Warm-ups are only permitted before the event begins. Once the actual event starts, all warm-ups cease, regardless of the throwing order. Throwing order is typically determined by random draw order and is under supervision of a tournament judge. Any discus throws done during warm-up are not measured and do not count for the competition.
During the prelims, each contestant is allowed three throws. Depending on the competition, there may be a time limit (such as 1 minute) within which the contestant must make a throw upon entering the ring. The top contestants advance from the prelims to the finals, where they will be given three more throws.
The assistant takes the zero-end of the tape out to the landing site while the official reads the measurement at the throwing circle. The distance is measured from the exact landing spot to the closest inner edge of the throwing circle, measuring in a straight line. A discus that lands on the line of the sector is called a foul. A flag or other such marker is placed at the site of the competitor's best throw.
Rules for Fouls
A foul throw may be called if the contestant throws the disc with two hands. A discus landing on or outside a designated sector can result in a foul. Contestants may not step outside the circle before their discus lands. Walking out the front half of the circle after the discus has landed also constitutes a foul.
The sport of discus throwing dates back to ancient Greece, where the sport was prized for its display of an athlete's precision and coordination, combined with his physical strength. Discus was one of the earliest games played in the Olympiad, along with other similar sports, such as the javelin. Still a widely practiced competitive sport today, discus throwing hasn't changed dramatically over the past few thousand years.
Discus throwing emerged in ancient Greece...