A supervised breathing practice alternating short spells of low-oxygen and oxygen-rich air to build resilience, in the same broad spirit as exercise. The most dependable benefit is improved fitness, especially in older or less-fit people, with weaker signals for blood pressure, blood sugar, and well-being. Claims about sharper thinking, cellular energy, and longer life remain largely unproven. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Resting SpO2 | 95–99% at rest | Baseline oxygenation and safety margin for hypoxic dosing |
| In-session SpO2 | ~80–88% (halt if <~75%) | Confirms an effective yet safe hypoxic dose |
| Blood pressure | <120/80 mmHg | Tracks a primary cardiometabolic benefit and cardiovascular safety |
| Resting heart rate | ~50–70 bpm | Marker of autonomic adaptation and training load |
| Hemoglobin / Hematocrit | Hemoglobin ~13.5–15 g/dL (♂), ~12.5–14 g/dL (♀) | Adequate oxygen-carrying capacity for safe hypoxic exposure |
| Fasting glucose | 70–90 mg/dL | Tracks metabolic benefit in at-risk individuals |
| HbA1c | <5.4% | Captures durable glucose-control changes |
| hs-CRP | <1.0 mg/L | Screens for net inflammatory/oxidative stress balance |
Cadence: In-session SpO2 and heart rate continuous; blood pressure and resting heart rate weekly; glucose, HbA1c, lipids, and exercise capacity at baseline and end of a 3–6 week course, then every 3–6 months if repeating courses