Key takeaways
- 1A 60-second home test that estimates CO₂ tolerance.
- 2Exhale normally, hold, count until you need to breathe.
- 3Simpler than BOLT — stops at strain, not first urge.
- 4Good starting point for home practice; BOLT is stricter for training decisions.
What it is
The Auralize CO₂ tolerance test is a simplified home check for CO₂ tolerance. Exhale normally, pinch your nose, and hold. The clock stops when you need to breathe — a slightly looser stopping rule than BOLT. The test is available as a standalone route (not tied to your Auralize account) and as an embeddable widget.
How it differs from BOLT
BOLT stops at the first definite urge to breathe — the first involuntary swallow, twitch, or throat spasm. The CO₂ tolerance test stops at the point where continuing feels uncomfortable, which is later. Same shape of measurement, looser stopping rule, higher numbers. Neither is "right" — they measure the same underlying tolerance from slightly different angles.
When to use which
Use the CO₂ tolerance test for a first home check or when introducing someone else to the concept. Use BOLT when you want a training benchmark you can track across weeks or months. Auralize\'s automated pacing (box breathing interval scaling, program gating) uses BOLT specifically because the stricter rule makes it more repeatable.
Score interpretation
The Auralize CO₂ tolerance test outputs a level 1–5. Higher levels indicate more room to breathe deeply and hold comfortably. The mapping to BOLT is approximate, not exact — expect a 5–10 second gap in the same direction.