The discus is a sport of great antiquity. The discus thrower is a competitor immortalized by Homer and other classical Greek writers as the perfect symbol of all that athletics represented. The discus was a men's event at the first modern Olympic Games in 1896; a women's discus event was added in 1928. In addition to its place as a freestanding Olympic sport, the discus is one of the events that comprise the decathlon. Discus is also a competition sanctioned by the International Amateur Athletics Federation (IAAF) at the biennial World Track and Field Championships.
As with all of the events from the ancient Games that have survived into modern times, the discus is a deceptively simple sport: the object is to hurl a slightly elliptical, circular-shaped disc from a defined throwing area further than one's competitors. The throw is started in a throwing circle that has a circumference of 8.25 ft (2.5 m). The completed throw must fall within an area on the field that is bounded by a 40° wide arc. The discus is constructed of wood, with a metal rim encircling the disc itself; the discus used in men's competition weighs 4.4 lb (2 kg), with the female version weighing 2.2 lb (1 kg).
The most successful Olympian in the history of discus is American Al Oerter, who won gold medals in four consecutive Olympic Games, between 1956 and 1968.
Strength is an important component in achieving success in the sport of discus. The ability to deliver the discus with maximum force requires a strong and supple upper body, supported by powerful legs to move the athlete through the throwing circle explosively prior to the release of the disc. As with all other Olympic field events, muscular strength must be paired with a smooth and dynamic technique. In the early days of Olympic competition, the discus throwers assumed a crouched stance, facing away from the field where the throw would be delivered. The athletes then made a quick half turn, releasing the disc at the end of the motion, extending from the crouch to impart the power of the body's upward movement to the disc on release.
The original throwing circles were a grass surface; with the advent of a concrete throwing circle in the 1950s, the athlete could move much more quickly across the throwing area, thus generating significantly greater power that was transferred to the disc on release. The throwing technique subsequently evolved to a movement that was a three-quarter turn by the thrower in the circle, accompanied by a skip as the thrower prepared to move explosively from the starting crouch position to generate greater throwing power. The most important factor in the creation of acceleration for the discus is in the power of the thrower's legs as the athlete moves through the throwing circle. The general attention paid to the powerful crouch position in discus is biomechanically similar to the sports of shotput and hammer throw.
Discus has a feature unique among Olympic sports: the aerodynamics of the disk as it travels from the hand of the thrower. The angle of release achieved by the thrower will ultimately determine the success of the throw. As the discus travels through the air, it is affected by the two fundamental physical principles of aerodynamics, lift and drag. If a disc is delivered from the hand of the athlete at an angle precisely parallel to the ground, the air flowing both over and under the moving disc would be expected to travel at the same speed. If the discus is thrown so as to create an angle of attack, causing the air moving over the top of the discus to travel faster that the air below, the slower air will create a higher pressure on the surface of the disc than the air on its top, creating lift and forcing the discus upward. This relationship between the effect of air speed and the generation of lift is known as Ber-
Drag is a minor component in the assessment of the flight characteristics observed in discus, as the profile of the object as it presents to the air is very narrow and the surface of the object is very smooth, with little skin friction to slow it as it passes through the air.
The determination of the most appropriate angle of attack of the disc upon release will be dictated by an important variable: wind direction. Science has determined that a discus delivered by an elite thrower at the optimal angle into a head wind with a velocity of approximately 20 mph (32 km/h) will receive the additional effect of air speed passing over the discus and the resultant lift created that will produce a throw that travels 25 ft (8 m) further.
The available IAAF data suggests that the optimum angle at which the discus should be released is between 33° and 38°. If the angle of attack is too great (i.e., the area making contact with the wind as the leading edge of the discus is too large), there will be a greater measure of drag, negating any beneficial effect of lift. If the angle is sufficiently severe, creating a separation of airflow over the discus, lift cannot be achieved.
SEE ALSO Hammer throw; Javelin; Shotput; Track and field.