What is HRV (heart-rate variability), and what's a good number?
HRV (heart-rate variability) is the variation in time between consecutive heartbeats, measured in milliseconds. A higher HRV generally signals a well-recovered, adaptable nervous system, while a drop often means stress, fatigue or illness. There's no universal "good" number — HRV is highly individual, so what matters is your own baseline and trend over time.
How HRV is measured
HRV is derived from the tiny differences between successive R-R intervals (the gaps between heartbeats). Consumer wearables mostly report RMSSD, a short-term metric that reflects parasympathetic ('rest and digest') activity, usually sampled during sleep when conditions are most stable. An Apple Watch samples HRV periodically (reported as SDNN in Apple Health); a WHOOP measures it continuously overnight and anchors its recovery algorithm on it. Because devices measure at different times with different math, never compare an Apple Watch number to a WHOOP number directly — compare each device against its own history.
What's a normal HRV by age?
HRV declines with age and varies hugely between individuals — genetics matter as much as fitness. Very rough population reference ranges for overnight RMSSD: 20s ≈ 55–105 ms, 30s ≈ 45–95 ms, 40s ≈ 35–80 ms, 50s ≈ 30–70 ms, 60+ ≈ 25–60 ms. Endurance athletes often sit well above these bands, and perfectly healthy people sit below them. That's exactly why the absolute number is a poor scoreboard: the useful signal is your own 30–60 day baseline and which way you're drifting against it — up (adapting, recovering well) or down (accumulating stress).
How to raise your HRV
HRV responds to the same levers as recovery, because it *is* the recovery signal:
- Consistent sleep and wake times — schedule regularity beats extra duration
- Cut alcohol, especially near bedtime — the most reliable single HRV killer
- Regular Zone 2 aerobic base work — raises the baseline over months
- Alternate hard and easy training days — chronic intensity suppresses HRV
- Breathing practice / meditation — slow exhale-weighted breathing acutely lifts parasympathetic tone
- Manage life stress and late caffeine — both show up in tonight's number
How Vita uses HRV
Vita reads HRV from your Apple Watch or WHOOP and uses it — together with resting heart rate and sleep — to compute your daily Recovery score and factor into your Body Age. Instead of a raw number, you get a plain-language read on whether to train hard or rest today, and the AI coach references your HRV trend when you ask why you feel flat.
FAQ
Is a higher HRV always better?
Generally yes, relative to your own baseline — higher HRV reflects better recovery and autonomic balance. But compare against your own trend, not other people's numbers.
What is a good HRV for my age?
Rough overnight RMSSD bands: 20s ≈ 55–105 ms, 30s ≈ 45–95, 40s ≈ 35–80, 50s ≈ 30–70, 60+ ≈ 25–60. Individual variation is huge — treat these as context, not a target; your own trend is the real signal.
How do I measure HRV?
An Apple Watch or a WHOOP band measures it automatically, mostly overnight. Vita reads it from Apple Health or WHOOP — no manual input needed.
Why is my Apple Watch HRV different from my WHOOP's?
Different sampling windows and math (Apple reports SDNN snapshots; WHOOP uses overnight RMSSD). Both are valid — just never cross-compare devices; compare each against its own history.
Why did my HRV drop?
Common causes: poor sleep, alcohol, hard training, stress or illness. A single low day isn't alarming; a sustained downward trend is worth acting on.
Can I train my HRV up?
Yes, slowly: consistent sleep, regular Zone 2 cardio, sensible training load and less alcohol raise the baseline over weeks to months. Quick fixes don't exist — the baseline moves at lifestyle speed.
Metric explanations on this page are based on published research — see our sources & methodology.