What are the false start rules, and what counts as the commencement of a start?

Under the World Athletics Technical Rules (Rule 16.7), an athlete who has assumed a full and final starting position must not commence their start until after the report of the gun. If, in the starter's judgement, they do so earlier, it is a false start.

The commencement of the start is:

• Crouch start: any motion that includes or results in one or both feet losing contact with the foot plates, or one or both hands losing contact with the ground.
• Standing start: any motion that results in one or both feet losing contact with the ground.

If the starter determines that, before the report of the gun, an athlete began a movement that was not stopped and continued into their start, that is also a false start.

Other points from the rules and guidance:

• No false start should generally be charged if the athlete has not lost contact with the ground or foot plates. It may be a reason to warn, or disqualify after a previous warning, for improper conduct under Rule 16.5.
• Accidental over-balancing in a standing start should be called "unsteady", and athletes pushed or jostled over the line before the start are not penalised.
• Except in combined events, the athlete responsible is disqualified (Australian Athletics applies one free false start per race at Under 14 and below at its Championships).

Sources: https://worldathletics.org/about-iaaf/documents/book-of-rules, https://www.athletics.com.au/wp-content/uploads/2026/04/2026-Australian-Track-and-Field-Championships-Technical-Regulations-2026-04-08.pdf