What is readiness?

There is no agreed formula for readiness. Each app builds its score in its own way, so a number from one app can’t be compared with a number from another. No readiness score, Vital’s included, is a medical test or a clinically validated measure. It’s an estimate.

What goes into a readiness score

Most readiness scores draw on a few of the same signals.

• Sleep: how long you slept, and sometimes how settled the night was. The NHS says most healthy adults need around 7 to 9 hours a night, although the exact amount differs from person to person.
• Heart rate variability (HRV): the small changes in the gap between one heartbeat and the next. Harvard Health explains that HRV tends to fall as your heart rate rises, such as during exercise or when you’re under stress.
• Resting heart rate: how fast your heart beats when you’re still. The British Heart Foundation says a normal resting heart rate for adults is usually between 60 and 100 beats a minute.
• Recent training: hard sessions take time to recover from, so some scores also look at how much exercise you’ve done over the past days and weeks.

Why your own usual matters

HRV and resting heart rate vary a lot between people. A review of HRV research by Shaffer and Ginsberg names age, sex, heart rate and health status as important factors, so two healthy people can have very different readings.

That’s why most readiness scores compare today’s readings with your own recent average instead of a figure for the whole population. Researchers who study elite endurance athletes have argued that long-term HRV monitoring is needed to understand each person’s own pattern. A change from your usual tells you more than the raw number.

It also means a new score needs time. Until an app has collected enough of your readings, its idea of your usual is still forming.

What can move it

A low score doesn’t always mean something is wrong. The British Heart Foundation lists alcohol, smoking, some medicines, infection or fever, anxiety and stress, heat and dehydration among the things that can change your heart rate. A few drinks, a stressful day or the start of a cold can all show up in your readiness.

How to use it

Treat readiness as one input, alongside how you actually feel. A high score doesn’t mean you have to train hard, and a low score is a prompt to think about rest. If you feel unwell, rest whatever the number says.

A readiness score can’t tell you whether something is medically wrong. If your resting heart rate is often above 100 beats a minute, or below 60 with symptoms such as fainting or tiredness, the British Heart Foundation advises seeing a GP.

Vital gives general information about fitness and wellbeing. It is not medical advice, and it does not diagnose or treat any condition.