Metric guide
HRV is a baseline, not a readiness grade
The useful version
Use HRV as a trend that can prompt a question. Do not let one low night make the decision for you.
What the number measures
HRV describes variation in the time between successive heartbeats. It reflects autonomic nervous-system activity, but it is not a direct measurement of recovery, fitness or illness.
The absolute value depends on age, genetics, measurement method and the conditions of the reading. That is why a personal baseline matters more than a leaderboard.
How to read the trend
A sustained shift below your normal range can coincide with accumulated training stress, poor sleep, illness, alcohol or psychological stress. The number tells you that something changed, not which cause is responsible.
Read it beside resting heart rate, recent load, symptoms and perceived effort. Agreement between signals is more useful than treating HRV as a single veto.
Where the metric stops
Consumer wearables estimate overnight HRV from an optical sensor and apply proprietary filtering. Device fit, movement and missing data still matter.
HRV can support a decision you already understand. It cannot prescribe today’s workout or diagnose why the value moved.
Go one step further
Questions
What people usually ask
Is a higher HRV always better?
No. HRV differs substantially between people. Your own baseline and sustained departures from it are more useful than comparing your number with someone else’s.
Should one low night change my training?
Usually not by itself. Alcohol, illness, travel, sleep disruption and measurement noise can all move one reading. Look for a pattern and compare it with how you feel.
Why does Garmin only measure HRV during sleep?
A consistent overnight window reduces the effects of posture, movement and immediate activity, making day-to-day comparisons more useful.