CO2 Tolerance Training Loop
Use controlled air hunger and measurement to retrain an overactive breathing drive
- Difficulty
- Moderate
- Time to result
- ~weeks to results
- Steps
- 7
- Confidence
- 96%
The loop treats carbon-dioxide tolerance as a flexible respiratory baseline rather than a fixed trait. First, the practitioner measures a consistent baseline using a normal inhale, normal exhale, and a comfortable hold until the first clear impulse to breathe, or by counting steps during a controlled exhalation hold. Training then uses quiet nasal breathing with deliberately reduced airflow, allowing carbon dioxide to rise enough to create mild or medium air hunger without panic. Repeated exposure teaches the body that a modest increase in carbon dioxide does not require immediate rapid breathing. Measurements are repeated under similar conditions to detect adaptation. The intended output is a slower, quieter default breathing pattern and a delayed urge to over-breathe, not a record-setting breath hold.
Origin
Extracted from Deep Dive with Ali Abdaal as Mike Maher explained carbon-dioxide baselines, breath-hold measurements, and his own six-week improvement.
Core principles
- 01Air hunger initially reflects rising carbon dioxide more than depleted oxygen
- 02Chronic over-breathing can lower the threshold that triggers faster breathing
- 03Carbon-dioxide sensitivity is adaptable
- 04Controlled exposure should remain tolerable and repeatable
- 05Measurement makes gradual adaptation visible
How to run it
- 1
Establish a baseline
After a normal inhale and exhale, hold comfortably until the first definite impulse to breathe and record the time. Alternatively, record the steps taken during a controlled exhalation hold.
Pro tip Measure at the same time and in similar conditions.
Watch out Do not turn a baseline test into a maximal endurance attempt.
- 2
Settle into nasal breathing
Breathe normally and quietly through the nose before training. Let the respiratory pattern stabilise without deliberately taking large preparatory breaths.
Pro tip Use breath awareness to detect upper-chest movement or noise.
Watch out Large preparatory breaths can distort the exercise and lower carbon dioxide.
- 3
Reduce ventilation gently
Make each inhale and exhale slightly quieter, slower, and smaller. Continue until a mild or medium desire for more air appears.
Pro tip Use a hand beneath the nostrils as airflow feedback.
Watch out Do not push into severe distress, dizziness, or loss of control.
- 4
Stay with manageable air hunger
Maintain the reduced pattern without taking a compensatory gulp. Interpret the tolerable urge to breathe as the training signal.
Pro tip Relax the shoulders and abdomen while maintaining the smaller breath.
Watch out Air hunger should be controlled, not overwhelming.
- 5
Recover normally
Return to ordinary nasal breathing and allow the respiratory pattern to settle. Avoid exaggerated recovery breaths.
Pro tip Notice how quickly comfort returns.
Watch out Repeated gasping indicates that the training intensity was excessive.
- 6
Repeat consistently
Practise in short daily sessions over several weeks. Consistency supplies the repeated stimulus needed to shift the baseline.
Pro tip Track practice alongside the measurement rather than relying on memory.
Watch out Irregular maximal sessions are less useful than sustainable repetition.
- 7
Retest and adjust
Repeat the original measurement and compare the trend rather than a single result. Increase difficulty only when reduced breathing remains calm and controlled.
Pro tip Use a weekly median to reduce day-to-day noise.
Watch out Do not ignore deteriorating results accompanied by symptoms.
In the wild
Maher practised reduced-airflow breathing consistently and tracked his comfortable breath hold. He reported moving from roughly fourteen seconds to roughly thirty seconds over six weeks.
→ The longer hold provided a practical indicator that his tolerance and breathing pattern had changed.
A desk worker records a comfortable twelve-second baseline, then performs ten minutes of quiet reduced nasal breathing each morning and evening. He allows only manageable air hunger and records a weekly median rather than chasing daily records.
→ After several weeks, his urge to take large breaths arrives later and his resting breathing is quieter.
Common mistakes
Mistaking air hunger for immediate oxygen loss
The transcript explains that the early urge to breathe is largely driven by rising carbon dioxide while oxygen saturation may remain high.
Training at maximal intensity
Strong distress encourages gasping and makes the exercise difficult to repeat consistently.
Comparing inconsistent tests
Different preparation, timing, or effort levels can make breath-hold scores misleading.
Is it for you?
Best for
It is best for healthy adults who want a measurable, gradual approach to reducing habitual over-breathing.
Not ideal for
It is not appropriate for unsupervised strong breath holds during pregnancy or for people with relevant medical contraindications such as epilepsy or uncontrolled high blood pressure.
From the transcript
“So it's not your body run out of oxygen, it's the co2 that's rising.”
“And so what's happening here is we've all got this co2 baseline, which is flexible, this is the problem and a good thing. It's a…”
“And so I did that. And it took me about six weeks to get my breath hold from about 14 seconds. It's about 30, which…”
From the episode
Why You’ve Been Breathing Wrong Most Of Your Life - Breathing Expert Mike Maher