CO₂ tolerance is a limiting factor for many athletes. The urge to breathe is driven more by rising carbon dioxide than dropping oxygen. Training your system to tolerate higher CO₂ allows calmer, more efficient breathing under stress.
What CO₂ Tolerance Really Means
Central and peripheral chemoreceptors respond to CO₂ and pH changes. With practice, athletes can reduce over‑breathing, improve gas exchange efficiency, and maintain performance with fewer, more effective breaths.
Simple Assessment Ideas
- BOLT‑style time after a normal exhale (non‑maximal, comfortable)
- Cadence walk tests using nasal breathing at set tempos
- Talk test thresholds during progressive efforts
Safe Training Progressions
1. Nasal Cadence Breathing
Establish a steady inhale:exhale rhythm at low intensity. Extend the exhale gradually to build CO₂ tolerance without breath hunger or panic.
2. Controlled Breath Holds
Use small, repeatable holds after an exhale during walking. Keep RPE and urge to breathe low to moderate. Avoid maximal or hypoxic efforts.
3. Interval Breathing
During intervals, regulate CO₂ with longer exhales on recovery and consistent nasal breathing on work bouts as tolerated.
Common Mistakes
- Chasing max holds that spike stress instead of adapting gradually
- Confusing “more air” with “better performance”
- Ignoring recovery breathing and cadence in between efforts