run, baby, run

BookishjenlucShhh! Try to keep it down to a low whisper, will ya? Jen-Luc Piquant is currently lost deep somewhere in the final Harry Potter book, having waited patiently for her turn — and somehow avoided all the online spoilers in the process, no mean feat by now. (Anyone considering trying to ruin the surprise for her should be forewarned: she is ruthless when wreaking her revenge. When you least expect it, she will emerge out of Cyberspace via your computer monitor, just like the ghoulish Samara in the horror flick The Ring, who comes oozing out of the TV to claim her victims. Better yet, she'll send Oscar the Cat, a.k.a., the Feline Harbinger of Death, to sit and stare at you expectantly with those unblinking almond eyes. Aieee!) While waiting for myself and Future Spouse to finish our respective readings, Jen-Luc perused the biology of Harry Potter (courtesy of the Biology in Science Fiction blog) and re-read Roger Highfield's entertaining The Science of Harry Potter to keep herself in that Rowling frame of mind. 

Oscar_the_cat_of_death Certain skeptical types might assume that it is pointless to look for science in a children's fairy tale, but that just demonstrates an overly literal mind or limited imagination, in our humble opinion. It's all a matter of perspective; as Highfield ably demonstrates in his book, quite a bit of cutting-edge modern technology is, in its own way, quite magical — electronic paper, for example. And just this week, Wired reported that DARPA — described as "the Pentagon's way-out research arm" — wants to design a software suite that can help battlefield commanders predict the future. Seriously. They're developing a "digital crystal ball" capable of foretelling how any given military mission will turn out beforehand. Professor Trelawney would be so proud. And maybe Oscar the Cat can help with the divination aspects.

There's been another Oscar in the news this week: Paralympic champion sprinter Oscar Pistorius, a.k.a. "the Blade Runner," a double-amputee since he was a baby in South Africa. Pistorius was born without fibulae in both of his legs, which were amputated halfway between his knees and ankles just before his first birthday. He's always worn prosthetics, taking his first steps on fiberglass pegs, and has always been highly athletic, playing rugby, water polo, tennis, even wrestling before taking up track and field after suffering a serious injury in rugby. He's known for refusing special treatment, even perfectly legal ones, like handicapped parking spaces. He says his motto has always been, "You're not disabled by the disabilities you have, you are able by the abilities you have."

[UPDATE: There's a fascinating post up at my new favorite blog, Neurophilosophy, on the discovery of the 300o-year-old prosthetic foot. Check it out!]

That motto has served him well thus far. Not yet 21, Pistorius has racked up an impressive string of titles, and is the current Paralympic double amputee world record holder in the 100, 200 and 400 meter events. A few weeks ago, he made his international debut against the world's top able-bodied runners by running the 400 meter event at the Norwich Union British Grand Prix in Sheffield, England. He didn't fare very well, given wet conditions; he placed seventh in a field of eight, and was ultimately disqualified for running outside his lane.

Now Pistorius has set his sights on qualifying for the 2008 Summer Olympics in Beijing — and therein lies the controversy. It's not unprecedented: according to a May 15 article in the New York Times, there have been at least three disabled athletes who have competed in the Summer Olympics: an American gymnast with a wooden leg (George Eyser); a paraplegic archer from New Zealand (Neroli Fairhall); and a legally blind American runner (Marla Runyon, who competed in the 1500 meters at the 2000 Summer Olympics in Sidney). There's never been an amputee competing in an Olympic track and field event; Pistorius wants to be the first.

The sticking point is whether his prosthetics give him an "unfair advantage" over able-bodied athletes. "But the man is a double amputee!" you may well exclaim. I certainly did. Nonetheless, that's the gist of objections, and the International Association of Athletics Federation (IAAF) is still mulling over the issue before deciding whether or not Pistorius can compete. (There's very little question of his qualifying.) They throw around a lot of impressive scientific jargon when discussing his case, talking about measuring the maximum amount of oxygen his body uses in one minute, per kilogram of body weight (known as an athlete's VO2 max), or assessing the mechanical efficiency of his stride using a dizzying array of different techniques, including force plates and 3D kinematics. They've already used high-definition cameras to film his running motion.

Just what's so special about those prosthetics? These days, Pistorius runs on a pair of high-tech prosthetic limbs made out of carbon graphite, called Cheetahs, since the J-shaped design mimics an actual cheetah foot. They make a telltale "snick-snick-snick" sound on the asphalt as he runs — a sound competitors have come to dread; one fellow runner said he felt like he was "being chased by a giant pair of scissors."  They're also a bit longer than natural limbs, which some believe enable him to cover more ground with every stride — those naysayers include single-amputee Paralympic athletes Marlon Shirley and Brian Frasure, both of whom were beaten by Pistorius this past May at the Paralympic competition in Athens. (Jen-Luc thinks this sounds a bit like a case of sour grapes.) That's not something Pistorius can help: the Cheetahs must be longer than biological legs, to compensate for their imperfect biomechanics. Also, the design means Pistorius runs pretty much on tiptoe.

In fact, the more I read about the objections, the more it sounds like people are basing their objections on perception rather than solid science. Any cited perceived advantage is easily outweighed by everything else that Pistorius must overcome. The Cheetahs are not without their drawbacks. For instance, Pistorius doesn't experience the lactic acid buildup that plagues able-bodied athletes, but they don't have to contend with the possibility that the carbon in an artificial limb will snap at an inopportune moment, sending Pistorius to the ground in a movement that more closely resembles a skier wiping out on the slope than a runner stumbling.

He's a slow starter, since he needs to exert more energy to get moving out of the starting blocks that his able-bodied competitors; unlike them, his later stage of a race is his strongest and fastest. For that reason, he'll never be as strong in the shorter 100-meter event; he really shines in the longer 400-meter event, because there he has time to find his rhythm after the inevitable shaky start. As the Sheffield competition made clear, if it's raining, he has trouble with traction. And a stiff, strong wind can blow his legs sideways. Most runners lose speed coming out of a turn, but Pistorius might actually gain energy — the downside is that once the Cheetahs get going, they can be really tough to control.

Most damning of all is what you find when you crunch the numbers of energy return for Pistorius' artificial limbs. The Cheetahs rely on a passive spring to absorb energy as the foot lands, returning energy to propel the next step forward — pretty much the same biomechanical concept behind how an able-bodied person walks. but the Cheetahs can't generate anywhere near the propelling force of a biological limb: landing on a human foot in a running stride has a 241% energy return, thanks to the contraction of leg muscles, compared to a roughly 82% spring efficiency for a passive prosthetic foot like that on the Cheetahs. So Pistorius actually has to work at least 30% harder than his  able-bodied competitors to compensate for not having the usual collection of muscles, tendons, ligaments, joints and bones — and all that power must come from his hips, producing a weird, slightly waddling stride as he runs. The field of prosthetics hasn't yet come close to matching Mother Nature's design.

Pistorius has plenty of supporters, not just detractors. Hugh Herr, director of MIT's Biomechatronics Group and himself a double amputee, thinks Pistorius has "a distinct disadvantage" in track and field: "He's just really fast." Robert Gailey, an associate professor in the University of Miami's department of physical therapy, agrees with that assessment: "There is no science that he has an advantage, only that he is competing at a disadvantage," he told the New York Times. Imagine running on stilts: that's essentially what Pistorius is doing. He's just really, really good at it because he's been walking and running on stilts since birth. His handlers are fond of saying that anyone who thinks having carbon-fiber legs will automatically make them a faster sprinter, should have the operation and meet them at the track.

True, he does have an innate advantage over Shirley and Frasure, both of whom still have one natural leg. Mixed leg sprinters aren't as smooth or fast, according to Gailey, because they lose energy to vertical movement by pistoning up and down. Pistorius might waddle a little, "but his gait has a circular smoothness." Short of amputating their other legs, Shirley and Frasure will just have to accept this innate shortcoming, or find some other means of compensation.

Pistorius isn't some futuristic cyborg, just a gifted runner with two artificial limbs. It's easy to confuse the passive prosthetic limbs used by Pistorius with more active models using bionics and robotics. For instance, Herr has developed a computer-controlled robotic ankle giving an amputee a faster and more natural gait, as well as the Rheo Knee, which has a microprocessor and numerous sensors to allow it to adapt to changes in speed, load, and uneven terrain. The motor generates extra power if the user is walking uphill, while downhill, the ankle uses a brake-like device to dissipate some of the energy. The robotic ankle is powered by a rechargeable battery capable of storing sufficient power for a walk of several miles. Similar work on an artificial foot and ankle that can adapt to changing terrains and walking speeds is being done at Northwestern University. (At the very cutting edge is Cyberkinetics in Massachusetts, which implanted 100 electrodes onto the motor cortex of a paralyzed man that enables him to operate a computer or move an artificial arm using just his thoughts. Yikes!)

Despite all the technological bells and whistles, such devices still aren't as strong or powerful as natural limbs, and they don't respond automatically to signals from the brain, because they aren't linked directly to the central nervous system. But someday they might be. In so, then those types of prosthetics conceivably could confer an unfair advantage on a disabled athlete in the not-too-distant, according to Gailey — which might be why the IAAF is concerned about setting a future precedent. Nobody wants to see track and field turn into the massive global embarrassment that has become this summer's scandal-plagued Tour de France. "If there are no constraints placed on what technology can be used, at some point there will be an advantage," Herr admitted to the New York Times; in fact, that's the ultimate goal of such research.

Pistorius' success is pushing hard against the traditional boundaries separating disabled and able-bodied athletics, and it's raising a lot of questions and making a lot of people uncomfortable in the process. Nor is the issue likely to go away: a single amputee named Jeff Skiba competed in the US indoor track and field championships last year. The IAAF recently amended its competition rules to ban the use of "any technical device that incorporates springs, wheels, or any other element that provides a user with an advantage over an athlete not using such a device." They claim this is not intended to target Pistorius, merely to better define what constitutes therapy versus an enhancement.

Even the head of the organization's medical and anti-doping commission, Juan Manuel Alonso, admitted to the New York Times that "There is no real grounds to say he [Pistorius] should not be allowed to compete" in the Olympics. I say, enough already. Let the man compete. He's had to overcome enough. Don't make him a poster boy for futuristic technology he's not even using. Yet.

ADDENDUM: Cocktail Party Physics will be hosting the next Philosophia Naturalis blog carnival, slated for April August 15th. Jen-Luc Piquant expects to be finished with Harry Potter any moment now, and is quite keen to begin sifting through submissions. So if you've got anything, be sure to send it along to her at

7 thoughts on “run, baby, run”

  1. “The sticking point is whether his prosthetics give him an “unfair advantage” over able-bodied athletes.”
    That reminds me of the Tour de France riders suggesting that Lance Armstrong’s chemotherapy drugs were performance enhancers.

  2. Janet, blog carnivals are kind of like anthologies on the web. They’re a collection of the best of the best in a particular interest area, usually appearing once a month hosted by volunteers. There’s a central clearinghouse for carnivals here:
    Most carnivals have their own sites that tell you a bit about the carnival and where and how to submit. You can submit your own work or nominate someone else’s by submitting a link to it. Hope that was helpful.

  3. The idea of “Harry Potter Science” sounds kind of fun.
    I just wanted to point out, though, that the idea of software that predicts the outcome of military field maneuvers is hardly new. Quite the opposite: the desire for military predictions, and strong encryption (also for military purposes) were the two driving forces that led to the development of the digital computer in the first place. Initially, it was predicting ballistics. Then, other predictions based on multiple, rapid calculations. Then, battlefield simulations… and so on.
    While the wording may be new, there is nothing actually new about this, at all. It is exactly the same thing, different day.

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