Butterfly is the last stroke a class teaches, and for most adult swimmers it is optional. It will not make you fitter than freestyle, it will not make you faster across a kilometre, and it carries the highest injury rate of the four strokes. What it does is teach body undulation, timing and rhythm, and it makes every other stroke feel easy by comparison. Learn it as a drill: three to six strokes, then rest. Do not learn it as a distance stroke. Do not try it at all if your shoulder already hurts.
Two corrections first, because both errors appear everywhere.
Do not lift your head to breathe. The chin skims the surface, low and forward. The moment the head rises, the hips drop and you are swimming uphill.
Do not keep your legs straight. The dolphin kick is a wave that starts at the chest and travels through the hips to the feet. The knees bend only as the wave passes through them. Rigid legs produce nothing.
Build It From the Kick
Butterfly is a kicking stroke with an arm recovery attached. Build the dolphin kick until you can cross a pool with it before you try a single arm stroke.
Press the sternum gently down. Let the movement travel through the hips and let the legs follow like the tail end of a whip. Feet together, ankles relaxed. The knees bend only as the result of the wave passing through, never as its driver.
Practise in three positions, a length of each: on your front with arms extended, on your back with arms at your sides, and on your side with one arm extended. The side kick shows you where the power lives.
Spend a month here before adding arms. There is no butterfly available to a swimmer whose dolphin kick does not independently move them.
Then the Timing
One arm cycle, two kicks.
- Kick one as the hands enter in front. This drives the hips up and sets the body line. This is the kick most beginners forget, and forgetting it is why the front of the stroke collapses.
- The pull. Hands sweep out, in toward the navel, then back past the hips in a keyhole shape.
- Kick two as the hands exit at the thighs. This launches the arm recovery.
- Recovery. Arms sweep low and wide over the surface, relaxed, little fingers rotating upward for entry.
Drill it as single-arm butterfly: one arm stroking while the other extends in front, full dolphin timing underneath. Twelve lengths of that teaches more than a hundred lengths of thrashing a complete cycle.
Then Breathing
Breathe low and forward, chin skimming, as the arms sweep past the hips on the exit. Face back in before the arms swing forward. Head down, then hands past.
Breathe every second stroke while learning. Every stroke is also fine, and is what most adult swimmers settle on after a few weeks.
The Order Matters
| Stage | Practise | Move on when |
|---|---|---|
| 1. Dolphin kick | Front, back, side; no arms | You cross the pool without a kickboard |
| 2. Timing | Single-arm butterfly, both sides | Two kicks arrive without thinking about them |
| 3. Arms | Three strokes, then rest; build to six | Six strokes stay consistently smooth |
| 4. Breathing | Low chin, every second stroke | Head goes down before arms come around |
| 5. Distance | 25m, never more at first | Whenever it stops looking like a drowning |
Never swim butterfly tired. It is the stroke where fatigue produces technique so poor that stopping mid-length is worth it.
Common Mistakes
- Learning the arms before the kick. Universal error. Build from the kick, always.
- One kick per arm cycle instead of two. The entry kick disappears and the front of the stroke sinks with it.
- Lifting the head to breathe. Chin skims. The hips stay up only while the head stays down.
- Straight legs, or kicking from the knee. The wave originates at the chest.
- A high, stiff-arm recovery. Low, wide, relaxed. High recoveries load the shoulder capsule.
- Swimming lengths of it immediately. Three to six strokes, then rest, until the timing is automatic.
- Swimming through a sore shoulder. Stop. See a physiotherapist. Not later.
Safety
Butterfly is the hardest stroke on the shoulders and the lower back. Overuse injuries accumulate quietly and arrive suddenly.
Keep the arm recovery low and relaxed. Stop at any twinge. If your lower back aches after butterfly, your hips are dropping — a technique fault, not a core-strength problem, and the fix is correct head position, not more sit-ups.
Never use underwater dolphin kick sets as breath-holding practice. Extended breath-holding — especially after hyperventilating deliberately — causes shallow-water blackout: a silent, warning-free loss of consciousness that has drowned experienced swimmers in supervised pools. Surface and breathe. There is no competitive version of this that is safe.
Swim where a lifeguard is on duty. Butterfly is exhausting and fatigue arrives faster than most swimmers expect. Children should not be pushed into butterfly volume: a few strokes in a lesson is plenty.
Who Should Skip It
Anyone with a shoulder that hurts in freestyle. Anyone who cannot yet swim a comfortable freestyle length. Anyone swimming purely for fitness, who will gain more from an additional freestyle interval set.
Everyone else can enjoy it as a drill: three strokes at the start of a warm-up, once a week, to remind the body what rhythm feels like.
If you are still working on a first stroke, start with freestyle for beginners. Adults learning butterfly for the first time progress faster with someone watching from the deck — through private lessons for adult butterfly learners or in group swimming classes where butterfly is introduced in a structured progression. Serious swimmers usually first attempt butterfly properly in a masters squad. Practise between formal sessions — see swimming in a condominium pool.
Pool schedules and programmes are published by ActiveSG.
Frequently Asked Questions
Do I need to be strong to swim butterfly?
Less than you think. Timing and undulation carry the stroke. Strong swimmers with poor timing exhaust themselves in ten metres.
How many kicks per arm cycle?
Two. One as the hands enter, one as they exit. Beginners almost always omit the first.
Should I lift my head to breathe?
No. The chin skims forward, close to the surface. Lifting the head drops the hips.
Why do my legs feel useless in butterfly?
Your kick is starting from the knee rather than the chest. The movement should flow down from the sternum, through the hip, to the feet. Practise the kick in each position — front, back, side — before adding arms.
Why does my lower back hurt?
Your hips are dropping, usually because you are lifting your head to breathe. If the pain persists, see a physiotherapist before your next session.
Is butterfly worth learning?
As a drill, for most fitness swimmers — yes. It improves feel for the water and timing in all strokes. It is also the fastest route to a shoulder injury if rushed.
[…] If you want a lower-impact challenge first, a cleaner freestyle technique or breaststroke will build your feel for the water before you commit to butterfly volume. Butterfly is also taught as a structured class skill — see when group classes introduce butterfly. […]