It's an open secret in American football that a lot of the players, especially the 300 lb+ guys, are dying in their forties and fifties, because the stress they put themselves through is so extreme that it just destroys their bodies and ruins their hearts. These are people who are basically performing at the scientific extremes of what the human body is capable of: from physical exertion, to the impacts of such massive people colliding, over and over again, at full speed.
Heavy NFL players twice as likely to die before 50