False start

In sports, a false start is a movement by a participant before (or in some cases after) being signaled or otherwise permitted by the rules to start. Depending on the sport and the event, a false start can result in a penalty against the athlete's or team's field position, a warning that a subsequent false start will result in disqualification, or immediate disqualification of the athlete from further competition.

False starts are common in racing sports (such as swimming, track, sprinting, and motor sports), where differences are made by fractions of a second and where anxiety to get the best start plays a role in the athletes' behavior.

A race that is started cleanly, on the contrary, is referred to as a fair start or clean start.

In American football and Canadian football, a false start is movement by an offensive player (other than the center) after he has taken a set position. For offensive linemen, this movement might be as minimal as a couple of centimeters, although the rule's intent is to prevent offensive players from unfairly drawing the defense offside. A false start brings a 5 yard penalty. Unlike an offside penalty, where the play is run as usual, the play after a false start penalty immediately becomes dead. This is done to prevent a defensive player reacting to a false start from hitting the quarterback while going through the snap count, which would make the quarterback more susceptible to injury.

At the end of the 2005 NFL season, owners complained regarding false start penalties on players whose flinches have little effect upon the start of the play, such as wide receivers. In response, the NFL competition committee has said that they plan to inflict fewer false start penalties on players who line up behind the line of scrimmage.

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