"As you know, the new Performance Enhancing Substances Policy includes HGH testing. Testing for HGH will begin on Monday, October 6th," NFLPA president Eric Winstonwrote in a letter to players. "Each week of the season, 5 players on 8 teams will be tested. No testing will occur on game days. We negotiated to ensure that the methodology of testing be conducted in the most professional and safest manner for players. Importantly, after three years of negotiating, players won the right to challenge any aspect of the science behind the HGH isoforms test in an appeal of a positive test."