How to tread water without getting tired

Almost nobody searching for this wants to learn the gesture. They can already keep their head up for twenty or thirty seconds — what they cannot do is keep it up for ten minutes without their legs burning and their breathing going ragged. The question is not how do I tread water. It is why does it cost me so much.

That turns out to be a question with measurements behind it. A research group at the University of Otago put 52 people in a swimming flume with a gas analyser and a heart rate strap and had them tread water four different ways. The numbers do not say what the internet says they say.

The short answer

Use upright breaststroke: legs sculling out and in together like a breaststroke kick turned vertical, hands sweeping flat side to side at chest depth. Keep your head back and low, breathe continuously rather than in gulps, and press your hands outward instead of pushing down. If you are still tiring, roll onto your back and float — floating costs far less than treading.

What counts as treading water, and the standard worth aiming at

Treading water means holding an upright position with your head clear of the surface, under your own power, in water too deep to stand in. It is not a stroke. It has no distance and no finish — which is exactly why it is hard to practise and easy to put off.

The American Red Cross builds it into what it calls water competency, a set of five skills it says every swimmer should be able to perform in every kind of water they might end up in: enter water over your head and return to the surface, float or tread water for at least one minute, turn over and turn around in the water, swim at least 25 yards, and exit the water. One minute is the bar. Not ten.

Notice the or. The standard treats floating and treading as interchangeable for that minute, and that wording comes back later as the answer to the ten-minute version of this question.

If you are nowhere near that minute yet, the problem is probably not your legs. Start with getting comfortable in deep water and the adult learn-to-swim sequence, because a body braced against the water sinks and a relaxed one does not.

The four ways people tread water

One study catalogued eight distinguishable behaviours across a range of skill levels and distilled them into the four patterns every piece of research since has used:

“Running” is what an untrained adult falls into without being told anything, and the fast flutter kick is what a lap swimmer falls into, because it is the kick they already own. Those are the two defaults. They are also the two that cost the most.

What each one costs, measured

Twenty-one skilled treaders — water polo players, a synchronised swimmer, competitive swimmers — held each pattern for three and a half minutes in a flume, breathing through a snorkel wired to a gas analyser. Oxygen consumption, heart rate and perceived effort all separated the four patterns the same way.

Heart rate followed: 147 beats per minute on the flutter kick and 140 running, against 129 for both breaststroke and eggbeater. Perceived effort on the Borg scale, where 6 is no exertion at all and 20 is maximal, dropped from 13.9 running to 10.6 on the eggbeater. Same people, same water, same three and a half minutes — the only thing that changed was the shape of the movement. About a fifth less oxygen and eighteen fewer beats a minute is the entire prize here, and it is not available by trying harder.

Why the eggbeater is not the beginner's answer

Here is where the usual advice goes wrong. Search this topic and you will be told to learn the eggbeater, because it is what water polo players use. The follow-up study tested whether that transfers, by running the same protocol on three groups: 21 treading experts, 15 experienced swimmers with no specific treading background, and 16 inexperienced swimmers.

It did not transfer. For the inexperienced group, the flutter kick and breaststroke patterns produced the lowest reported physical and task load, and oxygen consumption, heart rate and reaction time did not separate the four patterns at all. For the intermediate group, breaststroke alone came out lowest on heart rate and oxygen cost. Only in the experts did the eggbeater's advantage show up.

The authors also measured something most studies skip: how long participants took to respond to an audio cue while treading, as a proxy for how much attention the movement was eating. Reaction time was slowest during the eggbeater — the pattern was the hardest to coordinate, across the board. Their own conclusion is that because the eggbeater is challenging for many people, upright breaststroke is an adequate alternative to adopt in survival situations.

Upright breaststroke, the pattern that worked for everyone

So this is the one to learn first. It is the only pattern that came out economical for all three skill groups, and it is the one you already have most of if you can swim breaststroke at all.

Take your normal breaststroke kick and stand it up. Both feet turn outward, sweep out and around and back together underneath you, then recover. The two legs move in phase, which is the whole reason it is easy: symmetrical movements are what untrained bodies do naturally, so there is nothing to fight.

Your hands scull flat at about chest depth, palms angled slightly down, sweeping outward and inward — not pushing down. The sweep is wide and unhurried, roughly shoulder width, and the palms change angle at each end so they keep catching water on the way back.

The timing to aim for: as the legs recover and produce nothing, the hands are sculling. That gap is the structural weakness of this pattern next to the eggbeater, and busy hands are what paper over it.

The eggbeater, and when it is worth the trouble

The eggbeater is the same sculling idea with the legs out of phase, so one leg is always producing lift while the other recovers. No gap, continuous support — which is why water polo players use it: it holds a stable platform while the hands do something else entirely.

Each knee stays wide and fairly still, and the work happens below it: the lower leg swings and the foot traces a circle, one leg clockwise, the other anticlockwise. Motion capture and pressure sensors on water polo players' feet found the biggest pressure difference sat around the big toe, from suction on the top of the foot, and that foot angle was the kinematic variable that most distinguished good technique from poor.

Which tells you what to practise. The eggbeater is not a leg-strength movement but an ankle and foot movement, and loose ankles that can hold an angle through the sweep are what make it work. If your ankles are stiff — common in runners and cyclists — it will feel like nothing is happening, and nothing much is. Learn it at the wall, over weeks. It is worth owning; it is not worth being the thing you reach for before you own it.

Your head is the thing you are holding up

Every treading pattern is a machine for holding one object out of the water: your head. The higher you insist on holding it, the more lift you have to make every second, and lift is expensive.

So hold it as low as the situation allows. Chin at the surface, head tipped back rather than craned forward, waterline across your ears. Looking down at your own hands — which is what people do when they are checking whether the technique is working — pitches you forward and drops your hips, and now you are fighting to stay vertical too.

A low, steady head buys the second thing that matters: you can breathe continuously. The failure mode in treading water is gulping — a breath snatched in a hurry because the mouth is only clear some of the time, paired with a surge of effort to lift higher for the next one. Three or four of those and the effort has compounded into panic. The same principle runs underneath freestyle breathing: a rhythm you can keep beats a big breath you have to earn.

Sculling: pressing out, not down

The single correction that changes the most is this one. Water is not a floor. Push down on it and it moves out of the way, you drop, and you have to push again — which is precisely why the “running” pattern, all vertical pushing, was the most expensive thing measured.

Sculling works differently. The hand travels mostly sideways, held at a slight angle like a tilted blade, and generates lift as the water flows past it — the same way a wing does. You are not shovelling but slicing continuously, and the pressure under the palm never has to be rebuilt from zero. The Otago authors proposed exactly this as the reason for the gap between patterns: sculling generates lift continuously, where pushing movements include a recovery phase that produces nothing.

You can feel the difference with a drill that needs no equipment. In chest-deep water, sweep your hands side to side at the surface in a flat figure of eight, rolling the palms to lead with the thumb on the way out and the little finger on the way back. When it is right there is a firm cushion under your hands throughout; when it is wrong there are two brief catches and two dead spots. The dead spots are where your energy goes.

Why beginners run out first

There is one more finding in the three-group study worth sitting with. Across every technique, the inexperienced swimmers used more than 40% more energy than the other two groups to do the same job of staying afloat.

Not on a particular pattern — on all of them. And it compounds, because the same people typically have less fitness to spend, and time to exhaustion falls away faster than power output does as fitness drops. Less efficient, smaller tank, steeper cliff: that is the honest reason why “just tread water until help comes” works much better for some people than others.

The lever on that is general aerobic fitness, not treading drills. Building swimming endurance does more for how long you could last than any amount of eggbeater practice, and the CSS calculator turns two timed swims into the pace you can hold aerobically — the closest thing to a measurement of your tank.

The real answer to "ten minutes": stop treading and float

Go back to that or in the Red Cross standard. Float or tread for one minute. Treading water is work; floating is close to rest. If you need to stay in deep water for ten minutes, the answer is not a better treading technique — it is to tread only when you need to and float the rest of the time.

The RNLI built its whole public safety message on this, and it is worth following to the letter. Their five steps: tilt your head back with your ears submerged, try to relax and breathe normally, move your hands and legs gently to help you stay afloat, spread your arms and legs out for stability, and accept that your legs may sink, because everyone floats differently. Once your breathing is under control, then call for help or swim to safety.

That last clause is the sequence that matters: breathing first, decision second. And the fourth step removes the thing most people panic about — your legs sinking is not a failure of floating but normal body composition, and a diagonal float with the legs hanging still works.

So when do you actually tread? When you need your head high to see over chop, when you need your hands free to signal or hold something, and when you need to look around and decide. Those are the jobs floating cannot do. Everything else is rest.

Cold water changes the arithmetic

Everything above was measured in a warm indoor flume. Open water is a different problem, and the difference is not a detail.

The RNLI defines anything below 15 °C as cold water — which is most of the year in most of the places people swim outdoors in the UK, and plenty of US and Australian water too. Sudden immersion triggers an involuntary gasp, and breathing rates can change uncontrollably, in some cases increasing as much as tenfold. That is the mechanism behind a lot of drownings that get written up as exhaustion.

There is a second cost. The same Otago group's review of the older immersion literature notes a 1975 finding that actively treading water raised the rate at which people cooled by 35% compared with resting still in a heat-escape-lessening posture. Moving keeps you up and cools you down. In cold water those two are in direct conflict, and the resolution is a flotation aid, not a technique. If you swim outdoors regularly, read the first open-water swim checklist and consider whether a wetsuit belongs in your kit — buoyancy you do not have to generate is buoyancy that costs nothing.

Is treading water good exercise?

It can be, and the published figures show how wide the range is. The 2024 Adult Compendium of Physical Activities lists treading water at moderate effort at 3.5 METs and treading fast at vigorous effort at 9.8 METs — the same activity, 2.8 times the cost.

That is MET times body weight in kilograms times hours, the same arithmetic set out in the guide to calories burned swimming — including the reasons every MET-based figure runs somewhat high. Treat it as a scale, not a readout.

Read the table the other way round, though, and it is a technique diagnostic. The gap between those two rows is roughly the gap between sculling and shovelling. If ten minutes of treading leaves you as wrecked as a hard interval set, you are near the 9.8 row — and that is information about your technique, not your fitness.

How to practise your minute without taking risks

The RNLI's fifth step is to find your float by practising at a supervised location, and that applies to treading too. Deep water, with a lifeguard, and with the wall within reach.

A progression that works: in the deep end, hold the edge with your feet off the bottom and drill the leg pattern alone for 30 seconds at a time until it stops feeling like effort. Then let go with one hand. Then both, for 20 seconds, a metre from the wall. Then build the time, not the intensity — the goal is a minute that feels like nothing, which is a different goal from a minute you survive.

Two useful tests once the minute is comfortable. First, tread for one minute and then swim a continuous 500, because in any real situation the treading comes before a swim, not instead of it. Second, run your own times through the pace calculator: “the bank looks close” is a judgement people make badly while out of breath, and knowing that 200 metres costs you four minutes is a better basis for deciding than optimism. More drills sit in the technique guides, and the workouts section covers the fitness side.

When to stop, and what trouble looks like

Two hard rules, and neither is negotiable. Do not practise this alone, and do not practise breath-holding to extend it. Hyperventilating before going under or holding a breath to stay down is how competent swimmers drown in shallow water, and it is never part of treading practice.

Learn what distress looks like, because it is quieter than people expect. The Red Cross lists the signs that someone in the water needs help immediately: they are not making forward progress, they are vertical in the water but unable to move or tread water, or they are motionless and face down. That middle one is a person who was treading water and has run out. It does not look like thrashing. It looks like someone standing still.

Drowning remains one of the most preventable causes of death there is — the WHO counts around 300,000 a year worldwide, with children and young adults under 30 making up over half of them. A minute of competent treading water and a reliable back float are two of the cheapest pieces of insurance available, and unlike almost everything else on this site, they are worth having even if you never intend to swim fast.