The NFL and NFL Players Association are progressing toward league-wide testing for human growth hormone, and it could be implemented in 2013, according to NFL.com's Albert Breer.
The two sides agreed to test for HGH in 2011, but since then, they haven't been able to come together on how it should actually be done. Players will be required to submit blood samples during training camp to determine "normal" HGH levels, per USA Today. The NFLPA has objected to the World Anti-Doping Agency's testing procedures and desired its own population study due to the belief that NFL players have higher levels of HGH than average people.
An email from the NFLPA to players obtained by USA Today addresses those issues with testing procedures:
"The current stalemate regarding HGH testing and the League office is about whether the NFL, and others working with them, can force the Players to accept an unfair testing and discipline protocol when the collective bargaining process requires mutual agreement by both the Players and the NFL."
Major League Baseball is currently the only major American sports league to test for HGH in season.