How to Breathe When Running: The Science-Backed Guide to Better Rhythm and Stamina

You trained. You sleep well. Your legs are strong. But something about your breathing feels wrong — you're gasping earlier than you should, getting side stitches, or running out of steam before you're physically tired. Breathing technique is almost certainly part of the problem.

The Basics: Diaphragmatic Breathing

Most people — especially under exertion — breathe with their chest, using the secondary respiratory muscles (neck, shoulders, intercostals). This is inefficient. The diaphragm is the primary breathing muscle and can move 10x more air per contraction than chest breathing.

You can practise diaphragmatic breathing at rest: lying down, place a hand on your belly. It should rise on inhale, fall on exhale. Your chest should barely move. Take this pattern into running — belly out on the inhale, belly in on the exhale.

Rhythmic Breathing: The Secret of Elite Runners

Elite runners unconsciously adopt rhythmic breathing — a set ratio of footstrikes to breath cycles. Research by exercise physiologist Budd Coates and breathing expert Claire Kowalchik shows that a 3:2 ratio (three footstrikes per inhale, two per exhale) is optimal for most recreational runners at moderate pace.

Why does this matter? Rhythmic breathing ensures that the start of each exhale alternates between left and right foot landing. Since the diaphragm relaxes on exhale, and this relaxation creates a small impact stress, always landing on the same foot during exhale creates cumulative asymmetric stress — a common cause of side stitches and injury.

At easy pace: try a 3:2 pattern (inhale left-right-left, exhale right-left). At hard effort: 2:1 or 2:2 is more natural. Experiment until it feels automatic.

Nose vs. Mouth Breathing When Running

This is contentious, and the answer is nuanced:

Nasal breathing (nose only, in and out) is advocated by researchers like Patrick McKeown (author of The Oxygen Advantage). Nose breathing filters air, humidifies it, and — critically — produces nitric oxide in the sinuses, which dilates blood vessels and improves oxygen uptake. Nasal breathing also produces more CO₂ tolerance over time, which is what actually limits running performance at aerobic paces (not oxygen shortage, but CO₂ sensitivity triggering the breathing urge early).

Mouth breathing allows higher air volumes at high intensity. Most runners naturally switch to mouth breathing above their aerobic threshold — this is fine and physiologically appropriate.

The practical recommendation: Train nasal breathing on easy runs (below your aerobic threshold). On hard efforts, races, and intervals, breathe however the body demands. Over months of nasal training, your CO₂ tolerance improves and you'll find your easy pace naturally improves too.

What Causes Side Stitches and How Breathing Fixes Them

Side stitches (exercise-related transient abdominal pain) are usually caused by stress on the ligaments connecting the diaphragm to internal organs, combined with shallow breathing and poor core engagement. Fixes:

• Exhale fully — incomplete exhalation leaves the diaphragm raised and tight
• Breathe diaphragmatically rather than from the chest
• Slow down briefly and take 3 deep belly breaths
• Press fingers gently into the site of pain and exhale hard — this often releases it

Training Your Running Breath Off the Road

Breathwork off the road builds the respiratory capacity and CO₂ tolerance that pays dividends on the run. Coherence breathing (5 seconds in, 5 out) and extended exhale practice build diaphragm strength and HRV. Breath-hold walks (walking while holding breath after exhale) are the best drill for building CO₂ tolerance without running.

Breathwork for Runners in Selah

Selah's Athletic Performance track includes diaphragmatic breathing drills, CO₂ tolerance training, and a pre-run breathwork warm-up. Use it three times a week and notice the difference in stamina, recovery, and breathlessness on your runs within four weeks.