The prosthetic legs double-amputee sprinter Oscar Pistorius uses provide less air resistance than normal legs, the IAAF said Monday.

Pistorius, who wears curved, carbon-fiber prosthetic legs, finished second in Rome on Friday and last against elite able-bodied athlete at the British Grand Prix on Sunday. He hopes to compete at the 2008 Beijing Olympics.

The International Association of Athletic Federations has been reviewing footage from two high-definition cameras that filmed Pistorius in Rome to determine if his prosthetic racing legs give him an unfair advantage.

"The guy Oscar beat on Friday — the stride length was the same, but the speed through the air was slower for the able-bodied guy," IAAF spokesman Nick Davies said. "This research makes us want to do more."

Davies said the initial research also showed the way Pistorius distributed energy was virtually the opposite to able-bodied runners. And unlike able-bodied runners, Pistorius was faster at the end of the race instead of the beginning.

Pistorius ran 46.90 seconds in Rome. But in his first race against an elite field on Sunday in Sheffield, England, he finished last (47.65) in heavy rain and was disqualified for running outside his lane.

Pistorius has set world records in the 100, 200 and 400 in Paralympic events. To make next year's Olympics, Pistorius would have to run a 46.3 before the July 2008 qualifying deadline.

The IAAF introduced a rule in March banning any runner deemed to benefit from artificial help from competing, but Davies said that was not necessarily meant to include athletes like Pistorius.

"Maybe he's overreacting over certain things. He seems to think that we've banned him then decided he was eligible," Davies said. "We clarified the situation. No one has banned him. We want to give him the benefit of the doubt."

Davies also said the IAAF was not discriminating against disabled athletes, citing legally blind runner Marla Runyan of the United States, who competed in the 1,500 at the 2000 Olympics and in the 5,000 in Athens four years later.

"We need to separate emotion from the science," Davies said. "We all wish him well. The point here is what's going to happen in 10 years? What happens if it continues to evolve?"

Davies said the IAAF's research was being overseen by director of development Elio Locatelli, who is a former chief coach of the Italian athletics team, and the governing body of the sport hoped to work with Pistorius in the biomechanics department of the Cologne-based German Sport University.

Pistorius was born without fibulas — the long, thin outer bone between the knee and ankle — and was 11 months old when his legs were amputated below the knee.

He began running four years ago to treat a rugby injury, and nine months later won the 200 at the 2004 Paralympic Games in Athens, Greece.