06 / 08
The 0.1-Second False Start Rule in Athletics — Reaction Time in Sports
World Athletics' rule that treats a reaction under 0.100 seconds after the starting signal as a false start, the reasoning behind it, and what reaction time means in other sports.
Sprinting is a prime example of a sport where reaction time is defined by the rules. Moving too quickly after the starting signal doesn't improve your time — it gets you disqualified.
The rule
World Athletics Technical Rules specify that, in competitions using an approved Start Information System, an acoustic signal indicating a possible false start sounds if an athlete's reaction time is less than 0.100 seconds. On hearing this signal, the starter recalls the race and checks the reaction time records to identify the athlete responsible.
How is reaction time measured?
Sensors attached to the starting blocks detect changes in the force of the athlete's feet pushing against the blocks and measure the time difference from the starting gun (or electronic starting signal). Speakers are placed near each athlete's ears so that all athletes hear the signal at the same time.
Why 0.1 seconds?
It takes a certain amount of time for a person to hear a sound, decide and move their muscles. A reaction faster than 0.1 seconds is considered anticipating the signal and moving early rather than reacting to it. There are counterarguments and studies suggesting some athletes can actually react within 0.1 seconds, so the debate continues.
This site's 100 ms rule
Following the same idea, this site treats input less than 100 ms after the signal as an anticipation, discards it and retakes the trial. The same goes for input before the signal (early presses). The random wait time is also there to prevent you from memorizing the rhythm and pressing early.
Reactions in other sports
- Baseball, tennis, cricket — The time until the ball arrives is similar to or shorter than simple reaction time, so players react by anticipating from cues such as the pitching motion or stance.
- Soccer goalkeepers — In penalty kicks, they often move early based on the direction of the kicker's body.
- Esports — Choice reaction and decision speed matter, and choosing equipment that reduces device latency becomes part of performance.
In sports, top athletes often excel not because their simple reactions are extremely fast but because of their ability to read the situation and anticipate.