what is heart rate variability?

and how can we use it to "read" what our body is saying?

Like many of you, I have a morning ritual. I wake up, feed the dogs, make my coffee, and sit down with my phone– not to start my social media scroll (that will come later)– but to take my heart rate variability (HRV) measurement.

HRV is a super easy way to take a look at how our bodies are handling stress. It measures the variability between heartbeats– that is, how quickly your heart rate recovers from beat to beat as it encounters stress. Remember that your system is designed to oscillate between activation and ease– you see a bear, your nervous system ramps up; you run away from the bear, and the nervous system settles again. Generally speaking, the higher your HRV, the better; we want to be able to recover quickly and shift easily from one state to another.

Your HRV is the only (practical, accessible) way that you can measure the activity of your autonomic nervous system (ANS).

In a recent post, I talked about how important it is to understand and support the nervous system. We can learn to interpret the somatic language that our body speaks; in my body, I recognize the symptoms of overwhelm and can often adjust accordingly. Sometimes I miss the signs, or choose to override them. That’s where having a digital readout of the ANS can be extra helpful as an objective measurement.

I use a super simple app called HRV4Training. It’s inexpensive, easy to use (you just put your thumb over your phone’s camera and try not to move for a minute), and it gives me some quick information about how my body’s handling stress. The app allows me to put in additional information that it takes into consideration– how sore are my muscles? How stressful is my life right now? How much did I sleep last night? Then, it makes suggestions about how intense my training session should be that day.

In this screenshot, you get an insider’s perspective into my HRV since September. You’ll

notice that there are some peaks and valleys– that’s normal– and that the red bars indicate days where my HRV was exceptionally low. If you could zoom in, you would notice that one of them was November 4– US Election Day. My ANS was responding to the stress I’d been experiencing as it approached. Other low days might occur because I haven’t slept well; I’m fighting off some kind of illness; or if I had an exceptionally challenging day yesterday (perhaps I saw more clients than I could comfortably handle, or trained really hard). It might also be low because I had a really fun or exciting day– and that wore me out.

So, low HRV isn’t always a bad thing– it’s just an indication that my system needs a little more recovery time. Make sense?

At its simplest, you can use an HRV readout as a tool to validate or explore what your felt sense of health is in your body. Many of us don’t have a really clear understanding of what our body is trying to say. Its signals feel confusing, or we may have been taught to push through or ignore them completely. Maybe you’ve seen that saying that goes, “If you listen to your body when it whispers, you will never have to listen to it scream.” That’s great advice, but if you’re having a hard time hearing the whisper, you’re not alone. When I first began measuring my HRV, I was often baffled by its readouts. I literally had no idea I was feeling so run down (or why I kept getting injured…!). For those of us who are still learning the language, HRV is like a closed caption that gives us a hint of what we might start to pay attention to.

Of course, it’s not always that simple to understand how and why HRV works, which is where having a tool like HRV4Training really helps. It analyzes long-term trends and correlates factors to help support my decisions about what kind of training to do. Right now, I am just coming out of a two-month stretch that was really challenging– on top of my election stress, I was going through some major changes in my work, and had very little time off, which taxed my system more. You can notice that my overall HRV (look at the black line) was higher in October than in November and December. This corresponds to my feeling more tired and achey than I was in October, so I’m taking it easier in my training right now to allow for fuller recovery. I’m also happy to report that much of the external stress has shifted, so I’m looking forward to training harder and feeling better again in the next couple of months!