Butterfly Swim

Anton YefanovUpdated September 6, 2026

Butterfly moves both arms together: they enter overhead, pull through under the body and recover over the surface while the legs beat as one in a dolphin kick. Electromyographic analysis of twelve shoulder muscles found pectoralis major and latissimus dorsi generating the power through the pull, deltoids and rotator cuff controlling entry and recovery, and serratus anterior and subscapularis staying active throughout, so shoulder load runs continuously through the stroke cycle. The body teeter-totters around the hips, so the trunk works continuously to hold the rhythm.

How to do the Butterfly Swim

Start prone with your body long and both arms extended in front of you.
Press both hands out and down together, keeping the elbows high.
Drive both arms back past your hips to finish the pull.
Sweep both arms over the water simultaneously into the next entry.
Beat both legs together in a dolphin kick timed to the entry and the finish.
Breathe forward once every second or third cycle as the arms clear the water.

Muscles worked

Primary:: Back and Chest
Secondary:: Shoulders, Core, Triceps, and Traps

Why train it

Loads back, chest and shoulders through the widest range of the four strokes.
Demands whole-body timing between the arm pull, kick and body wave.
Delivers the highest intensity of the competitive strokes for short efforts.

Common mistakes

Lifting the head high to breathe, which sinks the hips and stalls the recovery.
Pulling with the arms only, so the body wave and kick stop contributing.
Mistiming the second kick, which leaves the arms to drag the body through the entry.
Swimming long sets while fatigued, exactly when shoulder mechanics start to break down.

Frequently asked questions

What muscles does the Butterfly Swim work?

The Butterfly Swim works the back and chest hardest, with the shoulders, core, triceps, and traps pitching in. As cardio, though, the bigger demand is on your heart and lungs rather than any one muscle.

What equipment do I need for the Butterfly Swim?

Only a pool. There is nothing to lift: your own body does the work.

Is the Butterfly Swim suitable for beginners?

Not as a first stroke. The Butterfly Swim is rated advanced: it only works once your breathing, body position and kick timing are automatic, which comes after freestyle and breaststroke feel easy.

Can I do the Butterfly Swim at home?

Not unless you have a pool. The Butterfly Swim needs water deep enough to swim in, so it happens at a lap pool or in open water. The alternatives below train the same muscles on dry land.

How long should I do the Butterfly Swim for?

Short repeats of 25 or 50 metres with a full rest at the wall, adding up to 200 to 400 metres inside a longer swim. Butterfly falls apart when you are tired, so stop the set once the kick timing goes.