Markus Rehm – blade jumper

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Photo: Olaf Kosinsky / Wikipedia

Markus Rehm is a really good long jumper, despite the prosthetic limb on his right leg.  Or perhaps because of it.  He competed at London 2012 in the paralympics (in the F42/44 category) with a winning distance of 7.53 m. He now holds the IPC world record with 8.40 m, the 3rd longest distance in any long jump event.

There are now calls for Markus to compete at the Rio Olympics just as Oscar Pistorius did in 2012.  The same questions arise as they did with Pistorius: are prosthetics an advantage or disadvantage?  Should he be allowed to run with ‘able bodied’ runners? Is Rehm an en-able bodied runner?

If you watch Rehm’s run up, you can see that his gait is asymmetrical, oscillating side to side perhaps a little more than a jumper without a prosthetic.  He takes off on his right leg – the one with the prosthetic – with a beautiful clean trajectory that appears to rely on the springiness of his carbon-fibre foot.  If it has no advantage, one might ask, “why doesn’t he take off with his left leg instead?” (although the answer could be that the right is his ‘natural’ take-off leg).

What are the differences between the prosthetic limb and a human leg?

  1. The prosthetic has a smaller mass in comparison to a lower leg so will be easier to swing between steps.
  2. The prosthetic limb can be adjusted for length.  Of course Markus’ legs have to be equally long, but the prosthetic can curve around to create a long foot so that its length is longer than a lower leg.
  3. A leg has an ankle which allows the foot to pivot while a prosthetic limb clearly doesn’t.  The effect is for Markus to appear as if he is on tip toes.  Without a pivoting foot, it is more difficult for the prosthetic runner to push off at the start.
  4. The prosthetic limb is made of carbon fibres in a polymer resin (usually epoxy).  The design of the limb (as with pole vaults) is optimised for the athlete’s height, weight and force production.  If it isn’t stiff enough, the limb will flex too much, contact times will be long and the run will be slow.  Too stiff and it will be uncomfortable and energy will be lost in deforming the running track.  Getting the limb right is a complex process of science and art (of the designer).
  5. As David James commented in a previous post, research claims that prosthetic limbs give both advantages and disadvantages.

Should the IAAF allow Rehm to run at the Olympics in Rio?

Rehm has admitted that the philosophical argument is a tough one: when he wasn’t winning his prosthesis didn’t seem to be an issue but now that he’s into his training, optimising his technique and improving rapidly, it appears that people are worried that he might win.

And this is where Rehm is between a rock and a hard place.  If he loses, that’s fine.  If he wins, then people will complain that his leg gives him an unfair advantage.  The ‘worse-case scenario’ probably, is if he wins by a huge amount.  What if he was to double the world record?  A crazy scenario maybe, but  there would be a huge outcry that it was an anomaly, that the leg is doing all the work, that it is tantamount to technical doping.  So how much would Markus be allowed to win by before we complain?  100 cm? 10 cm? 1 cm?

The only thing that research seems to agree on is that a prosthetic limb is different to a human leg.  The physiology may be different (or not) but the mechanics certainly are.  Given that sport is arbitrary, with arbitrary rules made up to ensure fairness, all we can try to do is make sure that athletes that compete together are not different.

Markus Rehm is a fantastic athlete with a prosthetic limb and seems a really nice bloke.  My heart wants him to compete in the Rio Olympics.  Whether his prosthesis gives him an advantage or a disadvantage is not the point, though.  He is just different and belongs in a different race.  For this reason, I think the IAAF are unlikely to want him to compete in Rio.  Whether Rehm takes this to the court of arbitration, as Pistorious did, is another matter

Professor Steve Haake

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About stevehaake

Steve did a first degree in Physics at the University of Leeds before landing two job offers: the first with BT turned out to be in a porta-cabin in the middle of a marsh, while the second was supposed to be image processing but was really smart-bomb design. This left a third option – a PhD in the mechanics of golf ball impacts on golf greens for a person who’d never hit a golf ball. It was a simple choice (the PhD if you didn’t guess) which led 25 years later to being head of a research team of 30-40 looking into similarly unlikely topics. Highlights of the career so far? The early years setting up the ISEA with the likes of Steve Mather, Ron Thompson, Clive Grant and Ron Morgan; the fact that the 1st International Conference on Sports Engineering in Sheffield in 1996 didn’t also turn out to be the last; and getting out the first issue of the first journal on Sports Engineering in 1998. The absolute high point, though, was being in the British Club in Singapore as a guest of the High Commission when the bid for the 2012 Olympics was announced. This has led to the team delivering projects with Olympic athletes that every scientist with a love of sport can only dream of. Steve is now a Senior Media Fellow funded by the EPSRC to encourage the public to engage in science, particularly in the lead up to the London 2012 Olympic Games.