Reduced-volume breathing to raise CO2 tolerance

Breathe slightly less than your body demands — a mild air hunger — to recalibrate the CO2 set point.

Why it works

Habitual over-breathing trains the chemoreceptors to demand low CO2 — triggering the urge to breathe too soon. Deliberately sustaining mild air hunger for short periods (without breath-holding) de-sensitises the chemoreceptors gradually, shifting the set point upward so that normal breathing becomes slower and deeper without effort.

How to do it

1. After a normal exhale, breathe in and out at about 70-80% of your normal volume for 3-5 minutes.
2. The goal is a tolerable but noticeable air hunger — not discomfort or dizziness.
3. Stop if you feel light-headed; the exercise should remain gentle throughout.
4. Practice 2-3 times daily before meals.

Evidence

The Buteyko method, which includes reduced-volume breathing, has clinical evidence for reducing asthma medication use and improving symptoms, though it is less studied in healthy performance contexts. (clinical)

Evidence is primarily in asthma populations. Extrapolation to athletic performance or cognitive benefits in healthy people is mechanistically plausible but not independently confirmed by RCTs.

Sources

• Cowie et al. (2008), Buteyko breathing technique in asthma, Journal of Asthma

Common mistake

Pushing into strong air hunger thinking more is better — this activates the stress response and defeats the purpose. The target sensation is mild, sustainable, and tolerable.