What is RMSSD?
RMSSD (root mean square of successive differences) is the primary HRV metric reflecting short-term autonomic nervous system activity. It is the most widely used HRV measure in wearable fitness devices, sports science, and cardiac health monitoring.
What is ln(RMSSD) proxy score?
The natural logarithm of RMSSD is a derived HRV metric that normalizes the skewed distribution of raw RMSSD values. It provides a more statistically linear scale for comparing HRV across populations and monitoring physiological trends over time.