Readiness scores are measuring the wrong kind of tiredness

Morning recovery metrics tell an athlete plenty about their nervous system and almost nothing about the muscle damage that will decide tomorrow.

A green readiness score on the morning after a hard track session is one of the least useful pieces of information in modern sport, and athletes keep organising their week around it.

Take what these systems actually sample. Heart rate variability, resting heart rate, sleep duration, maybe respiratory rate. That collection is a reasonable window onto autonomic state, which responds fast and recovers fast. It says something real about whether you are stressed, ill, dehydrated or short of sleep. What it cannot see is the mechanical damage sitting inside the muscle after repeated high-force eccentric contacts, and that is the fatigue which actually limits a sprinter or a hurdler two days later.

So you get the characteristic failure. Athlete does a heavy plyometric session, sleeps well, wakes with a calm heart and a cheerful number, trains hard again, and picks up a hamstring strain on the Thursday that the app never hinted at. The system was not broken. It was answering a question nobody asked.

I am not arguing for throwing the wearables in a bin. Trends over weeks are genuinely informative, and a sustained drop is a signal worth acting on. My argument is narrower and more annoying: the daily score should not be allowed to overrule a plan, because a single day of autonomic data carries a noise level comparable to its signal. One bad night with a hotel air conditioner moves the number as much as a genuine overreach would.

The better instruments are older and cheaper. Countermovement jump height, tracked on the same device at the same time of day, drops when the muscle is beaten up and stays down until it is not. Sprint times over a fixed short distance do the same. A short subjective questionnaire, honestly answered, outperforms most of the hardware and costs nothing.

There is a behavioural cost too, and I think it is underrated. Athletes who check a score before deciding how they feel start deferring to it. Give a young athlete a red morning and they will find the soreness to match. That is not recovery management. That is suggestion.

Use the watch for sleep and for illness. Use a jump mat and your own eyes for training load.

And if the number says green while the athlete is limping into the warm-up, believe the limp.