The technology that makes walking possible for amputees is also making running possible at the Olympics. On Saturday in London, South African Oscar Pistorius will run on artificial limbs in the 400-meter sprint. Pistorius is a double amputee who runs world-class times on his carbon-fiber legs.
At last month's Prefontaine Track and Field Classic in Eugene, Ore., Pistorius ran in the inside lane of the 400-meter race. He leaned forward on his knees and fingers, and slipped his feet into the starting blocks — well, they're not actually feet.
Instead, Pistorius slipped the flat and spiked bottoms of his curved carbon-fiber legs into the blocks. In the other lanes, all the blocks were filled with track shoes, tied tight around flesh, blood and bones.
After the starter's pistol went off, a careful listener could hear a unique sound among sprints: the tap, tap, tapping sound of carbon blades hitting the track.
As Pistorius raced past, his gait was fluid, like a gazelle. But he looked otherworldly: a man's body from head to knees, fixed atop curved carbon blades. His nickname, in fact, is "the Blade Runner."
Pistorius finished last in this race, but he has qualified for the Olympics, and he'll race with the best runners in the world.
"It's not that I don't want to run Paralympic or disabled races, or races for those athletes who are handicapped, or amputees," he says. "But this is just a challenge for me, and any good sportsman that wants to be better has to face up to challenges that aren't always as easy as some of the others."
There's actually some question about whether Pistorius has it easier, or has some advantage over runners with fully biological legs.
Before the 2008 Olympics in Beijing, the international track federation refused to let him run; so he launched a challenge. The Court of Arbitration for Sport ruled he had no advantage, and couldn't be barred from the Olympics if he ran a qualifying time. That ruling was based on the work of prosthetics researchers, including Alena Grabowski at the University of Colorado.
"So we had him come into the lab. We measured his oxygen consumption — or, how much energy it takes him to run," Grabowski says. "We did a series of different speeds and compared him to elite athletes of similar caliber, and found that his metabolic energy is the same as other elite athletes. So, we didn't see any differences there."
Grabowski and other researchers found there's a big difference between carbon fiber and bone and muscle. They put Pistorius on a treadmill, where he hit his top speed of around 25 miles an hour.
"He was able to swing his legs a little bit faster, so he had a little bit quicker turnover," Grabowski says. "But he wasn't able to exert as much force on the ground during top-speed sprinting. So, we actually perceived that as a disadvantage. If you're not able to push off on the ground as hard as other people, it could be that that device is limiting that ability, and you're not able to sprint as fast."
Researchers at another lab brought in other runners — each of them had one biological leg and one artificial leg. The biological legs generated 9 percent more force. So at the start and around the track, the stiffer artificial leg has less power.
Still, Pistorius ran fast enough to make the South African team. (NBC, the official network of the Olympics, did a "Science of Olympics" piece on how Pistorius' blades work.) In an interview recently, he told the BBC that he's alone with that distinction which indicates something about natural ability.
"Out of the tens of thousands of prosthetic legs they've made, there's never been any 400-meter athletes run under 50 seconds," he said. "So, if this was such a technologically advanced prosthetic leg, then how come not everyone's qualifying, or coming close to the qualification time, then?"
Pistorius is not posting times that put him close to a medal. And if he competed for a country with a deeper field of runners, like the United States, he probably wouldn't make the Olympic team. Still, he and his Cheetah legs will make history Saturday in a preliminary heat, breaking an Olympic barrier because together, they run fast enough.