HRV is a method for assessing changes in the cardiac cycle1. Simply put, HRV “refers to the time between heartbeats,” explains Bradley Serwer, MD, FACC, a board-certified interventional cardiologist and the Chief Medical Officer of CardioSolution. “While most people have a relatively regular heart rate, there is always some variability in the time between individual beats.”
As for how your heart rate variability works, the autonomic nervous system, or ANS, controls your heart rate2 and, ultimately, your HRV. The ANS comprises the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) responses.
“When the autonomic nervous system is in balance, there tends to be a higher variability in time between heartbeats,” said Serwer. “When the autonomic nervous system is out of balance either due to increased stress (physiologic or psychological), illness or autonomic dysfunction, the variability between heart rates decreases.”
Your HRV varies depending on your age and gender, so there’s no exact number to reference (it also fluctuates over time). Talk with your doctor to get a better idea of the exact range you should aim for based on your health.
