The Super Bowl, the biggest football game of the year is sure to come with some big hits. It's a job that could cost those players a lifetime of personal sacrifice.
A study by the Center for the Study of Retired Athletes finds that NFL players who suffered three or more concussions during their career feel the long term effects of brain injury, memory loss depending on how bad the blows.
"How many have you before, of those that you had were they mild grade one concussions - were they serious, severe grade three concussions," said Dr. Kevin M. Guskiewicz, of the University of North Carolina.
"It's scary what they're finding out, but what are you gonna do? it's football, you're gonna hit," said Ruben Brown, of the Chicago Bears.
It's not just memory trouble, but that study of more than 2,500 former NFL players found the more concussions in a player's career. The higher the risk of depression later in life as well.
The good news is that even though it is early in the studies head injury research has led to improvements in protective equipment and speed of an athlete's recovery.