Readiness: your traffic light

With a coach, this question is settled with a glance: “how are you today?” — “not great” — “then take it easy”. When there is no coach around, someone has to ask that question every morning. That is what the readiness traffic light does.

Four colours and what they mean#

Green — in the data known to the platform there are no warning signals that agree with each other, so you can work to plan.

Amber — your numbers have moved away from your usual level: it is worth easing the intensity or swapping hard work for something calm.

Red — today is a rest day. That happens when several of your numbers drift away from your own norm at once. The onset of an illness often looks exactly like that, but the platform does not recognise the illness itself.

Grey — there is not enough data yet. That is a proper answer, not a fault.

Grey is never quietly replaced by green. Saying “I don't know yet” is more honest than showing a reassuring colour with nothing behind it — and someone who sees green and heads out for a hard session with a cold will genuinely suffer for it.

Two systems, not one#

Your body as a whole and your muscles recover at different speeds, so the platform looks at them separately.

General recovery — from heart rate variability, resting heart rate and your answers in the morning check-in: sleep, fatigue, stress.

Muscles and joints — from muscle soreness and from accumulated impact and strength load.

The verdict for the day is taken from the worse of the known systems, not averaged. Your heart has recovered but your legs have not after a long session — then the muscular side decides the day. Caution here is cheaper than optimism.

We compare you only with yourself#

No tables of “normal variability for a 42-year-old man”. Tables like that are useless: the spread between people is enormous, and the only thing that matters is your own deviation from what is usual for you.

So the platform builds up your personal baseline: the last few days are compared with the four weeks before them — seven days for device signals, three for the morning-scale answers: soreness comes and goes within one to three days, and a seven-day average would lag behind it. For scale answers the norm is taken without the single best and single worst day of the month, and the spread is never narrower than one step of the scale — otherwise one unusual day entering or leaving the norm would change the colour with the very same answers. Inside the narrow band of your usual spread, swings count as noise — there is nothing to react to. A change becomes a signal only when it steps outside that band; for scale answers both the three-day average and the latest answer must agree, so a fade after hard days and a climb into them read differently. For a signal that has dipped, the day card shows “was → now”: your norm over the four weeks before this one and the average of the last days — in beats per minute, milliseconds or the words of the morning scale.

Two consequences follow, and they sometimes surprise people:

• The status is grey for the first few weeks. There is nothing to compare your baseline against yet.
• Changing device resets the baseline. A new watch or ring measures in its own way, and the old baseline does not apply to it — the build-up starts again. The same goes for the way a value is measured, once a source reports it: an overnight series and a morning spot reading are different series.

Where the signals come from#

From devices — watches, rings, bands and chest straps — the platform takes raw measurements only: variability and resting heart rate. Sleep reaches the traffic light through your own rating in the morning check-in, not through a device export. Variability counts as “higher is better” only up to a point: unusually high variability while you feel poorly is not treated as recovery and does not speed up lifting a yellow or red — under overload it often rises rather than falls in amateurs. A morning spot reading in an app and an overnight series from a watch are different measures, but until sources report how a value was taken we do not tell them apart.

We do not use proprietary readiness scores (Body Battery, Recovery Score and the like). Every manufacturer computes them with a closed formula, they cannot be compared with one another, and no explainable status can be built on them. We prefer to do the maths ourselves and tell you exactly how.

You may have no devices at all — then the morning check-in does the work: sleep, fatigue, stress, soreness. Under ten seconds, entirely optional, and it is what gives the traffic light its accuracy when there are no measurements.

Why the status does not flicker#

One random outlier should not redraw your plan. So the traffic light has protection against flicker: amber needs either two agreeing signals or one strong one; red needs two strong signals to hold for two days running; and going back to a calmer colour takes two days of improvement. Fewer false alarms means more trust in the status when it does light up.

What the traffic light does to your plan#

Amber — the platform will offer to lighten the day: swap out the intensity, cut the volume. Red — it will offer rest.

Ordinary changes arrive as a proposal with “accept” and “reject” buttons: the last word is yours. The only things applied in silence are hard safety rules — for example, stopping the plan when you have flagged an illness. You are always told about that directly. More in “How the plan adapts to life” and “Safety and where medicine begins”.

What the traffic light cannot do#

It does not diagnose and it does not assess your health. It is a planning signal built on a handful of crude measurements.

It cannot see what you have not logged: stress at work, a sleepless night with no watch on your wrist, an injury just starting. If how you feel disagrees with the colour, trust yourself rather than the screen, and note it in your check-in. If you fall ill, press “I'm not feeling well” on the day card: that is not the check-in but a separate entry that stops or cuts today's plan straight away (see “Safety”).

And it does not replace a doctor. With a fever, chest pain, breathlessness at rest or a pounding heartbeat you must not train, whatever colour the screen shows — and that is something to sort out with a doctor, not with an app.