Former Green Bay Packers quarterback Brett Favre says he may have suffered "thousands" of concussions during his 20 seasons playing in the NFL.
The hall of famer told The Bubba Army radio show that while he was still in the game, he might have estimated he suffered just of few concussions, which can cause chronic traumatic encephalopathy, or CTE.
But with the knowledge he now has about CTE, he expects that number to be much higher.
"The thing about concussions is we still don't know a lot about them. If you had asked me this 10 years ago, how many concussions I had, I would have said three," Favre said.
"The reason I would have said three is I thought concussions were where you get knocked out - where you black out for a period of time, you don't know where you are, memory loss, dizzy. A boxer gets knocked and tries to get up, his legs are rubber. That's a concussion," Favre told host Bubba The Love Sponge.
Favre says he was never diagnosed with a concussion. But just in regular seasons during his career, he was sacked 525 times, while playing for the Packers, Falcons, Jets and Vikings.
That includes the game playing against the Giants in 2004. Favre hit his head just before throwing a touchdown pass to Javon Walker. "That's what's kind of frightening about the concussion thing: it's the ones that seem minor that do the damage, because you're able to play and keep going," Favre said.
Favre speaks against concussions in young athletes
Since retiring from professional football, Favre has become an advocate. He served as a spokesperson for the Concussion Legacy Foundation and brought awareness to the risk of head injuries in young athletes playing tackle football.
The CDC defines a concussion as traumatic injuries caused by hits to the head or body that lead the brain to move around in the skull. Concussions over and over again can then cause CTE - which can bring long-term effects like trouble concentrating, depression and memory problems.