Shot put
The shot put is a track and field event involving "putting" (pushing rather than throwing) a heavy spherical ball—the "shot"—as far as possible. The shot put competition for men has been a part of the modern Olympics since their revival in 1896, and women's competition began in 1948. History. Homer mentions competitions of rock throwing by soldiers during the Siege of Troy but there is no record of any dead weights being thrown in Greek competitions. The first evidence for stone- or weight-throwing events were in the Scottish Highlands, and date back to approximately the  first century. In the 16th century King Henry VIII was noted for his prowess in court competitions of weight and hammer throwing. The first events resembling the modern shot put likely occurred in the Middle Ages when soldiers held competitions in which they hurled cannonballs. Shot put competitions were first recorded in early 19th century Scotland, and were a part of the British Amateur Championships beginning in 1866. Competitors take their throw from inside a marked circle in diameter, with a “toe board” or "stop board" about high at the front of the circle. The distance thrown is measured from  the inside of the circumference of the circle to the nearest mark made on the ground by the falling shot, with distances rounded down to the nearest centimetre under IAAF and WMA rules. Legal throws. The following rules (indoor and outdoor) must be adhered to for a legal throw: Foul throws occur when an athlete: At any time if the shot loses contact with the neck then it is technically an illegal put. Regulation misconceptions. The following are either obsolete or non-existent, but commonly believed rules within professional competition: Competition. Shot put competitions have been held at the modern  Summer Olympic Games since their inception in 1896, and it is also included as an event in the World Athletics Championships. Each of these competitions in the modern era have a set number of rounds of throws. Typically there are three qualification rounds to determine qualification for the final. There are then three preliminary rounds in the final with the top eight competitors receiving a further three throws. Each competitor in the final is credited with their longest throw, regardless of whether it was achieved in the preliminary or final three rounds. The competitor with the longest legal put is  declared the winner. Weight. In open competitions the men's shot weighs , and the women's shot weighs . Junior, school, and masters competitions often use different weights of shots, typically below the weights of those used in open competitions; the individual rules for each competition should be consulted in order to determine the correct weights to be used. Putting styles. Two putting styles are in current general use by shot put competitors: the "glide" and the "spin". With all putting styles, the goal is to release the shot with maximum forward velocity at an angle of approximately forty-five degrees . Glide. The origin of this technique dates to 1951, when Parry O'Brien from the United States invented a technique that involved the putter facing backwards, rotating 180 degrees across the circle, and then tossing the shot. Unlike spin this technique is a linear movement. With this technique, a right-hand thrower would begin facing the rear of the circle. They would typically adopt a specific type of crouch, involving their bent right leg, in order to begin the throw from a more beneficial posture whilst also isometrically preloading their muscles. The positioning of their bodyweight over their bent leg, which  pushes upwards with equal force, generates a preparatory isometric press. The force generated by this press will be channelled into the subsequent throw making it more powerful. To initiate the throw they kick to the front with the left leg, while pushing off forcefully with the right. As the thrower crosses the circle, the hips twist toward the front, the left arm is swung out then pulled back tight, followed by the shoulders, and they then strike in a putting motion with their right arm. The key is to move quickly across the circle with as little air under the  feet as possible, hence the name 'glide'. Spin. This is also known as the rotational technique. It was first practiced in Europe in the 1950s but did not receive much attention until the 1970s. In 1972 Aleksandr Baryshnikov set his first USSR record using a new putting style, the spin ("круговой мах" in Russian), invented by his coach Viktor Alexeyev. The spin involves rotating like a discus thrower and using rotational momentum for power. In 1976 Baryshnikov went on to set a world record of with his spin style, and was the first shot putter to cross the 22-meter  mark. With this technique, a right-hand thrower faces the rear, and begins to spin on the ball of the left foot. The thrower comes around and faces the front of the circle and drives the right foot into the center of the circle. Finally, the thrower reaches for the front of the circle with the left foot, twisting the hips and shoulders like in the glide, and puts the shot. When the athlete executes the spin, the upper body is twisted hard to the right, so the imaginary lines created by the shoulders and hips are no longer parallel . This action builds up torque, and stretches the muscles, creating an involuntary elasticity in the muscles, providing extra power and momentum. When the athlete prepares to release, the left foot is firmly planted, causing the momentum and energy generated to be conserved, pushing the shot in an upward and outward direction. Another purpose of the spin is to build up a high rotational speed, by swinging the right leg initially, then to bring all the limbs in tightly, similar to a figure skater bringing in their arms while spinning to increase their speed. Once this fast speed is achieved the  shot is released, transferring the energy into the shot put. Until 2016, a woman had never made an Olympic final (top 8) using the spin technique. The first woman to enter a final and win a medal at the Olympics was Anita Márton. Usage. Currently, most top male shot putters use the spin. However the glide remains popular since the technique leads to greater consistency compared to the rotational technique. Almost all throwers start by using the glide. Tomasz Majewski notes that although most athletes use the spin, he and some other top shot putters achieved success using this classic  method (for example he became first to defend the Olympic title in 56 years). The world record and the second-best all-time male results were completed with the spin technique, while the third-best all-time put of by Ulf Timmermann was completed with the glide technique. The decision to glide or spin may need to be decided on an individual basis, determined by the thrower's size and power. Short throwers may benefit from the spin and taller throwers may benefit from the glide, but many throwers do not follow this guideline. Types of shots. The shot is  made of different kinds of materials depending on its intended use. Materials used include sand, iron, cast iron, solid steel, stainless steel, brass, and synthetic materials like polyvinyl. Some metals are more dense than others, making the size of the shot vary. For example, different materials are used to make indoor and outdoor shot – because damage to surroundings must be taken into account – so the latter are smaller. There are various size and weight standards for the implement that depend on the age and gender of the competitors as well as the national customs of the governing body. World records . The current world record holders are: Continental records. The current records held on each continent are: