Why do sports scientists use ln(rMSSD)?

Raw rMSSD has a skewed distribution in human populations. The natural logarithm ln(rMSSD) linearizes the data, making it easier to track baseline shifts and calculate z-scores.

Updated: August 2026 • Verified v1.2

Heart Rate Variability (HRV) rMSSD & Recovery Score Calculator

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rMSSD = Sqrt( (1 / (N - 1)) * Σ (RR_{i+1} - RR_i)^2 ); ln(rMSSD) = ln(rMSSD)

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Understanding Your Results

Calculates rMSSD in milliseconds, natural log ln(rMSSD), average heart rate, a 0-100 recovery index, and actionable physiological training guidance.

Practical Guidance & Next Steps

Higher rMSSD indicates strong parasympathetic vagal tone and optimal training readiness; suppressed rMSSD signals systemic fatigue or overtraining.

What is this?

A sports physiology calculator that processes raw R-R interval data to compute the clinical standard rMSSD and recovery readiness score.

How does it work?

1. Paste raw R-R millisecond intervals from your heart rate monitor. 2. View rMSSD, ln(rMSSD), and mean heart rate. 3. Review autonomic readiness index and personalized workout guidance.

Why use it?

Provides open, scientifically validated recovery metrics free from wearable vendor proprietary score obfuscation.

Technical Scope & Calculation Limitations

Requires clean resting R-R interval recordings; ectopic beats and movement artifacts should be filtered prior to analysis.

Frequently Asked Questions

rMSSD stands for Root Mean Square of Successive Differences between adjacent R-R intervals. It is the gold-standard time-domain metric reflecting parasympathetic (vagal) activity.

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