01 August, 2014

On blade runners

I would have preferred a title like “Should blade runners be allowed to participate in competitions for two-legged athletes?” and let Betteridge’s law answer it (which states that “any headline which ends in a question mark can be answered by the word no”) but it is unfortunately too long. 

What motivated the present post is the recent outstanding performance of Markus Rehm who won the german championships with 8.24 m. 

Rehm has lost his right leg below the knee in an accident and he uses a prosthetic leg like the ones Oscar Pistorius is using. I was planning for some time now to write my ideas on Pistorius and the other “blade runners” and Rehm’s record gave me the motivation. 

Now, don’t get me wrong. I have great respect for athletes who train and compete despite their physical handicap. To attain the highest level requires not only great efforts but also lots of courage and confidence. However the question is that if we do not know for sure whether an athlete gets an advantage from the prosthetics that he wears, allowing him to compete with able-bodied athletes may turn out to be unfair to the latter.

Pistorius has double below-knee amputations, and competes in the T44 category (for single amputees, although, being a double amputee, he is entitled to participate in the T43 class). He has several gold medals from the 2004, 2008 and 2012 Paralympics, and world records with 21.30 at 200 m and 45.07 at 400 m. He runs with J-shaped carbon-fibre prosthetics. Pistorius’ prostheses weigh less than half as much as the limbs of an able-bodied male runner. 

Before reaching a conclusion on whether blade runners (and by this term I refer to all athletes in the T44 and T43 categories) should be allowed to compete with able-bodied athletes I would like to present some arguments. 

First, what do the rules say?

On 26 March 2007, the IAAF amended its competition rules to include a ban on the use of "any technical device that incorporates springs, wheels or any other element that provides a user with an advantage over another athlete not using such a device". (Pistorius challenged this decision at the Court of Arbitration for Sport and managed to obtain the permission to compete).

What do scientific studies say?

The first study was conducted by G.P. Brügemann (Univ. Köln) who concluded that the majority of work is done in the blade (without muscular work), that the blade returns 90 % of the energy compared to 60 % for the ankle joint and that this kind of locomotion entails lower metabolic costs. 

Looking at this data I wonder why hadn’t Pistorius ever tried to run a 800 m. Given the shape of the energetic cost of his effort he should have been even better over 800 m.
The presentation of Brügemann ends with two citations. First by H. Herr (MIT) who states that “People have always thought the human body is ideal. It is not”. Second by B. Nigg (Univ. Calgary) “I would like to challenge the biomechanics community to develop prostheses that will produce world records in many track and field disciplines. It should not be too difficult”. I feel that we are almost there.

The methodology of Brügemann was challenged in a study by Weyland and collaborators at Rice University. While they noted that Pistorius can reposition his legs considerably faster than other able-bodied sprinters because the blades are so lightweight, giving him an overall speed advantage, they concluded that, “running on modern, lower-limb sprinting prostheses appears to be physiologically similar but mechanically different from running with intact limbs.” That is to say that metabolic costs and endurance are similar to runners with intact limbs. Running at lower speeds does not seem to give Pistorius as much of an advantage (such as the speeds that would be used in longer races instead of sprints). Still I would have liked to see what an athlete like Pistorius could do over 800 m.

The discussion is going on concerning the existence or not of an overall advantage for blade runners. Arguments pointing out that, running with blades, the athletes must pop straight out of the blocks and face a greater air resistance or that they must work harder against centrifugal forces, are perfectly acceptable however unless precise, rigorous studies are carried through they remain qualitative.

What do able-bodied athletes say?

Following the stunning performance of Rehm, fellow competitor Sebastian Bayer said that Rehm's prosthetic limb could provide a catapult-like effect to his jump."The prosthetic seems 15 centimetres longer than the other leg" said Bayer. Rehm countered by stating that the prosthetic is three, four centimetres longer than his other leg, but the disparity keeps him from hobbling during the run-up to his jump. So, the length of the prosthetic limb appears to be an issue, which brings us to the next paragraph.

What do blade-runners themselves say?

Following the surprising victory of Brazil's A. Oliveira at the 200 m of the London, 2012, Paralympics, Pistorius, who was second in that race reacted by saying: “We aren't racing a fair race. I've never seen a guy come back from eight metres behind on the 100 m mark to overtake me on the finish line”. Pistorius was convinced that the running blades used by Oliveira and the bronze medalist Blake Leeper were too long, and called for the International Paralympic Committee to investigate. As expected, the next day Pistorius apologised for the timing of his comments saying that he would never want to detract from another athletes' moment of triumph.
It goes without saying that the IPC has rules regarding the length of the blades which is determined by a formula based on the height and dynamics of the athlete.

Just for completeness sake I must point out that the problem of Pistorius is that he cannot alter the length of his blades if he wants to continue to compete in able-bodied competitions. To do a crossover like that, he can only run on blades that have been cleared for use by the IAAF. Longer blades, of the kind Oliveira used, are only legal in Paralympic events. If Pistorius switched, he would not be able to run in non-disabled competitions. Besides which, he would undermine his own argument that his success is about the body above the knee, rather than the technology below it. Of course, all this will most probably become moot given the recent legal troubles of Pistorius.

So, what is the conclusion?

I think that blade runners (and jumpers) should contend themselves with their own circuit of competitions. They have Paralympic Games organised in parallel with the Olympic Games. They are getting more and more recognition and praise by the public and the media. I am looking forward to blade-runner records surpassing those of able-bodied athletes and I would definitely welcome them. After all wheelchair records have been leaving running records in the dust. But trying to have prosthetics-carrying athletes competing along able-bodied ones will only lead to suspicion and perhaps to the temptation of cheating. So, the answer to the question raised in the first paragraph is a resounding “no”.

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