Butterfly Undulation: Coordinated Chest and Hip Rise-and-Fall Training

Introduction

The butterfly is widely regarded as the most physically demanding and hardest to master of the four competitive strokes. Many swimmers can complete the stroke, yet their movements often look stiff and awkward, usually because of insufficient coordination in the undulation. The butterfly’s undulation is not random twisting, but a precise sequence of “chest press-down → hips lift → kick → chest lift-up.” If the timing of this sequence is off by even a fraction of a second, the entire motion loses its fluidity and propulsion.

This article will systematically break down each component of the butterfly undulation and provide targeted training methods.

The Mechanics of Undulation

Butterfly propulsion comes from two main sources: the arm pull and the dolphin kick. The role of undulation is to coordinate these two power sources so they complement rather than interfere with each other.

A full butterfly arm cycle includes two kicks:

• First kick (entry kick): As the hands enter the water and extend forward, the first kick is completed simultaneously. At this point, the body transitions from a chest press-down to a hip lift. The downward kick provides forward momentum and helps the hands “glide” into the catch position.
• Second kick (exit kick): As the hands finish the push phase beside the hips and prepare to exit the water, the second kick is completed simultaneously. This kick is usually stronger than the first and serves as the primary propulsive kick.

Common Coordination Errors

Error 1: Mismatched kick timing
The most common problem is the kick falling out of sync with the arm movements. An entry kick that comes too late (kicking only after the pull has already started) causes the body to generate two waves in different phases, canceling each other’s energy.

Error 2: Excessive undulation amplitude
An A-shaped wave (excessive up-and-down bobbing) may look like you are “swimming hard,” but it wastes a great deal of energy on vertical movement that contributes nothing to horizontal progress. Elite butterfly swimmers actually maintain a fairly compact undulation amplitude.

Error 3: Bending only at the waist
The undulation should originate from the thoracic spine and travel downward through the hips and legs, rather than being just a “worm-like wriggle” from the waist. Excessive waist bending causes core power to leak away and can easily lead to lower back pain.

Drills for Breaking It Down

Dolphin kick drill
Practice only the leg kick, with arms extended forward or held at the sides, focusing on feeling the wave transmission initiated from the chest. You can submerge with goggles to observe your body line underwater, or have a coach observe from above the surface.

Slow-motion butterfly
Deliberately slow down to half your normal pace, pausing for 1 second after each breathing cycle to feel the synchronization between the hand entry and the first kick.

Single-arm butterfly
Pull with one arm while the other extends forward, reducing coordination difficulty and allowing you to focus on the timing between one side’s arm and the kick.

Practical Tips

• Land-based undulation simulation: Lie prone on the floor or a yoga mat with arms extended forward, and practice transmitting the wave from the chest down to the hips. Build the movement memory before getting in the water.
• Fins as an aid: When first learning undulation coordination, using short fins (a monofin or bifins) helps you feel the propulsion generated by the kick, accelerating the development of proper coordination.
• Shorten each practice distance: Butterfly coordination training is best done in 25-meter increments, with full rest after each repeat to avoid form breakdown from fatigue.
• Video feedback: Underwater side-view filming is the most effective way to verify your undulation, paying particular attention to whether the vertical positions of the chest and hips match the expected timing.

Conclusion

Learning the butterfly undulation is a process of “feel first, technique follows.” Many swimmers try to “calculate” the timing in their heads, yet overlook that true coordination must be internalized through repeated practice. Accept the initial lack of fluidity, build the connected movement step by step through drills, and you will eventually discover that the butterfly can actually be the most efficient and fluid of the four strokes.

Related Reading

• Butterfly Undulation: Hip-Driven and Arm-Synchronized Coordination Training
• Butterfly Dolphin Kick and Body Undulation Coordination Training
• The Science of Butterfly Undulation: Hip Drive and Rhythm Coordination Training Guide
• Butterfly Wave Rhythm: Synchronizing Body Rise-and-Fall Tempo with Breathing Timing