How do you know if your sprinter is anticipating the gun?
World Athletics calls a false start under 100 milliseconds for a reason, and a slow-motion clip will tell you roughly where your sprinter actually sits against it.
A sprinter who is consistently the fastest off the gun looks like a gift until you start wondering whether they are reacting to the sound at all, or just guessing well. The two look identical from the stands. They are not identical, and the difference matters for how you coach the start.
The sport already drew the line
World Athletics, and most high school federations, call a false start on any reaction under 0.100 seconds, 100 milliseconds, from the gun. That number is not arbitrary. It comes from how long a signal takes to travel from the ear, through the nervous system, to a muscle contraction strong enough to move a foot against the pedal. Anything faster than that is not a fast reaction. It is a start that began before the sound did.
So the useful question is not "is my sprinter fast off the blocks", it is "is my sprinter's start time believable as a reaction". A start of 110 milliseconds from a well-trained sprinter is exceptional but real. A start that sits reliably under 100 is not talent, it is a pattern.
What guessing looks like across a season
- It is oddly consistent. A genuine reaction to sound has natural variance, a few hundredths either way, session to session. A guess timed off your voice or your habits tends to be more stable than that, not less.
- It survives a change in cadence. Vary how long you hold the set position before the gun. An athlete reacting to the sound is unaffected. An athlete anticipating the count gets caught out, at least the first few times.
- It disappears when somebody else starts them. If a different coach, or a recorded gun, produces a slower, more ordinary start, the fast time was never about the gun.
Where a phone actually helps
StatLap starts its race clock on the sound of the gun, which means a recording of a start session already has the exact moment the gun fired sitting in the audio. Filmed at 240 frames per second on a modern phone, each frame is about 4 milliseconds apart, close enough to count roughly how many frames pass between the bang and the first visible movement out of the blocks. That gives you a real number to look at instead of an impression from the stands.
It is not a certified reaction-time system, and it should not be treated as one. A legal false-start call needs pressure-sensitive blocks wired to the gun, not a phone at the side of the track. What frame-counting gives you is a training tool: a rough, repeatable check on whether an athlete's starts are believably reactions or believably guesses. For anything that has to stand up as an official call, that decision stays with the starter, not the video.
Time your next meet with the phones you already have
Timing, the Film Room and the speed gates are free forever. Publishing results to your own page starts at $59 a month.
Related
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You can, to about the accuracy of the two marks you put on the ground, which is better than it sounds and worse than a pair of gates.
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