Bilateral Breathing in Triathlon Swimming: Complete Beginner Guide (2026)
Learn how to breathe every 3 strokes in freestyle — why it matters for open water, the 4-week progression drill, and when to switch back to single-side breathing.
By Lotte
Bilateral breathing — breathing every 3 strokes, alternating sides — is one of the most-debated swim skills in triathlon. Done right it balances your stroke, helps you swim straight in open water, and lets you breathe away from chop or sun. This guide walks through the physiology, a 4-week pool progression, and when bilateral is actually slower than picking your strongest side.
Key takeaways
- 1Bilateral = every 3 strokes (left, right, left); single-side = every 2 (always same side)
- 2Bilateral builds a more symmetric stroke and helps you swim straighter open water
- 3On race day, switch to your stronger side if chop or sun forces it — adaptability matters most
- 4Most beginners need 4–6 weeks of pool work before bilateral feels natural
- 5Use a 'breathing ladder' set: 50 m every 2 / 50 m every 3 / 50 m every 5 — builds CO₂ tolerance
In this article
Quick answer: should I breathe every 2 or every 3 strokes?
Train bilateral (every 3) for 70–80% of your pool work. Race with whichever pattern lets you maintain pace and stay calm — usually every 2 on your stronger side in chop, every 3 in calm water. The goal is not 'always bilateral.' The goal is to own both patterns so conditions don't decide for you.
Bilateral training builds stroke symmetry, balances shoulder load, and dramatically improves your ability to swim straight in open water. But forcing every-3 breathing in a panicked race-day swim is a recipe for oxygen debt. Build the skill in training, then choose freely on race day. For broader swim work, start with improving your triathlon swim.
Why bilateral breathing matters for triathletes
Single-side breathers (always to the same side) develop three predictable problems:
- Asymmetric pull — the non-breathing side shortens its catch, the breathing side over-rotates. Net effect: you swim in a curve.
- Open-water blindness — if your race-day buoy or competition is on your non-breathing side, you can't see it.
- Shoulder imbalance — the dominant breathing-side shoulder takes 5–8% more load. Over years, this becomes injury.
Bilateral breathing fixes all three. The cost is short-term discomfort (less oxygen per minute) and a 4–6 week learning curve. For triathletes, the trade is almost always worth it — your race-day adaptability is the real win.
See our swim drills for triathletes for technique work that complements bilateral training.
The 4-week pool progression
Don't try to switch overnight. Build CO₂ tolerance gradually.
Week 1 — Foundation:
- 8× 50 m: 25 m every 2 (normal), 25 m every 3 (bilateral). 20 sec rest.
- Total bilateral volume: 200 m
Week 2 — Build:
- 6× 100 m: 50 m every 2, 50 m every 3. 20 sec rest.
- Total bilateral volume: 300 m
Week 3 — Endurance:
- 4× 200 m: every 3 the entire length. 30 sec rest.
- If breathless, switch to every 2 for one length, then back.
Week 4 — Breathing Ladder:
- 4× (50 m every 2 / 50 m every 3 / 50 m every 5). 30 sec rest.
- Trains CO₂ tolerance — every 5 is genuinely hard but makes every 3 feel easy.
By week 5, bilateral should feel like a natural option, not a punishment. Use it for 60–80% of base/aerobic swim work and reserve every-2 for hard threshold sets.
When bilateral hurts race performance
There are 4 race scenarios where forcing bilateral is slower:
1. Mass-start chop: First 200 m of an Ironman swim — bodies everywhere, water churning. Breathe every 2 on your most-rehearsed side to maximize air intake.
2. Sun directly on your bilateral side: If breathing every 3 means you eat sunlight half the time, swap to single-side away from the sun.
3. Drafting on someone's hip: You want to see the swimmer you're drafting. Breathe to the side of their hip; ignore bilateral.
4. Threshold/VO2 sets: When effort is at 90%+, oxygen demand exceeds what every-3 supplies. Drop to every 2 and don't apologize.
The principle: bilateral is a training tool. Breathing pattern in a race is a tactical choice. Adaptability is faster than dogma.
Common mistakes during the transition
1. Holding breath too long. Bilateral doesn't mean 'don't breathe' — it means 'breathe every 3.' Exhale steadily and forcefully through nose and mouth between breaths. If you arrive at stroke 3 with air still in your lungs, you've under-exhaled.
2. Twisting the head instead of rotating the body. The breath should come from your shoulder rotation, not your neck. If only your head moves, you'll feel strained and your hips will drop.
3. Skipping the weak side. Most swimmers have a 'good' breathing side and a 'bad' one. Force 50% of your bilateral work to start on the weak side. After 4 weeks, both sides feel equal.
4. Stopping when it feels hard. Mild oxygen discomfort is normal and goes away in 6–8 sessions. Don't bail to every-2 the second it gets uncomfortable — push through 50 m at a time.
For a complete pool-to-open-water plan, see open water swimming.
When to use each breathing pattern
| Pattern | Strokes Between Breaths | Best For |
|---|---|---|
| Every 2 | 1 stroke between breaths | All-out efforts, mass starts, sun in eyes |
| Every 3 (bilateral) | 2 strokes between breaths | Aerobic training, calm OWS, stroke symmetry |
| Every 4 | 3 strokes between breaths | Rare — usually only sprint efforts |
| Every 5 (training only) | 4 strokes between breaths | CO₂ tolerance drill — never racing |
| Mix (race-day) | Switch based on conditions | Open water with chop, draft following |
Recommended gear
Affiliate disclosure: Brick to Brick may earn a commission from qualifying purchases, at no extra cost to you. Unless a named method says otherwise, these are research-based recommendations rather than first-hand product tests.
FINIS Snorkel Center Mount
Removes head rotation from your stroke so you can isolate catch and pull. Best tool for fixing the asymmetry that bilateral breathing exposes.
View on AmazonFINIS Tempo Trainer Pro
Beeps inside your cap at a set stroke rate so you can hold cadence while learning bilateral — most beginners slow down 5% when switching patterns.
View on AmazonSpeedo Vanquisher 2.0 Goggles
Wide field of vision and low-profile fit make sighting and breathing comfortable on both sides. Cheap, durable, and the most-used training goggle in triathlon.
View on AmazonFrequently asked questions
Do all elite triathletes breathe bilaterally?
Most train bilaterally but race with whatever pattern conditions demand. Lucy Charles-Barclay and Kristian Blummenfelt both switch sides freely based on chop, sun, and competition position. Adaptability beats dogma.
How long until bilateral breathing feels natural?
Most beginners need 4–6 weeks of consistent practice (3 sessions per week, 200–400 m bilateral per session). The first 2 weeks feel oxygen-starved; weeks 3–4 the discomfort fades; week 5+ feels normal.
Can I bilateral breathe in open water?
Yes, and it helps you swim straighter and see both sides for navigation. But on race day, if chop is one-sided or the sun is on your bilateral side, switch — don't force it.
Is it bad to always breathe on the same side?
Long-term, yes — it creates an asymmetric pull, swerving in open water, and a shoulder load imbalance. Train bilateral; race with the best side for conditions.
Should I exhale fully between breaths?
Yes — a slow, forceful exhale through nose and mouth. Most beginners under-exhale and arrive at the next breath with full lungs, which feels like suffocation. Exhale empty, then inhale fast.