EP 135: Reading the Nervous System: What HRV, Heart Rate, and Autonomic Signals Are Actually Telling You in Clinical Practice

I've said this before and I always kind of come back to it and I just sit here and I think back to, I think back to the days when good old Natasha was a physio student and we learned about the autonomic nervous system and it was this thing that was like out of reach, right? It was this, almost like this mythical thing that just worked in its background and did its own thing and we had no way to touch it, right? We had no way to work with it.

It was just the autonomic nervous system.

So when I discovered that we actually could work with it and we could influence it and we could train it and we could adapt it, holy fuck, was I a happy girl.

So one of the tools...

One of the outcomes, when you start looking at how people measure the autonomic nervous system after concussion, in particular, when you look at the concussion research in the autonomic nervous system, they're using heart rate variability.

That is the measure that comes up again and again and again.

HRV isn't just a fitness metric, right? So I got my Oura ring, right? I look at my HRV every day.

It's a cool thing.

The Whoop bands, the Garmins, the Apple watches, they all track HRV.

And they filter, I'm pretty sure like every fitness device has its own algorithm to give you that readiness score, right? So people look at that readiness score and they're like, sweet, I'm good to go train.

And you guys, awesome.

And it's so much more than a fitness metric, okay? We're gonna talk about this today.

It is really the window into the i say it's a window into it into the state of the health of your autonomic nervous system this is really kind of what it is it's looking into the balance between your sympathetic and your parasympathetic systems it's looking into the nervous system's capacity to be dynamic and to adapt and to regulate, which we really want in a healthy nervous system, okay? It is not just this fitness thing.

It is a window into some extraordinary insight into our physiological autonomic health is how I look at it, okay? So what actually is it? Heart rate variability is not actually about the heartbeat.

So when someone says I have a heartbeat of 68 beats per minute, that's an average, right? So heart rate variability is, we have something called our QRS complex, which is the heartbeat.

And so I'm drawing in the air.

So if you're on the video, you can see this.

Otherwise you're like, I don't know what she's doing.

But the R, it kind of looks like a little mountain.

And the R is the top of the little mountain.

It's the peak of the mountain.

And that's, it exists in every beat of your heart.

But there is a variability, a time variability, you guys, between these little peaks.

And there should be.

And so that's what, that's what heartbeat variability is, is it's the variability between this like RR interval is what it's called of your heartbeat if you want to get really nerdy about it the greater the variability reflects the greater adaptability and the greater dynamic nature and of the nervous system so when we look at the number of the heart rate of heart hrv higher hrv tends to be linked with a healthier nervous system a more adaptable nervous system a nervous system that spends that can shift and is capable versus a lower heart rate variability tends to be someone who is spending much more time in that sympathetic dominant state and is less adaptable, okay? It is associated with things like stress, with illness, with higher overall mortality rates, with impairments into cognitive function.