Heart-Rate Variability or HRV is the beat to beat changes in your heart rate, and is due to the synergistic action of the two branches of the Autonomic Nervous System (ANS) – the part of the nervous system that regulates most of the body’s internal functions. The sympathetic nerves act to accelerate heart rate, while the parasympathetic (vagus) nerves slow it down.
Scientists and physicians consider HRV to be an important indicator of health and fitness. As a marker of physiological resilience and behavioral flexibility, it reflects our ability to adapt effectively to stress and environmental demands.