What Are the Rules for the 100-Meter Sprint?

The 100-meter sprint is an exciting event. One of the truest forms of human competition, sprinters must run in a straight line as fast as possible. The winner of the 100-meter sprint is the first runner to cross the finish line.

Competition rules for the 100-meter sprint are governed by World Athletics, previously known as the International Association of Athletics Federations (IAAF).

Every 100-meter sprinter must begin the race with their feet in starting blocks. Officials will call the sprinters to their blocks and, on command, the runners will adopt a set position.

The set position, as shown in the photo above, involves having both feet in the blocks with your body weight in your hands on the track.

On the starter's signal, all runners begin sprinting the race.

A false start is called when a runner leaves the starting blocks before the starting pistol has gone off.

Sensors in the starting pistol and on the starting blocks measure false starts, according to World Athletics. A false start is ruled when the reaction time of a runner is less than 0.1 seconds after the gun. The sprinter in question will be disqualified.

In youth and amateur events, a false start might be called by the starter or another race official.

Each sprinter lines up in their own lane on one of the straightaways of a standard 400-meter track, according to World Athletics.

Leaving your lane or obstructing the path of another sprinter will get you automatically disqualified from the race. Stepping on the white lines of the lane is ruled as having left your lane. If a runner is disqualified, the race referee can order the race to be run over again.

The lanes are 1.22 meters wide, give or take 0.01 meters, including the lane line on the right, according to World Athletics. The white lines marking the lanes are 50 millimeters wide.

The finish is the decisive stage of the race and can be very exciting when sprinters are of similar speeds and abilities.

The World Athletics sprint finish line regulations state that the time of a runner is "recorded when any part of their bodies (i.e. torso, as distinguished from the head, neck, arms, legs, hands or feet)" crosses the nearest edge of the finish line.

In youth and amateur 100-meter sprint races, the winner may be decided by a race referee at the finish line.

Professional competitions use technology to record finish times, which are reported to 0.01 seconds, per World Athletics.

There are typically three concrete phases of the 100-meter sprint, called acceleration, maximum speed and deceleration, according to a small March 2015 study in the ‌Journal of Human Kinetics.‌

Professional runners typically sprint faster and faster for the first 35 meters, reach their maximum speed between 50 and 70 meters and hold that speed for the next 20 meters or so, the study authors wrote. The last 10 meters or so, they may be decelerating if they cannot sustain their maximum speed any longer.