I wore five devices to bed for two weeks to see how their readings compared.
As I’vediscussed before, the numbers we get from our smartwatches fall into a few different categories.
What is HRV, anyway?
HRV, or heart rate variability, is a measure of how steady your heartbeat is.
Not how fast or how slow, but howdifferentof a time frame passes between beats.
Your HRV will change from day to day, and thats where these devices come in.
What counts as a good HRV depends on your own history; its not worth comparing yourself to others.
How does HRV differ from resting heart rate (RHR)?
Your resting heart rate isalsoa number that reflects stress on your body, including fatigue and illness.
Resting heart rate can also change over time as you become more fit.
Its important to note that these numbers usually assume that youre sitting quietly in a doctors office.
When youre asleep in your own bed, your heart rate can dip a bit lower.
During the night, your gadget monitors your heartbeat.
It may sample and average different readings, and each equipment measures and calculates its numbers slightly differently.
Often the app or equipment will tell you how your numbers compare to your usual.
What you do with that information is up to you.
That way, the two watch bodies won’t clack against each other.
I entered each days resting heart rate and HRV from each equipment into a spreadsheet.
When it comes tousingthis data, I already have a sense of how the numbers compare to my experience.
Whoop tends to stick pretty close, with Fitbit and Garmin not far behind.
For resting heart rate, things are a bit more consistent.
In general, the lines tend to all go up together, and all down together.
(Mostly…looking at you, Apple Watch.)
Switch devices, and all bets are off.
So pick a gadget, stick with it, and you’ll probably get numbers worth paying attention to.
What you do with them, of course, is another matter.
