Sapere.
Honesty & the science
Every number in Sapere shows where it comes from. This page is the short version of that promise.
Not a medical device
Sapere is a training & wellness tool. It does not diagnose, treat, predict or monitor any illness or medical condition, and it does not give medical advice. If you feel unwell, talk to a clinician — not an app.
The recovery-deviation signal. When several of your recovery signals drift away from your own baseline together for two or more days, Sapere flags that something is off and suggests an easier day. It is a non-medical attention signal built from training-and-wellness data — it does not detect, diagnose or predict illness. Wrist temperature is read as a deviation from your baseline; breathing rate the same. No labels about fever, infection or disease — only "this is off your normal".
Sapere is not a medical device and does not provide medical advice.
Estimates are labelled
Where a number is modelled rather than measured, Sapere marks it “≈”. On a fresh account it tells you it is still building your baseline instead of faking precision. Some metrics need a power meter — Sapere says so and shows the honest fallback when one isn’t present.
The models behind the numbers
- Load & form (CTL · ATL · TSB) — impulse-response training model: Banister (1991); CTL/ATL/TSB as popularised by Coggan / TrainingPeaks.
- Build-up — we lead with ramp rate and TSB. The acute:chronic ratio (ACWR) is shown only as dimmed context and labelled disputed — it is not an injury-risk score (Impellizzeri et al., 2020).
- Readiness — HRV, resting heart rate and sleep scored against your personal baseline with robust z-scores. HRV is read as a 60-day baseline, smoothed against a 7-day rolling average; we use SDNN (what Apple provides natively) and don’t claim the separate rMSSD evidence base.
- Power-duration profile — the rider-type radar follows the Allen & Coggan power profile, normalised per axis to a percentile band (never raw W/kg).
- W′-balance — a model, not a measurement: Skiba et al. (2012); Clarke & Skiba (2013). Race-conservative by design.
- Efficiency & decoupling — efficiency factor is a personal trend, not a benchmark; decoupling is only meaningful on steady rides (Friel).
- Draft estimate — a model of solo vs in-the-wheel power (Martin et al., 1998): an estimate, not a measurement, and it needs a power meter.
- Durability — fatigue resistance is emerging science with no consensus thresholds (Maunder et al., 2021). We present our reading, not "the standard".
Your data, your control
Your sign-in token stays on your device; we keep no database of your training data. Read-only except for the workouts you create. See the privacy policy for the full detail.