How PulsVy estimates biological age
No black box. Every marker below comes from a published study, and every number can be checked.
The core idea
Large studies report how much a measure such as resting heart rate changes the risk of dying from any cause — a hazard ratio (HR). Adult mortality rises about 8.5% per year of age (the Gompertz law), so a hazard ratio can be expressed as years: years = ln(HR) ÷ 0.085. This is the same conversion Levine's PhenoAge uses.
PulsVy averages each marker over the last 30 days, converts it to years, caps any single marker at ±6 years, and multiplies the sum by 0.6 because the markers overlap (fit people tend to have both low resting heart rate and high HRV). Your biological age is your actual age plus that total.
Markers and sources
| Marker | Effect used | Source |
|---|---|---|
| Resting heart rate | HR 1.09 per +10 bpm; lowest risk near 60 bpm, no extra credit below 50. | Zhang et al. 2016, CMAJ (meta-analysis) |
| Cardio fitness (VO₂ max) | HR 0.87 per +1 MET, compared with the age- and sex-specific 50th percentile. | Kodama et al. 2009, JAMA; FRIEND registry (Kaminsky 2015) |
| Heart rate variability (RMSSD) | Lowest vs highest tertile HR ≈ 1.5, compared with age norms. | Hillebrand et al. 2013; Nunan 2010; Voss 2015 |
| Sleep duration | Short sleep HR 1.12, long sleep HR 1.30 vs 7–8 hours. | Cappuccio et al. 2010, Sleep (meta-analysis) |
| Sleep efficiency | Below 80% linked to ~1.9× mortality; 85%+ is the clinical norm. | Dew et al. 2003 |
| Daily steps | Log-shaped dose–response with a plateau around 8–10k steps. | Paluch et al. 2022, Lancet Public Health; Saint-Maurice 2020 |
| Active minutes | 150 min/week HR 0.69 vs inactive; 3–5× that HR 0.61, plateau beyond. | Arem et al. 2015, JAMA Intern Med (661k adults) |
| Systolic blood pressure (cuff) | Log-linear from 115 mmHg; conservative HR 1.10 per +10 mmHg. Needs 2+ readings in 30 days. | Lewington et al. 2002, Lancet (61 cohorts) |
What we deliberately don't count
- Estimated VO₂ max calculated from resting heart rate (Uth et al. 2004) is shown but not counted — it would count resting heart rate twice.
- A single blood pressure reading. Cuff pressure only enters with at least two readings in 30 days.
- Today's partial data. Daily totals use completed days only.
Limits
Hazard ratios come from population studies; they describe averages, not you. Wearable sensors have error. Treat the estimate as a trend to watch, not a diagnosis. PulsVy is a wellness tool, not a medical device.
Want a quick version? Try the free biological age calculator.
See your real numbers from Google Health
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