Measurement

Key Takeaways HRV is a measurement, not a wellness score. It is a summary statistic of autonomic activity with standardised time- and frequency-domain definitions published in 1996. Two autonomic branches write different rhythms into the heartbeat. The parasympathetic (vagal) branch dominates the high-frequency band (0.15–0.40 Hz); the sympathetic branch dominates the low-frequency band (0.04–0.15 Hz).…