Commissioner Roger Goodell, NFL have pushed the union to attempt to implement blood-testing of players for HGH (Associated Press)

The league and players’ union have made progress in their negotiations over having players blood-tested for human growth hormone, but obstacles remain before such a test is implemented, several people familiar with the deliberations said.

Those people confirmed that the union has told players to be prepared to provide blood samples during training camp to be used in a population study aimed at determining the proper threshold for a positive HGH test for an NFL player.

Such a population study has been described by the union as a necessary precursor to the implementation of league-wide blood-testing for HGH, and the two sides have haggled over the specifics of such a study at various times during their long-running deliberations on the matter.

One person familiar with the negotiations said there has been “progress” but there is “still a ways to go,” adding that the league and union “have been close before and could not get it done.”

But another person familiar with the league’s view of the matter said the two sides are “getting there” on reaching an accord on the issue and the union increasingly appears to be “ready to agree to something.”

The league issued a written statement that said: “We are in active discussions with the NFLPA regarding the implementation of HGH testing for NFL players. Those discussions are focused on a full resolution of any remaining issues, including the role of a population study.”

The league and union agreed to have players blood-tested for HGH as part of their 2011 labor deal. But they first had to agree to the details of the testing, and their inability to do so kept the implementation of testing on hold for the 2011 and 2012 seasons. Among the key issues separating the two sides have been the population study, which the league often has called unnecessary, and the appeals process for players who test positive.

NFL officials have said the testing should have begun long ago, soon after the 2011 agreement. Union officials have said they would agree for players to be tested once they were satisfied the testing was safe and reliable and players’ rights were protected properly. Members of Congress have attempted to persuade the parties to reach an agreement to get the testing started.

HGH is on the NFL’s listed of banned performance-enhancing substances, but players are not tested for it.

The league and union have jointly hired a doctor, Alan Rogol, to conduct the population study, according to a union memo sent recently to players in leadership positions. The memo, a copy of which was obtained by The Washington Post, said the blood drawn from players during training camp “will immediately be sent to the laboratory for analysis only for the purpose of the hGH population study; no other use will be made of any blood sample. After the laboratory has processed all player blood samples, the scientists will perform the calculations and analysis necessary to determine the proper decision limit for NFL players.”

The union’s memo also said: “There are, however, several additional issues which must be collectively bargained to agreement before final implementation of the hGH and Performance Enhancing Substances drug policy. One of those issues is the issue of discipline. The parties continue to discuss the issue and when a final proposal is reached, we will bring it to you for your review and vote.”