Butterfly Stroke Timing: Why Your Kick and Pull Timing Is Killing Your Speed

Why Butterfly Feels So Hard

Ask most swimmers about butterfly and they will describe it as exhausting, awkward, and difficult to sustain. This experience is almost universal among recreational swimmers — and it is almost entirely caused by timing errors.

Elite butterfly swimmers make the stroke look effortless because they have mastered the two-kick timing cycle that drives efficient butterfly. When the kicks are timed correctly, the body undulates naturally, the arms recover with minimal effort, and the stroke feels powerful rather than laborious.

The Two-Kick Cycle

Butterfly uses two dolphin kicks per arm cycle. These kicks are not equal in purpose or timing — each serves a specific function in the stroke cycle.

The First Kick (Entry Kick)

The first kick occurs as the hands enter the water at the front of the stroke and begin the catch phase. The timing is: hands enter the water → first kick drives downward.

The purpose of the first kick is to initiate the pull phase. The downward kick drives the hips upward, which positions the body at the optimal angle for the catch. When the hips are elevated, the hands can catch deeper water, which increases the effectiveness of the pull.

A common error is delaying the first kick — waiting until the hands are already pulling before kicking. This misses the opportunity to use the kick to position the body for the catch.

The Second Kick (Exit Kick)

The second kick occurs as the hands exit the water at the back of the stroke and the arms begin their recovery over the water. The timing is: hands exit the water → second kick drives downward.

The purpose of the second kick is to drive the body forward and upward, creating the momentum that carries the arms over the water during recovery. Without a strong second kick, the arms feel heavy during recovery because the body is not providing the forward momentum that makes recovery effortless.

The second kick is typically stronger than the first kick in elite swimmers because it is the primary propulsive kick.

Body Undulation: A Consequence, Not a Cause

Many swimmers try to practice body undulation as a separate skill — deliberately waving the body up and down. This approach is counterproductive because undulation is a consequence of correct kick timing, not a separate movement.

When the kicks are timed correctly, the body naturally undulates because the kicks drive the hips alternately up and down. Trying to add undulation on top of incorrect kick timing creates a chaotic, energy-wasting movement.

The practical implication: focus on kick timing, not undulation. Correct timing will produce natural undulation automatically.

Breathing Mechanics

Breathing in butterfly is one of the most technically demanding aspects of the stroke. The head lifts forward (not to the side) during the exit phase of the stroke, when the hands are pushing backward and the body is at its highest point in the water.

Common breathing errors:

• Lifting the head too early: Lifting during the pull phase rather than the exit phase disrupts the stroke rhythm and sinks the hips.
• Lifting too high: The chin should just clear the water surface — excessive head lift slows the stroke and makes arm recovery more difficult.
• Breathing every stroke: Most swimmers should breathe every two strokes (or every three for competitive swimmers) to maintain stroke rhythm.

How AI Analysis Helps

SportsReflector's underwater motion analysis can detect kick timing relative to the arm cycle by tracking hip and hand position frame by frame. The app identifies whether the first kick is occurring at the correct moment (hands entering the water) or is delayed, and whether the second kick is timed to the hand exit.

These timing errors are invisible at normal speed — they require slow-motion analysis to detect.

Quick Fix Summary

• First kick: time it to occur as the hands enter the water and begin the catch.
• Second kick: time it to occur as the hands exit the water and the arms begin recovery.
• Do not practice undulation separately — focus on kick timing and undulation will follow.
• Breathe during the exit phase, not the pull phase, and keep the chin just above the water surface.
• Use underwater video to check kick timing — it cannot be self-assessed above water.

References

[1] Butterfly Stroke Timing and Efficiency in Competitive Swimmers. Journal of Sports Sciences. [2] Two-Beat Kick Coordination in Butterfly Swimming. International Journal of Sports Biomechanics. [3] Breathing Mechanics and Performance in Butterfly. Journal of Swimming Research.