BOULDER, Colorado – They are called blade runners, elite athletes who are among the fastest in the world. The fastest running with only one or even no legs and they are among the first to break records with a new generation of prosthetics.
Jessica Heims and Alex Klein were children when they lost limbs.
"I had a little baby foot, but that was amputated when I was a year old," said Jessica, a track and field paralympic.
"I had cancer when I was eight," explained Alex, an athletes from Louisiana State University.
Running faster, stronger, longer is what brought Alex and Jessica to the University of Colorado where they are helping sprint onto the world stage.
"We're at a place right now where athletes are very high caliber and they're working extremely hard to be able to compete at the highest levels and I'm hoping that we can start to keep up with them," said Alena Grabowski, a biomechanics professor at the University.
She is focused on optimizing a prosthetics stiffness, height, weight, shape.
"How they move, how they walk, run, sprint, hop, jump," she said.
"That first day I felt like I could just run forever and never stop." - Paralympian Jessica Heims
They use cameras and sensors to measure how these sprinters move, track their force, and test these new carbon fiber blades.
Designers have redesigned the "blades" runners use by enlarging the curves and adding a compound curvature that gives a bigger snap and response.
"I think something like that is going to work better around curves," explained Grabowski.
"I'm on a sprinting blade which when I jog on it, it feels different because it's thicker," said Jessica.
Designers say by splitting the blade it gives athletes more ground on ground contact.
World class sprinter Blake Leeper, born without legs, is called the fastest human on earth and in Grabowski's lab was clocked at about 25 miles per hour.
Other sprinters are taking notice.
"I don't feel like anything is holding me back," said Alex.
"I feel like I can do whatever whenever I want."
It's still to be decided if amputees like Blake Leeper will be allowed to run in the 2020 Olympics in Tokyo.
The International Association of Athletics Federations banned amputees from running against other runners after a German study concluded that blades allowed the runner to expend 25% less energy, even though researchers at Rice University concluded that was false.
The Rice study stated blades put the runners at a disadvantage because they pushed off with less force than a biological limb would.