Readiness score: how it works, and how to improve it

A readiness score is a number, usually out of 100, that estimates the state of your body every morning: are you ready to handle a big day, or still paying for the previous ones? Popularized by Whoop and Oura, the concept rests on a simple idea: progress doesn't come from training itself, but from the recovery that follows it. The score tells you where you stand in that cycle.

How is a readiness score calculated?

Formulas vary from one app to another, but the ingredients are almost always the same:

• Heart rate variability (HRV) — the most sensitive signal of the state of your nervous system. It drops when your body is under pressure (here's HRV explained in detail).
• Resting heart rate — measured overnight. A few beats above your normal = incomplete recovery, an illness coming on, or alcohol from the night before. A 2020 Stanford study showed that an abnormal rise in resting heart rate could have flagged 63% of Covid-19 cases before the first symptoms.
• Your sleep — the duration and quality of your night, compared with your need (how many hours you really need).
• Your recent load — your training over the last few days, because a hard session takes its toll: according to a 2013 review, your autonomic nervous system recovers within 24 hours at most from an easy session, in 24 to 48 hours from a threshold session, and in 48 hours or more from a very intense session.

The key point: everything is compared with your own baseline, built over weeks of data. A good score never compares you with an average of other people — an HRV of 45 ms can be excellent for you and mediocre for someone else. Across more than 8 million smartwatch wearers, HRV drops markedly with age and varies over the course of the day.

How to read your readiness score

Three rules prevent most misreadings:

• The trend beats today's number. A single bad score means almost nothing; five mornings of decline tell a real story. Researchers who monitor Olympic athletes also smooth HRV over several days.
• The score is advice, not an order. A 55 doesn't forbid you from training — it suggests going easier, or trading intensity for technique work. Even HRV-guided training doesn't work miracles: a 2021 meta-analysis found only a small, non-significant advantage for fitness and performance.
• Don't check it ten times a day. It's calculated when you wake up, based on your night. The rest of the day doesn't change it.

How to improve your readiness score

The levers are boring, and that's good news: they're all within your control.

• Getting enough sleep, at regular times — the number one lever.
• Truly alternating hard days and easy days, instead of stacking medium-effort sessions every day.
• Limiting alcohol in the evening: in 4,098 Finnish employees, recovery measured by HRV dropped by 9 points with a small dose, and by 39 with a large one.
• Eating enough on heavy training days — a large calorie deficit weighs on recovery.

Key takeaways

• A readiness score combines HRV, resting heart rate, sleep and recent training load, compared with your baseline.
• Read it as a trend; it guides the day's intensity, but it doesn't decide for you.
• Regular sleep, alternating hard and easy days, rare alcohol: that's what raises it for good.