The NFL Players Association "tentatively agreed" to let the league take 40 blood samples for HGH tests each week during the season, with a positive result drawing a four-game suspension, according to a memo the union sent players.
A copy of the NFLPA's email, written in a question-and-answer format, was obtained Tuesday by The Associated Press.
The memo says "a computer program will randomly select" five players apiece from eight teams each week to take the blood tests.
First, though, every player participating in NFL training camps this year will provide a blood sample and information about "height, weight, age, and race/ethnicity" for a "population study" to determine what level of HGH will result in penalties, the union wrote.
The NFLPA's letter says that if more than 5 percent of all training camp samples are above that threshold, players who fail will have "reasonable cause" testing during the next two seasons -- meaning they'll be subject to additional testing. A player testing positive again during the 2013-14 or 2014-15 seasons will get an eight-game suspension. A player without another positive result in that time will be removed from the extra testing program.
Tuesday's email to players indicates the union has signed off on various aspects of the HGH program and says owners and players "will likely finalize soon" the in-season weekly testing. But the memo does not make clear what exactly the NFL has agreed to at this point or give specifics about what stands in the way of a final accord.
No date has been set for the start of testing, because there are still issues that need to be negotiated between the NFL and union, including whether the commissioner or a neutral arbitrator will handle certain types of appeals of discipline.
League spokesman Brian McCarthy declined to comment on any specifics in the NFLPA memo, writing in an email to the AP: "We do not have yet a comprehensive agreement for HGH testing."
The league and the union originally paved the way for testing in the 10-year collective bargaining agreement they signed in August 2011, but two complete NFL seasons have come and gone -- and a third is right around the corner -- without a single HGH test being administered on a player.
During the two years since, the sides have haggled over various elements, including details of the appeals process and the union's insistence on a population study to determine what is a naturally occurring amount of HGH in NFL players.
HGH is a banned performance-enhancing drug that is hard to detect and has been linked to health problems such as diabetes, cardiac dysfunction and arthritis.
In January, shortly before the Super Bowl, House Oversight and Government Reform Committee chairman Darrell Issa, a California Republican, and ranking Democrat Elijah Cummings of Maryland wrote NFLPA head DeMaurice Smith to chastise the union for standing in the way of HGH testing and to warn that lawmakers could ask players to testify on Capitol Hill.
Late last year, that House committee held a hearing at which medical experts testified that HGH testing is reliable and that the union's request for a population study was unnecessary. But in March, a ruling by the Court of Arbitration for Sport in a case involving a cross-country skier raised questions about the reliability of thresholds for HGH tests.