The Player's Association has blocked the test from moving forward because of concerns about its validity and methodology. The players have complained that the World Anti-Doping agency, which will administer the test, has not turned over demographic information about that control group against which their HGH levels will be measured.

“Who was included in that study? What were the ratio levels? Were they tested, or was that population tested in conditions or similar situations that would mirror professional football athletes?" Smith said to the AP. "I don’t know. And that’s information that [WADA] refuse to turn over.’’

HGH naturally occurs in the human body, and the test proposed by the WADA is designed to detect synthetic HGH by measuring the ratio in a player's blood against the ratio that naturally occurs in the test group. But the player's association has argued that this method might be unfair, because it is possible that gifted professional athletes produce HGH at a significantly higher ratio naturally.

Travis Tygart, CEO of the US Anti-Doping Agency, also has been invited to meet with the Reform Committee.

The NFL says that it would like to proceed with testing immediately and has disputed the players' claim that the test may not be valid.

"The population studies that have are done are broad-based and include thousands of people cut across a number of different nationalities, races, ages, et cetera," said Adolpho Birch, vice president of law and labor policy for the NFL. "There is no fluctuation in the ration. To ask for a sports-specific, or a NFL-specific group flies in the face of the scientific evidence.

Birch said that continued requests from the player's union amounted to a stall tactic to prevent implementation of the test.

"We have spent the better part of three years talking about it, the better part of the last six weeks explaining the science - at some point it becomes clear the requests they have are the whole point," Birch said.

The NFL has said that they will cooperate with the Congressional inquiry.

“We are disappointed in the union's failure to follow through on its commitment to HGH testing to ensure the integrity of competition on the field, protect the health of NFL players and send the right message to young athletes,” NFL spokesman Greg Aiello said in statement. “We appreciate the committee's interest and look forward to cooperating with the members on this matter.”

This will not be the Oversight Committee's first foray into drug testing in professional sports. In 2008, the committee heard testimony from Major League Baseball officials and players about the pervasive use of performance enhancing drugs in the sport.