Oscar Pistorius: Materials and Athletics at the Limits
by Richard J. Lombard
In baseball, there are the infamous pine tar and cork incidents. In swimming, talk still swirls around manufactured sharkskin suits. Nowhere, however, is the topic of materials and their impact in sports more curious than in the case of Oscar Pistorius.
Pistorius, a double amputee since early childhood, has been a competitive sprinter for the past five years. Racing in the Paralympics and other competitions for athletes with disabilities, Pistorius has risen to the top of his field which includes runners with lesser disabilities. He has been able to run competitively thanks to unusual prosthetics known as “Cheetahs.”
The Cheetah prosthetic foot, manufactured by Ossur in Iceland, is a curved carbon-fiber plate that attaches to a custom socket that Pistorius fixes to each of his knees. The feet, also known as “blades”, are created from multiple layers of carbon fiber laid one on top of the other. As with so many sports where the difference between first and second place is measured in hundredths of seconds, the number of layers is carefully calculated dependent upon the weight that the foot needs to support. Large pieces of layered sheets are bent to form the shape of the blade, and then cut to create the individual prosthetics.
These remarkably delicate looking pieces are very light – an example we used in an exhibition weighed less than 1.5 pounds (.7 kg) – yet are capable of withstanding not only the weight of an adult runner, but the forces generated during world-class sprinting. During the development process Pistorius cracked more than a few prototypes, keeping the Ossur team focused on making them stronger and stronger. With a price of some US$15,000 per blade, those are some expensive wipe-outs.
As he became more and more dominant in Paralympic competition – he is the current world-record holder in the 100-, 200-, 400-meter distances – Pistorius began to enter competitions not restricted to disabled athletes. Running in the IAAF (International Association of Athletics Federation) Golden Gala in Rome, Pistorius finished second; but in the British Grand Prix he slipped in the wet conditions, placed seventh, and was later disqualified for running out of his lane.
His ultimate goal, though, has been to run in the Olympics; and to that end he hoped to qualify for this year’s Beijing Games. Unfortunately, the IAAF ruled that his prosthetics gave him an advantage over regularly-abled runners. This was decided after they reviewed extensive testing and found a number of possible advantages in the carbon fiber blades.
The most oft-cited result of the testing was that Pistorius was able to use 25% less energy over a measured distance than an able-bodied runner, an indication that his blades gave him a mechanical advantage. However, other tests seem to indicate that the blades are less efficient than the human leg, and lose 20% of the energy that are put into them. Other arguments against his participation focus on the fact that the length of his stride could be lengthened by the prosthetics; while those in favor of his running cite the fact that the prosthetics have little traction in wet conditions, and that Pistorius has to constantly adjust his stride to accommodate for small movements between his legs and the sockets. There are relatively few absolutes in this debate, and it will most likely rage for quite a long time.
Wherever materials interact with human performance, there will always be questions as to who or what is actually responsible for that performance. What cannot be questioned, however, is the fact that materials can enable a person without legs to not only walk, but to run with the fastest people on the planet. Wherever his career takes him, Oscar Pistorius is an inspiration to many and a shining example of the limitless resources of the human spirit and technological progress.
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