Professional football in America dates back to around 1920. The college game goes back even further. Theodore Roosevelt loved how the game built athleticism, character, teamwork and willpower. In 1905, there were far fewer players than today, and yet 18 died during games in that one year alone. Deciding that the risks outweighed the benefits, President Roosevelt threatened to outlaw the game unless something could be done. A number of new rules were implemented, including the forward pass, which spread the defense and reduced some of the violence at the line of scrimmage. The following year only 6 players died, and the concept of player safety began to take hold. By 1907, player deaths were back up to 11, as coaches found ways to work around the rules and recapture the violent intensity of the game. When the death toll had risen to 33 in 1909, another round of changes took place. Over 100 years have gone by, but if you think the problem has been solved, just Google “Jonathan Vilma” or “Junior Seau”.

http://abcnews.go.com/Entertainment/junior-seau-dead-suicide-nfl-linebacker/story?id=16263047#.T61uqsWDFtA