Should Every Swimmer Undulate while Butterfly Swimming?
If you watch any elite Butterfly swimmer—from Phelps to today’s top age-group stars—you’ll notice one thing immediately: the wave. That smooth, controlled body-line motion is what coaches call undulation in the Butterfly, and it’s a crucial part of the stroke. But here’s the question I get all the time: Should every swimmer undulate while Butterfly swimming?
The short answer: YES. Absolutely.
But the degree of undulation is where swimmers and coaches need to get strategic.
Undulation in Butterfly:
When swimmers talk about a Swimming Undulate Butterfly Stroke, they’re referring to the wave-like motion swimmers create around their short axis—essentially around the hips. This motion isn’t random. It’s a coordinated pattern that allows swimmers to link their Butterfly Pull, Butterfly Kick, and breathing rhythm into one fluid sequence.
A helpful way to visualize it:
Think of your body as a sea serpent gliding forward. The head leads the rhythm, the hips follow, and the chest naturally rises and falls as part of the stroke cycle. That smooth wave is what creates power, momentum, and efficiency.
This is also where Undulation Swimming Drills come in. They help swimmers exaggerate or isolate parts of this wave so they can feel how their body should move through the water.
Why is Undulating Important?
1. It Puts Swimmers in a Stronger Physical Position
It puts swimmers in better physical positioning to complete a stronger Butterfly Pull and Kick. When swimmers undulate, they are constantly moving their hips back and forth. The point in their stroke at which the hips are at their highest is right after entry. From there, as swimmers continue their pull – their hips start to sink towards the bottom – hitting their lowest point at the time of the breath or about ¾ of the way through the pull. As the hands finish the pull and exit the water, the hips start the journey back up towards the surface again.
2. Undulation Drives the Rhythm of the Stroke
If you think about this constant rhythm within the Butterfly stroke, by keeping the hips high after the hands enter allows a swimmer to really engage their chest muscles and pull down, aggressively. Also, the couple of the lowest (hip) point during the Butterfly pull with the second kick – allows for snapping of the arms around to the top of the stroke again.
3. Your Posterior Chain Depends on It
Swimmer’s back muscles are constantly firing during the Butterfly stroke. You must have a strong posterior chain to complete this stroke. Dryland Exercises like superman’s, back extensions, and hollow holds are great representations of how strong your posterior chain is.
Why Do YOU have to Undulate?
Swimmers have to undulate in Butterfly for 3 reasons:
1.) Larger Distance Per Stroke
If you want efficiency, you need length.
Larger DPS = faster swimming with less energy spent.
When swimmers undulate, they create a longer, more effective pulling pathway. Without that wave, you’re essentially muscling through the water—and that’s not the Butterfly way.
2.) It Allows You to Breathe Without Straining Your Neck
Without undulating, it is EXTREMELY hard to get the breath in in fly. It’s very hard on swimmers necks to breath without bringing a part of the spine up as well. If you’re skeptical, try it and let me know what you think!
3.) It Creates a More Efficient Kick
Essentially without undulating, swimmers entire stroke will fall apart. If you don’t undulate, your legs will be more towards the surface during the stroke – which as we’ve discussed in previous posts, if you move air – you don’t go anywhere. We want swimmers to move water. Both the kick and the pull (without undulation) become significantly inefficient. Undulating is the real reason a swimmer can have a smooth Butterfly stroke.
Why Do People then Discuss NO Undulation?
We can thank Michael Phelps for that. There are some swimmers out there who swim with a FLATTER Butterfly stroke– Michael is one of them. But, what most people are forgetting is that Michael STILL undulates – he just keeps his body-wave smaller than others.
Be sure to stay tuned for next week’s post, where we will discuss the two types of undulating motions in the Butterfly stroke.
Your Next Step: Feel the Wave
If you want to experience true undulation, grab a snorkel and try this quick Undulation Swimming Drill:
Body Dolphin with Narrow Arms:
- Arms extended in a tight streamline
- Lead the wave with your chest
- Let the hips and legs follow naturally
- Keep the rhythm soft and continuous
This drill teaches swimmers what the Swimming Undulate Butterfly Meaning feels like without worrying about timing the breath or arm recovery.
Final Takeaway
If you want a smoother, more powerful Butterfly stroke, you need undulation.
Start small, build awareness, and learn how your hips drive your rhythm.
Try adding one undulation-focused drill to your next warm-up and feel how much more connected your stroke becomes.
Want Personalized Butterfly Feedback?
If you want clear, customized guidance on your Butterfly stroke, try our Video Analysis Packages. You’ll get coach-tracked timing, hip angle notes, kick efficiency breakdown, and specific drills to improve your undulation pattern.
Until Then,
Abbie Fish
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