There is a sport, a sport which only the toughest, meanest, most bloodthirsty can play. Mere mortals should never even dream of trying to play this game. No, it's not Rollerball. It's not The Running Man. It's not even American football - those guys wear pads. And they get to stop every ten seconds or so to rest!No, it's wheelchair rugby. Or, as the players like to call it - Murderball.Murderball is also the name of the documentary about the men who play this sport, and, a somewhat wimpy ending aside, if there is a more testosterone-laden, manly film in the history of documentary moviemaking, it would have to be a film about a man who gets into fights with grizzly bears. (What? You mean there is one? Oh, dear...)Regardless, this is the story of wheelchair rugby, a game played only by people who have impairment in two or more of their limbs. The rules are somewhere between basketball, rugby, and demolition derby, and if there's a visual analogy to watching a game, it's the last ten minutes of The Road Warrior if it was a competitive sport.