When many people think of extreme sports, they tend to think of hockey or rugby. However, one of the most original and oldest extreme sports is simply a more violent variant of soccer. It is called harpastum and it involves many of the same rules, and a lot of different variations for play and defending when the ball is in motion through the arena. Players are allowed, and in fact encouraged, to throw elbows, knees, and pin their opponents to get the ball. In short, they are allowed to get as violent as they need.