Heart rate variability (HRV) is a topic I have spoken about in the past. If I revisit it today, it is simply because it is possibly the most important variable you should know about yourself. After body fat percentage, perhaps. So why is HRV so important?
At the risk of oversimplification, we need one metric that critically captures what is happening to our body at any given point in time, day or night. We have a whole bunch of options.
Blood pressure, SPO2 (made famous during COVID), temperature, and so on. However, many of these metrics are very useful when you are inflamed. Take temperature, for example. It is excellent for telling you that you are sick, have an infection, or even have cancer.
However, if your temperature is normal, it still does not tell you whether your body is working optimally. Hence HRV. So what is HRV?
When your heart beats, it does not beat with the consistency of a metronome. It varies. For example, in one minute, it could beat 50 or 150 times. Which means there is a variation in the manner in which it beats.
This variation indicates how well your body and its entire nervous system are coping.
At the risk of oversimplification, you want a higher variation or high heart rate variability. A higher variation means your heart thought it was fine to pause. To beat less often per minute.
The body is sending signals to the heart, saying, Look, things are fine; there is no crisis; I do not need to run anywhere; there is no threat. So even if they are milliseconds, take a break.
This signal is then transmitted to the nervous system, which sighs in relief and says, Great, I do not need to alert my entire body and flood it with chemicals to signal danger. Think of this happening day in and day out, again and again.
You can see why having a high HRV, or variability, is great for creating a sense of calm in your body.
The best way to measure is with a chest strap. Your watch measures pulse, not heartbeat.