HRVHeart Rate Variability

HRV (Heart Rate Variability) is the natural variation in the time interval between consecutive heartbeats. Higher variability generally reflects a well-recovered, parasympathetically-dominant state; a sharp drop can signal stress, illness or incomplete recovery.

It matters because tracked against your own baseline, HRV is a useful daily readiness signal — but it is highly individual, so absolute values are best compared only to yourself.

In practice, HRV is measured overnight or on waking by wearables and chest straps, and interpreted as a trend rather than a single number.