View Full Version : amputee sprinter

05-17-2007, 01:04 AM
Ton and biomech-L: May 17, 2007

About Oscar Pistorius and his carbon fiber feet. Do
they give him an unfair advantage?

Wouldn't it be great if there were a scientific answer to
this question?! :) But for now, as best I know, no-one has
a reasonable predictive model that could confidently predict
whether a given passive orthotic helps or hurts and how much.
There are exceptions, for example we could confidently
predict that plyers and levers help increase the
forces people can apply. But for locomotion I don't think
we understand the mechanics well enough.

Many pros and cons we can list, of course, as others have
done already in answer to your question. And this understanding
will help motivate new designs. But knowing ahead of time,
without experiments on people, what will help or hurt and how
much is more than the state of the art. At least as it looks
to me.

`Scientific' claims on either side are not credible.
That muscles can give back more work than they absorb
is a nonsense explanation of how muscles make things
easier/faster than synthetic springs. That springs
are necessarily helpful is also not informative.

But there is a scientific answer.
Empirical measurement and statistics are science.
Once there is a data base then we will see whether springy
orthotics let amputee athletes, on average, do better than
athletes with feet. Even one guy might provide suggestive
statistics. If one guy all of a sudden brakes
lots of records by a lot, even an n of one, would be pretty
indicative. That is, if this one guy gets a gold medal
it means he's pretty special. And since there is something
conspicuously special about him, his feet, that would be
the likely (though not assuredly) best explanation. That
is, if I was the judge, this guy would have trouble
convincing me that he was the "best" athlete even if
he is, which he seems to be, incredibly good. He could
be _the_ best, but that is not what occam's razor would
say. And I don't see any 'science' that would make a better

My personal guess is that in the coming years, with orthotics
some people will gain a speed advantage in running,
even if starting with a disability. Why not? Would
one doubt that a double BK amputee could swim pretty
fast with fins? Why should running be so different?

About the ethics. All competition is unfair, the better
one's have an advantage. To make the outcome less
predictable, to give more people a chance to win,
to make it more of a challenge for all, sports
officials put competitors in
bins that have historically been shown to be
predictive, e.g., by sex (men vs women), by weight (heavyweight
vs lightweight), by number of people (1,4, or 8 in
a boat), by age (youth vs adult), and even by ability
(major league vs minor league). Once there are a lot
of carbon foot runners that run, on average, faster than
skin-and-bone runners there can be a class for them too.

In the mean time, I hope they let the guy run and see
how he does. "Fair" or not I don't know, but an inspiration
for biomechanics and orthotics for sure.

-Andy Ruina, ruina@cornell.edu, http://ruina.tam.cornell.edu
Universal phone (SkypeIn, works wherever I am): 607 821-1442
Finland cell: +358 40 872-6255 (+ means dial 011 from USA)

On May 17, 2007, at 1:25 AM, Ajit Chaudhari wrote:
> -----Original Message-----
> From: * Biomechanics and Movement Science listserver
> [mailto:BIOMCH-L@NIC.SURFNET.NL] On Behalf Of Ton van den Bogert
> Sent: Wednesday, May 16, 2007 10:59 AM
> Subject: [BIOMCH-L] amputee sprinter
> Yesterday's New York Times had an article about a double amputee from
> South Africa who runs 100 m in 10.9 seconds and appears to be still
> improving.
> There is debate whether he should be allowed to run in the 2008
> Olympics, if he qualifies.
> The IAAF says that his energy-storing feet are an unfair advantage.
> Others say they are not, since they only return 80% of the energy.
> There are
> calls for further research.
> The athlete, Oscar Pistorius, said "I think they're afraid to do the
> research. They're afraid of what they're going to find, that I
> don't have an
> advantage and they'll have to let me compete."
> What do the Biomch-L subscribers think? I know we have some
> subscribers
> who are experts on this topic.
> The full article is here:
> http://www.nytimes.com/2007/05/15/sports/othersports/15runner.html
> Ton van den Bogert, Biomch-L co-moderator
> http://www.Biomch-L.org
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