Question 1

What is Heart Rate Variability (HRV)?

Accepted Answer

HRV measures the variation in time between consecutive heartbeats. Higher HRV generally indicates good autonomic nervous system regulation and recovery; lower HRV may indicate stress, fatigue, overtraining, or health issues. HRV is a key indicator of overall health and recovery status.

Question 2

What is RMSSD?

Accepted Answer

RMSSD (Root Mean Square of Successive Differences) is the most commonly used time-domain HRV metric. It reflects parasympathetic (vagal) activity. Formula: RMSSD = sqrt(Σ(RR[i+1]-RR[i])²/(n-1)). Normal adult RMSSD typically ranges from 20-80ms.

Question 3

How do I measure RR intervals?

Accepted Answer

RR intervals can be obtained from: 1) Smartwatches/heart rate monitors (Apple Watch, Garmin, Polar); 2) Phone apps with camera flash; 3) ECG devices; 4) Manual pulse timing. Measure in a quiet resting state for at least 1-5 minutes for accurate data.

Level	RMSSD (ms)	Meaning
Excellent	> 60	Well recovered, good autonomic regulation
Normal	30 - 60	Normal autonomic function
Low	20 - 30	Possible stress/fatigue
⚠️ Very Low	< 20	Rest recommended, assess health

🫀 HRV Heart Rate Variability Calculator

📊 Enter RR Interval Data

📋 Analysis Results

📖 HRV Reference Ranges (RMSSD)

🫀 HRV Heart Rate Variability Calculator

📊 Enter RR Interval Data

📋 Analysis Results

📖 HRV Reference Ranges (RMSSD)

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