A lot of coaches watch breaststroke stroke rate and assume higher is better. It isn’t that simple. Swimming velocity is the product of two things: stroke rate and distance per stroke. Push one up without checking the other, and speed can actually go down.

Female swimmer racing with AIM Systems analysis in use

This isn’t a new idea. Craig and Pendergast established the relationship back in 1979 with a simple formula: velocity equals stroke rate multiplied by distance per stroke (V = SR × SL). Their research showed swimmers can hit the same velocity through very different combinations of the two. There is no single “correct” stroke rate — it’s a tradeoff, not a fixed target.

Why breaststroke makes this tradeoff obvious

Breaststroke exposes this tradeoff more than any other stroke. The glide phase means a swimmer can easily add stroke rate by cutting the glide short. But if that shortens distance per stroke more than it adds cycles, the swimmer goes slower while working harder.

You’ve probably seen this in practice. A swimmer starts to fade late in a 100m breaststroke and instinctively “stroke rates up” to fight it. Their arms turn over faster, but their hips drop, the glide disappears, and distance per stroke collapses. The stopwatch says they slowed down anyway.

What to actually measure

Watching stroke rate by itself only tells half the story. You need distance per stroke alongside it, lap by lap, to know whether a change in rate is helping or hurting. This is exactly where automated tracking earns its keep.

AIM Systems records stroke count and lap time for every lap of a captured swim, then lets you compare those laps against a swimmer’s own past best times or a manually entered reference time. Line up stroke count against lap time across a race, and the tradeoff between rate and distance per stroke stops being a guess. You can see precisely which lap the stroke rate rose while the lap time also went up — a clear sign distance per stroke broke down.

The continuous stroke-rate graph, with every individual stroke marked, makes this even clearer. You can see exactly where in the race rate started climbing and match it against hip depth at the same moment, since a dropping glide often shows up as hips riding lower before the stroke count changes.

Coaching the tradeoff, not just the number

The stroke-technique coach Bill Boomer built his “Posture, Line and Balance” approach around this kind of thinking. Rather than drilling arm and leg mechanics in isolation, Boomer’s methodology treats body alignment and balance in the water as the foundation everything else — including stroke rate and distance per stroke — gets built on top of. Boomer himself co-authored research on the stroke rate and distance-per-stroke relationship in elite swimmers, so this isn’t just a coaching hunch. It’s a framework with real published backing.

For a coach on deck, the practical takeaway is this: never coach stroke rate as a number in isolation. Ask what happened to distance per stroke at the same time. A swimmer holding stroke count steady while rate climbs slightly is usually swimming better. A swimmer whose stroke count balloons as rate climbs is usually falling apart.

If you want to see how this tradeoff plays out lap by lap for your own swimmers, with actual data instead of a guess from the pool deck, get in touch with AIM Systems. No pressure — just a look at what the data shows.

Sources

  • Gonjo, T., & Olstad, B.H. (2021). Race Analysis in Competitive Swimming: A Narrative Review. International Journal of Environmental Research and Public Health, 18(1), 69. https://doi.org/10.3390/ijerph18010069
  • Craig, A.B., & Pendergast, D.R. (1979). Relationships of stroke rate, distance per stroke, and velocity in competitive swimming. Medicine and Science in Sports, 11(3), 278-283. https://doi.org/10.1249/00005768-197901130-00011

Coaching Perspectives Referenced