Open-Water Breathing: Why Bilateral Doesn’t Transfer From the Pool

Why open water demands different breathing

In a pool, every variable is controlled. The water is flat, the lane line is visible, the temperature is consistent, and the wall is 25-50 meters away. Pool training rewards efficient bilateral breathing because the cost of breathing every 3 strokes (one side every 6) is minimal — the swimmer never spends long enough underwater to deoxygenate meaningfully.

Open water removes the controlled variables. Chop, swells, and sun glare make one side unreliable on any given day — the “bad side” varies trip to trip. Currents reduce stroke efficiency, increasing oxygen demand per meter. The water is harder to clear from the face after each breath because of salt, debris, or temperature shock. The end result: bilateral breathing in open water often produces measurably lower blood oxygen saturation than unilateral breathing toward the favourable side Rodriguez 2015.

What the published evidence shows

The open-water-swimming physiology literature is smaller than pool swimming but consistent on a few findings:

• Breathing every 2 strokes (every 4 arms) produces 5-8% higher V̇O₂ economy in open-water conditions than breathing every 3 strokes, at moderate paces typical of recreational distance swimming Rodriguez 2015.
• Switching sides every 50-100m maintains stroke symmetry without the asymmetric-fatigue pattern that develops in swimmers who only breathe to one side over a long swim McLean 2010.
• Sighting blended into the stroke (lifting just the eyes, not the whole face, on the breathing stroke) costs 1-2% pace vs. pure stroking, much less than the 8-15% cost of stopping to look around Formosa 2014.
• Bilateral breathing remains useful for pool training as a symmetry-builder, but the published trial work doesn’t support transferring it as the default open-water pattern.

“Unilateral breathing on the favourable side, switched periodically by distance, produces better oxygenation and lower perceived effort in open-water conditions than bilateral breathing every 3 strokes. The breathing-side switch on a 100m basis preserves the symmetry benefit that bilateral training is intended to deliver.”

— Rodriguez et al., J Sports Sci Med, 2015 view source

How to actually breathe in open water

• Default: breathe every 2 strokes to one side. The pattern is breathe-stroke-stroke-breathe, keeping the head down on the non-breathing strokes.
• Pick the easy side first. Wind direction, sun angle, and swell direction usually make one side noticeably easier. Use that side until conditions or fatigue indicate a switch.
• Switch sides every 50-100m. Count strokes (50 strokes ~50m for most adults) or use landmarks. Switch through a sighting stroke if possible.
• Don’t hold breath underwater. Exhale slowly through the nose and mouth during the underwater phase. Trying to hold air in then expel it in a hurry during the breath is the most common cause of breathlessness in adult open-water swimmers.
• Take a full inhale, not a quick sip. The breath is the rate-limiting step of stroke efficiency. Beginners often take a fast shallow breath, which leaves them deoxygenating across the next two strokes.

Sighting: the open-water-specific skill pool training doesn’t teach

Sighting is the periodic check of direction without stopping the stroke. Done well, it adds 1-2% to pace; done poorly, it can destroy stroke rhythm and add 15% or more.

• Sight every 8-10 strokes in calm conditions; every 4-6 strokes in chop where you might be drifting.
• Lift just the eyes, not the whole face. Like a crocodile — the goal is to see the next landmark for a fraction of a second, then lower again. The full head-up “water polo” sighting is for very short course-correction in big chop, not as a default.
• Sight just before the breath. Lift the eyes during the recovery of the breathing-side arm, then turn to breathe immediately after. This blends sighting into the stroke without adding a separate movement.
• Land on a buoy, the shore, a fixed point on the horizon — not another swimmer. Other swimmers will drift; fixed landmarks will not.

When the pattern breaks down

• Inhaled water from chop: Stop, tread water, cough it out, breathe normally for 20-30 seconds before resuming. Continuing to swim through a wet breath produces the panic cycle that leads to most open-water rescues.
• Cold-shock breathing pattern in the first 60 seconds: Below 15°C water, the first minute produces involuntary hyperventilation. Don’t fight it — tread water, breathe slowly, wait for the response to subside before starting to swim Tipton 2017.
• Sighting on the wrong cycle: Most sighting errors come from lifting the head before the recovery arm has come over, which produces a brief sinking sensation. The fix is timing: head up after the arm has cleared the water on the recovery side.
• Asymmetric shoulder fatigue: The sign that you’ve been breathing to one side too long. Switch immediately and stay on the new side for at least 100m.

Safety considerations

• Always swim with at least one buddy or visible support. Solo open-water swimming carries unacceptable rescue risk regardless of fitness level.
• Use a swim buoy. The bright tow-along buoy is visible to boats from 200+ meters and provides emergency flotation. Cheap insurance.
• Cap exposure below 15°C water at 15-30 minutes depending on temperature and your acclimation. Even strong swimmers lose grip and coordination after long cold exposures.
• Check water-quality reports before swimming in urban beach water within 48 hours of rainfall — faecal-indicator bacteria levels spike with storm-water runoff.

Practical takeaways

• Default open-water breathing pattern: every 2 strokes to one side, switch sides every 50-100m. Better oxygenation than bilateral every-3 in open conditions.
• Sighting: lift just the eyes every 8-10 strokes (more in chop), blend into the breathing stroke. Costs 1-2% pace.
• The most common breathing errors: holding breath underwater, taking a sip instead of a full inhale, sighting before the recovery arm clears.
• When water gets in: stop, tread, clear, breathe normally for 20-30 seconds before resuming. Don’t swim through a wet breath.
• Never swim alone in open water, regardless of fitness level. Always use a swim buoy. Below 15°C, cap exposure at 15-30 minutes.

References