Heart rate variability (HRV)
Heart rate variability (HRV) is the variation in the time between consecutive heartbeats. A higher HRV relative to your own normal usually means your nervous system is relaxed and recovered; a drop below your baseline can signal fatigue, illness, stress or poor sleep.
How HRV is measured
Most wearables measure HRV overnight or in a short morning reading and report rMSSD, a measure of beat-to-beat variation in milliseconds. Measure it the same way every day — same device, same time, same position — because the number depends on how it is taken.
How to read your HRV
HRV varies hugely between people, so comparing yours with a friend's says little. What matters is your trend against your own baseline, usually a rolling average over a week or more. A single low day is noise; several days well below baseline, especially with a rising resting heart rate, is a reason to train easier.
In The Next Race
The Next Race reads HRV from Garmin, Polar, Apple Health and Oura and compares it with your own baseline. It is the strongest single input to your daily recovery, alongside resting heart rate, sleep and your check-in.