Sprint

Sprint

 the act of running over a short distance at (or near) top speed. It is used in many sports that incorporate running, typically as a way of quickly reaching a target or goal, or avoiding or catching an opponent.

In athletics and track and field, sprints (or dashes) are races over short distances. They are among the oldest running competitions. The first 13 editions of the Ancient Olympic Games featured only one event—the stadion race, which was a race from one end of the stadium to the other. There are three sprinting events which are currently held at the Summer Olympics and outdoor World Championships: the 100 metres, 200 metres, and 400 metres. These events have their roots in races of imperial measurementswhich were later altered to metric: the 100 m evolved from the 100 yard dash, the 200 m distances came from the furlong (or 1/8 of a mile), and the 400 m was the successor to the 440 yard dash or quarter-mile race.

Common contemporary distances

60 m

• The 60 metres is normally run indoors, on a straight section of an indoor athletic track. Since races at this distance can last around six or seven seconds, having good reflexes and thus getting off to a quick start is more vital in this race than any other.
• This is roughly the distance required for a human to reach maximum speed and can be run with one breath. It is popular for training and testing in other sports (e.g., speed testing for American football, although 40 yards is more common there).
• The world record in this event is held by American sprinter Maurice Greene with a time of 6.39 seconds.
• 60-metres is used as an outdoor distance by younger athletes when starting sprint racing.

Note: Indoor distances are less standardized as many facilities run shorter or occasionally longer distances depending on available space. 60m is the championship distance.

100 m

Tyson Gay completes a 100m race

• The 100 metres sprint takes place on one length of the home straight of a standard outdoor 400 m track. Often, the world-record holder in this race is considered "the world's fastest man/woman." The current world record of 9.58 seconds is held by Usain Bolt of Jamaica and was set on 16 August 2009, at the 2009 World Athletics Championships. The women's world record is 10.49 seconds and was set by Florence Griffith-Joyner.
• World class male sprinters (sub 10.10s) need 41 to 50 strides to cover the whole 100 metres distances.

200 m

• The 200 metres begins on the curve of a standard track (where the runners are staggered in their starting position, to ensure that they all run the same distance), and ends on the home straight. The ability to "run a good bend" is key at the distance, as a well conditioned runner will be able to run 200 m in an average speed higher than their 100 m speed.
• Indoors, the race is run as one lap of the track, with only slightly slower times than outdoors.
• A slightly shorter race (but run on a straight track), the stadion, was the first recorded event at the ancient Olympic Games and the oldest known formal sports event in history.

A 200 m bend

• The world record in this event is 19.19 seconds, held by Usain Bolt and was set on 20 August 2009, at the 2009 World Athletics Championships.

400 m

• The 400 metres is one lap around the track on the inside lane. Runners are staggered in their starting positions to ensure that everyone runs the same distance. While this event is a sprint (according to some), there is more scope to use tactics in the race; the fact that 400 m times are considerably more than four times a typical 100 m time demonstrates this.
• The world record is currently held by Michael Johnson with a time of 43.18 seconds.

Relay

• The 4×100 metres relay is another prestigious event, with an average speed that is quicker than the 100 m, as the runners can start moving before they receive the baton. The world record in this event is 36.84 seconds, held by the Jamaican team as set 11 August 2012 at the Games of the XXX Olympiad held in London.
• The 4x400 metres relay is often held at track and field meetings, and is by tradition the final event at major championships.

Rules

The start

Jeremy Wariner beginning a race from the starting blocks

Starting blocks are used for all competition sprint (up to and including 400 m) and relay events (first leg only, up to 4x400 m). The starting blocks consist of two adjustable footplates attached to a rigid frame. Races commence with the firing of the starter's gun.The starting commands are "On your marks" and "Set". Once all athletes are in the set position, the starter's gun is fired, officially starting the race. For the 100 m, all competitors are lined up side-by-side. For the 200 m, 300 m and 400 m, which involve curves, runners are staggered for the start.

In the rare event that there are technical issues with a start, a green card is shown to all the athletes. The green card carries no penalty. If an athlete is unhappy with track conditions after the "on your marks" command is given, the athlete must raise a hand before the "set" command and provide the Start referee with a reason. It is then up to the Start referee to decide if the reason is valid. In the event that the Start referee deems the reason invalid, a yellow card (warning) is issued to that particular athlete. In the event that the athlete is already on a warning the athlete is disqualified.

False starts

Sprint lanes as seen from the 100 m starting point

According to the IAAF rules, "An athlete, after assuming a full and final set position, shall not commence his starting motion until after receiving the report of the gun, or approved starting apparatus. If, in the judgement of the Starter or Recallers, he does so any earlier, it shall be deemed a false start."

The 100 m Olympic Gold and Silver medallist, Linford Christie of Great Britain famously had frequent false starts that were marginally below the legal reaction time of 0.1 seconds. Christie and his coach, Ron Roddan, both claimed that the false starts were due to Christie's exceptional reaction times being under the legal time. His frequent false starting eventually led to his disqualification from the 1996 Summer Olympics 100 m final in Atlanta, Georgia, USA due to a second false start by Christie. Since January 2010, under IAAF rules, a single false start by an athlete results in disqualification.

Lanes[edit]

For all Olympic sprint events, runners must remain within their pre-assigned lanes, which measure 1.22 metres (4 feet) wide, from start to finish.^[19] The lanes can be numbered 1 through 8, 9, or rarely 10, starting with the inside lane. Any athlete who runs outside the assigned lane to gain an advantage is subject to disqualification. If the athlete is forced to run outside of his or her lane by another person, and no material advantage is gained, there will be no disqualification. Also, a runner who strays from his or her lane in the straightaway, or crosses the outer line of his or her lane on the bend, and gains no advantage by it, will not be disqualified as long as no other runner is obstructed.

The finish

The first athlete whose torso reaches the vertical plane of the closest edge of the finish line is the winner. To ensure that the sprinter's torso triggers the timing impulse at the finish line rather than an arm, foot, or other body part, a double Photocell is commonly used. Times are only recorded by an electronic timing system when both of these Photocells are simultaneously blocked. 

Photo finish systems are also used at some track and field events.

http://en.wikipedia.org/wiki/Sprint_(running)#Biological_factors_for_runners