Vikings running back Adrian Peterson says he is certain that NFL players use HGH. (Scott Halleran/Getty Images)
Peterson wants to silence the critics raising questions about how he came back so strong and welcomes being tested for human growth hormone to prove he is clean.
He also said that he is certain that NFL players are using HGH and wants the league to establish a testing program to start "evening out the playing field."
"You've got HGH, something that doesn't show up on a test, and you've got guys out there trying to provide for their families," Peterson said to ESPN.com. "They're going to try to get that edge, get that advantage, especially if they're not worried about trying to get caught. Yeah, it's being used."
Peterson was back on the field less than nine months after his knee surgery. He capped off the season by rushing for 2,097 yards, 12 touchdowns and was named the league's Most Valuable Player.