Cummings and committee chairman Darrell Issa, a California Republican, both said additional hearings are expected.
"It is our hope (to) move these parties closer together," Issa said.
"This isn't the players" who are objecting to the test, Issa said after the hearing. "This is lawyers making a statement. Players want to know that the rules are the rules for everybody. ... We're not seeing a vast amount of players stand up. We're seeing a few lawyers stand up on an unfounded technicality."
The NFL and union were not invited to testify at the hearing, but representatives of both attended Wednesday's session.
Asked about Cummings' comments, NFLPA spokesman George Atallah said after the hearing: "I respect his opinion. We have a contract, and the contract says both sides have to agree to protocols to move forward."
Atallah said the union was "absolutely not" trying to back out of the agreement on HGH.
NFL senior vice president Adolpho Birch, who oversees the league's drug program, called the union's insistence on a population study to determine whether current HGH tests are appropriate for NFL players a delay tactic.
"As a league, we need to look at it in terms of competitive integrity, in terms of being consistent with the NFL having a leadership position in the world of performance-enhancing drugs," Birch said. "And frankly, I think this delay in implementing this program has put our leadership position at risk."
Even once scientific issues are resolved, there will be other matters the league and union need to figure out, including who administers the test and what the appeals process will be.
"First, I applaud the NFL and players for taking a bold and decisive position on HGH in their 10-year agreement. Now let's get on with it," one witness, Pro Football Hall of Famer Dick Butkus, told the committee Wednesday. "The HGH testing process is proven to be reliable. It's time to send a clear message that performance-enhancing drugs have no place in sports, especially the NFL."