Commissioner Roger Goodell speaks during a news conference at the NFL's spring meetings in Boston in May. (Photo: Elise Amendola, AP) Story Highlights The NFL and players union plan to give ex-players HGH and incorporate their HGH levels into a study 
 
 By measuring the levels of HGH in ex-players receiving HGH and a placebo, the league and union hope to determine a threshold for catching cheaters 
 
 It's unclear whether any former players have agreed to take part in the experiment 
 
 MANKATO, Minn. — Dozens of former NFL players will be administered human growth hormone as the NFL and its players union try to determine the impact of use on players' HGH levels, three people with knowledge of the plan told USA TODAY Sports on Wednesday. 
 
 The people spoke on the condition of anonymity because the study has not been announced publicly. 
 
 The tentative plan is for roughly 100 former players to participate in the study, with two-thirds receiving HGH and the other third receiving a placebo. Their HGH levels will be measured before and after the trial. 
 
 It's part of the scientific design of the population study that will include blood draws from all current players to determine the so-called decision limit — i.e. the highest HGH level a player can have without facing discipline under the new performance-enhancing drug policy that is still being finalized, the people said. 
 
 Current Minnesota Vikings players were informed of the plan Wednesday during a visit from their designated advocates from the NFL Players Association, Martin Bayless and Ernie Conwell. 
 
 ADRIAN PETERSON: HGH accusations are a 'compliment' 
 
 It was unclear whether any ex-players had agreed to participate in the study, when the HGH would be administered or how prescriptions would be obtained for the drug. 
 
 Human growth hormone is naturally produced by the body, stimulating cell reproduction and regeneration. It also can be administered artificially and is banned by most international sports organizations as a performance-enhancing drug. 
 
 The NFL and the union agreed to blood testing for HGH in the collective bargaining agreement that was finalized two years ago. But a series of issues, including the NFLPA's insistence on the population study to determine what a "normal" HGH level is for an NFL player, has delayed implementation. 
 
 Two people with knowledge of negotiations told USA TODAY Sports this week there remains optimism HGH testing could begin in 2013, though a comprehensive agreement has not been finalized. 
 
 Follow Tom Pelissero on Twitter @TomPelissero. 

 The NFL Players Association has "tentatively agreed" to human growth hormone testing and accompanying punishment for the 2013 regular season, according to a union memo obtained Tuesday by NFL.com's Albert Breer. 
 
 The memo says that a first offense for any player who tests positive for HGH will bring a four-game suspension. The NFLPA will allow the league to obtain 40 blood samples for HGH tests each week during the testing, according to the tentative agreement. 
 
 The evolution of the NFL: 
 
 Take a look at how the NFL has evolved from its humble roots, and the efforts being made to ensure it continues to grow. 
 
 
 
 
 
 The NFL denies that an agreement has been finalized. 
 
 "We do not have yet a comprehensive agreement for HGH testing and decline to comment on the union's memo," NFL spokesman Brian McCarthy said. 
 
 Breer reported earlier this week that the sides agreed on all procedural aspects of HGH testing. The last sticking point remaining, according to Breer, is the appeals process and the presence of a neutral arbitrator. The memo from the NFLPA revealed some of the details of the testing. 
 
 Every player in the NFL will provide a blood sample in training camp for a "population study" that will determine what level of HGH will result in penalties, the union wrote in the memo. Eight players randomly will be chosen from five teams each week during the regular season for testing. The memo says the comprehensive agreement likely will be finalized soon. 
 
 The entire memo can be seen here. 
 
 The Around The League Podcast is now available on iTunes! Click here to listen and subscribe.
– In this case, the NFL will not only condone doping but actually supply the dope. A new plan calls for about 70 former players to take human growth hormone in a controlled study, reports USA Today. Another 30 or so will get a placebo, and researchers will keep a close eye on before-and-after HGH levels. The idea is to get a better handle on what normal levels should be (the body does produce HGH naturally) as the league gets ready to put into place a testing policy. NFL.com reports that HGH tests on current players could start this season, with first offenders getting a four-game suspension.