Protocol Glossary
Science-backed definitions for every term in your health data: plain English and the mechanism behind it.
Cortisol Awakening Response (CAR)
The first hormonal signal that sets your day
→ Read definitionCRP (C-Reactive Protein)
Your body's systemic inflammation signal
→ Read definitionFasting Glucose
Your baseline blood sugar after an overnight fast
→ Read definitionFerritin
Your iron storage tank, and an inflammation marker
→ Read definitionHeart Rate Variability (HRV)
Your nervous system's daily readiness signal
→ Read definitionHemoglobin A1c (HbA1c)
A 3-month average of your blood sugar control
→ Read definitionHOMA-IR (Homeostatic Model Assessment of Insulin Resistance)
The earliest measurable signal of insulin dysfunction
→ Read definitionRespiratory Rate
Breaths per minute: your body's quiet early warning signal
→ Read definitionResting Heart Rate (RHR)
How hard your heart works when it doesn't have to
→ Read definitionRMSSD (Root Mean Square of Successive Differences)
The beat-to-beat calculation that powers your HRV score
→ Read definitionSDNN (Standard Deviation of NN Intervals)
The HRV metric Apple Watch uses, and why it reads higher than Oura
→ Read definitionSpO2 (Blood Oxygen Saturation)
The percentage of your red blood cells carrying oxygen
→ Read definitionVagal Tone
The strength of your parasympathetic recovery signal
→ Read definitionVO2 Max
The strongest single predictor of long-term health and longevity
→ Read definitionMore terms added regularly. Check back for new entries across all categories.
