BOLT (Body Oxygen Level Test) measures breath-hold duration after a normal exhale (not maximum). You hold until the first distinct urge to breathe — not to your limit. Shorter BOLT indicates lower CO₂ tolerance and less efficient gas exchange; 40+ seconds suggests optimized function.
Key Points
- •Not maximal — BOLT is submaximal; it reflects chemoreceptor sensitivity
- •Trainable — breathwork (box breathing, apnea tables) can increase BOLT
- •Practical — correlates with exercise performance and stress resilience
In ONDA Life
The CO2 Tolerance article covers BOLT testing and protocols to improve it.