calf, and during hopping, it rises to about 16%. Therefore, for sprinting, we might assume it is between 10 and 15%. This is a remarkably small amount, when you consider that the reduction in mass is probably 90%. So he is losing maybe 15% of his ability to push forward, but he also loses 90% of the weight of the lower limb, and about 40% of the total weight of the limb.

    In Pistorius’ case, then, the main muscles that are working during running are the hip flexors – these are the muscles that drive the knee forward. These muscles are without any doubt doing less work considering the greatly reduced mass that they are responsible for accelerating.

    Key scientific argument 3

    Stride length and frequency

    In the initial stages of the bid to be allowed to compete, one of the key factors put forward by the IAAF and myself were the possibility that the prosthetic limbs would provide a longer stride than for an able-bodied athlete of the same height. There are two reasons why this might be so:
    1. The spring effect of the limbs, which was discussed previously. I have already commented on this, and the fact remains that the limbs are designed specifically to PASSIVELY return energy to the runner. An able-bodied athlete must ACTIVELY contract the muscle to capture and use this energy.
    2. The fact that the prosthetics are designed to simulate the ability of the runner to run on his toes. In sprinting, runners usually land on the ball of the foot, but the problem is that the ankle, which is a hinge joint, “Collapses” and causes a great deal of inefficiency. If the ankle could be locked in place, it would increase stride length and mechanical efficiency substantially. Now Pistorius has this advantage automatically. This is, in fact, the reason that he is able to beat the single-leg amputees so easily – they have to have one leg shorter than the other, because otherwise, their natural leg would collapse every stride, the prosthetic would not, and they would rock from one side to the other substantially more than an athlete does anyway.
    Therefore, the opportunity to design a limb that maximizes stride length is a potential advantage. I am not suggesting that he has longer legs than he would otherwise have had. However, the fact that he is pushed onto the “ball of the foot” artificially increases the stride length and efficiency, providing an advantage.

    Evaluation of the counter-arguments. What claims are made by Pistorius?

    Having described the evidence that I believe is suggestive of an advantage, we now need to consider the opposing view, namely that the legs do not confer an advantage. These opposing views are drawn from articles published on the internet and in newspapers in the last 3 months.

    Scientific rebuttal 1 – the limbs are less efficient than a human limb

    The claim has been made that the Cheetahs are in fact less efficient than a normal human limb. A scientist has made the claim that the human Achilles Tendon is able to release 240% of the energy it stores. This claim is patently incorrect – I have quoted studies that have shown that the Achilles tendon can only return between 30% and 75% of the energy it stores. Further, the human calf and tendon cannot take force in one direction and convert it to another – the prosthetic limb can do this, as I explained. Finally, and this is also explained in detail above, the human limb does not return most of the energy passively – it requires active muscle contraction. The assertion then, that a human limb is more efficient is not correct. My feeling is that these claims are made by scientists who will say whatever is required as soon as the price is right.

    Scientific rebuttal 2 – Oscar has as much lactic acid as other runners

    In a recently published article in the Sunday Independent, Pistorius made the following claim in response to issues about the metabolic cost of running:

    Obviously I don't have a build-up of lactic acid in the legs, but I have the same ratio of blood per muscles in my body as everyone else, and the only way you'd get less lactic acid would be if that ratio was less. The IAAF haven't spoken to me and they haven't spoken to my physios, who work on my back every day because it's screwed up with so much lactic acid in it. I have to ice my back every day so I can train the next day because of the lactic acid build-up.

    Firstly, it must be pointed out that lactic acid is not responsible for his back pain to begin with – lactic acid is gone from the body within the first 30 minutes after stopping exercise, and so back pain felt even one hour later is NOT caused by lactic acid. This is a theory that exercise science has debunked in the last ten years, and is thus out-dated.

    Now, the next consideration relates back to the two points I raised previously. Firstly, the fact that the Cheetahs return energy passively rather than actively means that the metabolic cost of running is reduced. Second, the main muscles of locomotion are doing less work to accelerate a lighter mass during sprinting with Cheetahs. As a result, the reason for the lower lactic acid levels is not the ratio of blood to muscle to begin with – it’s the work being done by the muscle that is reduced. The base assumption is thus incorrect.

    Scientific rebuttal 3 – Oscar is the only athlete to run these times on the limbs, so it must be him, and not the technology

    This particular argument has been made on numerous occasions. The claim, essentially, is that the limbs have been around for 14 years, but no one has run these times, so it must be Pistorius who is responsible and not the limbs.

    First of all, the Cheetahs were only developed in 1996, and Ossur bought the design in 2000, so the feet as we see them today are only about 6 years old. Of course, prosthetic limbs have been around longer, but if the whole argument is that technology is advancing, then old technology is not valid. In fact, if you think about it, this whole “best athlete in history” claim actually supports the theory that the legs improve performance – if it was natural athletic ability, then it is more likely that someone in the last twenty years would have been close to these performance times. 

    Instead we have a situation where an athlete is only emerging now, which happens to co-incide with what is arguably the biggest boom in technology that the world has ever known – we are in the age of technology. The company Ossur is now making limbs with intelligent, electronic knees, which improve stability massively. It does not seem to me to be too big a jump to assume that limbs are improving at the same time. So the claim that the SAME LIMBS have been around for 14 years is patently incorrect. Further, Pistorius’ own coach, father and himself have been quoted in the media talking about how they were able to run faster when they received new limbs. So it is the growth of technology that may explain why Pistorius is the only runner to run these times.

    Remember, I explained earlier why a single-leg amputee will never be able to run these times – they are unbalanced. So the point is that Pistorius, as a double amputee is advantaged against single-leg amputees. The next question is what about double amputees? Why are there no other double amputees? The reason is relatively simple – it requires an absolutely remarkable series of events to produce a double-amputee who is also athletic. The following factors must all come together to produce a double-amputee athlete:
    1. The athlete must be born without legs, they cannot lose them after they have started walking or have learned to walk. It is almost impossible to “relearn” the motor control patterns that would be needed to run and sprint again
    2. The athlete must be wealthy. Even basic prosthetic limbs are too costly for a lot of amputees to afford. As a result, the vast majority of potential runners cannot afford to compete on an even-playing field. The beauty of athletics is that it allows all athletes, regardless of income and wealth, to compete. This is why the Kenyans, who may be impoverished, can race equally against Chinese, Australian, Swedish and American runners. In the category of double amputees, this is impossible. I am informed that the Cheetahs cost about $18 000 EACH. Few athletes can afford this.
    3. The athlete must have physical therapy from a young age. Learning to walk on prosthetics is a huge advantage, and so too is the therapy from a young age, which enables the person to function relatively normally and gain the necessary balance to perform sporting activities. This is not available to all children who have amputations.
    A final consideration is that the amputation must be below the knee, because the loss of the knee joint and the stability and power it provides would be impossible to overcome. Needless to say, Pistorius received all four of these essential requirements. And while his achievement is no less remarkable, he finds himself in the ONLY possible situation to be able to run – it is a very small percentage of people who fall in this category to begin with. This, combined with the advances of technology are the explanations why we are seeing this situation now.

    Acknowledged disadvantages

    At this stage, it is important to identify the single factor that is without doubt a disadvantage to Pistorius. And here, I have no hesitation in saying that Pistorius is at a disadvantage and that is from the starting blocks. Because of the double amputation, and the fact that Pistorius is running on legs that have a very small contact area with the ground, his balance from the blocks is compromised. It is for this reason that he starts so slowly and then has to catch up distance on his rivals. However, in the 400 m event this disadvantage is greatly reduced, and is almost minimized, and that is the reason why I suggested in an interview after the 2004 Athens Paralympics that he should consider stepping up to the 400 m event. 

    I’m sure that this was the plan anyway, but it made sense, because the start in the 100 m and 200 m events are so crucial. In the 400 m event, this is less important and the result is that his disadvantage is reduced. I dare say that the 800 m event is even more likely to be a strong one, particularly since the metabolic theory seems so obviously correct – no peripheral metabolites regulating performance will result in a massive advantage, perhaps even greater than in the 400 m – you read it here first!

    So an objective analysis of the situation tells us that he has this disadvantage, which is partially offset by the fact that he is now running in the longer 400 m event

    The implications of technology in athletics – the role of the IAAF

    I think that it is critical for people to realise that the IAAF, as custodian of the sport, must make a decision that stands up to scrutiny in ten years’ time. Therefore, it must be emphasized that this is not an issue about IAAF vs Pistorius, or about Tucker vs Pistorius. At the heart of the issue is the introduction of technology to the sport, and the future consequences of this decision. I would appeal to everyone to try to consider the situation from the perspective of the IAAF. It is not a question of fear or embarrassment that a Paralympic athlete can compete with the able-bodied athletes. They are not “scared” of the reality. Their concern is how their decision now will impact on the future of the sport, regarding technology.

    And the key here is that technology makes it very difficult to regulate how improvements in sport are achieved. This is analogous to the situation in F1, where advances in technology made cars faster and faster, until the point was reached where driver skill was becoming increasingly minor to the performance of a car. Now, in athletics, we may be faced with a situation where a 0.5 second improvement can be achieved through the slight manipulation of equipment, and this is not acceptable, since it means that training is difficult to quantify.

    In fact, there is little evidence that over the last 3 years, Pistorius’ improvements in the 400 m event have been the result of anything other than technological advancements – articles on the matter have mentioned how Ossur and Pistorius have worked together over the last few years to improve on the technology. In a letter to a website, Pistorius’ prosthetist has described how they have to align the limbs for best results, how they have to set them correctly, ensure that they are strong enough, manipulate the elasticity, work on the aerodynamics etc. This to me suggests very clearly that what happens OFF THE TRACK, in terms of the engineering and preparation, plays a vital role in the on-track performance. 

    Now, we have a situation where an athlete has improved and we cannot account for the ORIGINS of this improvement. Was it due to training? Or was it due to improved aerodynamics? The mere fact that the athlete and the scientific and engineering team work so closely to develop prototypes is an indication that the limb design does play a role in performance and that’s not a situation that the IAAF can afford to create. We are in danger of opening Pandora’s Box and introducing a new realm of performance enhancers to the sport.

    All of this invites the obvious study that needs to be done. I would anticipate that many people, notably those who are pro-Pistorius, will be claiming that aerodynamic advantages and technological advantages are there for all to benefit from. So what I would suggest is that Pistorius must run in limbs that were used in the 1996 Paralympic Games. And Jeremy Wariner must run in shoes and clothing that were worn in the 1996 Olympic Games (both in Atlanta). And then we will immediately see whether the change in technology affects one athlete more than the other. My suspicion is that Wariner will run almost exactly the same time in the shoes from 1996 as he can in the shoes from 2007. What will happen with Pistorius? Because if he can’t run the same time, then we have the answer – the improvements are technological.

    And if the improvements are technological, then allowing him to run at the Olympic Games will present the whole world with an opportunity to benefit from the SAME technology. Because you cannot outlaw technology for some athletes, but not for others. And before you realise it, Nike, Adidas, Mizuno and Reebok will all be designing shoes that have the same spring properties as the Cheetahs. It will have opened Pandora’s Box, and my prediction is that a sub-40 second 400 m will be achieved within five years.

    I was asked in a debate on TV last night whether I felt that Oscar Pistorius was a gifted athlete. I said, Yes, absolutely. And I meant this – there is no doubt that he is a very talented athlete. Most of all, his determination and courage have stood out as inspirational to a lot of people. But we have to realise that there are probably 10 000 people in the world who can run a 400 m race in 47 seconds. There are only 500 people who can run it in 45 seconds. Oscar is one of those – but whether it’s natural ability or technology that is responsible, that’s the question. And perhaps most telling of all is the following statement, which was made by a journalist who wrote a feature article on Oscar Pistorius for a magazine that is published and produced by Ossur. I emphasize that this article is biased in favour of Pistorius, since it’s written by the very people who make his Cheetahs and thus have a direct financial interest in him running in Beijing:

    “To give me a sense of how they feel, Ossur’s engineers bolt a pair of Cheetahs to the back of two rigid plastic and leather motorcycle boots. I clamp in and trot across the room a few times. The Cheetahs seem to bounce of their own accord [emphasis added]. It’s impossible to stand still on them, and difficult to move slowly. Once they get going, Cheetahs are extremely difficult to control”
    Does this sound like a passive device? Do human limbs bounce of their accord? Does it sound to you as though these Cheetahs do not play an active role in assisting bounce and movement? And of course, the big challenge is to control them. That’s not easy, and that’s what Pistorius does best. But then he learned to walk on them, it’s not that unusual. Gymnasts are able to balance on a 5cm wide beam because they practice for hours a day. I could not imagine being able to do that either. But it’s possible. And it’s possible that in five year’s time, if the IAAF let this through, that a 26-year old American sprinter will run the 400 m event in 39.5 seconds, because the “shoes” he wears make it “difficult to move slowly” and “bounce of their own accord”.


    See also An Open Letter to the IAAF on Oscar Pistorius, published 2 July


    Anonymous said...

    Very interesting article. I fully agree with what you are saying in this article. But, in the same breath, Pistorius is an excellent athlete and I salute what he has achieved. We can learn a lot from him. However, I think that the whole argument, at this point, is about discriminating against people, and it’s being used as an argument very effectively. Our country’s constitution states it too. People see him, the person, not the legs! Enough said about that. But you are absolutely correct: Technology must not play a factor in enhancing performance. And anybody can see that they do and will! So, allowing this will then open that door where technology makes or breaks the athletes. So, in 5 years time you will probably have athletes lining up, each with rocket propelled shoes. Once again, great article. Dr. Tertius Kohn

    Anonymous said...

    A very interesting article, but, has anyone considered the fact that anatomical legs are in "one piece", prosthetic legs are only attached in some way to residual limbs, a small shifting of the sockets makes a huge difference in the foot alignment - and makes the prostheses extremely uncomfortable, and even a little pistoning increases energy cost?

    Peter le Roux said...

    Thanks for this article.

    It would be interesting to compare the improvement in world record times for able-bodied and double amputee athletes over time, and see what the improvement is like. If there is a large jump in performance corresponding with the introduction and improvement of the Cheetah prosthetics, it speaks to a correlation between the technological improvement and the performance improvement. If it's possible to look at improvements by athletes other than Pistorius when they begin using these prosthetics then it might add weight to this analysis.

    An example of the kind of 'jump' that has a technical basis is in the high jump- looking at this graph from Wikipedia, the revolution sparked by Dick Fosbury's flop technique is clearly visible. I imagine a similar jump can be observed in the pole vault relating to the introduction of energy-storing poles (fibreglass, aluminium, steel etc.) and also the backwards 'jump' associated with the re-design of the javelin.

    There is still the possibility that an athlete is just far beyond their competitors in a particular field- Bob Beamon's long jump and Sergey Bubka's dominance in pole vault are an example but I'm guessing these are statistically different from the improvement due to technical and technological improvements.

    Ross Tucker and Jonathan Dugas said...

    Hello everyone

    First of all, thank you very much for your very thoughtful comments. This is exactly what we like to encourage at The Science of Sport, so it's a pleasure to try to respond.

    I can only agree with Dr Kohn that Oscar is still an amazing athlete - that is unquestionable and not up for dispute. And he has inspired many others, both athletes and non-athletes, and one should not ever detract from that. But whether he is a 45 second 400m runner is another story, because this MAY be a function of the technology which has allowed him to run these times. This is of course one of the points to be made. But bigger than this is the impact of technology of running, and rocket shoes aside, I just don't want to see a situation where times come down drastically because of technology.

    Now, Peter (welcome back, Peter, good to hear from you!) makes the point that events have improved from this in the past. And he's right - pole vault, javelin (they even had to change the specs because people on the other end were in danger of being pierced!) and high jump all benefitted from technology. I guess the difference is that all athletes had this equipment, and this current situation presents the possibility that only some will benefit.

    And then finally, agreed that a little pistoning would increase energy cost, but they design the limb to reduce this as far as possible. It is perhaps for this reason that a 10 000 m runner has never succeeded on Cheetahs, but for an event lasting 50 seconds, I don't think that the comfort is an issue. In fact, the carbon fiber blades are designed to absorb shock (see the Ossur website for the details) so this means that a runner on prostheses may have LESS impact loading and less eccentric muscle work than an able-bodied runner. That's something I didn't raise the first time around, but also be a factor. All in all, I feel that the blade is designed specifically to enhance performance, and that's not a situation that I would wish to introduce to Olympic sport.

    Anonymous said...

    How about this for a good rule-of-thumb test:

    Humans with all of their limbs use the same legs all of the time - for running, walking, sitting, sleeping, etc.

    Does Pistorius walk around in his daily function wearing these Cheetahs, or does he use them solely for running?

    Ross Tucker and Jonathan Dugas said...

    Thanks for your comment. To answer the question - the Cheetahs are used solely for sprinting. IN fact, check out the following two sites, and you'll see telling pictures:



    These pictures show the change of legs. The issue with the Cheetahs is that they lack stability and you can't stand still on them for any length of time. I included that quote at the end of my article where the writer says how it's difficult to control the Cheetahs. That's the issue, and that's what Pistorius does better than anyone else. I certainly would concede that balance is a factor, and I tried to account for that in the post, I hope it came across.

    But I hear you on the legs. Of course, what they say is that runners also have special spikes to run in, and that in fact is an indication of just how much of an advantage the Cheetahs must give. Any runner who has ever run in a pair of sprinting spikes will say how the stiff sole makes a huge difference to performance. And now you have this situation where the whole leg is stiff, and designed to be springy and elastic. That's not possible for anyone else.

    One thing that your question does invite is the whole thing about fatigue. Remember, an able-bodied runner slows down (or fails to speed up) because the muscle becomes increasingly fatigued during the race. What happens when that 'muscle' is "unfatiguable"?

    It means that Pistorius doesn't have to worry about losing speed as much as anyone else - all he has to do is drive the knee forward (which is easier, because the mass of hte leg is lower, as I've said in the post) and the bounce takes care of itself. For able bodied runners, the bounce and force that the muscle can produce just gets lower and lower as the race goes on.

    Thanks again for your post!


    Peter le Roux said...

    Here is a (loose) parallel: In 1997 Garry Kasparov, one of the greatest chess players ever, was beaten by Deep Blue, a chess computer built by IBM. Kasparov protested the outcome of the tournament, on the grounds that IBM's programmers were able to alter the programme between matches, essentially giving Deep Blue a 'new brain' from one game to the next.

    Is this very different from a runner who is able to improve the fundamental aerodynamics, mass and rigidity or flexibility of his legs by wearing a different pair of prosthetics?

    alan sleath said...

    What a great inspiration and role
    model he is for the global world of sport and that is what it should be.Let there be a poll for all the "athletes" concerned.The debate will rage on and the various bodies will decide but the end of the day Oscar will always be an inspiration to all

    Peter le Roux said...

    Oscar's race on Friday was great, and emphasised his finishing speed, overtaking several athletes on the final straight. It looks like the lack of control of the legs worked against him on a wet track on Sunday, though, resulting in a disqualification for running outside his lane, and also in him crossing the line last.

    I'm not too familiar with international rules, is it required for all athletes to use starting blocks for timing purposes? I wonder whether he might not be better off starting from an upright crouch.

    Anonymous said...

    Ross and John, this is a fantastic article and one that does a great job summarizing both sides of the issue. This is not a black and white issue and one that might puzzle scientists for years to come, but this article certainly gives a good start as to some of the issues present. Again, it is extremely important that technology does not play a role in athletic performance and one that needs to be actively addressed.

    A comment on the prosthesis itself - while they design the leg to reduce pistoning as much as possible, it is never truly eliminated. I realize that everyone is already aware of this, but might not be aware of how large an effect this actually has. In a high power/high impact sport such as sprinting obviously the effect of pistoning will be exponentially higher than a normal person under walking conditions (for which the majority of studies currently exist). The body does not truly accept the prosthesis as it is an external device. This means that, regardless of how much 'mass' you're losing on the body, it could still take the same or more energy in simply walking with the socket system (ask any amputee and you will find that they get tired much faster than a normal person even doing simple everyday activities... an indication of the excess strain on their bodies). The way I understand it is that losing body mass through amputation does not represent a linear model... Said another way, losing 6 kg of leg and adding 1 kg of metal does not mean you are 5 kg lighter in terms of energy efficiency, there are too many other factors present. A lot of energy will be expelled to use this prosthetic 'tool' to run or even walk (a leading argument for procedures such as osseointegration to remove the energy losses and skin breakdowns associated with a socket).

    Possibly just as important though as this pistoning motion, is the cognitive energy associated with simply donning a prosthesis. The proprioception is significantly less for an amputee, who has no feedback to find out where their prosthesis is in space. This leads to falls and unbalance (also as previously mentioned). Again though, while this lack of proprioception might have a minor effect on walking in normal people, for Oscar to sprint at full speed it must take incredible mental strength. Not only must he focus on his sprinting and race strategy (which is enough for most athletes), he must watch out of the corner of his eye where his feet are at all times and plan accordingly for the corners of the trac (vision is the only feedback to see where his legs are in space). It is my opinion as a runner that no amount of training could overcome this. Not sure how this could be measured, but again many studies exist to show that cognitive energy is significantly higher in amputees who have to watch their prosthesis every step of the way.

    Another point to bring up is that a prosthetic device (specifically with a socket) greatly limits the range of motion through the hip joint. In the case of a bilateral amputee, this would cause further limitations as both hips are affected. Combined with the overuse of the hip flexor muscle group (which hasn't been stated but I do believe this would occur with Oscar), I would bet the farm that's where his back problems begin and end (and why the pain probably will stay with him for awhile). In this overuse scenario, the legs are not working the way they were designed by mother nature, and the hip flexors/glutes will be overworked and fatigue, not being able to keep up, causing the lower back muscles to compensate for lost power and the strain being felt through the rest of the body (my own personal opinion, having dealt with hip problems before during running).

    One last thing, I have been following this debate very closely as a non-scientist and have been impressed by the perspectives (such as this article) on the issue. Just remember though that Oscar is an athlete and deserves the same respect as any other athlete (not saying that anybody here has disrespected... just something to remember in the future). In my opinion, he does not have the obligation to prove anything to the scientific community unless he wants to (which I believe he does).

    Thanks for listening, please keep up the good work here! Fantastic article and fantastic discussion!


    Anonymous said...

    Just a few comments:

    Tendons have decent energy storing capabilities, but what they really accomplish is the ability of the locomotor system to allow muscle to act in the optimal range of the force-length and force-velocity curves which allows for work and power amplification and for adaption between different strides and running positions. Prosthetic legs cannot provide this which is a huge disadvantage.

    Another point that hasn't been highlighted in the media relates to the nature of the soft tissues of the residual limb. The musculoskeletal system transmits forces through bones to produce movements. In intact individuals, this is no problem because the bones can essentially be considered rigid bodies with little deformation. But amputees must transmit loads through the socket to the prosthesis. Picture yourself sticking your arm into a large bowl of jello. If you want to move the bowl, you have to slide your arm through the jello until you make contact with the surface of the bowl. Amputees essentially do this with every step. It's called psuedoarthridosis, and as you might imagine, can be painful and certainly results in a higher metabolic cost of ambulation.

    For further reading on tendons, see:
    Kubo et al. (1999) J Applied Physiology
    Ettema (1996) J Exp Biology
    Wilson et al. (2003) Nature
    Roberts (2002) Comp Bio and Physiology
    Roberts et al. (2003) J Exp Biology
    Roberts et al. (1997) Science

    Ross Tucker and Jonathan Dugas said...

    Hey everyone

    Fantastic comments! I love it! The whole purpose of this blog was to stimulate thought and debate and to go out on what might be controversial limbs to get people thinking. And sure enough it's happening. It's taking far too much of my time to keep responding, so please forgive me for being slack in doing so, but a few comments now:

    First, thanks to Spencer. I've had a few email chats since, but Spencer has really helped out enormously.

    Then to anonymous, points taken. The problem here is that you highlight how difficult it is for Pistorius and his team to get the setup of the limbs right because of this movement and force transmission through the soft tissues. This opens up all sorts of ramifications, because if for some reason this could be improved, perhaps by better shock absorbing properties of the prosthetic limb, then suddenly we MIGHT see a 1 second reduction in time. So the issue, as I've tried to emphasize, is not that there are disadvantages and advantages, because clearly there are. Rather, the issue is whether the introduction of this technology to the sport will affect how we interpret performance - next time Pistorius runs a 400 m race and improves his PB by 1 second, how do we know that it wasn't a change in the limb setup, or a better design in shock absorbtion, or perhaps new materials? That's not a situation I want to see and I can't see the IAAF wanting it either. ANd that's really important. So I think it's acknowledged that there are disadvantages, but there are advantages too. Will we ever know which outweighs the other? i doubt it - my instinct says advantages wins, others will disagree and that's fine. But what I can't see as being fine is that this technology introduces a massively influential variable into the performance equation and that won't do.

    Thanks again!

    venom986 said...

    A point for consideration:

    The human leg, and its underlying musculoskeletal system, has evolved over millenia. The technological advancements of the prosthetic is still playing catchup; this is why you see substantially more world records being broken in paralympic competition.

    The human body is an extremely efficient and evolved machine; one which technology might not ever be fully capable of emulating. An abled body runner utilizes all of the muscles in their hip, uper and lower leg, as well as the tendons and joints of the leg. Oscar must achieve that same power using only his hips, upper legs and knee joint. The question to be asked shouldn`t be ``Do the Cheeta`s give a passive return of energy due to their springlike nature``, but rather ``Does the Cheeta`s passive return of energy surpass the energy developed by a biological leg``.

    I also have to agree with many of Spencer`s comments. This is a much more complex question than simply looking at the effect of the loss of mass due to the lack of lower limbs and the difference in energy return of the springlike nautre of the cheetah`s. There is a complex interaction that must be fully understood and studied before one can determine whether Oscar is at an advantage, a disadvantage, or on a level playing field with able bodied athletes.

    Ross Tucker and Jonathan Dugas said...

    Hi Joel

    yes, I agree with much of what Spencer has said as well. But the key points that you raise are in fact very incriminating AGAINST the fact that Pistorius be allowed to complete.

    Firstly, you write that: "The technological advancements of the prosthetic is still playing catchup; this is why you see substantially more world records being broken in paralympic competition."

    This is exactly my point - in fact, it's one of the most important points I have made in ALL the posts. You cannot seriously be telling me that in 10 years from now, maybe even 2 years, you would accept a performance of a guy running on Cheetahs when he goes out and runs 35 seconds! So the point is that the potential for technology is precisely the reason it must be prevented.

    The second thing you write betrays that you have really missed the point of all the posts. For you say that "The question to be asked shouldn`t be ``Do the Cheetahs give a passive return of energy due to their springlike nature``, but rather ``Does the Cheetahs passive return of energy surpass the energy developed by a biological leg``."

    First of all, this is an impossible question to answer, the way you have put it. How do you propose we establish that? Secondly, you have again missed the point. Because what you, and a number of others have missed, is that this is not a debate about Pistorius NOW. I HAVE NEVER BASED MY OPINION ON THIS MATTER ON THE SPECIFIC SITUATION OF PISTORIUS. If I had, then I would be arguing that Pistorius should not run for a number of other reasons.

    Instead, the ENTIRE argument, which is laid out in this and other posts, is that the Cheetahs have this design to offer passive energy return. Therefore, any development in technology stands to IMPROVE this return and thus eventually outstrip the human leg.

    Finally, if you actually look at what happened when Pistorius ran his first race, you'll see what can only be described as a "unique" pacing strategy. This vinidicates much of the argument I have put forward, but still, the key is the future, and many have missed this point. But your opening paragraph in particular, emphasizes quite nicely why Pistorius should NOT be competing.

    Ross Tucker

    venom986 said...


    I think perhaps you missed my point. Until the technology reaches the point where it outstrips the potential of a biological leg, it is simply a tool compensating for a disability.

    In 1904, George Eyser won the gold in gymnastics while competing on a wooden leg. One argument used against allowing Pistorius to compete is the reduction in lactic acid buildup in his missing muscles. George Eyser provides precedence for discounting that argument.

    In 1984, Neroli Fairhall competed in the archery events of the Olympics. Neroli was a paraplegic, but was allowed to compete despite the fact that she was seated while able-bodied competitors had to stand.

    Although I admittedly initially felt that Oscar should be allowed to compete, I have fallen back on a more reserved opinion. That of reserving final judgement until an actual scientific and engineering study is done to determine whether the Cheetah out-performs a biological leg.

    Ross Tucker and Jonathan Dugas said...

    Hello Joel

    Thanks for the reply. I hope you get this one as well...

    My point is that the POSSIBILITY that the technology will eventually catch up means that the decision taken NOW must be to prevent the use of the prosthetic limbs. Your previous point was that the technology is still developing - I agree. Therefore, in 10 years, there is no guarantee that the new and advanced Cheetah will not be better than a human leg.

    What we CANNOT evaluate NOW is whether the Cheetah is currently better than a human leg. But that's not the key point. Rather, we should be asking whether the introduction for this technology has the POTENTIAL to improve performance, and I do believe this is a very simple answer - YES.

    Now, the point about George Eyser is interesting. I'm not sure of the merits of a wooden leg vs. human leg in gymnastics, but one thing it does not do is prove anything about lactic acid. The idea that lactic acid is involved in the development of fatigue is first of incorrect - there's no basis for this. And so when Pistorius and his team use this argument, they betray a lack of basic physiology knowledge. Lactic acid does not influence the fatigue process, Pistorius' argument is wrong. It was never my argument. In fact, I was actually saying that the lactic acid was never the problem to begin with, not that this was where his advantage would come from. So I think you may have missed the scientific relevance of that argument. Pistorius used it, but should not have - it was one of those that I was critical of.

    And then the comparison of an archer who was seated is an interesting one - I dare say that would not happen now, there'd be a good case for that being an advantage. But the Pistorius situation is still different, for here, we are talking about a device that may actually confer an advantage THAT CONTINUES TO DEVELOP AS TECHNOLOGY DEVELOPS. That's the key - you cannot introduce technology that confers an advantage.

    lastly, have a look at the very latest, most recent post I did on the topic. In it, you will see pacing splits from his debut 400m in Rome and you'll see splits that have never ever been seen in a decent 400m race. If that does not provide evidence of something "unusual" (a euphemism for suspicious), then I'm not sure what would.


    Anonymous said...

    I see the main point that it's all in the technology (or mostly) and that as it improves, so too will Pistorius. But have you considered that maybe it's just leveling the playing field? Consider the 1996 Atlanta example. It's very possible that an equal handicap to match the 1996 prosthetics for Wariner would not be spikes from 1996, but rather lead boots. Or to be more generous, shoes from 1800. Because serious athletics prosthetics have been around for so little time, they are improving rapidly, just like any new technology. That's why the times are improving so fast. So instead of an unlimited technological advancement which will see, as you say, a 39.5 second 400m, perhaps we are just nearing the limits of technology, as prosthetics approach real legs. 20 years ago they were way behind, but have improved rapidly to be (arguably)just slightly behind. Why assume that they will continue to improve at that rate instead of plateuing off as they approach what real legs can do (just like shoe technology improvement has slowed). Perhaps we will see a 1 second improvement over the next few years (which may not be due to the prosthetics, rather Pistorius' maturing (he is still young) or training zeal (making the Olympics as a motivator)) but that may be all there is for prosthetics technology to improve as it catches up with the rest of athletics technology.

    Does that make sense? It seems hasty to say that since the technology has improved so rapidly, it will continue to; and that is why Pistorius is suddenly fast, and further cannot be allowed to compete.

    Thanks very much!

    Ross Tucker and Jonathan Dugas said...

    Hi Edward

    Thanks for the comments and the readership.

    A few key things in response to your post:

    I don't think my argument rests on the premise that technology will continue to improve as rapidly as it has been. It's irrelevant how quickly it happens - all that matters is that it will...

    The argument I make, that the potential for technological advancements means one should not allow Pistorius to run does not depend on how quickly those technological improvements are made. It doesn't matter whether the improvements happen at the same rate - that was never the issue. The only issue is that improvements are still possible, and at a MUCH higher rate than in the able-bodied runner.

    And in fact, your argument actually contradicts itself, because if the technology of prosthetic limbs is in in its very young stages (which we both agree it is), then the chances of it levelling off any time soon are far lower than for the technology of the able-bodied athletes. For that reason, your argument could very well become a reason NOT to let Pistorius run. At first, reading your argument, i didn't understand it, because you say that we are approaching the point at which the "technology is levelling off". I disagree entirely - the fact that the technology is still new means it's nowhere near levelling off. Of course, over the years, it will slow down, because that curve does flatten over time, but it's nowhere near the limits already reached by the able-bodied athletes. This is like saying that the technology of the internet must be levelling off because the internet is relatively new - clearly it's not happening slowly enough. I still believe that if they allow the prosthetic limb, we'll see a sub 40sec in not too long.

    Secondly, you are already assuming the prosthetic limbs are not up the standard of normal legs - I maintain that they are. If you read the posts, you'll see ample evidence why Pistorius has an advantage. Of course these points can be debated, we welcome that here at the Science of Sport, but the bottom line is that when Pistorius ran in Rome, he produced a 400m race that was never seen before, and to be blunt, physiologically impossible. That suggests to me that the Cheetah prosthetics are already conferring an advantage. So to suggest that the technology is bridging the gap is in my opinion, incorrect - I believe the technology is EXTENDING the advantage, not closing it down.

    As for whether a 1 second improvement over the next year is due to Pistorius' zeal and motivation or his Cheetah Prosthetics, all I can say is...Prove it! Because you can't. You will never know if the athlete has improved because of training or because of technology. At least when you watch Jeremy Wariner, you know that (most) of his improvement is training related (or dare I say, in many cases, doping!). But you can't prove this when it comes to Pistorius - a new design here and there, and you have an Olympic Champion, thanks to the wonders of modern engineering. So again, can anyone prove that there is NO advantage? If you can't, then I'm afraid I can't see how he can be allowed to run.


    Anonymous said...

    Thanks for the reply, I can definitely see what you're saying. Although, I think it's impossible to say what stage of technological advancement we are at with anything; we just don't know until it happens. Sure, it's fair to say that because the tech has not been around for long it's in its infancy. But then again, it's harnessing a lot of the technological advancements already made, so what may have been a 50 year progression 100 years ago is now only a 10/15 year progression. Still, impossible to say.

    But it's true I had assumed that the prosthetics were still laging behind fully able legs. And this makes it interesting. Then the debate moves away from tech and to whether he has an advantage NOW or not.

    I agree, having watched the Rome race. In fact, I watched it before finding this site, and the first thing that struck me how well he finished in the last 100m. I went from sympathising with him, to starting to be suspicious.

    So I have two more points to make. Is it possible that while most 400m runners slow down over a race, this being the most effective strategy, Pistorius, because of his start, is in a position where he is forced to almost jog the first 100m. In that case, a fast finish is inevitable?
    And watching the race, I really think he looses more than 10m. The other runners roughly keep the stagger for the first 200m, give or take, except Pitorius, who slips back 4 places, a distance of more like 25 metres.

    Finally I want to suggest why we are in this unique situation of arguing this point. I say it's pyschological. Because while running 46 seconds, Pistorius is at the exact point where one would think "he is as good as any able bodied runner, but has a 1-2 second disadvantage". Unfortunately there are a few psychological errors at play here. 1) Because we are used to able bodied runners, when we see someone different, we natually assume they are weaker. Those who are different to us are assumed to be, amoung other things, worse at what they do. Unfortunate, but true; it's evolutionary. And at 46 seconds, Pistorius plays that role of being slightly slower perfectly.
    2) Also, and slightly related, because Pistorius is 1-2 seconds off the pace, BUT is running in an open elite meet, we subconsciously assume he must be as good as the rest; and therefore his times reflect his handicap. We don't entertain the possibility that instead of being a 45 second runner who is handicapped, he may be a 49 second runner with an advantage. And really, it's impossible to ever know.

    I put this out there because people tend to overlook the psychological causes behind reasoning, which is fairly interesting. With Pistorius, it all hinges on his running 46 for the 400m. The psychological causes become clear; when you look at his 100/200 races, you want to say that he is disadvantaged, because he is so far behind the rest. There's no psychological uncertainty in his position.

    But if he stepped up to 800m, looking at the way he runs and taking some of your postulations to heart, its possible he would break 1:40. And if he did, there would suddenly be no contest, he would never be allowed to run, and his advantage would be clear. It's my guess that he knows this and will never run an 800m because of that (maybe he already has in training?). But while he stays at 400m the uncertainty, where he is just on the edge, provides him with that unique position. If he were running 50 seconds, we would probably say he was disadvantaged; if he ran 42 we would say he has a clear advantage. Its the 46 that causes us the psychological uncertainty that puts us in this position.

    I hope that all makes sense, it may be a little long winded. I suggest the only way of knowing is to get Pistorius to run a 600m or 800m race!

    Also, you said somewhere that you wanted to know the tests the IAAF were running. Incase you haven't seen this already, they're outlined here:
    Results soon hopefully!


    Anonymous said...

    Thank you for your comprehensive evaluation of this thorny situation. In the wake of the IAAF ban on Olympic competiton for Pistorius, there is much confusing and conflicting information in the media. I appreciate the logical way in which you examine the issues. I suggest we look to Kurt Vonnegut for a final solution, a la "Harrison Bergeron".

    Anonymous said...

    A few more thoughts/questions on a tough issue:

    Would you let Pistorius or anyone else in a similar situation compete with able-bodied athletes if it could be proven that their prostheses--which, let us remember, help them overcome a disability--could be proven to match them with their able-bodied competitors?

    Will/Should Pistorius be prohibited from competing at ParaOlympic-level meets now, because his false legs out-class even able-bodied runners' legs, never mind those of other disabled athletes?

    Rocket-propelled shoes may be a bit of hyperbole, but let us think clearly about technology in sports. Yes, it is conceivable that there will be "improvements" to running sneakers. (Aren't we supposed to want to jump like Mike Jordan?) But where is the line? Where is the line in swimming now that full-body suits supposedly give an edge over Speedos? Unless we return to the good old gymnosophical (ie. naked) standards of ancient Greece, we will have to consider the interactions of athletes' bodies and any number of technologies (including hormones, diet, etc.).

    But really, are you afraid runners are going to start amputating their legs in order to enjoy the benefits of Cheetas? No? So there must be some disadvantage that Pistorius has had to overcome to get where he is. I hate the "overcoming" model of disability, but it really does look like, in this instance, Pistorius has earned the right (partly through his training, partly through his particular kind of technology) to try out for his country's team.

    Ross Tucker and Jonathan Dugas said...

    Dear Chocolatta

    Thanks so much for the complimentary words. Always good to hear - we've tried to be logical and objective and stick to the science, which is where the media differs, as they have capitalized on the human-interest aspect, at the expense of the science (which was the reason for the blog's creation, incidentally). But a very thorny issue, and any debate is good.


    Ross Tucker and Jonathan Dugas said...

    Hi anonymous

    If it was possible to prove that the prosthetics conferred no advantage, then yes, it would be feasible that the athlete could run against athletes on a level playing field. But there are three problems with this (actually more, but we'll summarize into three points):

    1. The practicalities of implementing this type of law are impossible. For one thing, he would have to be tested in this same way every single season to ensure that the blades had not altered. The problem with this, apart from the lack of resources to do the testing (it's highly specialised) and the cost, is that the testing circumstances must be identical to allow the comparison each time. If you then start testing other athletes, then you need to take into account their mass, height, limb lengths etc. because all this will alter their mechanics and hence the design of the "zero advantage" prosthetics. I can't see that this is possible to enforce - it turns the sport of athletics into Formula 1, where a team of independent engineers must assess the limbs constantly to ensure they adhere to the guidelines.

    2. The second point, leading on from this, is that if you allow the technology, then other athletes would have access to it too. I have little doubt that Nike, Adidas, Mizuno and the like are currently looking at this situation saying "Hey, if this guy gets 30% advantages, and our elite athletes only need 1% to make the difference between winning and losing, then we need to integrate THAT technology into our shoes". It would be quite easy, in principle, to ban this in those shoes, but now all the athlete's equipment would have to be checked as well. It comes very messy.

    3. The final point is that if we suddenly design limbs that confer ZERO mechanical, elastic or energetic advantage, then, and I hate to bring it up, but we would not be having the debate at all, because Pistorius would be running a 400m time in the 50-second range. Difficult to know how much he'd slow down, but we're talking seconds, not milliseconds. So suddenly, the whole issue would become a moot one - he'd be running a 52-second race, let's say.

    Now, in the next 10 years, perhaps, an athlete would appear who can run 46-seconds on the "zero advantage blades" and then the IAAF would need to consider how to allow the athlete to run. I'd have no problem with that, but I can pretty much forsee that the sport would go through a very difficult time with all athletes objecting and complaining and pushing the boundaries themselves.

    But in theory, no problem with it. it won't happen in this case, though.

    The final point you make about an athlete earning the right through training and technology is very dangerous. Marion Jones "earned" the right to win 5 Olympic Medals through her training and the controlled use of drugs (also a passive performance enhancer, but still one where you need to train to enjoy the benefit).

    So too, half the world's cyclists are training harder than any human should and can, but they earn their right by using drugs and combining this with 5 hours a day in the saddle. I'm just making the point that you don't "earn" your right by using technology that only you have access to. Here's an example - a swimmer was once banned because he sewed his fingers together to create a web to enhance performance. That, to me, is clearly different from wearing a newly designed costume that is available to everyone who walks into the store. That's the line - is it passive, is it available to only a select few, and does it provide unnatural advantages? In this case, all of the above.

    Anonymous said...

    Very well written and thoughtfully put together.

    What I found most appalling about most discussions on this topic was the amount of kneejerk reaction of people asking to "give him a break, let him compete because he's crippled..." which is just outright condescending.

    I'm in agreement with you on all points. I find people just haven't been looking at the issue clearly and using their "hearts" to think. Although I highly suspect, as I'm sure you do, that these prosthetic "blades" outperform natural legs.

    I have a strong feeling Pistorius' team knows full well the blades give him a clear advantage over other runners (under the right conditions). Just because a person is disabled doesn't mean they aren't willing to win at any cost possible. From looking at his videos, the way he wins just doesn't look humanly possible. I'll eat my words if I'm ever proven wrong.

    At any rate, the complexiy and cost of allowing performance enhancing prosthetics technology into the rulebook would financially break the system completely with each and every individual testing and confirmation that has to be done for each tech item brought to the competition.

    I'm looking forward to the ruling on this issue. Even if proven to not give clear advantages, I have grave doubts about allowing it as a general ruling.

    Ross Tucker and Jonathan Dugas said...

    Hi Suspecting

    Thank you for the email, great to hear from you!

    Just a very quick (and very important) word before I respond and comment - THE VERDICT IS OUT. It was announed on 14 January that Pistorius' carbon fibre blades have been banned, which confirms your suspicions (and ours, from this post, written last year in July). You can read the results of this decision by the IAAF at the top of this page - I've provided a link. Otherwise, just go to the right hand column of the blog and find the heading "Recent posts" and you'll see the two posts we did in response to the announcement.

    In any event, I agree with everything you've said. In fact, it was this emotional response, and the media's one dimensional portrayal of the issue that stimulated the posts in the first place. As I wrote on this post, I was involved in a TV debate on this issue, and it was one of the most frustrating experiences I've had. There was no debate. For every scientific statment or fact I tried to make, I was batted off with assurances that Pistorius was courageous and trained hard, so deserved his chance!

    And yes, he is courageous, and maybe he does train hard (that is subjective) and yes, he's a role model. But the point is that if these advantages exist, then he's a 52 second 400m runner, not a 46-second runner. Therefore, he should not compete simply because the media think it would make a great story and he feels they'd be discriminating against him if they didn't allow it!

    And then I absolutely agree that the Pistorius team knows they had a lot to lose by trying to bring science into it - it's the only reason I can think of for their reluctance to present scientific facts and their very weak arguments. For them, the battle was always going to be fought in the hearts, not the mind. I guess that tactic was to be expected.

    So don't worry, it does not look as though you'll be eating your words any time soon! We'd have been dining on them together!!!

    Thanks for the post, it was very well written and thoughtful!


    P.S. Check out the latest posts - the result is analysed, and you'll see that this argument from July is pretty much confirmed, word for word, as are your thoughts!

    Anonymous said...

    To Jonathan Dugas and Ross Tucker 23rd January 2008

    Oscar Pistorius’ prosthetics

    Hello. I am new to this debate and much impressed by its confinement to the scientific issues (if I disregard whether or not psychology is a science).

    Incentive clarification

    Mine is that, although no athlete myself, I do run, and athletics has been my main sporting interest for over 65 years. I agree that judgement of the case must be solely on the applied scientific issues. Even though a debate can have sides, it is not a contest. I have no vested interest one side or the other, and am prejudiced only to the extent of my understanding of mechanics.

    This is perhaps the stage at which I should add that, as I do not understand the arcane physiological terminology in the postings, I am not able to know whether I agree or disagree with some of them.

    Tests at the German Sport University, Cologne

    It seams from what you have posted about them, now completed, all we presently have is the conclusions. Whilst noting that, as you expected the prosthetics give an advantage over human limbs, you are unsurprised at that conclusion but surprised at its magnitude, I think, as I feel you also will, that the details of the report are needed before too much is made of its conclusions. I would want to know enough of the tests to be able to judge their appropriateness, the measurement values and the reasoning connecting the conclusions to those values.


    I note that, in your response of 21st October 2006 to Joel, you make clear the fundamental issue for you: that we cannot evaluate now whether the Cheetah is currently better than a human leg, which is not the key point. Rather, you contend, we should be asking whether the introduction of this technology has the potential to improve performance, and that you believe it has.

    What you are therefore contending is that, whether or not he has already done so, man can produce a more efficient two legged running machine than can, according to ones convictions, the good Lord or the processes of Darwinian evolution. Provided he does not wish to take part in sport, always leaves his house early enough to catch his bus by walking and does not live among thugs, modern man can get through his life without ever running a single stride. Our forefathers had to be able to run to survive. So, if springs as lower legs were better for running than calf muscles, ankles and feet, we would have them.

    My musing aside, the philosophy upon which you disallow the Cheetah stage of development has to be demonstrated, which I do not think you have done. If you have and I have missed it, do please correct me. So, if the philosophy has not been validated, specific examples that might support it, e.g. the Cheetahs, have to be. Accordingly, Joel’s point of 16th July 2007 - that “The question to be asked shouldn’t be do the Cheetahs give a passive return of energy due to their springlike nature, but rather does the Cheetahs’ passive return of energy surpass the energy developed by a biological leg?” - has validity because, provided the running is on level ground and in the same wind conditions, all of the energy therein expended has to be provided by the athlete.

    My concern over the question is different - that it is likely not answerable. That is why knowing precisely the testing methods used by Cologne University is important. The basis of comparison has to be between the forward propelling power developed by the wholly biological leg and that of the combined prosthetic/biological one - both have biological thighs. But the same thighs could not be used in the subject (Pistorius) and comparator athletes. So, however good the measurements of power production, I do not see how their apportionments between the thighs and calves can be known but, of course, am open to that being demonstrated.

    In one posting, a situation has been looked at by an analogy with Formula One motor racing. I too draw on F1 to illustrate the difficulty in establishing equivalence, or its absence here. If it were wanted to allow use of a gas turbine in a F1 car, how would its size to give equivalence to the 2.4 litre conventional engine be determined? They are the same to the extent that they are both internal combustion engines. But their mechanisms are so different that, I am sure, an incontrovertible basis of comparison would not be established, least of all agreed. The piston engine has a geometrically fixed displacement per revolution; the turbine has not. And their rates of revolution are fundamentally different, as distinct from specific design differences.

    Decades ago Rover ran a gas turbine powered car at Le Mans, where the foregoing issue did not arise because there was no requirement for engine size equivalence.

    As stated, on level ground and in the same wind conditions, Pistorius and a fully able bodied athlete are the same in that they both have to provide all of the energy for their running. (Pistorius’ ‘springs’ cannot be ‘wound up’ prior to the race for release during its progress.) But their running mechanisms are sufficiently different that, I am sure, establishment of an incontrovertible basis of comparison is not possible.

    Although you express it in a different way, I think that in your posting of 19th November 2007 in response to Edward we are saying pretty much the same thing. And Edward himself in his response to you of the same date - “And really, it’s impossible to ever know” - seams to be agreeing.

    It might seem from that - seeing the situation as irresolvable - I should here rest my contribution. But I do not for a few reasons. Because, Pistorius having been tested, and provided the tests were appropriate, an opportunity has been created for evaluating the theoretical musings. It should provide an answer, of incidental value to your philosophical case, for those concerned with Pistorius’ specific case rather than your broader one. For some it will have purely academic appeal.

    Also, although I agree that Pistorius has both advantages and disadvantages (both of which I am unable to quantify), I am not happy with some of the reasoning that has been posted.

    The biological and prosthetic legs running actions

    Yes, the Ossur website is, as you quote it, “effectively saying that the prosthetic limb is able to take the forces that are generated during landing, store them and translate this into forward movement. In effect the limb is able to propel the athlete forward.” Strictly speaking, of course, it is energy not forces that is stored and, surely, not all of it is translated into forward movement on recoil.

    Now, although you say that a human limb is similar in respect of being able to store energy, I am not clear as to how and where. In your jumping off a box illustration (sub-paragraph 2 of that paragraph) you write that almost all of the energy that might have been stored is lost. As, I presume, the Achilles tendon has elasticity, I also presume that such energy to which you refer as being stored is in it. But, as the tendon is very stiff, meaning that its elastic deflection will be small, its energy storage will also be small.

    Given that, whilst the drive-off from the prosthesis will be passively so from stored energy, that from the human limb will be from its active - meaning its muscle - contraction. So, as most of the impact energy going into the human limb is lost, talk of amounts, that might be 70 or 30 percent, of that energy being “recovered” is misplaced. It is not energy being recovered from a store into which it has been put, but being replaced from a new source - the active calf muscle. Provided the claim made by Ossur is correct, then Pistorius does have a contribution to forward propulsion, derived from energy consumption efficiency, that is not available from a human limb. Whether that amounts to a net benefit requires consideration of the contribution of the ankle and foot, equipment that Pistorius does not have.

    In sub-paragraph 1 you correctly write that, unlike as claimed for the Cheetahs, “A human limb cannot take a force in one direction and convert it to another without requiring muscle contraction.” Importantly, it so does in the case of the foot with the bell-crank action of the ankle and the jib action of the toes.

    That this action is a significant source of driving force will be understood by those of a certain age who recall that, before Dick Fosbury came along with his ‘flop,’ when the ‘straddle’ was the high jump technique of choice, jumpers added a thick block to the forepart of the shoe of their drive-off foot to increase the range through which that force is applied. It was quickly banned.

    So Pistorius has muscles that generate significant driving force in a fully able bodied athlete but which he is denied use of.

    You interpret his having redundant muscles as a potential enormous advantage on the basis of absence of metabolic cost and related fatigue when running because its energy cost “may” be reduced. Now, if Pistorius is able to switch that reasonably presumed energy saving to all other of his muscles used in running, then a net benefit to him seems a fair conclusion. But there is no hypothesis that that is possible, and not enough is yet known of the Cologne tests for it having been shown to be a reality. But, if he is not able to make that switch, he is at a disadvantage because he has energy that he is not able to make use of. That he might, or actually is, using less energy overall is of no benefit to him. It is not the objective of racing to cross the finishing line with more unused energy in reserve, because of its unavailability, than have your opponents, even though loosing. If giving all that you have got is necessary to win, you do it and, if prevented by some physiological deprivation, then a feeling of being disadvantaged is valid.

    An analogy with motor vehicles is again available. If a four wheel drive vehicle is deprived of the drive to one of its pair of wheels, then it will not be able to cross difficult terrain as quickly and, as a result, will use less fuel and consequentially, on one definition, could be correctly said to be more efficient and thus at an advantage. But, against the objective of getting across the terrain as quickly as possible, it is not.

    Thus, on this springs-v-muscles aspect of the issue, I see Pistorius as having a clear disadvantage as well as the advantage you detail. How the two weigh against each other I do not know. And, for the work in Cologne to give any clarity on that, its measurements will have to separate the forward drive from the runners feet contributed by their lower legs from the contribution of whole legs, which I cannot see how they can do.

    Reduced limb mass and stride frequency

    This is the clincher. It is incontrovertible that Pistorius has a significant advantage. The only issue is its magnitude.

    Estimation of the advantage by quantification of the relative lightness of his lower leg and consequentially of his whole leg is too simplistic. Because of the accelerating rotary motion of the upper leg about the hip and the even more complex motion of the lower leg about the knee which is under accelerating rotation about the hip, it is the moments of inertia of these members about their pivots that are the significant parameters.

    Again I doubt that the advantage can be estimated by measurements of energy consumption because that would require separate measurement of the consumptions for the accelerations and decelerations of the different parts of the leg, which I cannot see how it can be done. But I am open to enlightenment on that.

    So the general problem which concerns me - that, as much as we can theoretically compare the merits of the two limbs, it is fundamentally impossible, because of their different mechanisms, to establish an incontestable quantifiable comparison - has expression in this specific.

    Stride length

    This is a moot issue with its own ‘swings and roundabouts’.

    If the prostheses do simulate running on the toes, this can be seen as a disadvantage because they do not provide the stride length gain of the normal foot as it rocks from the ball upon which it has landed to the toes.

    As for the hypothetical locking of the hinge joint of a normal ankle increasing efficiency because it prevents its collapse, it is that collapse which maximises the range through which the drive of the calf muscle operates.

    Scientific rebuttal 1 - relative efficiencies of the two limbs

    Like you, I am at a loss to make sense of the comment you attribute to a scientist that the human Achilles tendon is able to release 240 percent of the energy it stores.

    You write that: “the human calf and tendon cannot take force in one direction and convert it into another” which, of themselves, indeed they cannot. But of the equipment set of which they are parts which includes the ankle, they can, which you earlier recognised with the qualification, omitted here, of “without requiring muscular contraction.”

    But the concept of limb efficiency is of dubious meaning. Efficiency is the ratio of the energy coming out of a system as useful work to that going in. Provided the comparator athletes are running on level ground, the only useful work output at constant speed is that in overcoming air resistance. All else is in the ancillary actions contributing to that, and in internal losses (heat). How are the energy inputs and air resistances of the different subjects known? And, of the inputs apportionments to the limbs, how are those and the outputs from the limbs known?

    The ‘unfatiguable’ muscle concept

    I know that you are not implying that the Cheetahs are muscles. But the energy they store and return is supplied by other of Pistorius’ muscles that are fatiguable. Now, if that energy were supplied by muscles which fully able bodied athletes cannot make use of, there would be an unfair advantage case to answer; but they are not.

    Your comment “For able bodied runners, the bounce and force that the muscles can produce just gets lower and lower as the race goes on” recognises that they make a contribution, even though fatiguing, that Pistorius does not have.

    So, yet again, it comes down to the validity of comparing two fundamentally different mechanisms and whether the tests really do legitimise and quantify the hypothesising.

    Anonymous’ 16th July 2007 comment

    I am again puzzled by the reference to the “decent energy storing capabilities” of tendons, as well as to their contribution to the “work and power amplification.”

    Anything having finite elasticity can store energy. If tendons were infinitely stiff, and so could not store energy, their function would surely not be compromised, they having finite stiffness being a reality of their structure, not a functional requirement. I wonder if what is really meant is energy ‘transmitting’, because they transmit its force component, not “storing”.

    The work and power is provided by the muscles and, as much as tendons are parts of the mechanisms that amplify or attenuate their force and displacement components, for there to be work or power amplification an additional source of energy is implied - but where?

    ‘Potential to’ becoming ‘does’

    In response to your contention that we should be asking whether the introduction of this technology has the potential to improve performance, which you believe it has, Joel writes (13th October 2007): “Until the technology reaches the point where it outstrips the potential of a biological leg, it is simply a tool compensating for a disability.”

    That approach leaves the problem of what is to be done when that point is reached. Do the powers that be freeze the technology at that level of development, which would, in effect, be specifying the “zero advantage blades” concept you use in your posting of 15th January 2008 in response to Anonymous? And how would they define “the” technology, bearing in mind that what we loosely refer to as “the” technology of a device is actually a combination of technologies?

    We could have a situation in which developer ‘A’ adds a feature which, making that fateful step, is disallowed. But developer ‘B’ already has it and has not overstepped the forbidden line because he lacks a feature used by ‘A’ which, if he then introduced it, would take his development over the line. It would be a legislator’s nightmare and, more seriously, divisive, as you suggest in your aforesaid posting, because both pieces of equipment would, by definition, incorporate features conferring advantage, but not the same ones.

    The problem with this particular issue is the concept of compensating because the prostheses are neither compensating nor correcting a disability; they are circumventing it, which is what makes the issue intractable.

    The acid test

    I refer, of course, to Pistorius’ unknown (at least in the public arena) abilities of distances above 400m.

    At World level (Olympic and World championships) there have been many examples of athletes winning at two adjacent distances: 100/200m; 200/400m; 400/800m; 800/1,500m; etc. But not at three in the modern era, as far as I am aware, although ability at the highest level at a third distance has been demonstrated. For example, Alberto Juantorena competed in the 200m at the ’72 Olympics, though not reaching the final, and went on to win both the 400m and 800m in ’76.

    So being the best at three distances would be something unique and, if Pistorius could be that, it would sent a powerful confirmatory message that the energy saving contribution of his blades is worth more than the energy use denial his impediment inflicts.

    If I am correct in believing that he is also a winner at 200m, even though not with the supremacy he has at 400m, then I see that ‘unknown’ 800m ability as a key measurement in settling whether the extent of the energy conservation feature of his blades is ‘unfair’. It is frank of Edward to voice the suspicion (posting, 19th November 2007) that his team may already know the answer.

    I trust that I have not been too nitpicking. Stanley Eckersley

    Anonymous said...

    I think it would be very difficult to come to a final conclusion as to what kind of prosthetic limb would completely match the biological limb in every aspect (and would therefore be "fair").

    Running on prosthetic limbs involves a very different set of muscles and differs from running on normal legs quite drastically; one could almost argue that it's a whole different "sport".
    Does the energy return outweigh the difficulty of balancing prosthetic limbs? Does the lack of lower-leg muscle usage balance the need for unconventional hip and knee muscle usage? With all the variables and differences between the normal and prosthetic runner, these things might not even be able to be compared.

    But--! If we cannot accept a prosthetic runner into competition with normal people on the basis that we "never can be sure as to how much advantage is conferred by (said) prosthetic", then will there ever be a time a prosthetic runner can run alongside a normal runner?

    Anonymous said...


    Great Blog. As a South African I am embarrassed by Oscar Pistorious. I feel that he is on a crusade to be famous for all the wrong reasons.

    If he was to run in the "everyday" legs rather than the carbon fibre legs this would be a different matter. I think the simple solution would be for him to use 8kg ballast on each carbon fibre leg. This might go a long way to getting him into the 2008 Olympics.

    Natalie Du Toit who has a leg missing does not swim with a leg fitted and she still wins without the use of science legs.

    Agreed Oscar is different by having no legs below the knew. Run in human shaped and weighted legs!

    Ross Tucker and Jonathan Dugas said...

    Hi Anonymous

    Thanks for the comment. You'll see if you read the latest posts on the subject (particularly the last two) that I too am becoming frustrated by the ongoing play for media time that is going on. To date, i've seen nothing that even suggests the science is important. Just today, in fact, there are articles reporting that Pistorius has done tests in Texas and has found that the IAAF result is wrong and now he believes he has the proof to challenge the ban.

    Trouble is, the tests are "hidden", and his lawyer even refused to reveal where they had been done, and by whom. So the shroud of secrecy remains, and it's been that way since this began - the IAAF on the one side are piling up evidence from the world's best laboratory, and Pistorius is dismissing it as having serious flaws. Well, what are those flaws, and where is the evidence to suggest he's right? To date, none is forthcoming, and I'm not holding my breath.

    It's clear to me that this whole campaign is financially driven, I agree with you on that note. There's so much that will unfortunately never come out, but there really is a lot going on behind the scenes that would embarrass the Paralympic committee on this one. Yet despite it all, Pistorius remains a role model, and I for one wish he'd adopt that position, instead of pursuing this with such a lack of nuance.

    As for Natalie du Toit, imagine if she strapped a prosthetic limb on and put a flipper at the end of it! Would people stand for that? Of course not, so why this issue? There's so much theory, evidence and data that suggests that Pistorius receives a massive advantage, and nothing so far to suggest he does not.


    Anonymous said...

    Hi Ross

    The latest test by the Pistorius camp is disgraceful. If they want to be believed then reveal who/when the tests were done.

    The IAAF is right not to accept the tests. He should just accept that if he wants to compete in the "normal" olympics then change the legs. I thought the uni-suit worn in the Ozzie Games was just as far a technology should go.

    An earlier post about Formula1 was right, that is why the A1 GP was formed, same cars. The skill is on how you setup the car and the race is decided by the skill of the driver. So should the Olympics 10 runners same shoes first to the finish wins. None of this hi-tech shoes and clothing. If you wear it so should all other runners in the race.

    Maybe we should go back to Olympia and do it sans clothing ie au natural. If it was good then, then it should be good now!!

    That will end all arguments about the technology in sport.!!!

    Ross Tucker and Jonathan Dugas said...

    Hi JP

    Thanks for the comments - can you imagine the Olympics without any clothing?! I wonder if TV audiences would go up or down...?

    In any event, the results announced by Pistorius today are even more peculiar, given the fact that Pistorius recently contacted certain institutions in SA to potentially help him with the research and testing. This was perhaps a week or so ago - that is, to me, a clear indication that there is no structured defence. All the papers and news stories that are reporting the "evidence" don't gel with the fact that his group was really "fishing" for possible research to help them out!

    So I was very surprised to actually read that someone in Texas had done work to prove the IAAF wrong. Note that the German research used by the IAAF is perhaps one of the best in the world, and the University of Cologne is perhaps THE BEST. So this university in Texas has proved the world-leader wrong - I'd love to know how, but I'm not holding my breath, because little in this story suggests that the science will be credible or even believable.


    Anonymous said...

    Hi Ross

    I wonder what Prof Noakes thinks about the whole matter, as fellow South Africans, this whole matter leaves a sour taste in the mouth.

    Prof Noakes is a leading expert in sports medicine and the Sports Centre is world class, where are they in this saga.

    Tv ratings would drop. Maybe Natalie could whisper in Oscar's ear he is making a toss of himself in the world.

    Ross Tucker and Jonathan Dugas said...

    Hi again JP

    I work with Prof Noakes, just two doors down the hallway, actually, so I do know his take on the matter. And while I would love to report it, I don't want to bring him into a pretty controversial subject unwillingly. All I will say is that his opinion is based on science and the available theories, for which evidence can be gathered. And then I'll leave it at that...

    And on the note of the other athletes, I'd love to know their opinion in a formal survey of some kind. I know 5 Paralympic athletes personally, and so far, 5 out of 5 are opposed to the campaign. Not a huge sample, sure, but then a few journalists have contacted me and reported other athletes who feel the same way. There was also a survey of the British Paralympic team about a year ago, and about 80% of the respondents opposed the bid as well - problem is, I can't find this article in the archives anymore (it was in an English paper), so it hasn't come up. But this all adds up to making something of a mockery of Pistorius' claim that he's doing this for Paralympic athletes everywhere.

    Again, though, evidence is required, either way...short of having it, I can't agree with your last statement, though it may be true, who knows?

    Ross Tucker and Jonathan Dugas said...


    Just to respond to your other question of "where is the Sports Science Institute in this saga?"

    You may have noticed in the article above that I do refer to having been contacted by members of the Pistorius group. About 4 years ago, there was very nearly a chance of doing some research, because it was widely being advised that Pistorius needed to have some scientific evidence to support his bid. Both Prof Noakes and myself were involved in this 4 years ago.

    Yet despite our suggestions and advice that evidence was required, none was ever obtained, and instead Pistorius embarked on what he called a "support generating tour" in the USA, where he met sponsors and funders and so forth.

    Since then, no involvement at all. I must point out that we couldn't possibly match the research done in Germany though - we have some great research here, but the equipment and the specialised expertise used by the IAAF in Cologne when Pistorius was tested is second to no-one, and it's the best of the best. As for Texas, I'm not so sure.

    But to answer your question, we're not involved, apart from what you read here, and that's not an official position by any stretch (though I was once asked to resign my position with the Sports Science Institute for suggesting that Pistorius had an advantage!) - such is the emotion of the issue, I guess...


    Anonymous said...

    Hi Ross

    Yes it is an emotive issue, in a way what he is doing is right, but for all the wrong reasons. He does not want to accept the fact that he is not "normal", by that I meen has two normal legs. With the help of modern technology he can compete. But the want to compete has driven him too far. The cheetahs are way too far as levelling the playing field.

    He must accept that he cannot participate in the Olympics as he is dis-abled, there are many people who would love to compete, for them it is only about having the funds to allow them to compete.

    Such as was the case with the 4 swimmers from the last games. Their disability was that they were too tall to travel cattle-class, having to travel from the US to Durban to compete in qualifiying races, some of them did not want to unless they could travel 1st class. I understand why, my brother is tall and the legroom in coach is tight even for me who is 5feet tall in socks.

    Life is not fair, that is a fact. Oscar does not want to accept this fact as far as I can make out!!!!

    Steve said...

    I am a single below knee amputee who has competed in Sydney and Athens in the 400m. You've made some interesting comments which I'll give my perspective on. Firstly, the technology hasn't changed in 12 years. I run on the Ossur 'Cheetah', and have since 1997 when I started running competively. Some comment has been made on Oscar running negative splits and how this is unseen in a quality 400m runner. The reason Oscar runs a negative split is because he runs a very conservative first 200m. Do some quick calculations on his 200m best vs his 1st 200m of a 400m and you'll arrive at 88% which is very conservative way of running a 400m. If Wariner was to run 88% of max first 200m he would go through in 23sec and be capable of negative splitting. Most top 400m runners go out in 92-95% which creates more lactic and therefore slow second 200m. In terms of the lactic build up or lack of it due to no muscles in the lower leg, I can only say that my experience is that my prosthetic side experiences far more lactic fatigue in the hamstrings and hip flexors than my good side. Admittedly I have a slightly different setup to Oscar in that I have to wear a silcon sleeve over my knee which reduces knee flexion, making a longer lever which obviously requires more work by the hamys and hip flexors to overcome. I believe much of the arguements look at the prosthesis in isolation and don't consider how the rest of the body has to adapt and work with the prosthesis. On the weight of the legs: I actually have placed lead weights on the prosthesis because as has rightly been stated, the legs by themselves are light. I find this a disadvantage and have weighted them in order to created enough momentum to cause a 'cyclic' action. Without the weight, the leg tends to move in a more pendulum motion which isn't helpful for speed. In summary I would say that I notice a clear disadvantage on my prosthetic side. This comes mainly from the extra effort required to generate knee flexion. As far as amputees competing at the Olympics, I would rather see 'pure' competition. There are far too many variables and questions that are very difficult to answer.

    Ross Tucker and Jonathan Dugas said...

    Hello Steve

    Thanks for the comments and inputs.

    Two things:

    Firstly, the concept that lactate causes fatigue is fundamentally flawed, so the whole model and basis for the slowing down is incorrect. there may of course be some other metabolite or chemical, but it's not lactate.

    Secondly, every single 400m runner in history runs a postive split. I agree that if Jeremy Wariner went out in 24 seconds, he'd negative split. But his second half would never make up the time lost in the first half, and his overall performance would be a substantial underperformance.

    So that leaves you with one of two possible explanations:

    Either Pistorius is currently under-performing by about 2 seconds. As a coach and a scientist who did a PhD on fatigue and pacing strategies, i can guarantee you that if an athlete wants to optimize their performance, they have to run the first half about 1.5 to 2.0 seconds faster than they can run the second half. Therefore, a guy wanting a 44 second time must hit halfway in 21 seconds, and run 23 for the second half. If he can run 22-22, then his best performance is likely a 43, if he runs 21-22. I hope this makes sense - the reality is that you cannot run an optimal race with this pacing strategy.

    The second point is that if this is Pistorius' deliberate strategy, then he'll go out and run a 44 second time if he just gets it right. In that case, his coach should be fired, because the idea that you should save something for the second half is so incorrect it deserves as much.

    Finally, considering the overwhelming evidence that says that optimal performance is achieved with a faster start and slow second half, it's quite clear that Pistorius doesn't have this problem, and should be banned on the basis that he displays what can only be called immunity to fatigue.


    Steve said...

    Hi Ross,

    I agree entirely with your comments on 400m pacing. I don't believe Oscar has immunity to fatigue, in fact I've seen him fatigue in a 200m race to the point where he nearly fell over. A fear of this fatigue maybe the reason that he doesn't push himself into that red zone where he has to control his balance. It's embarrassing to admit it, but I actually fell over the finish line in the Athens 400m final because the fatigue on my prosthetic side meant that I clipped the ground with my prosthetic toe due to a lack of knee lift. This is the kind of fatigue that I know and it is generated by the extra work I'm doing to try to keep up with my good leg. The first time I saw Oscar run a 400m, I thought he could run alot faster by going out harder, but he hasn't a yet.

    Just on the pacing issue itself: Oscar runs about 21.4 for 200m yet goes through in 24.4. This is 87.7% of his max. If Michael Johnson went out in 87.7% of his max. it would be 22.0sec. I read that he actually came home in 21.9 in his world record run off a 21.2 1st 200m. You would expect that he could run a 21.5 2nd 200m off 22.0. Given that Oscar has such a slow start and his 100m and 200m times aren't a real indication of his top end speed, I don't find his splits so abnormal in terms of fatigue - just a poor tactic to run a fast 400m.

    Lastly on lactic acid. All I know is that lactic acid is a by product of oxygen deficit. Whether the lactic causes my pain or is a spectator I don't really know but the levels in my system go through the roof when I run at intensity over 200m. I think most 400m runners express this fatigue as 'lactic' whether it is technically correct or not.


    Anonymous said...

    you are being unfair. If swimmers can use specially designed swim suits, and tennis players can use specially designed raquets, then why cant he use specially designed legs. he loves to run and is no different from any other sprinter who dreams of being in the olympics. the difference is, that he is able to do it and they wont let him because of somthing he can not control. It is only a few steps away from not letting people of a certain racial, religeos or polictical group compete.

    Anonymous said...

    excuse me? u said that if u land on the floor u dont bounce. well i, being a kid, notice little things that adults tend to overlook and take PLEASURE in wierd little thinks like bouncing. when u jump u bounce after u land. even on a marble floor. i tried it, its very slight and u dont reli notice it cuz u steady urself at the same time so when ur feet land it feel diliberate. u bounce, reli. Maybe were not as different from fake legs as u think.

    Ross Tucker and Jonathan Dugas said...

    Hi to both anonymous posters

    To the first one, your analysis is far too basic - you're ignoring so many of the major issues that your argument is very clearly an emotive one, and you haven't thought through the ramifications of competing. This is not nursery school, where everyone gets a chance. Your logic can be used to say that drugs should be allowed in sport, because some people are born without the natural ability and so drugs to help them is fine - after all, they love to run or cycle. So give them a chance! Not quite this simple, I'm afraid.

    Then to the second one, thanks for the message, maybe next time you can use full sentences, it's difficult to understand your SMS language. In any event, your experience is interesting - maybe one day, you'll get to bounce on the carbon fibre blades called Cheetahs and then you'll really know the difference.