How/when does the Apple Watch calculate resting heart rate? Typically, they tell you to take your HR first thing in the morning, but if I check my resting HR in the Health App, sometimes there’s no reading until after I’ve been up for a couple of hours. I have also noticed that even if there’s a number, sometimes it will be replaced with a lower value, later on.
Apple Watch
If you're at rest, the watch only measures occasionally. That's why your watch face may say “70 bpm, 9 min ago.” But when you open the heart rate app, it takes a fresh reading. The heart rate sensor can only detect readings between 30 and 210 beats per minute.
Here is a fuller explanation....https://vitals.lifehacker.com/understand-your-apple-watchs-heart-rate-numbers-1831767054
I am asking specifically about the “Resting Heart Rate” metric that shows up in the Health App (and on the Watch itself, if you scroll down in the HR app).
This is useful for training purposes. An elevated RHR is an indication that you’re not recovered from the previous day’s effort. Most commonly, you’re told to check your RHR first thing in the morning, before you’ve started moving around. I’ve noticed that this field is often blank until several hours after I wake up. This morning, for instance, I used the HR app and read my HR. That was a while ago and the RESTING heart rate field still has no number in it.
I have also checked it at some point during the morning and read one thing, then noticed a lower number in that field later in the day - as if it checked while I was not moving and got one thing, then later in the day, checked again and said “This number is lower, I’ll use that”.
Resting heart rate calculation
