Every recovery wearable now ships a readiness number: WHOOP has Recovery, Oura has Readiness, Garmin has Body Battery and Training Readiness. What almost none of them ship is an explanation. You get a number out of 100 and a colour, and you are asked to trust it.
We think that is backwards. A score that tells you whether to train hard today should show its working. So here is ours, in full.
The shape of the score
A readiness score answers one question: how ready is your body to take on training load today? The research points at a small set of signals that, tracked against your own normal, reflect how well you are recovering: heart rate variability, resting heart rate, and sleep (Sensors, 2025; JFMK, 2024).
Readiness Coach combines them like this:
Recovery: 45% of the score. HRV is the primary signal. Your overnight reading is compared to your personal baseline and normalised, so the score reflects deviation from your normal, not from a population chart. Resting heart rate works the same way in reverse: lower than your baseline is good. When both are present, HRV carries more weight than RHR, because the research treats it as the more sensitive recovery marker.
Sleep: 40% of the score. Duration is half of the sleep component, measured against a 7-hour target. Why 7 and not 8? Because the joint consensus of the American Academy of Sleep Medicine and the Sleep Research Society recommends adults sleep 7 or more hours per night (Journal of Clinical Sleep Medicine, 2015). Deep sleep, REM and efficiency make up the rest, and the weights renormalise over whatever your device actually reports. A watch that only tracks total sleep time is not penalised for stages it cannot measure.
Stress: 15% of the score. Tiered by what your device provides: a native stress score if one exists, otherwise an HRV-based proxy, otherwise elevation of daytime heart rate above your resting baseline.
Personal baselines, not population averages
The single most important design decision is that everything is scored against you. Your first seven days build your baselines; before they exist, the app says so plainly and marks the score as low-confidence rather than pretending.
This is also why any readiness product, ours included, is nearly useless on day one and genuinely useful by week two. If an app gives you a confident score the first morning, it is scoring you against strangers.
What the score is not
A readiness score is a decision aid, not a verdict. If the score says 45 and you feel great, the disagreement itself is information. And it is worth saying clearly: this is a general wellness tool. It does not diagnose, treat or predict any medical condition, and no consumer wearable score should claim to.
Try it against your own intuition
The honest test of any readiness score is a few weeks of comparing it to how you actually feel and perform. Readiness Coach is free to try, with every new account getting the full app for its first week while your baselines calibrate. If you wear a Garmin and wonder how your HRV gets in, we wrote about that too.