What is HRV?
As popular as the metaphor may be, a healthy heart doesn’t beat as regularly as a metronome — in fact, it changes its rhythm with each beat. This constant variation in milliseconds between your heartbeats is known as your heart rate variability, or HRV.
Some situations result in an increase in variation (high HRV), while others cause the intervals between beats to stay more constant (low HRV).
You may be unaware of these subtle variations, but they reflect your heart’s ability to respond to different situations. HRV can react to stress and/or illness before resting heart rate (RHR), which makes it one of your body’s most powerful signals—providing useful insights into your stress levels, recovery status, and general well-being.