Discus: the sport
The discus throw is an event in Field Athletics, in which an athlete throws a heavy disc (called a discus) in an attempt to mark a farther distance than his or her competitors.
The discus throw goes a long way back in time: as well as a discipline on its own, practiced with stone or bronze discs, it was part of of the ancient pentathlon, which can be dated back to 708 BC. It was publicly celebrated by ancient artists such as the Greek Myron with his 5th century BC statue Discobolus (the discus thrower). As an iconic image of ancient Olympiad it has gained a place in modern collective sport imagery, and has featured in many instances of sport communications, such as the 1948 London Olympics official poster. As a discipline, discus throwing has been part of the men’s Olympic program since 1896, while the ladies first threw their discs in the 1928 Olympics.
The discus is a lenticular disc with a diameter of 220 mm and a weight of 2 kilograms for the men's event, and a diameter of 181 mm and a weight of one kg for the women's event. It usually consists of a metal core surrounded by a rim of rubber, plastic or wood. The placement of the weight is critical: if it is centred in the core, the discus is easier to throw and more stable in the air; a discus with more weight in the rim produces greater angular momentum for any given spin rate, and thus more stability and more effectiveness in flight, although it is technically more difficult to throw.
To make a throw, the competitor starts in a slightly recessed concrete-surfaced circle of 2.5 meters diameter. The thrower takes an initial stance facing away from the direction of the throw. He then spins around one and a half times through the circle to build momentum, then releases his throw. The discus must land within a 35-degree arc marked by lines on the landing zone, and the competitor must not exit the circle until the discus has landed, then must wait for the judge to give clearance to exit the ring from the rear half. The distance from the front edge of the circle to where the discus has landed is measured, and distances are rounded down to the nearest centimeter. The competitor's best throw from the allocated number of throws, typically three to six, is recorded, and the competitor who legally throws the discus the farthest is declared the winner. Ties are broken by determining which thrower has the longer second-best throw.
The discus-throwing technique involves a minute control of the athlete’s entire body, from the feet to the fingertips. It is slow and difficult to master, and often the best discus throwers are relatively older athletes with long experience. The throwing motion consists of a forehanded sidearm movement. The discus is spun off the index finger or the middle finger of the throwing hand, spinning clockwise when viewed above for a right-handed thrower, and vice-versa. As well as achieving maximum momentum in the discus on throwing, the discus' distance is also determined by the trajectory the thrower imparts, as well as the aerodynamic behaviour of the discus. Generally, one wishes to throw into a moderate headwind to achieve maximum throws. Also, a faster-spinning discus imparts greater gyroscopic stability.
