HRV Score Interpretation Guide

Heart rate variability (HRV) measures the variation in time between consecutive heartbeats. A higher HRV generally indicates better recovery, lower stress, and greater autonomic nervous system flexibility. It is one of the more useful metrics from wearables because it reflects both sleep quality and stress load before you consciously feel them.

What RMSSD means

Most wearables (WHOOP, Oura, Apple Watch, Garmin) report HRV as RMSSD: the root mean square of successive differences between heartbeat intervals. This is measured in milliseconds. Higher is generally better, but your personal baseline matters far more than any population average.

Age matters significantly. HRV declines with age — roughly 1-2 ms per year of RMSSD after the mid-20s. A 40-year-old with an HRV of 50ms is likely healthier than a 60-year-old with 50ms, but the 60-year-old may be in excellent shape for their age.

The rough expected RMSSD by age:

• Age 20-30: 55-100 ms average
• Age 30-40: 40-80 ms
• Age 40-50: 30-65 ms
• Age 50-60: 25-50 ms
• Age 60+: 20-40 ms

Day-to-day trends matter more than absolute numbers. A 10-15% drop from your 7-day rolling average is a meaningful signal — usually indicating incomplete recovery, elevated stress, illness onset, or alcohol in the system from the night before. A consistent HRV 20% above your baseline suggests you are well recovered and ready for hard training.

Rather than comparing to population averages, track your own 7-30 day rolling average as your personal baseline and watch for deviations.