Heart rate variability, or HRV, is the variation in the time between heartbeats. Even at a steady average heart rate, the gaps between individual beats aren’t identical.
It reflects several influences, including the autonomic nervous system, and can be useful when looking at recovery trends. But “higher means healthy, lower means unhealthy” is much too simple. The measurement method, time of day, your own baseline, and the context all matter.
What changed in my data
After adding more cardio, I saw my average HRV move from around 79 ms towards 100 ms. That’s an observation from my own tracking, not proof that cardio alone caused the change or a target someone else needs to reach.
The other things I was paying attention to were fairly ordinary:
- Sleep: more consistent bedtimes and a bedroom that’s easier to sleep in.
- Training timing: finishing demanding sessions earlier when possible, so I have time to wind down. Late exercise doesn’t affect everyone the same way.
- Recovery between sessions: easy days instead of treating every workout as a test.
- Stress: trying meditation, yoga, and unforced breathing exercises.
- Less alcohol: one of the more obvious relationships in my own recovery data.
I also thought evening magnesium might be helping because I felt I slept better. I hadn’t isolated that effect, and I wouldn’t recommend a supplement just to chase an HRV number.
How I measure it
I use Whoop 4.0, which gives me an overnight HRV measurement for comparison with my usual values. I look at the trend under broadly similar conditions rather than compare that reading directly with someone else’s device or an all-day spot check.
If you want to try it, here’s my Whoop affiliate link. It can support the blog; the current offer is shown by Whoop.
The point is to notice patterns that help me make sensible decisions. A wearable number isn’t a diagnosis, and feeling unwell matters even when the app is green.
Archive note: restored from my 2023 notes. The publication date is approximate, and products and routines reflect that period.