Track and field's governing body ruled today he is ineligible to compete this summer in Beijing — or any other sanctioned able-bodied competitions — because his "Cheetah" racing blades are "technical aids" that give him a clear advantage.

"An athlete using this prosthetic blade has a demonstrable mechanical advantage (more than 30 percent) when compared to someone not using the blade," the International Association of Athletics Federations said.

Pistorius had long learned not to consider his artificial legs a hindrance, even refusing to park his car in a spot for the disabled.

His manager, Peet Van Zyl, called the IAAF ruling a "huge blow." Van Zyl spoke briefly with Pistorius, saying he "could hear from his voice that he is disappointed."

"He has been competing in South African able-bodied competition for the past three years," Van Zyl said. "At this stage it looks like he is out of any able-bodied event."

The 21-year-old runner said last week he would appeal "to the highest levels" if the ruling went against him. He could take his case to the Court of Arbitration for Sport in Switzerland. The International Olympic Committee said it "respects" the IAAF decision.

"This decision has nothing to do with Oscar Pistorius' athletic merits. What is important is to ensure fair competition," the IOC said in a statement.

South Africa's national track and field federation says it is bound by IAAF rules and must keep Pistorius from some national races he has entered for several years.

"If we had our rules and our own competition it would be easier," South Africa federation president Leonard Chuene said. "It is a huge problem."

Pistorius finished second in the 400 meters at the South African national championships last year against able-bodied runners.

The IAAF based its decision on a study in germany by professor Gert-Peter Brueggemann. He found several indicators the Cheetah blades provided an unfair edge.

The federation said Pistorius had been allowed to compete in some able-bodied events until now because his case was unique and such artificial protheses had not been properly studied.

"Now we have the science," IAAF spokesman Nick Davies said.

No one directly questioned the findings of Brueggemann. The producer of Pistorius' Cheetahs and the International Paralympic Committee said more tests should be undertaken.

The ruling does not affect his eligibility for Paralympic events, in which he was a gold medalist in Athens in 2004. Pistorius has set world records in the 100, 200 and 400 in Paralympic events.

The runner worked with Brueggemann in Cologne for two days of testing in November. The goal was to learn how the j-shaped carbon-fiber extensions to his amputated legs differed from the legs of fully abled runners.

Brueggemann found that Pistorius was able to run at the same speed as able-bodied runners on about a quarter less energy. The professor said that once the runners hit a certain stride, athletes with artificial limbs needed less additional energy than other athletes.

The professor determined that the returned energy from the prosthetic blade is "close to three times higher than with the human ankle joint in maximum sprinting." The IAAF adopted a rule last summer prohibiting "technical aids" deemed to give an athlete an advantage.

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 competitively four years ago to treat a rugby injury, and nine months later won the 200 meters at the 2004 Paralympic Games in Athens.

Pistorius competed in the 400 at two international-level able-bodied meets in 2007. He finished second in a B race at a Golden League meet in Rome on July 13 and, two days later was disqualified for running out of his lane in Sheffield, England.