The league and NFL Players Association haven't given up on getting human growth hormone testing in place for the 2013 season, even after a significant stalemate in talks occurred earlier in the year.

According to union and league sources, the NFL submitted a new proposal on human growth hormone testing to the union on April 24. It included a concession in the elimination of game-day testing, which had been part of previous proposals.

One union source said the issue now is that the league's proposal calls for testing to begin immediately. The samples would then be tested, and results would be stored, until the World Anti-Doping Agency comes up with the baseline standard for acceptable levels. The union, per the source, would rather wait to start drawing blood and testing until the baseline is determined and full testing is ready to be implemented.

"A population study that both parties agreed to a year ago would have resolved the issue of accuracy," union spokesman George Atallah said.