The heart always beats, but when you go still — lying down, breathing evenly, worrying about nothing — it drops to a minimum. That calmest rhythm is called your resting heart rate. It asks almost nothing of you, yet it tells you about your body more honestly than most things.

What it is and how tri catches it

Resting heart rate is the lowest rate the heart settles to when it has nowhere to hurry. It is seen most accurately at night and towards morning, while you sleep: no movement, no coffee, no rush to work.

You do not need to measure anything by hand. Through the whole night the tri band keeps a finger on your pulse — the optical sensor on your wrist reads the rhythm, and you later see the lowest, steadiest value of the night in the app.

Why it is an honest measure of fitness

The fitter you are, the more economically your heart works. A strong muscle used to load needs fewer beats to move blood around the body — so as fitness grows, resting heart rate usually falls.

Important: there is no single “correct” number. One person's calm rhythm is closer to sixty beats, another's is noticeably lower, and both can be healthy. So do not compare yourself with your neighbour or a table from the internet — compare yourself with your earlier self.

When it rises, the body is signalling

If your morning resting heart rate is suddenly above the usual, that is your body's quiet way of saying “this is harder for me right now”. Common reasons:

  • You have not recovered from a hard workout or a short night.
  • A cold is coming on — the rate often creeps up before the first symptoms.
  • Alcohol the night before — even a couple of glasses noticeably lifts the night-time rhythm.
  • Heavy stress, a stuffy bedroom or a late heavy dinner.

One such morning is nothing to worry about. Several days in a row of an elevated resting rate is a good reason to cut the load and let yourself rest.

Watch the trend, not a single night

The value of resting heart rate is not in today's particular number but in where it moves over weeks and months. A flat line or a gentle decline means you are in good shape and keeping up with recovery. Creeping upwards with no obvious reason is worth listening to: how you sleep, how much load you take, what is going on in life generally.

Look into the app every couple of days, get used to your usual rhythm — and you will start noticing any deviation before your body makes you feel it.

Sources

  • A higher resting heart rate is linked to increased mortality and cardiovascular risk — Aune D. et al., Nutr. Metab. Cardiovasc. Dis., 2017. read
  • A high resting heart rate predicts mortality independently of fitness — Jensen M. et al., Heart, 2013. read

tri helps you notice things but does not diagnose. If a high rate persists, worries you, or comes with feeling unwell — see a doctor.