For a runner the usual causes are fatigue from training, a cold coming on, poor sleep, alcohol, heat or stress. A beat or two up or down is noise. Several beats above your normal for several days in a row is worth acting on.
How does Apple Watch measure it?
Apple Watch works out your resting heart rate from the readings it takes in the background through the day, using the moments when you have been still. It is not a single measurement, which is why it can shift a little with how your day went.
What pushes it up?
| Cause | How long it usually lasts |
|---|---|
| A hard session or a big week | One to three days |
| Alcohol the evening before | A day or two |
| A short or broken night | A day |
| A cold or infection starting | Often rises a day or two before you feel ill |
| Heat, dehydration | Until you have adapted or rehydrated |
| Stress, travel, jet lag | As long as it lasts |
| Time off training | Drifts up slowly over weeks |
What does it mean for my training?
- Up for one morning: ignore it, or keep the day easy if you also feel flat.
- Up for several days after a hard block: you are carrying fatigue. Take two or three easy days and watch it come back down.
- Up together with a lower HRV and runs that feel harder than they should: this is the pattern to respect. See How can I tell if I’m overtraining?.
- Drifting down over months: what endurance training is supposed to do.
When should I see a doctor?
If it stays clearly raised for more than a couple of weeks with no explanation, or comes with palpitations, dizziness, chest pain or breathlessness. A watch can show you a trend. It cannot tell you why.
What does Kiiro show?
Kiiro shows the resting heart rate trend your Apple Watch records, next to your HRV and your training load status, so you can see whether a rise lines up with a jump in load. Kiiro also uses your resting heart rate to make your training load personal to you. See the glossary entry.
Related questions
- What is a good HRV on Apple Watch?: There is no single good number. HRV differs widely between people and falls with age. What matters is your own baseline and whether you are above or below it.
- How can I tell if I'm overtraining?: No single number tells you. Look for several signs together: training load well above what you are used to, a raised resting heart rate, a lower HRV, and runs that feel harder than they should.
- What is a good cardio recovery on Apple Watch?: Cardio recovery is how much your heart rate drops after you stop exercising. A bigger drop generally means a fitter heart, and your own trend matters more than any single number.
