Mechanics of Oscar Pistorius's running blades
The mechanics of the running blades used by South African former Paralympic runner Oscar Pistorius depend on special carbon-fiber-reinforced polymer prosthetics.
Pistorius began running in 2004 after a rugby knee injury which led to rehabilitation at the University of Pretoria's High Performance Centre[1] with coach Ampie Louw.
Because he was unable to find suitable running blades in Pretoria, Vanderwatt ordered some to be made by a local engineer at Hanger Orthopedic Group.
These quickly broke, and Vanderwatt referred Pistorius to American prosthetist and Paralympic sprinter Brian Frasure to be fitted for carbon-fibre blades by Icelandic company Össur.
[4] After further research was presented, the Court of Arbitration (CAS) ruled that his running prostheses were not shown to provide a net competitive advantage over biological legs.
[7] Carbon fibre is actually a carbon-fiber-reinforced polymer, and is a strong, light-weight material used in a number of applications, including sporting goods like baseball bats, car parts, helmets, sailboats, bicycles and other equipment where rigidity and high strength-to-weight ratio is important.
Research was conducted in Össur's Iceland lab using a pressure-sensitive treadmill and film at 500 fps to measure the blade strike, and produced a spike pad which includes a midsole of two machine-molded pieces of foam of different densities to cushion impact, with a carbon fibre plate on the bottom.
An analysis published by Engineering & Technology magazine estimates that in using the blades, Pistorius must generate twice the power from his gluteal and quadriceps muscles that a normal sprinter would.
This results in a gait that waddles slightly, as Pistorius swings his upper body to balance the springing action of the blades.
[8] To resolve questions about the blades, Pistorius was asked to take part in a series of scientific tests in November 2007 at the German Sport University Cologne with Professor of Biomechanics Peter Brüggemann and IAAF technical expert Elio Locatelli.
[18] In December of that year, Brüggemann stated to Die Welt newspaper that Pistorius "has considerable advantages over athletes without prosthetic limbs who were tested by us.
However, because Pistorius was relatively new to the sport of running, he may not have trained enough to maximize his physical potential and reach his peak performance when the IAAF study was conducted.
To obtain the most accurate understanding of how the prostheses affect Pistorius's performance, he should be compared to athletes with similar physical potential.
Consequently, the IAAF study may have been flawed because it compared Pistorius, who might have the physical potential to run faster than his current times, against athletes at their peak.
[22] In 2008 a team of seven researchers conducted tests at Rice University, including Peter Weyand, Hugh Herr, Rodger Kram, Matthew Bundle and Alena Grabowski.
In comments on the article, Peter Weyand and biomechanist Matthew Bundle noted that the study found that Pistorius re-positioned his legs 15.7% faster than most world record sprinters, allowing for a 15–30% increase in sprint speed.
[26] In 2008 a research team including Alena Grabowski, Rodger Kram and Hugh Herr conducted a follow-up study of single amputees with running blades which was published in Biology Letters.
The team measured leg swing times and force applied to the running surface on a high-speed treadmill at the Biomechanics Laboratory of the Orthopedic Specialty Hospital, and also studied video of sprint runners from the Olympics and Paralympics.
They also found that single running blades reduced the foot to ground force production of the tested runners by an average of 9%.
[citation needed] The improvement in running time and the wide broadcast of the race results provided a public demonstration of how the blade length affects performance.
