Why we compare you with yourself
Vita's recovery, load and sleep scores are not compared with population norms but with your own trailing 28-day baseline, computed from the median and median absolute deviation (MAD), and requiring at least 7 days of data.
Inputs and weights
- Window: 28 rolling days, excluding today
- Centre: the median, not the mean
- Spread: median absolute deviation, not standard deviation
- Minimum: 7 days, below which no score is produced
Why not population norms
HRV varies enormously between people — two equally healthy individuals can differ severalfold at rest. Comparing an absolute value with a norm therefore tells you mostly about your constitution, not about today. That is precisely why the consensus in sports science is to monitor HRV against a personal rolling baseline.
This has a direct product consequence: we publish no absolute thresholds, because such a threshold would be meaningless for an individual.
Why the median and MAD
One unusual night — a drink, an illness, a badly worn watch — drags a mean-and-SD baseline off course, and the next several days of scores inherit the distortion. The median and median absolute deviation are far more robust to that.
We also floor the spread, because an unusually flat stretch would otherwise drive it toward zero and turn any tiny fluctuation into an extreme score.
Limitations
- New users get no score for the first 7 days, deliberately — a baseline from 3 days offers a misleading sense of certainty.
- The baseline follows you. After months of consistent training your "usual" rises, so scores drift back to the middle — that is not regression.
- Coming back after a long gap, the baseline spans two eras and scores stay unsettled for a few days.
- Baseline-relative scores are reference indices describing you against your own usual. A reading away from baseline is not a health finding and does not replace a professional diagnosis.
References
Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M. Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Medicine. 2013;43(9):773-81.
What it supports：HRV should be read against a personal rolling baseline rather than population norms — the direct basis for why we publish no absolute thresholds.
Leys C, Ley C, Klein O, Bernard P, Licata L. Detecting outliers: Do not use standard deviation around the mean, use absolute deviation around the median. Journal of Experimental Social Psychology. 2013;49(4):764-6.
What it supports：Using the median and median absolute deviation instead of mean and SD keeps a single outlier from contaminating the baseline.
What it supports：Definitions, measurement windows and population norms for HRV metrics.
Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Heart rate variability: standards of measurement, physiological interpretation, and clinical use. Circulation. 1996;93(5):1043-65.
What it supports：The standard method for measuring and interpreting HRV, including when time- and frequency-domain metrics apply.
Related metrics
Every metric on this page is a reference index for observing your own trends. It is not medical advice and cannot replace a professional diagnosis. If you have health concerns, consult a qualified clinician.
Source module: lib/vitality/baseline.ts
Download Vita free — see your Body Age and Recovery in minutes
Download on the App Store