Roller derby

Roller derby is a fast-paced contact sport played on an oval track.

It involves two teams competing in a series of short, intense segments. These segments are called jams. A full game, or bout, typically lasts 60 minutes. This time is divided into two 30-minute periods. Most modern roller derby is played by amateur athletes. There are approximately 1,250 amateur leagues worldwide. While it is very popular in the United States, it is an international sport.

Each team usually has a roster of about 15 skaters. During a jam, five skaters from each team are on the track. One player is the jammer, identified by a star on their helmet.

The other four players are blockers. One blocker may also serve as the pivot, marked by a stripe on their helmet. The jammer is the only player who scores points. They score by lapping opposing blockers while skating counterclockwise. To earn a point, the jammer must be upright and in-bounds. If a jammer passes the entire pack, it is a four-point trip called a "grand slam."

Blockers play both offense and defense at the same time. They use their bodies to hinder the opposing jammer. They also maneuver to help their own jammer pass through the pack. Blockers can form a "wall" by skating side by side. This formation makes it difficult for the opponent to move through. However, blockers cannot link arms or grasp each other to stay connected. They must also avoid using hands, elbows, heads, or feet to block. Contact is also prohibited above the shoulders or below the mid-thigh.

Strategy is a vital part of the game's complexity. The lead jammer is the first person to break through the pack. This player earns "lead jammer" status. This allows them to stop the jam at any time by placing their hands on their hips. This is a key tactic to prevent the other team from scoring. Another strategy is the "star pass." This occurs when a jammer hands their star helmet cover to the pivot. The pivot then becomes the new jammer. This can happen because of fatigue or a better scoring position.

Rules are strictly enforced by referees to ensure fair play. If a skater commits a foul, they are sent to a penalty box. They must stay there for 30 seconds of jam time. While a player is penalized, their team must play short-handed. This can lead to a "power jam." In a power jam, one team has a numerical advantage. This advantage can have a major effect on the final score. If a player receives seven penalties, they "foul out" and must leave the game.

Roller derby has a unique history that has changed over time. It began in the 1930s with banked-track roller-skating marathons.

Leo Seltzer and Damon Runyon helped evolve it into a competitive sport. In 1940, more than 5 million spectators watched the sport in American cities. For many decades, it became a form of sports entertainment with scripted winners. However, a grassroots revival in the early 2000s changed this. Modern derby has abandoned scripted results in favor of real athleticism. It now maintains a "do-it-yourself" ethic mixed with punk and camp styles.

Safety is managed through specific equipment requirements.

All players use quad skates, which have four wheels. They must wear helmets, wrist guards, elbow pads, and knee pads. Mouth guards are also common. Some leagues require extra gear like padded pants or hard-case sports bras. The sport is governed by various organizations. The Women's Flat Track Derby Association (WFTDA) is a major governing body. In 2010, over 98% of competitions used WFTDA rules. The sport is so widely recognized that it was considered for the 2020 Summer Olympics.