AI Swim Start
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Where the targets come from

The research behind the numbers

Every target range this app scores you against is either taken from published swimming biomechanics research or clearly marked as our own estimate. Below is both lists, and the papers themselves.

What’s measured against published research

These targets come from the studies below, using the same anatomical landmarks the papers did — an angle only transfers if it’s measured between the same points.

What’s still our own estimate

We couldn’t find a published measurement for these that matches how we measure them, so the target ranges are our best engineering judgement rather than research. They still affect your score — we’d rather tell you that than imply a precision we haven’t earned.

The papers

The effect of body position and mass centre velocity at toe off on the start performance of elite swimmers
Ward C, Sanders R, et al. (2021) · Sports Biomechanics
Which parts of a start actually predict a fast time — trunk position matters, individual limb angles at takeoff do not.
24 elite swimmers (12 men, 12 women)
Key Parameters Affecting Kick Start Performance in Competitive Swimming
Matúš I, Ružbarský P, Vadašová B (2021) · Int. Journal of Environmental Research and Public Health 18(22):11909
Front and back knee angles at the set position, and the entry angle.
18 male competitive swimmers, 50 m freestyle 23.3 s
Changes in the front and rear knee angles depending on the body and kick plate positions during the kick start
Matúš I, Kandráč R, Vadašová B, Čech P, Ružbarský P (2020) · Journal of Physical Education and Sport 20(S6)
The only study here that changed swimmers' set-up and timed the result — the basis for the back knee range.
10 swimmers across 15 block configurations, 45 starts each
Predicting dive start performance from kinematic variables at water entry in (sub-)elite swimmers
van Dijk MP, Beek PJ, van Soest AJK (2020) · PLoS ONE 15(10):e0241345
The entry angle, confirmed independently against the source above.
14 sub-elite and elite swimmers, 349 starts
The effect of knee angle on force production, in swimming starts, using the OSB11 Block
Slawson SE, Chakravorti N, Conway PP, Cossor J, West AA (2012) · Procedia Engineering 34:801–806
Set-position knee angles in the fastest starts, measured against actual force production.
10 national-level sprint swimmers on a force-instrumented block
Factors affecting the underwater phase of the swimming start
Tor E (2017) · PhD thesis, Victoria University
Block time and entry benchmarks, and the distinction between body-line and trajectory angles.
14 elite swimmers on an instrumented OSB11 block
Engineering Elite Swimming Start Performance: Key Kinetic and Kinematic Variables with Reference Values
Born D-P, Nussbaumer L, Buck M, Ruiz-Navarro JJ, Romann M (2026) · Bioengineering 13(2):180
The take-off speed comparison range. Not a target — even its slowest swimmers are national-team level, so it shows where a number sits rather than grading it.
136 national-team swimmers, including Olympic medallists and a world-record holder

A word on what a score can tell you

Filming conditions alone — camera angle, lighting, video quality — move the score by around 10 points on the same dive. So treat a small change between sessions as noise, not progress. That’s why the progress page leads with the mistakes you keep repeating rather than a score trend line: a repeated fault is a far more reliable signal than a few points either way.

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