Roller derby

Roller derby is a contact sport played by two teams of five members roller skating in the same direction (counter-clockwise) around a track. Game play consists of a series of short match ups (jams) in which both teams designate a jammer who scores points by lapping members of the opposing team. The teams attempt to hinder the opposing jammer while assisting their own jammer—in effect, playing both offense and defense simultaneously. The Jammer can be spotted from the star on their helmet.