Heart Rate Variability (HRV) – The Magic Number

I love tracking. My phone has several tracking apps. I sleep with my phone on my bed for tracking my sleep. I measure my fasting glucose levels on a regular basis. I remember myself sitting at the bar of the long gone Tout Va Bien in New York City when I was 20-something, discussing the ideal heart rate with my friend Damien. After a while, he paused and said: And with all the girls at this bar, it’s HR we’re talking about? As far as I remember, I’m measuring something.

Now the question you might be asking is: for what? That’s a good question, to which I have several honest answers. This first one is: I’m an engineer at heart, I need to measure. Next, I sometimes struggle with imprecise health issues, such as borderline hypertension, not-ideal energy levels and could-be-better sleep. Life has taught me one important thing about imprecise health issues: do not consult a medical doctor about an imprecise health issue, or you’ll end up with a multivitamin, with advice on stress, or with both. Keep MDs for those well-documented issues that absolutely need a prescription drug or surgery, if you want my own personal opinion.

Back to measuring: when I struggle with an issue, I need to do something about it, and the first step is to get data. Data that varies. My long-lasting passion for reading about health and fitness brought me to Heart Rate Variability, or HRV. HRV is the magic number. HRV tells you how irregularly your heart is beating, and the more irregular the better. You’d think the opposite, right? Like, if the heart is that perfect machine, then the more regularly it beats the better. Such is not the case. A very variable heart rate corresponds to a very reactive body, constantly adjusting to whatever minor change happens in your environment, your body and even your mind. This makes sense, when you think about it. Why do I say it’s a magic number? Because if there’s one measurement I’d bring with me to an hypothetical desert island, it would be HRV. My HRV first thing in the morning tells me if I slept well, if there’s something wrong in my body and how my day will be. It’s that much of a crystal ball.

These days my HRV is between 70 and 75. The HRV score varies between 1 and 100, the higher the better, with everyone apparently having an ideal top level. Mine must be about 80, because when the score is 76, 77 or above, I feel like nothing’s going to stop me. And the bottom numbers? When do you hit 1, for example? In my case, if I do 15 minutes of bodyweight exercises, pushups and burpees and squats, and that I then measure my HRV, the value shown is 1. My body is so stressed out that my heart is beating like a metronome to recover. That’s the extreme example, as far as I’m concerned, but maybe not the most interesting one.

Recently, I was testing a new promising natural remedy, olive leaf extract. Olive leaf extract has a reputation for lowering blood pressure. I tried it in the morning and felt something was wrong with my stomach. I don’t take much of a breakfast on most days, so I supposed that this remedy on an almost empty stomach wasn’t a good idea. So I switched to taking it in the evening, and my stomach was fine, or so I supposed. Suddenly, my morning HRV wasn’t in the seventies any more, it was in the sixties, even though I was on vacation sleeping 9 hours a night. I knew something was wrong but didn’t make the connection. Later on, I was down in the fifties and wondering what had gone wrong. Then my olive leaf extract supply ended and I started a new brand. Next morning I was down to 49, and finally it ticked. Olive leaf extract wasn’t for me. I stopped and in a few days I was back up in the seventies. Using HRV showed me that the remedy was making me sick, and with some practice I would of figured it out much earlier.

Quite as useful, my HRV score tells me what my energy will be for the day. At level 75 I can sit down for hours and focus on my task. At 49, needless to say, I’ll just be good at reading emails and recording the actions I’ll work on when I’m back to 75. I therefore encourage everyone with an interest in feeling great (e.g. everyone) to test HRV. How? You need a fairly recent smartphone, a certain type of HR monitor, an app, and 3 minutes every morning:

  • An iPhone, iPad or an Android phone running Android 4.3 or newer. These use Bluetooth 4.0, which is how the phone and the monitor communicate.
  • An HRV monitor such as the $/€50 Polar H7.
  • An app such as Elite HRV (the one I use) or SweetBeat HRV (another HRV leader)

Once you’re equipped, the basic way of using it is as follows: you wake up, you go sit somewhere quiet, you put the strap on, open the app, and (in Elite HRV) run the “Morning readiness” test. Wait for your body to stabilize for about 30 seconds, then run the test for the 2:30 required minutes. During these 3 minutes, keep your mind as clear and as positive as you can, and don’t start thinking about that meeting at 9AM. Read the score. Draw your conclusions. That’s it.

Now there’s much more to HRV than what I’ve discussed here. Athletes use it to make sure they’ve recovered, for example, and this was the initial use of HRV. Some wear the strap at all times to determine what events and interactions stress them out during their workday. I’m still exploring the subject.

More on heart rate variability?

Mark’s Daily Apple on HRV

The Quantified Body – HRV podcasts

HRV Training – HRV Explained

Elite HRV app

Sweetwater HRV app

Polar H7 on Amazon


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