Heart rate variability — the variation in time between consecutive heartbeats. Higher HRV generally reflects better autonomic flexibility.
HRV reflects the interplay between sympathetic and parasympathetic branches of the autonomic nervous system. It is used as a proxy for recovery, resilience, and vagal tone. Slow paced breathing near the cardiovascular resonance frequency (about 6 BPM) reliably increases HRV in real time and, practiced consistently, raises resting HRV.
See also
Glossary · Physiology
RSA (Respiratory Sinus Arrhythmia)
The normal variation in heart rate across the breath cycle — faster on inhale, slower on exhale.
Glossary · Physiology
Vagal tone
The strength of parasympathetic activity carried by the vagus nerve. Higher vagal tone correlates with resilience.
Learn · Science
HRV and Coherence Breathing: What the Research Shows
Heart rate variability rises when the breath is slow, steady, and near the cardiovascular resonance frequency. Here is the mechanism and the evidence.
Learn · Techniques
Coherence Breathing (5.5-5.5): The HRV-Peak Rhythm
Coherence breathing sits at 5.5 breaths per minute — roughly the resonance frequency of the cardiovascular system. It is the single most reliable way to raise heart rate variability on demand.