Health & fitness glossary
Plain-language definitions of the metrics and concepts Vita tracks — HRV, VO₂max, recovery, strain, sleep stages, Zone 2, healthspan, biological age and more — and how each one shapes your recovery and Body Age.
What is HRV?
What is HRV (heart-rate variability), and what's a good number?
What is VO₂max?
What is VO₂max, and why does it matter for longevity?
Resting heart rate
What is a good resting heart rate?
Sleep debt
What is sleep debt, and can you pay it back?
Biological age
What is biological age, and how is it different from your real age?
Recovery score
What is a recovery score, and how is it calculated?
Strain / training load
What is strain (training load), and how much is too much?
Deep sleep vs REM
Deep sleep vs REM: what's the difference, and how much do you need?
Zone 2 training
What is Zone 2 training, and why is it good for longevity?
Healthspan vs lifespan
Healthspan vs lifespan: what's the difference?
Sleep efficiency
What is sleep efficiency, and what's a good percentage?
Lean body mass
What is lean body mass, and why does it matter as you age?
Overtraining
What are the signs of overtraining, and how do you avoid it?