Roller Derby is a team sport of fast, furious, and often violent action that first appeared in the mid-1930s. The games take place on a banked oval track, where two squads of five men or five women—the sexes do not usually compete against each other—skate around the track, with each team sending out "jammers" in front of the pack. Points are scored when jammers lap an opponent. Like rugby or football, other players act as "blockers" clearing the way for the jammer.

Long-distance bicycle races and marathon dances inspired the original game, invented in 1935 by Leo Seltzer. The objective was to make 57,000 laps around the track, a distance of 4,000 miles. While at that time it was a true athletic contest, it was also quite boring for the spectators because matches would last for hours on end. Similar to the development of professional wrestling...