The World Anti-Doping Agency defended its test for human growth hormone on Wednesday and accused the NFL players union of being "extremist" for questioning its validity.

WADA director general David Howman said the union was acting "the way they've operated the last few years" in trying to block the introduction of HGH testing in the National Football League.
"I would expect the players association to take a stance which is extremist," Howman told The Associated Press in a telephone interview. "What we've got to do is get to reality and not to a position that is an extremist position."

The NFLPA questioned the HGH test again after Tuesday's ruling by the Court of Arbitration for Sport in the case of Estonian cross-country skier Andrus Veerpalu.

The court lifted the three-year suspension imposed by the International Ski Federation on the two-time Olympic champion for use of HGH, citing "procedural flaws" in the limits established by WADA to determine a positive test.

But the three-person CAS panel also said it believed Veerpalu did take HGH and it backed the WADA testing method as a whole.

"What we have to do is actually look at the decision in a very calculated, objective fashion," Howman said. "What CAS has decided is that the test is OK and what they want is for there to be a bigger population-based study in terms of the impact of it. We'll take that on board and we'll go further."

The NFL players said the decision highlighted its long-running concerns about HGH testing in pro football.