The Design and Controversy of Running Blades Prosthetics

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Prosthetics designed for athletes have a 40-year legacy. These ingenious “blade” prosthetics shied away from earlier heavy designs and focused on the mechanics of muscle movement. Their invention spurred an athletic renaissance in which amputees run competitive distances, climb mountains, and downhill ski.

Yet the ongoing campaign for amputees to compete against able-bodied athletes is mired in controversy. Science has yet to definitively say whether or not an athlete with running blades has an advantage over an able-bodied runner.

In this post, we explore the invention of the running blade, how they work, and why this athletic controversy is still ongoing.

Van Phillips and The Invention of The Running Blade

Van Phillips, father of the running blade. Photo Credit: Max Morse via The New York Times

Running blades were invented by American inventor Van Phillips, who lost his lower leg in a water skiing accident in 1976. Depressed by the limited athletic function of prosthetics at the time, he enrolled as a student at Northwestern University Medical School’s Prosthetic-Orthotic Center.

He quickly recognized that while most prosthetics tried to mimic human bones, he could focus on replicating ligaments and tendons. He came up with the idea for running blades by observing animals like kangaroos and cheetahs, as well as the mechanics of diving boards and pole vaulting. The result was Flex-Foot – his model of carbon fiber blade prosthetics and the name of his company.

His contribution to the history of prosthetic legs has inspired generations of athletic amputees.

So How Do They Work?

Phillips’ initial designs were J-shaped and included a heel, but able-bodied runners don’t use their heels while in motion. He soon came up with the now commonly-seen C-shaped blade design.

Today’s blades are made of 80 hair-thin layers of carbon fiber, harder than steel and able to store kinetic energy like a spring. There are variations for both above-knee and below-knee amputees. 90 percent of all Paralympian runners use some variation of Phillips’ original design.

The blades are able to replicate the stance and swing phases of running. The curve of the blade absorbs stress that otherwise would be felt in the knee, hip or back. The “toe” area of the blade has spikes on it to provide a better grip on the track.

Studies of Phillips’ design have shown that while sprinting the blades return 90% of the energy stored as motion. However, a biological leg returns 249% of stored energy, seemingly giving running blades a disadvantage in sprinting.

Despite this, there are still many who claim running blades provide an unfair advantage against an able-bodied runner – and also that some blade designs give an unfair advantage against other “blade runners.”

The Controversy and Ongoing Scientific Debate

Running blades have been used consistently by Paralympians since 1996. It was only in 2012 that Oscar Pistorius became the first individual with an amputation to be allowed to compete in the Olympics.

In 2007, Oscar Pistorius competed against able-bodied runners in the British Grand Prix. The same year the International Association of Athletics Federations (IAAF) banned “technical aids” in competition. This rule prohibited “use of any technical device that incorporates springs, wheels or any other element that provides the user with an advantage over another athlete not using such a device.”

Tests that the IAAF ran on Pistorius at the time suggested he expended 25% less energy than other competitors when sprinting. He was disbarred from competing at the 2008 Olympics as a result.

He later appealed with other studies that suggested his blades provided no meaningful benefit over able-bodied runners. He was finally able to compete in the Olympics in 2012, but even the studies he cited failed to provide consensus from the seven researchers involved.

An article from Scientific American breaks down one of the main points of contention – limb positioning time:

“The average elite male sprinter moves his leg from back to front in 0.37 second. The five most recent world record holders in the 100-meter dash averaged 0.34 second. Pistorius swings his leg in 0.28 second, largely because his Cheetahs are lighter than a regular human leg. Pistorius’s rivals are swinging a lower leg that weighs about 5.7 kilograms, whereas his lower leg only weighs 2.4 kilograms.”

One pro-blade argument suggests that the light weight of the blades can’t transmit as much force to the ground, so wearers need to push harder. On the other hand, some suggest that because the blade will never tire, it gives wearers an advantage in the second half of a race.

The reason it is difficult to come to a consensus is that the IAAF rules are vague, and the very nature of “providing an advantage” is up for debate.

In the 2012 Paralympics, Pistorius himself accused the winner of the T44 200m final, Alan Fonteles Cardoso Oliveira, of having an unfair advantage. The reason? Pistorius’ blades were four inches shorter than his rivals’. But every runner’s blades are personalized based on how long an athlete’s missing leg would be. So is this an unfair advantage?

These debates are still ongoing today, and likely to get more complex with new developments in athletic prosthetics and footwear.

Controversy in professional competition aside, running blades allow young and old amputees alike to run like the wind. Phillips was able to turn a tragic accident into a legacy that allows everyone to enjoy sport at the same level!

Where Can I Learn More About Running Blades?

Check out the website Prosthetic Running to learn more about running blades, running form and exercises. They walk you through the baby steps of learning to run with blades, and how to prevent injuries in the process.

Athletic prosthetics are usually not covered by insurance as they are not deemed “medically necessary.” If you are looking to buy running blades, be sure to read our guide on financial assistance for prosthetic services and apply for programs that may help cover all or some of the cost.

Featured Image Credit: Evening Standard.