On a rolling start, a team of four runners runs equal lengths, often 100m and 400m apiece, while passing the baton to one another. A relay race, one of the most exciting spectacles in a sports event, is regarded as the ultimate expression of collaboration and synchronization. There are three types of relay races: the loop, the linear, and the cascade. In a loop race, each runner takes two turns around a circular track, passing the baton to the next runner who then takes his or her turn. This type of race is used in athletics events such as the 100m, 200m, and 400m races. A variation on this race is the hammer relay, where each runner uses a different type of projectile (such as a rock or ball) and tries to hit a target with it. In a linear race, each runner covers the same distance as in a loop race but does so by running down the side of the track rather than around it. This type of race is used in field events such as the long jump, triple jump, and pole vault. A variation on this race is the shuttle run, where each runner runs down the side of the track until they reach a tape or line on the ground, where they stop and wait for their next partner to catch them.