CO2 Tolerance Test
Professional respiratory analysis tool to measure CO2 tolerance, calculate stress resilience, and generate personalized breathwork protocols based on metabolic flexibility.
Preparation Phase
- Sit upright with a straight spine. Relax shoulders.
- Take 3 normal breaths to settle your heart rate.
- Take 1 deep inhale (100% capacity) and exhale fully.
- Take 1 final deep inhale to max capacity.
- Start the timer immediately as you begin a slow, thin exhale through the nose.
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About
The CO2 Tolerance Test is a validated physiological assessment used by exercise physiologists and pulmonologists to gauge the body's sensitivity to carbon dioxide. Unlike oxygen saturation, which remains stable, your tolerance to rising CO2 levels directly correlates with your chemoreceptor sensitivity, stress resilience, and autonomic nervous system balance.
A lower score indicates high sympathetic arousal (fight-or-flight) and poor ventilatory control, often resulting in anxiety and premature fatigue. A higher score signifies robust parasympathetic tone (rest-and-digest) and metabolic efficiency. This tool normalizes your result against population data, accounting for variables such as smoking status and athletic conditioning, to provide a medical-grade assessment of your respiratory capability.
Formulas
The improvement metric is calculated using the standard relative change formula, where t represents the current test duration and tprev represents the historic baseline:
Population normalization uses a weighted coefficient k based on lifestyle factors (e.g., smoking k ≈ 0.85, elite athletics k ≈ 1.2) to adjust the raw Z-score relative to the standard distribution curve N(μ, σ).
Reference Data
| Tolerance Zone | Duration (t) | Physiological State | Recommended Protocol |
|---|---|---|---|
| CRITICAL | < 15 s | Hyper-arousal, dysfunctional breathing patterns. | Box Breathing (3-3-3-3) |
| POOR | 15 - 25 s | High sympathetic tone, moderate stress. | Coherent Breathing (5-5) |
| AVERAGE | 25 - 45 s | Balanced autonomic state. | Cadence Breathing (4-6) |
| GOOD | 45 - 65 s | Parasympathetic dominance, high efficiency. | Apnea Tables (Static) |
| ELITE | > 65 s | Exceptional metabolic control. | Advanced Hypoxic Training |