[00:00:00] Speaker A: Welcome to the Heart Rate Variability podcast. Each week we talk about heart rate variability and how it can be used to improve your overall health and wellness. Please consider the information in this podcast for your informational use and not medical advice. Please see your medical provider to apply any of the strategies outlined in this episode. Heart Rate Variability podcast is a production of Optimal LLC and Optimal HRV. Check us
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[00:00:32] Speaker B: Welcome, friends, to the Heart Rate variability podcast. I'm back here with my good friend, brilliant thinker and HRV biofeedback mindfulness, Dr. Ina Hazan Ena, how are you doing today?
[00:00:46] Speaker C: I'm doing well, thanks, Matt.
[00:00:48] Speaker B: Well, I'm excited to kind of continue our series that we've been touching on for the last couple of months. Really, in your book, Biofeedback and mindfulness for everyday life, there was this chapter where you sort of outline other biometrics. And I think it's really important because sometimes these get kind of siloed in some ways, maybe because they are siloed, but in other times, really connecting these with other biometrics and obviously a heart rate variability. So I love, there's this paragraph in this chapter, kind of after a quick introduction and exercise you walk people through. That includes, I just got to name these off because I love it. Gavonic skin response. Luigi, we got Carl Jung in there. You even throw in Freud.
We have gavananometer, which sounds good, which you have to define. We got frog legs twitching. And my friends, yes. That is all one paragraph in Ena's book. So besides that literary gym you just dropped at the beginning of this chapter, let's start out with defining what is skin conductance. What are we looking at here from kind of a biometric perspective?
[00:02:08] Speaker C: Certainly. So skin conductance is one term for something called EDA, meaning electrodermal activity. So electroelectricity, dermal skin activity. Right. So your skin is active. It's not crawling or anything, but it is active with electrical signals and its response.
We learn a lot about our body's activities through the way in which our skin conducts electricity. So EDA electrodermal activity is an excellent way of measuring it. And galvanic skin response is actually one of the earlier names for EDA. It was used by Carl Jung over 100 some years ago. It's one of the earlier biofeedback devices that we had. And he was really looking at people's emotional responses to various laden words. Right. So he's famous for his word association tasks where he would say, a word and see how the person responds. And he could actually measure that emotional response using galvanic skin response, which we now know as electrodermal activity. And we specifically use skin conductance. So, to define that, and I need to tell you exactly what that means.
Skin conductance tells us how much electricity is conducted through your skin. So in the palm of our hands and kind of the soft part of the fingers, we have ekrin sweat glands. And those sweat glands are very responsive to any kind of activation, physical activation, emotional activation. So these sweat glands start producing moisture. They start producing sweat whenever we're activated in any way. And we all know that moisture is quite conductive to electricity. So when the palms of our hands get more sweaty, more moist skin conductance increases. So that tells us that the nervous system is becoming more activated. So skin conductance is one of EDA responses. There's also skin resistance, which is the opposite of skin conductance, meaning that as we are calmer, as our activity decreases, those sweat glands become less reactive. They close, they produce less sweat, meaning less electrical signal is conducted through that. So, skin resistance tells us how relaxed you are. Skin conductance tells us how activated you are. In practice, skin conductance is probably the easiest to use because it's much more intuitive. Higher skin conductance means you're more activated. Lower skin conductance means you're less activated.
[00:05:14] Speaker B: Can I clarify? Are we talking sympathetic activation when we talk? Okay, got you.
[00:05:21] Speaker C: Yes. So thank you for clarifying. This is specifically measuring sympathetic activation. So, the ecrine sweat glands are regulated by sympathetic nerves only. We are not measuring parasympathetic activity here at all. Of course, when we are more relaxed, parasympathetic nervous system is more active.
That typically means that sympathetic nervous system is less active, which will reduce skin conductance. But what we're actually measuring is sympathetic activity.
[00:05:54] Speaker B: I know for my HRV nerds out there, got to ask this follow up question because it always seems to enter. So, are we talking true sympathetic activation, or are we talking about less ventral vagal?
I know you probably saw this coming. Are we talking about less vagal breaking less vagal tone?
Because a past conversation is just for those that might be joining us, new and kind of don't get, the inside joke that continues throughout this podcast is really kind of HRV. I don't think we're measuring sympathetic activation. If I'm being a good student of yours, we're measuring more parasympathetic activation with this. So are we really true sympathetic activation, or are we kind of lesser vagal tone where there's maybe more sympathetic energy within the system as we all try to still figure this out.
[00:06:58] Speaker C: Excellent question. And you're absolutely on target, Matt, as always. So skin conductance is a measure of actual sympathetic activation.
[00:07:06] Speaker B: Okay.
[00:07:08] Speaker C: Which is different from what we can measure with the very low frequency of heart rate variability signal. So very low frequency measure of heart rate variability. In a long term recording, several hours, 24 hours recordings, that will also give you a measure of sympathetic activity. But the way we typically do our measurements, whether it be just daily tracking or biofeedback training, these are short term recordings, and in a short term recording, very low frequency signal, we simply don't get enough data, as the name implies, very low frequency signal. It's very low frequency. That wave is very slow. So we have to have quite a long recording in order to get enough data to truly be able to say something about sympathetic activity. So when on a heart turability recording, we get an increase in very low frequency.
What we can say is there is vagal withdrawal occurring, meaning the vagal nervous taking its foot off the brake, allowing kind of activation to increase, and it may be accompanied by an increase in skin conductance. The reason for that is because very low frequency in those short term recordings is often associated with worry and rumination and kind of going over all the what ifs in your head, which typically is accompanied by sympathetic activation and vagal withdrawal. So they are related. But sympathetic activity in a short term recording is truly measured by skin conductance.
[00:08:50] Speaker B: Fascinating. So it gives us a little bit of if we combine it, which I think you do clinically with HRV measures, what are you kind of looking for? Are they usually complementary to one another? Are we getting into the barrel reflex system, trying to bring that piece in here? But what are you, skin conductance. You get HRV from the biofeedback. Clinically, what are you sort of seeing or looking for? When you start to look at those numbers together.
[00:09:28] Speaker C: It completes the picture. Ultimately, there are certainly times when the person might be starting to worry and get onto the what ifs and kind of that ruminative state. Well, you'll see an increase in very low frequency and you'll see an increase in skin conductance.
It doesn't always work that way. That's part of the reason it's so helpful to get multiple physiological measurements is because our human bodies, which are not all that perfect, don't always send all the same signals in one direction. That makes perfect sense for a very pretty picture.
Physiology doesn't really work that way. So it's nice to be able to get multiple measures because they really do complete the picture. When skin conductance goes up, it doesn't necessarily mean we're stressed because skin conductance can go up when we're super excited. Skin conductance is just responsive to an increase in sympathetic activation and it can be increase in physical activity. Right. You've just gotten up and done some jumping jacks. It could be because something changed in your breathing. It could be because you are talking about how much you're looking forward to some exciting activity you're about to do. It can also happen if you are really stressed. So the skin conductance signal in and of itself just tells us you're more activated. We have to have the context of what's going on in order to be able to interpret it properly. And this is actually really important. We don't want to say, oh, your skin conductance is up, you must be stressed. No, it just means you're more activated. And heart turbility measurements can help fill in part of that picture. If you are just kind of happy and excited about something, you're not likely to get as much of that very low frequency activation in your heart durability. And there's certainly just a self report of the person, hey, what's up? What's going on? But it's important to get that full picture rather than just going by the numbers.
[00:11:37] Speaker B: So when we look at the biofeedback experts experience of skin conductance, if I'm in a fairly calm state, if I don't have much sympathetic activation before the biofeedback session, right now I don't feel any sweat. I know that doesn't mean that I don't have any, but if I'm fairly relaxed state and then I do the biofeedback, which gets me even to a deeper level of relaxation or increasing my low frequency hrv, let's use the hrv.
Are you seeing much reduction if there's not a whole lot of sweat to begin with, are you still seeing noticeable changes in the electricity in the hands and the skin?
[00:12:33] Speaker C: Yeah. Yes.
Skin conductance is usually. The changes in skin conductance are usually imperceptible to us. There are some people whose sweat glands are much more active and they can tell. But for the most part, great majority of people, the only time we can really tell is if we're super anxious or just been working out. We'll literally feel hands getting sweaty most of the time, those changes are imperceptible. So if you are doing well, kind of at a neutral state. Your skin conductance is going to be somewhere on the lower end of the scale. And then you do your resonance frequency breathing, do some hre biofeedback, and likely get into an even better regulated, potentially more relaxed state. Not necessarily, but potentially more relaxed state. And that should be accompanied by a decrease in skin conductance. And you won't be able to tell unless you are actually measuring it, just like you can't tell what your heart durability is without measuring it. Skin conductance, you usually can't tell where it is exactly without measuring it. And that's, of course, what we aim to achieve with biofeedback, is for people to learn about their physiological responses and be able to tell a little more about their physiological state based on how they feel and connecting that with what they're seeing on the screen. But the only way to really measure it is to measure it.
[00:14:09] Speaker B: So I want to connect this to the last episode we did on temperature, because I would assume, and I think I'm wrong with everything we're talking about, is that the warmer we talked about, like melting chocolate in our fingers. I remember that you throw chocolate in, and that's definitely going to be a memory for me. So kind of like holding chocolate and you're raising temperature levels, I would assume. But after I may be assuming wrong. In fact, I bet I am. As I raise my temperature, I assume I would be sweating more. But maybe not. Is there any connection between our episode on temperature and skin conductance? Or are we talking about two distinct things that need to kind of remain, maybe siloed?
[00:15:03] Speaker C: They are very much related. So you are absolutely right about that. And yes, the melting chocolate is an awesome trick that I learned from Eric Pepper that I love teaching to other people. As many of Eric's tricks get propagated and taught by others.
That's awesome. So when we get more relaxed, our blood vessels dilate, which means more blood is coming to our fingers and finger temperature increases. But that typically does not make us more sweaty.
The sweatiness is a sympathetic response. So peripheral temperature increasing is usually. We usually don't actually feel hot the way we might if we are exercising or kind of getting overheated. There's a difference between peripheral blood vessels and major blood vessels and heat regulation between those. So when we are relaxed, hands, feet, noses, ears warm up, but without the activation of the sympathetic nervous system. In fact, actually, it's the opposite. Your blood vessels are also controlled by sympathetic nervous system the same way as your sweat glands are. But in the opposite direction as your fingers warm, that means a decrease in sympathetic activation. So there are sympathetic receptors in your blood vessels. And as your activation increases, it would result in increase in skin conductance and a decrease in temperature, because your blood vessels would constrict, and as you decrease sympathetic activation, your blood vessels would dilate, your temperature would increase, and your skin conductance will decrease. So they do go together, but typically in opposite directions also. Not always, but a lot of the time, they go in opposite direction. So when we do temperature training, skin conductance is actually a really good way to look at effort and unnecessary effort. Right. If somebody is really trying to warm up their hands, which does not work. Right. The more you try, the colder your fingers get. We can tell if that's happening by an increase in skin conductance, and we can track that same unhelpful, unnecessary effort in hrv biofeedback as well. So that's another way that you can combine the two together.
[00:17:38] Speaker A: Fascinating.
[00:17:41] Speaker B: It's so because I would always assume temperature increase in sweat would be correlated. But interesting how our nervous system, and obviously, if we're working out, that's a different thing. But it's kind of good to know. When I melt the chocolate, I don't have my sweat all mixed in with it as well. I guess that's a good thing. Maybe as we were creating our nervous system, you don't want sweat on your chocolate. So let's distinguish between those two things.
I love it. Is there anything else with skin conductance? I've got kind of a bigger final question for you, but anything else with skin conductance that you think it's important for our audience to consider? You've already blown my mind, like, three or four times in this episode in the short time we've been talking. But any other important aspects of this that you think our folks should know?
[00:18:36] Speaker C: Maybe just that skin conductance is a really neat, easy, simple way of showing mind body connection.
Skin conductance changes in response to activation extremely quickly. So if you're measuring skin conductance, and there is a number of devices out there that you can use, some of them are quite inexpensive. So there is a way of doing this without having fancy equipment.
When you start thinking about, I don't know, an exciting vacation, or if you are struggling with a math problem, or if you're worrying, starting to worry about a meeting you have the next day, your skin conductance goes up immediately. And actually, that word association game is really fun. I typically do it when I do my in person biofeedback. Workshops, because it's not terribly therapeutic, but it's fun to demonstrate to people. I might say to somebody, I may just say the word dog. If it's neutral for that person, their skin conductance will remain fairly flat, or maybe go up just a tiny bit. And then if I'm working with students, I say exam and whoosh. Their skin conductance goes way up, and it's sort of fun to demonstrate that. Or if I say something for somebody who really enjoys roller coasters, if I say roller coaster, their skin conductance is going to go up, too, because that's an exciting thought.
And that activation, that physiological activation doesn't know the difference between stress and excitement. It kind of all looks the same. So this is where our interpretation is important, but this is a really great way to demonstrate mind body connection.
[00:20:19] Speaker B: So is that kind of excitement sympathetic activation?
I just find that interesting because we talk so much about respiratory sinus arrhythmia and how inhale, exhale with the vagal tone. But it seems like, hey, getting excited about, let's say, me giving a presentation, for example, that that energy is going to serve me, that sympathetic activation would serve me well, which is usually not how we talk about increases in sympathetic activation. With that, am I hearing you right? That that could actually be a beneficial thing? So as skin conductance, kind of like the butterflies I used to get before a basketball game, not necessarily a bad thing, gave me kind of that energy. So even if we saw an increase in skin conductance, increase in sweat, not necessarily a bad thing, based on the context of that activation. Am I hearing you correctly with that?
[00:21:31] Speaker C: Absolutely. In fact, before performance, it's a very good thing. You want that.
If you're about to get out on the court to play basketball, if you're about to get out on stage to give a presentation, you don't want flat activation, right? You don't want to be falling asleep on stage. You don't want to be dragging your feet across the court. You want to be on, you want to be energetic, you want to be active. So you absolutely need that oomph. And it's going to come from sympathetic nervous system. It certainly has a bad rep out there. We absolutely need sympathetic activation, and we need it in various ways throughout pretty much every day.
The tricky part is we don't want that sympathetic activation to get out of control. We don't want it to overactivate, and we don't want it to have trouble coming down. We want sympathetic activation to come down fairly quickly once the challenge is over. But we absolutely want it and need it and cannot perform well without it.
[00:22:37] Speaker B: Excellent. Well. And I just love exploring the complexity of us with you because it's so fascinating to try to put all these pieces of the pie together. And again, before I ask you another ridiculously complex question, I do have to say biofeedback and mindfulness for everyday life. Your book does just a wonderful job of making this accessible to people while giving, if you're a clinician, giving you tools to use clinically, if you're a human being, giving you clinical or giving you tools just to live a healthier life. So I got to put that in. It was my kind of introduction to you. And it's just like I've integrated so much of this into my life and into my practice. All that asking forgiveness for this question.
I just love how the more I learn about the human body, the more I see the human body as an electrical system.
The synapses in the brain of this bioelectricity of the positive and negative charged ions, which action potentials heart rate variability.
I think I'm safe to say the heart is an electrical system with frequencies and charges and hertz and all this stuff. Now, the skin is also electrical charged. I would just like to give you, how do you look at human beings as electrical systems? And maybe you haven't thought about this at all, but everything that we dig into at the ground level seems to be electric, be a charge, the bioelectric system. And since we brought this up and had to with skin conductance, just kind of with your learning about human anatomy, how do you see us as a bioelectric system? I just love to hear any, just random thoughts that you have about this.
[00:24:50] Speaker C: Well, great question. I will confess I have not really thought about it. So happy to ramble and see what happens. But you are absolutely right.
Our life very much depends on proper electrical activity in the body. Right? The brain works by sending out electrical signals. All communication between cells happens through electrical signal. If I want to move my fingers, it's an electrical signal from my brain that's being sent very quickly, way quicker than I can talk about it to my fingers.
My heart is an electric. Very much depends on the electrical conductivity. Right.
If there's something wrong with the conductance of electricity within the heart, it doesn't work properly or it doesn't work at all. Right.
Arrhythmias have to do with improper electrical conductance in the heart. Your muscles won't work without proper electrical signals. Right.
And so much can actually mess with those electrical signals when we over breathe, right. If we don't have enough carbon dioxide in the blood, you think, what does the gas have to do with electricity? But because that gas influences the ph level and the ph level influences the movement of those electrically charged ions across the cell membranes, we get malfunctions, for lack of a better word, in the muscles, right? So you can get muscle pain and cramps and fatigue and things like that, because those electrically charged particles are moving into the cell as opposed to staying outside the cell, as one example. So those electrical signals are crucial for our everyday functioning. And in biofeedback, a lot of the signals we're measuring are electrical signals, right? Muscle tension. It's a sensor that's measuring the electrical signal that's being produced by the muscle cells. An EKG to measure heart activity, right. That's again a measure of the electrical activity that we know what kind of electrical signal is produced, at which stage of the heart cycle. So we know exactly what's happening.
Brainwaves, again, all of that with neurofeedback, it's all electrical activity. So it's both vital for just living and for improving our functioning as far as biofeedback is concerned.
[00:27:31] Speaker B: Yeah, absolutely. It seems to be, in some ways, the connector. Obviously, the autonomic nervous system is a connector. But it's just fascinating that this keeps coming up in the podcast either overtly or oftentimes just kind of coming around to it. But to start out really looking at this section of the electrical charges of your skin, just another fascinating kind of part of the overall equation of the bioelectric system that is you and me, which, if you want good reading, if you go back to the twitching frog legs, they did some really kind of disgusting things back in the day. But it's kind of how we got here.
But how we kind of came to this idea of electricity being a part of our system, I think is just a fascinating thing in the history of science. And the fact that we're here helping people through heart rate variability and other types of biofeedback, to use that science to help regulate the systems of the body is just really cool and fascinating to be part of that history. And we're not doing some of the grocer stuff that they did back in the day, which is always good. There's no frog legs involved anymore, at least in my work, and I'm sure your work as well doesn't involve twitching frog legs at this point.
[00:28:56] Speaker C: Thankfully not. Yeah, frog dissection in biology class was.
[00:29:00] Speaker B: Not my jam wasn't mine either so probably one of the reasons I'm vegan at this.
Ina, I want to thank you for walking us through this again. I can't more highly recommend a book than your biofeedback and mindfulness in everyday life book. I'll put the link to that in the show notes. If you haven't got it, you need to get it. Audiobook is also really great. If you're an audiobook fan like I am, highly recommend that as well. So ena, thank you again and hey, I look forward to the next time. I know we have a really exciting episode coming up in a few weeks around something called the Optimal zone. I'll just kind of tease that and I can't wait for our next episode as well. So thank you so much my friend. And as always you can find show notes
[email protected]. Thanks Sina thanks everybody. We'll see you next week.
[00:30:00] Speaker C: Thank you Matt. Thanks everyone.
