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Sunday, June 03, 2007

Oscar Pistorius - should he be allowed to run?

Check out our latest article on Oscar Pistorius (published 11 July) HERE

And: An Open Letter to the IAAF on Oscar Pistorius

You may have seen the picture of the day for the last while has been one of Oscar Pistorius, a South African Paralympic athlete, who runs on prosthetic limbs appropriately called Cheetahs.

Pistorius has been in the news recently because he is a man on a mission - he wants to be the first person to compete in the able-bodied Olympic Games without legs! In order to do this, he would have to run an Olympic qualifying time (established by the IAAF, the governing body for athletics). That may not be an unrealistic target, for his best at the moment over 400 m is only about 1 second off this! He is the current world record holder for double-amputees, and won the Olympic 100 and 200 m titles at the Paralympics in Athens.

The counter argument to all this is that the limbs he wears provide him with an unfair advantage, and the IAAF has stated that they do not consider it fair that he run in the Olympics unless it is proven that they do not give him some advantage.

So what do we as scientists make of Pistorius' claims to Olympic glory! I will begin by nailing my colours to the mast and then arguing the reasons thereafter. I do NOT believe he should be allowed to compete in the Olympic games for able bodied athletes. I am of the opinion that it is more likely that his prosthetic limbs give him an advantage than not, and so the burden is on him to prove that they do not. Up to now, he has not done so (for reasons we'll discuss subsequently), and so while I hate to rain on his parade, I think he should be blocked from competition, and would argue that from a scientific point of view.

Like all stories, however, this one has a beginning, and it came in 2004, just after he burst onto the scene at the Olympics in Athens. I happened to be coaching another athlete at those Olympics, and so my name somehow landed in the lap of a journalist who wished to write a story on him. She asked me whether I felt he would ever be able to compete with able-bodied athletes. My reply was that given the logical scientific argument that his prosthetic limbs were likely to assist him, the answer would be YES. I did say however, that he should consider stepping up to the 400 m event (up til then he'd only run 100 and 200 m). He duly did this (I don't know if I can take credit for that!!!!), and has gone on to threaten Olympic qualification.

Once Oscar's public relations team got into full gear, I received a call, this time from camp Pistorius themselves. They wanted me to state that he DID NOT RECEIVE an advantage from his legs. Of course, I debated this with them, and said that more than likely, he did receive some advantage, all that remained was to measure how much. Needless to say, this idea went down like a lead balloon, and I was not contacted again!! They did however contact Tim Noakes to ask the same question. His reply was much the same, and that was the end of our contact with team Pistorius!!

But on what basis have I formed my opinion. There are 4 things that I believe explain why Oscar should not be allowed to run:

1. The material used to produce the limbs is stiffer and therefore more likely to harnass elastic energy than normal limbs. remember, shoe companies are trying to make sprinting shoes as stiff as possible, precisely to reduce the amount of energy that is lost on impact and subsequent push off. Oscar would theoretically lose less than others.

2. The build of metabolic by-products would be greatly reduced by having such a reduced muscle mass. Remember that one of the key factors that prevents humans from running faster is that the brain is protecting us from damage that would be caused by such metabolite build-up. Oscar must have less than normal people, allowing a faster running speed.

3. Simple biomechanics - a prosthetic limb must weigh less than a normal skeleton and muscle and so to accelerate his limbs would require less effort than it would for you or I, resulting in greater stride frequency.

4. Casual empiricism, which is a fancy way of saying basic observation. I watched tapes of Oscar winning at the Paralympics and every single race he ran, he was about 15 m behind after the first 40 m because his start is so slow due to the lack of balance compared with people who have only one prosthetic limb. Yet he catches up, running 10.9 seconds to their 11.1. If you do a basic calculation, you can work out that he is about 1.5 seconds behind at 40 m, and then wins by 0.2 seconds. this means he covers the last 60 m in 1.7 seconds FASTER than any of his rivals. If his rivals cover 60 m in about 6 seconds, that means his last 60 m are faster than Asafa Powell and Justin Gatlin and Carl Lewis could ever run!!!! He's the fastest man on the planet when it comes to maximum speed, and that's just not explained unless he has an advantage!

Finally, you just have to look at the length of his strides to see the advantage. His strides are easily 2.5 to 3m long, when most able bodied runners take strides 2 to 2.5 m long. That big a difference is just not normal, unless his limbs give him an advantage. one last thing is that he does not have the build necessary to be a top sprinter. If you put him in a line up with Maurice Greene, Justin Gatlin, Carl Lewis and Linford Christie, he'd look like a pre-pubescent school boy with the First Team Rugby squad! And remember, in sprinting, strength equals speed. A sprinter has to be strong, not only to exert force and power to accelerate his body and maintain high speeds, but he has to be incredibly strong to CONTROL the movements. That's why the arms and shoulders are so big - they have to provide balance to the powerful legs. Oscar is not a powerful runner, he looks normal compared to you and me. That suggests to me that his speed comes from something other than strength, and that's not possible, unless the legs provide an advantage.

So that's the long and the short of it. And so while I applaud his bravery, I really do think that Oscar Pistorius needs to focus on being the best ever Paralympic athlete (which he already is) and stop chasing this ambition, which in my opinion is unjustified.

Of course, this whole argument could very easily be put to rest if he would just have it tested. Both Tim Noakes and I said to him that he should fly to Cape Town and we will test the limbs scientifically to establish whether they give him an advantage. And I'm sure others have offered. But to date, he has not taken it upon himself to be tested. Why not? I suspect that the answer is that he has too much to lose if he is tested. Of course, he has a lot to gain if it's shown that they don't help, but the risk of losing it all is far greater. If he just keeps quiet, he wins no matter what - if he runs at the Olympic Games, people will think he's a hero because of his courage and determination, whereas if is prevented from competing, they support him because of the discrimination of the authorities who refuse to let him run. That's a no-lose situation. testing himself introduces the possibility of losing, and that's why he'll never subject himself to testing. The debate will thus rage on...

Let us know your thoughts...

Until next time!!!



Peter le Roux said...

Just found your blog via comradesblog.com and I'm enjoying it.

Is it possible that Pistorius' relatively small upper body is explained by the lighter weight of his legs? My (admittedly small) understanding is that arm bulk is needed for sprinters to counterbalance their legs- lighter legs therefore mean lighter arms. Sure, he doesn't have the upper body build you'd expect from a sprinter, but the legs don't require it.

So, here's an interesting thought: say Pistorius agrees to testing and is found to have an unfair advantage. Is that the end of the road for Pistorius in open competition, or would it be reasonable to design sprinting prosthetics in a way that more closely models the stiffness/elastic energy conservation, centre of moment and mass of human legs? Granted, that still doesn't address the issue of reduced buildup of metabolic products (am I right in thinking that this buildup is more of an issue in 400m than 100m?) but does rectify the other discrepancies.

Something that seems obvious to me (with no training in biokinetics/anatomy) is that an above the knee amputation must surely be a disadvantage over an able-bodied runner who has control over this joint (Pistorius has one above the knee and one below the knee IIRC). How much of a disadvantage is this in reality?

Ross Tucker and Jonathan Dugas said...

Hey Peter

Thanks for the post, and I'm glad you are enjoying the blog! If you have any suggestions, let us know!

In terms of your questions, you make excellent points, you have a good understanding of what happens. The counter-possibility regardig the arms is that his arms might need to be even stronger to provide the balance during contact, since that is the big issue for him, particularly out of the blocks. His postural muscles must also be incredibly strong, though both these could happen without a huge increase in size. So, yes, it is possible that he does not require the arm strength in order to counter balance the weight/inertia from the legs. The next question is whether this is also in fact an advantage, since it reduces the training required to develop the arms? Interesting one....

As for the outcome if he is ever tested, perhaps the design of prosthetic limbs that don't confer an advantage would be considered - the difficult there would be implementation and 'quality control', which would be something that the IOC/IAAF would have to do. I think that if this was done, then any hope of reaching a qualifying time would disappear, even with any slight remaining advantages, because I really think that it's the weight of the limbs and the ease with which they can be accelerated that makes the difference. I've seen claims about the elastic energy, but I don't know for sure that it's ever been tested. And I guess that's the big thing - without testing it specifically, we have to speculate. I'm looking forward to the Beijing Paralympics, where I will be able to record a DVD of him running in order to properly analyze split times every 10 m, stride rate and stride length - we have equipment to do that at UCT, so that will shed some light.

To answer your question - the metabolite accumulation is probably more relevant during the 400 than the 100, but it's not as cut and dried, because in the 100, there is ATP depletion. The body's main energy source, ATP (I'm sure you know this, apologies), only lasts for roughly 6 to 8 seconds, and so the 100 m is right at the limit of maximal running speed. So as much as accumulation is an issue, so too is depletion.

Finally, I can't answer your final question, since I've never really seen biomechanical analysis of the prosthetic limb. They may have the technology now to design a limb with an 'intelligent' knee that functions like yours and mine. Again, I suspect it's a more efficient joint (and a lot of mechanical energy gets lost through our joints) and so the disadvantage might not be as great. This is speculation though.

Thanks for your comments though, they are very stimulating, and much appreciated!

Good luck running (I assume you run, hence your presence on the Comrades blog?). Did you run on Sunday? I hope I didn't see you in the medical tent!


Peter le Roux said...

Thanks for the quick response, Ross.

It seems like there are a lot of factors at work here, and it's a case of figuring out how much each contributes: is the increased stiffness of his legs enough of an advantage to offset the difficulty in starting etc. etc. etc.

One thing you don't discuss is how much the muscles in the lower legs contribute to sprinting. Surely the lower legs don't just function to store energy, but actively contribute energy into the system as well? While there is a more efficient mechanism for storing energy, surely this energy production loss needs to be taken into account?

I'm not sure I see how ATP depletion would be different for an amputee: ATP is contained within each cell, and isn't transported around the body like lactic acid or carbon dioxide. So why would the ATP density per cell be different (except that the load certain muscles are operating under is lower).

In semi-related news I see that Richard Whitehead successfully completed the Comrades as the first double-amputee entrant.

Thanks again, I'm not running anymore (but I should get round to it one of these days...) - I used to sprint at school and got interested in the technical aspects of track and field in particular.

Ross Tucker and Jonathan Dugas said...

Hi Peter

Good points again, and it highlights the argument/debate.

Just to address the questions, you're quite right - for every potential impairment, there's a chance that it helps too, and that's what testing needs to sort out. Classic example is that he does lose out on the contribution of muscles in the lower leg, but this loss may be offset by the stiffer substitute, the reduced mass (which I think is the biggest advantage, incidentally) and the lack of afferent feedback.

Again, however, let's test him so that we can start talking facts instead of maybes. But as I said, both the IAAF and Oscar have too much to lose from that, so I fear we'll never know. But I see that they have now effectively blocked his entry in the Paralympic Games, and so I guess these are all 'moot' points.

On the ATP issue, the key is that the brain must be sensing something from the periphery (and it's not lactate, we know that). It may be pH, but more likely it's a build of phosphate or a depletion in ATP, and in Oscar's case, I suspect his "Phosphate dynamics" are altered because the upper limb is doing relatively less work to accelerate and decelerate the limb. So it's not a case of more or less depletion, it's that the total feedback might be altered - this is conjecture though. The key, in my opinion, is that we have to analyse stride frequency and stride length during peak running (not out of the blocks) and see how that compares to guys running at the same speed. I suspect they'd be different, and to me, that would be conclusive.

But thanks for the feedback - you should consider going into sprint coaching - it takes two things, technical knowledge and motivation power - you certainly have one!

Cheers, and keep reading future posts, I look forward to your challenging comments!