What Is a Heart Rate Variability?

HRV is just a market of stress so regardless of your interest in training if you want to see your body's response to different stresses this is a thing I use for tooling that context. But technically what we measure is the variation between heart beats. The heart does not beat constantly there is always some variation and we quantify that over a certain period of time a minute or a few minutes. Now we care about measuring these differences between concept of beats because they are not due to challenge but they are due to how the body is responding to stress.