LONDON -- The prosthetic legs of double-amputee sprinter Oscar Pistorius give the South African a 10-second advantage over a 400-meter race, according to a study by researchers from two American universities.
Peter Weyand of Southern Methodist University and Matthew Bundle of the University of Wyoming found that Pistorius, who has been cleared to compete against able-bodied athletes, runs the 400 distance 10 seconds faster than he would if his prosthetic limbs acted like normal legs.
Their conclusion, as part of a point-counterpoint, will be published Thursday in the Journal of Applied Physiology.
"Pistorius' sprinting mechanics are anomalous, advantageous and directly attributable to how much lighter and springier his artificial limbs are," Weyand said in a statement. "The blades enhance sprint running speeds by 15 to 30 percent."
The counterpoint, written by seven other researchers from around the United States, disputed the claim by Weyand and Bundle.
"There is insufficient evidence to conclude that modern running specific prostheses provide physiological or biomechanical advantages over biological legs," the counterpoint claims.
Based on tests performed by German professor Gert-Peter Brueggemann, the IAAF banned Pistorius from competing against able-bodied athletes in January 2008. The decision was overturned by the Court of Arbitration for Sport in May.
The CAS ruling cleared Pistorius to compete at the Beijing Olympics, but he failed to run the required qualifying time of 45.95 seconds. His personal best is 46.25.
After failing to reach the Olympics in Beijing, Pistorius won three gold medals in the 100, 200 and 400 at the Paralympics last September. He also failed to meet the qualifier standard ahead of this year's world championships in Berlin.
The 22-year-old Pistorius, known as the "Blade Runner," is still hoping to qualify for the 2012 London Olympics.
Weyand and Bundle said the lightweight blades allow Pistorius "to reposition his limbs 15.7 percent more rapidly" than five of the most recent world record-holders in the 100 meters.
"The springy, lightweight blades allow Pistorius to attain the same sprinting speeds while applying 20 percent less ground force than intact-limb runners," the pair concluded, according to the statement. "The springy blades reduce the muscle forces Pistorius requires for sprinting to less than half of intact-limb levels."
The counterpoint disputed the lightweight prosthetics give Pistorius an advantage.
"Brief leg swing times increase the fraction of a stride that a leg is in contact with the ground and thus reduce the vertical impulse requirement for the contact phase," the counterpoint says. "But, the notion that lightweight prostheses are the only reason for Pistorius' rapid swing times ignores that he has had many years to train and adapt his neuromuscular system to using prostheses."
The counterpoint was written by Rodger Kram and Matthew T. Beale of the University of Colorado, Alena M. Grabowski and Hugh M. Herr of the Massachusetts Institute of Technology, Craig P. McGowan of the University of Texas, Mary Beth Brown of Georgia Tech and William J. McDermott of the Orthopedic Specialty Hospital.