Photo by Nataliya Vaitkevich on Pexels
Most runners don’t think about how they breathe — they just breathe. For easy runs, this is fine. But when effort increases, uncontrolled breathing becomes a limiter: side stitches, breathlessness disproportionate to the effort, and an inability to settle into a rhythm all relate directly to breathing mechanics.
Nose vs Mouth: Which Is Better?
The short answer: both. The practical answer: mouth breathing at running intensity is unavoidable and correct.
At easy pace, nasal breathing is possible for many runners and has some advantages — the nose warms and filters air, and nasal breathing promotes slightly slower, diaphragmatic breathing. Some runners train entirely nasal at easy efforts.
At moderate to hard effort, breathing volume requirements exceed what the nose can deliver. Mouth breathing is not a failing — it’s a physiological necessity at race or tempo pace. Breathe through both nose and mouth simultaneously at harder efforts.
Diaphragmatic (Belly) Breathing
The most common breathing mistake among runners is chest breathing — shallow breaths that primarily use the upper chest and don’t fill the lungs fully. This is inefficient, reduces oxygen delivery, and increases the likelihood of side stitches.
Diaphragmatic breathing uses the diaphragm — the dome-shaped muscle below the lungs — to draw air deep into the lungs. The belly visibly expands on inhale and contracts on exhale.
To practice before running: lie on your back, place one hand on your chest and one on your stomach. Breathe in through your nose — the stomach hand should rise; the chest hand should barely move. This is diaphragmatic breathing.
Training yourself to breathe this way while running takes practice but significantly improves breathing efficiency.
Breathing Rhythm: How to Match Breathing to Steps
A rhythmic breathing pattern — coordinating breaths with footstrikes — helps maintain consistent breathing and reduces asymmetric impact loading (which is linked to side stitches).
The most common recommended pattern for easy running is a 3:2 pattern: inhale over 3 footstrikes, exhale over 2. This means you don’t always exhale on the same foot, which distributes the impact force and reduces the risk of stitches on one side.
At tempo pace, a 2:1 pattern (in for 2 steps, out for 1) is common. At hard intervals or sprint efforts, breathing is less controlled and more instinctive.
The pattern should feel natural, not forced. Counting footstrikes while running takes practice but becomes automatic over time.
Side Stitches: Cause and Fix
A side stitch — the sharp pain under the ribs during running — is one of the most common problems beginning runners face. The most supported explanation is diaphragm spasm or irritation of the phrenic nerve that runs over the diaphragm.
Why stitches happen:
– Shallow, irregular breathing
– Eating too close to running (within 2 hours for larger meals)
– Breathing primarily on the same foot repeatedly
– Weak core muscles
How to get rid of a stitch during a run:
1. Slow to a walk or easy jog
2. Take a slow, deep belly breath in and hold for 2–3 seconds before exhaling
3. Exhale fully — push all air out
4. Repeat 3–5 times until the stitch eases
Some runners find pressing two fingers gently into the stitch site while exhaling also helps.
Prevention: Practice diaphragmatic breathing, avoid eating 2+ hours before running, and use a rhythmic breathing pattern.
Breathlessness: When It’s Normal and When It Isn’t
At easy pace, you should be able to hold a full conversation — the “talk test.” If you can’t speak a full sentence, you’re going faster than easy pace.
At tempo pace, you should be able to speak a short phrase but not carry a conversation.
At interval or race pace, you’ll be too breathless to speak — that’s appropriate.
If you’re breathless beyond what the effort justifies, the usual explanation is running too fast for your current fitness level — the solution is to slow down. Genuine fitness builds over weeks, not in a single session.
Note: Breathlessness that doesn’t improve with effort reduction, comes with chest tightness or wheezing, or concerns you for any reason warrants medical assessment. Runners with asthma should have an appropriate management plan before training at higher intensities.
Breathing in Cold Weather
Cold air is drier and can irritate the airways during running — particularly relevant for runners with exercise-induced bronchoconstriction (EIB) or asthma.
A buff or neck gaiter pulled over the mouth and nose warms and humidifies inspired air before it reaches the airways, significantly reducing cold-air-triggered irritation. This simple measure makes cold-weather running more comfortable for many runners.
Improving Your Breathing: Practical Steps
Add belly breathing practice: Spend 5 minutes before bed practicing diaphragmatic breathing — it builds the habit without the distraction of running simultaneously.
Slow down on easy runs: Most runners run easy runs too fast to settle into a comfortable breathing rhythm. Slowing to a truly easy pace — where conversation is comfortable — lets breathing patterns settle naturally.
Core strengthening: The diaphragm works in concert with the core. Exercises like dead bugs, plank variations, and bird dogs improve both core stability and diaphragmatic function over time.
Nasal breathing on easy runs: Some coaches recommend practising nasal-only breathing at easy pace for a training block. It forces a genuinely easy pace and trains diaphragmatic breathing. Uncomfortable at first; most runners adapt within 2–3 weeks.
Summary
How to breathe when running:
- Breathe through both nose and mouth at moderate-hard efforts — nasal breathing is fine at easy pace but mouth breathing is necessary at higher intensities
- Train diaphragmatic breathing — belly rises on inhale; chest barely moves; fills the lungs properly and reduces stitches
- Use a 3:2 breathing rhythm at easy pace — in for 3 steps, out for 2; distributes impact asymmetrically and reduces stitches
- Side stitches respond to slow deep breaths and full exhale — slow down, breathe deeply, exhale fully; they resolve in 1–3 minutes with this approach
- The talk test determines the right pace — easy runs should be fully conversational; if they’re not, slow down
Next read: Running cadence: what it is and how to improve it