The ambiguities about what makes the world's fastest humans so fast have put Oscar Pistorius at the center of a debate about competitive advantage. Pistorius, of course, is the Olympic sprinter and former Paralympic champion -- born without fibulas due to a congenital disorder, he had his legs amputated below the knee before his first birthday -- who will be representing South Africa in the London Games.
Pistorius runs locked into carbon-fiber running-specific prostheses (RSPs), J-shaped Flex-Foot Cheetahs which have been around since the mid-90s. The Cheetahs, designed by the Icelandic orthopaedics company Ossur, work like passive elastic springs, storing and returning energy the same way a biological pair of legs would.
Even so, the foreign nature of RSPs has many (even those in the scientific community) wondering whether he has an edge over able-bodied competitors. But consider this: To date, there is no definitive evidence indicating that Pistorius' prostheses are responsible for his track times.
"It's tougher to get a handle on sprinting mechanics than on feats of strength or endurance," said Peter Weyand, an exercise physiologist at Southern Methodist University. Weyand is also one of seven scientists who overturned a ban on Pistorius imposed by track's governing body, the International Association of Athletics Federation (IAAF), in 2008.
While athletes like cyclists can accurately predict the performance boosts resulting from more aerodynamic equipment or a slight shift in body positioning, sprinters are afforded no such luxury. "In sprinting, it's a black hole," Weyand continued. "You don't have those sorts of predictive relationships."
The question isn't whether he deserves to be in the London for the games. Pistorius, despite falling short of South Africa's qualifying criteria, earned a place in London by finishing under the men's Olympic A Standard for the 400 meter dash, 45.3 seconds. He'll be judged by the same stopwatch (or Scan'O'Vision photo-finish camera) as Team USA's Jeremy Wariner, and rightfully so.
The question is whether Pistorius' participation in the 2012 games sets a "dangerous precedent" that, ultimately, could destroy the Olympics.
That's a bit dramatic for my taste. But first, the science...
What We Think We Know
A year after the IOC ruling, in 2009, Weyand co-authored a study with Matthew Bundle, an assistant professor of kinesiology and health at the University of Wyoming, which appeared in the Journal of Applied Physiology. Weyand and Bundle's findings suggested that there are two ways a runner can increase his or her speed: 1) hit the ground with more downward force; or 2) exert the same force over a longer period of time (even if for just a fraction of a second longer).
Let's start with point No. 2.
Prostheses like the Flex-Foot Cheetahs help double-transtibial amputees like Pistorius run faster, the study indicated, because flexible artificial limbs spend about 10 percent more time on the ground than a human leg would. But that's not all. Similar lightweight prostheses also decrease the time it takes an athlete to pick their foot up and put it down again (known as swing time) by about 20 percent compared to runners with intact limbs.
These two factors, a combination of extended ground force and quicker turnover, could help a runner like Pistorius shave more than 10 seconds off his 400 meter dash time. That's kind of a big deal, as Sports Illustrated's David Epstein put it: "a boost so significant as to make the difference between a mediocre high school runner and an Olympian."
I'll serve your a** like John McEnroe
Not every human speed specialist has agreed with Weyand and Bundle; detractors have even included a handful of scientists who, one year earlier, joined Weyand and Bundle in support Pistorius in the Court of Arbitration for Sport (CAS), overturning the Olympic ban on the sprinter.
Rodger Kram, Craig McGowan, Mary Beth Brown, Alena Grabowski, and Hugh Herr challenged the report that prostheses do make artificially fast running speeds possible. The five scientists published a researched deconstruction of Weyand and Bundle's findings; the first line in the study read "You cannot be serious!" -- a reference to John McEnroe's iconic dispute with 1981 Wimbledon official Edward James.
"Every year, thousands of athletes run under 50 seconds, yet only one amputee (Pistorius) has ever broken 50 seconds," wrote the scientists representing MIT, Georgia Tech, the universities of Colorado and Texas and a biomechanics lab at an orthopedic hospital in Murray, Utah. "Would Weyand and Bundle predict that the world record holder, Michael Johnson, would run 31 seconds if he had both legs amputated?"
The data set quintet had more where that came from, arguing that lower-limb amputation and modern running prosthesis impair ground force generation and that "rapid leg swing times can result from learning and training but can only partially compensate for the force impairment incurred by current, passive-elastic running prostheses."
Their study revealed that RSPs, on average and at a runner's top speed, applied a downward ground force that was nine percent lower than that of an unaffected leg, leaving Pistorius at a disadvantage. Remember, the first rule of running faster, according to Weyand, is to increase downward ground force. (The world's fastest man, Usain Bolt, hits the track with an above-average ground force, one that is two and a half times his body weight, or about 900 pounds.)
As for the turnover related to the second rule of running, video analysis of the 2008 Olympic 100 meter dash revealed that bronze medalist, Walter Dix, ran with a leg swing time of 0.274 seconds. Pistorius recorded a slightly slower, yet comparable swing time of 0.297 seconds in the 100 meter dash in the Paralympics that same year, Paralympic silver medalist, single-amputee Jim Bob Bizzelli, had a shorter swing time with his unaffected leg than he did with his RSP. And so it seems that carbon-fiber prostheses are not the only determinant of swing times, but rather one part in a complex speed equation.
"The notion that lightweight prostheses are the only reason for Pistorius' rapid swing times ignores that he has had many years to train and adapt his neuromuscular system to using prostheses," argued the counterpoint study. "Weyand and Bundle argue that lightweight prostheses allow Pistorius to run faster than he should for his innate strength/ability to exert vertical [ground reaction forces]. An equally plausible hypothesis is that he has adopted rapid leg swing times to compensate for the force limitations imposed by his prostheses."
Data from Down Under
There may be a specific, legitimate reason why Pistorius continues to keep up with the pack, thanks to Tim Dorn, Anthony Schache and Marcus Pandy from the University of Melbourne's department of mechanical engineering.
This trio combined experimental data from test subjects with a detailed computer model of the human musculoskeletal system to learn the strategies employed by runners at different speeds. For sprinters flying around the track at speeds greater than seven meters per second, the hip muscles -- primarily the iliopsoas, gluteus maximus and hamstrings -- are the greatest determinants of performance. At slower speeds, it's the ankle and calf muscles that put in the most work.
Pistorius was born without bones below the knee. He learned to run differently than his peers. The result, according to Hugh Herr, one of the two MIT biomechanics and bionics experts in the conversation, was that Pistorius developed bigger hip muscles. And stronger hip muscles may produce faster speeds.
Pistorius has had a lifetime of training; he has always been drawn to athletics, a competitor from an early age.
"Rugby, superbikes, sometimes boxing, soccer -- I'm a big Manchester United fan," a 20-year-old Pistorius told Gareth Davies of The Telegraph back in 2007. "I watch as much athletics as I can."
Pistorius' first sporting memory is a primary school soccer game when he was seven, but he still has vivid memories of his first rugby test in Johannesburg held couple of years earlier -- the All Blacks, the fearsome New Zealanders, beat South Africa's Springboks that day in Ellis Park, 27-24. As a young teen, Pistorius played rugby for his local high school, competed in water polo and was a member of the state tennis team.
"I only started sprinting in January 2004," Pistorius said. "I thought that I would be going back to the rugby season at school in April 2004, but started sprinting as part of my training after an injury, entered the South African disabled championships, and never looked back."
The Sports Taboo
In 1997, Malcolm Gladwell shed a bit of light on the relation between race and athletic performance. Summarized succinctly in The New Yorker:
"Elite athletes are elite athletes because, in some sense, they are on the fringes of genetic variability. As it happens, African populations seem to create more of these genetic outliers than white populations do, and this is what underpins the claim that blacks are better athletes than whites."
In his story, Gladwell uncovered some rather fascinating physiology. Research indicates that the average African American man has greater bone and muscle mass than your average white American, while also having higher levels of testosterone and human-growth hormone (HGH) and variations in body type: mainly slimmer hips, wider shoulders and longer legs.
"In one study, the Swedish physiologist Bengt Saltin compared a group of Kenyan distance runners with a group of Swedish distance runners and found interesting differences in muscle composition: Saltin reported that the Africans appeared to have more blood-carrying capillaries and more mitochondria (the body's cellular power plant) in the fibres of their quadriceps," wrote Gladwell.
But there is also medical evidence that applies more directly to Pistorius, a South African.
"Another study found that, while black South African distance runners ran at the same speed as white South African runners, they were able to use more oxygen- eighty-nine per cent versus eighty-one per cent-over extended periods: somehow, they were able to exert themselves more.
"Such evidence suggested that there were physical differences in black athletes which have a bearing on activities like running and jumping, which should hardly come as a surprise to anyone who follows competitive sports."
It's sort of funny when you to piece together all the moving parts and begin to look at the bigger picture. Amid all the uncertainty about whether it's fair for Pistorius and his RSPs to compete in the games, people forget that Pistorius has not only overcome a potentially debilitating congenital disorder to qualify for the Games under his own power, but, as a white South African, he has done so with genetics working against him.
"To use track as an example-since track is probably the purest measure of athletic ability-Africans recorded fifteen out of the twenty fastest times last year in the men's ten-thousand- metre event," wrote Gladwell. "In the five thousand metres, eighteen out of the twenty fastest times were recorded by Africans. In the fifteen hundred metres, thirteen out of the twenty fastest times were African, and in the sprints, in the men's hundred metres, you have to go all the way down to the twenty-third place in the world rankings-to Geir Moen, of Norway-before you find a white face."
That's the tricky, often unspoken, but obvious racial component to athletic competition at the highest level. Gladwell even suggests that it becomes "foolish to deny the fact of black athletic prowess, and even more foolish to banish speculation on the topic."
No one is arguing that it's unfair for whites to be racing against blacks, nor should they be. But introduce a carbon-fiber foot to the conversation and you'd better brace yourself for a lecture on the ethics of fair play. But, then, is it fair that Paralympic runners who rely on RSPs to perform at the best of their abilities suffer training injuries at a rate nearly 60 percent greater than able-bodied athletes -- 9.3 injuries per 1,000 hours (about the same injury rate endured by collegiate American football players)?
Despite Pistorius' shortcomings, and the (ground) forces working against him, he has persevered. He's still the bullet in the chamber, ever ready to fire out of the blocks toward the finish line -- about a second and a half shy of an Olympic record.
You could argue that the 6-foot-1 (5-foot-2 without prostheses) 25-year-old is not competitive in the Paralympics, holding world records for sport class T44 in the 100, 200 and 400 meter dashes. Pistorius has the approval of the Intentional Olympic Committee (IOC). Why doesn't he have ours? What's the harm in letting him Pistorius test himself against the world's best?
Is it an obsession with conformity? Is it antipathy for a flawed human figure in a field of supposed perfection? Is it an innate fear of the unknown?
If and when the day comes where we can prove that RSPs boost performance, that's where officials should draw the line. And, if necessary, scratch tech-aided times from the record books. But, presently, RSPs are ergonomically insignificant and therefore less offensive than, say, caffeine which gives anaerobic athletes like sprinters a 16 percent jolt. Yeah, caffeine, "the most popular drug in sports," which is legal under IOC rules and was found in more than two-thirds of Olympic athletes in a recent study.
The Spirit of the Games
The Olympic creed, developed by Baron Pierre de Coubertin, father of the modern Olympic games and founder of the IOC, champions Pistorius' cause.
"The most important thing in the Olympic Games is not to win but to take part, just as the most important thing in life is not the triumph but the struggle," it reads. "The essential thing is not to have conquered but to have fought well"
Pistorius has arguably done more with less than any other elite athlete in the world. He has the drive, clearly, and yet critics are so focused on what Pistorius is missing, rather than appreciating what it is that ought to define him: a fierce determination. "Desire is the great intangible in performance, and unlike genes or psychological affect we can't measure it and trace its implications," wrote Gladwell -- and you thought the biomechanics of sprinting were a black hole.
Oscar Pistorius' participation in the Olympic Games is no threat to the spirit of the competition; fear-mongering, intolerance and corruption certainly are. It's his humanity, at times questioned and buried under inconclusive data, that has made the "Blade Runner" the fastest man on no legs.