Former NHL player Derek Boogaard filled an unofficial role known as an enforcer, which is a player whose purpose is to fight as a means of responding to dirty plays by the opposing team. After he died at age 28 in 2011, doctors examined Boogaard’s brain and determined that he had chronic traumatic encephalopathy, which is believed to be caused by repeated head injuries. 

Two other enforcers died within four months of each that same year, raising concerns about the physical, as well as mental and emotional, toll that fighting takes on players.