June 13, 2015
[03:26] About Dr. James Heathers
[06:38] About HRV in Psychology
[09:20] Interesting Uses of HRV
[18:52] HRV & Breathing
[22:15] What HRV Actually Measures
[26:26] How HRV Works
[31:28] Effect of Supplements on HRV
[41:59] Measuring HRV
[44:52] Webcams, Simbands & Bitalinos
[51:31] Using HRV at Home
[1:00:52] End of the Podcast
Ben: Hey, it's Ben Greenfield here, and I hope you're ready to strap on your propeller hat because today's podcast actually involves a pretty deep dive into something called Heart Rate Variability, and I got to be honest with you. I was a little bit afraid during about the first twenty minutes of this episode that this was just going to be extremely theoretical blue sky stuff, but especially towards the end of the episode, we got into some really interesting discussions about everything from how supplements and medications affect HRV to do-it-yourself ECG monitoring. That's literally the same qualities you can get at a hospital, to the concept of using something called Metabolic Breathing Ladders, and it really turned into a quite interesting, yet still very nerdy discussion.
So a couple of things, first of all, all of the show notes for this episode because there's plenty of links to research articles et cetera are over at bengreenfieldfitness.com/advancedhrv. And then, I honestly do not expect you to understand much of this episode unless you have a basic understanding of heart rate variability and HRV going into listening to this. So if you don’t have an understanding of HRV or heart rate variability, don't start here. There are other podcasts over at bengreenfieldfitness.com. I'm going to link to the best three podcasts and the best two articles that I've ever had appear over at the website that you can use as a way to really learn everything that you need to know about HRV prior to taking this deep dive into HRV. So I'll put links to all that stuff along with all of the show notes for this episode over at bengreenfieldfitness.com/advancedhrv. That's bengreenfieldfitness.com/advancedhrv, and since it sounds like I have a burglar attacking my house with the amount of dogs barking in the background, I should probably go and make sure everything's okay and leave you to enjoy this episode.
In this episode of The Ben Greenfield Fitness Podcast:
“There's an awful lot of people using HRV. There's still a really big knowledge gap between the center of the stuff that we know about, how it works and what people are using it to do.” “Meditation for instance. If you're the kind of person who's continually tense, if there's something that could be of great use to you individually, you may find a tremendous difference, but is that because specifically of the meditation or the outcome of the meditation.” “With the right magnification-slash-amplification, you can just get a webcam and turn the webcam on. Then you can turn that into heart rate over time.” “For your recovery when your heart rate goes too high, I would suggest breathing through your nose very slowly with your mouth closed which is extremely tough to do.”
Ben: Hey folks, my guest today, Dr. James Heathers, is a pretty interesting dude. So on a professional level, he's actually a PhD and an Endeavor Research fellow in electrocardiology at Poznan University of Medical Science where he researches stuff like heart rate and heart rate variability. And then on another level, he actually has a pretty cool blog over at jamesheathers.com, and at that blog, he writes about health, science, medicine, bioethics, and he has articles on things like medical sensors embedded in tattoos and how drinking alcohol affects sleep quality and how peptides are used for doping by professional athletes, a lot of other really interesting-slash-fringe-slash-cutting edge topics. So today, I thought It'd be really interesting to get Dr. Heathers on to talk about heart rate variability 'cause he actually is one of the leading thinkers when it comes to heart rate variability and HRV. He recently had a very interesting interview in one of the research digests that I subscribe to called the Examine Research Digest and some of the stuff that he talked about on there was really cutting edge and things we haven't discussed on the show before when it comes to HRV and heart rate variability which, as I've mentioned on other podcasts is one of the only self-quantification things that I do just about every day.
So it's near and dear to my heart, and I think it's near and dear to James' heart too. So James, thanks for coming on the show.
Dr. Heathers: You are most welcome.
Ben: Well you were an experimental psychologist if I'm not mistaken.
Dr. Heathers: Yes I was.
Ben: What happened? How'd you go from being an experimental psychologist to being involved in something like HRV research?
Dr. Heathers: [laughs] That's actually an extremely good question. The short answer is that psychologists use HRV all the time, and I had started to get interested in the work, and it was a simple matter of pushing back against the way that I saw people in behavioral research using HRV to do experiments. I wasn't particularly satisfied with the outcomes that people got from the experiments. I wanted to know what they actually meant when they said the things that they were saying.
So I started looking more closely at the methodology of HRV, and then eventually the signal analysis and cardiac environment sealed area where it's actually from and occasionally the cellular basis as well. So it was a path that started with wanting to know more about how you could use it for macro leveled human research and then just pushing back against it really, really hard for four or five years. Now I'm working electrocardiology proper.
Ben: I didn't know that HRV was actually used in psychology. What's an example of a way that it would've been used in psychology that would have turned your head back in the day when you were doing experimental psychology?
Dr. Heathers: One of the first papers I saw was using it as an outcome for a placebo measure. When psychologist use placebos, they're not the same as the medical science placebo where you give someone the actual pill. You usually test a psychological placebo as trying to make the placebo effect rather than trying to control for it. So you give someone something inactive, and you say that's a stimulant or that's a depressant or that's going to make you upset. Research that was doing that was using HRV to quantify the outcome of those experiments, but it's very widely used through attention and emotion.
There's an awful lot of studies on different psychopathologies, and anxiety patients in particular have really bad HRV, and they even have a worse HRV when it comes to stress challenges. Some of my favorite research is on what right now I should say, some of my favorite research is on the sensation of attention, what immediately happens when you stress someone for a little while, and then you stop, for what happens in the period and immediately after that which is a good question that hasn't been properly answered yet. Because obviously like sports science stuff, macro level changes to people and to the autonomic nervous system of people are relevant to how they behave. And imagine being stressed out by something you don't have to move around. It can be something that's an entirely psychological phenomenon, and you can measure stuff like that with HRV. Whether or not that research is any good is another question completely.
Ben: That's really interesting because most of what I've seen when it comes to HRV has not really been in experimental psychology or psychological research or research into anxiety and stress and depression, probably because I did more on exercise physiology and working as a fitness coach and some of most of what I see is from European soccer teams and the NFL using things like heart rate variability. So that's interesting that it was such a staple of something like psychological research prior to taking fitness world by storm which it seems like it's doing now.
So in your opinion, from what you've studied so far in terms of HRV, what are some of the more interesting uses of it that you think either flight or the radar or that people aren't aware of when it comes to HRV or some of the more intriguing ways that HRV is being used whether in both research or in the field?
Dr. Heathers: I'm quite happy with the current attention that HRV is getting in the athletic monitoring 'cause it's pretty good, so we'll put that to one side. There's two in particular that I think are going to be a lot bigger in the next five years because they're very definitely got relationships between HRV that you can legitimately actually measure and behavioral sorts of outcomes, and those two things are as adjuncts to computer games and to immersive environments, and the other is as an adjunct to an attentional state related to people who aren't scientists generally called slow. At least that's the easiest way I've got to conceptualize with them.
The reason for both of these things are relatively similar. It's the fact that we are pretty sure, and we have actually some of the earliest research in HRV in the 70s is on this, but it's one of those things that's been curiously under-researched even though it's really very obvious. When you are paying attention to something and you are continually on task, so you're watching something you have to respond to, and it's not cognitively challenging. It's a very easy thing to do. So an example would be a task where there's a dot that comes up on the screen, and all you have to do is respond to it every now and then, every couple of seconds. You have to pay continuous attention, but it's not cognitively different. Tasks like that seem to have their own concomitant HRV state that's characterized by very regular breathing and HRV that's constrained to that breathing and a change in the blood pressure fluctuations that are buffered into the heart rate, and that goes equally forward time on task sorts of things. So writing, paying attention to something, monitoring tasks and computer games as well. The reason that computer games are particularly interesting is because we're now starting to get the collective normalization of virtual and extensively two-and-a-half D and three D environments. So I've played around with this a little. It's very easy to make an immersive task where you naturally pay attention to it more than actually doing something on a computer, and there are monitoring methods that's no one's tried yet of sowing the two things together. Obviously there's research to these sorts of things.
Human factors were researched, it largely covers the attentional monitoring sorts of experiments, and there's a separate computer interface stream of research that covers the computer game stuff, and none of it's particularly advanced. It's interesting as well. This happens with sports science as well and exercise physiology and sports management, fatigue management, et cetera. There's an awful lot of people using HRV, and none of them do formal physiology or electric cardiology stuff. There's still a really big knowledge gap between the center of the stuff that we know about, how it works and what people are using it to do.
Ben: What do you mean when you say formal physiology or electric cardiology being used in conjunction with HRV? What would be an example of that?
Dr. Heathers: Something that I would find particularly interesting about people who deal essentially with the research topic of how HRV works and what it is rather than using it to compare to a separate outcome. So if you had like you said before, researcher at it, Europe, there's a bunch of people. There's a soccer team. I can call it that here, I don't have to say football. They've got a soccer team, they're using HRV to manage fatigue over time, and they're taking measurements of it. That's making a series of assumptions about what HRV does, what it can represent, et cetera. It's being operationalized as this is a measurement of fatigue. The sort of stuff that I do is usually concerned with what is HRV, how can we measure it, what do we do? So we do things like what's called graded tilt or also static tilt where you have someone who's lying down on a table that goes all the way from completely flat to vertical, and you look at the different responses between blood pressure and respiration and the heart rate through different environments that you change by changing essentially the direction of the gravitational access of the person. So we're pushing them essentially in the completely same position from lying down to standing up, and we're looking at the differences in a variety of contexts between the different measurements and the different angles. No other reason than factor we want to know more about how HRV works.
Now there's plenty of people doing research on this stuff. A lot of whom I've met, and it's a really good environment. It's quite a positive research environment. It's a nice one where you write e-mails to people, and they write back. People have a great deal of knowledge, usually about the specifics of how cardiological factors work and the specifics of how the signal analytical factors work. So how should we understand the series of heartbeats over time and turn that into information. So that's a very long winded way of me saying that there's two research traditions when it comes to this stuff, and people who do applied research a lot of the time shut down a bit when it comes to the finer details of what they do. That's perfectly normal, and it happens in all sorts of research areas, but it does mean that there can be gaps.
Ben: And where are you doing most of your research? Where is this Poznan University?
Dr. Heathers: I'm just about to go there. I had to do an updated bio. That's why I was at the consulate today, anything sorted. Poznan is in Western Poland. The Australian Government were kind enough to give me a sack of cash to go to Poznan and work at the hospital with some really excellent electrocardiologists whose work I've been reading for ages, and I'm specifically working on the problem of the fact that when we have high frequency heart rate variability, it is the variability in the heart that's modulated by respiration, by breathing. Now we measure that generally by doing spectral analysis by breaking it down into a series of sine waves and saying there's information present at certain frequencies like with the frequency of breathing obviously. The interesting thing about it is they're not really sine waves. The inspiration, breathing in, and expiration, breathing out, have different shaped responses. So your actual HRV is not a wave. It's actually a sort of a hunched back wave, and the hunched back wave, if anyone wants to look this up, I sincerely hope that there isn't anyone out there who's so interested enough in that they really want to try this, but if you want to look for it's got hunched asymmetry. Sorry?
Ben: I said you'd be surprised.
Dr. Heathers: Oh well, it's perfectly okay.
Ben: Got a lot of propeller hats listening in.
Dr. Heathers: Nice to have more people in the field. Heart rate asymmetry, we're looking at some different factors in heart rate asymmetry, and it probably has something to do with how the response in the pressure receptors in the lungs are actually modulated over time. I'm also particularly interested in the fact that in any normal ECG that you get when you're taking the measurement of the electrical activity of the heart over time. You actually have a breathing signal that's hidden in that because the shape of the ECG changes with the respiratory cycle because the direction of the current on the heart is moving in the chest. I'm not sure I can explain any simpler than that because I haven't done the research yet, and I don't quite know what I'm talking about. But we're looking at ways of getting the respiration signal out of the heart rate signal which is something that's been tried a few different times, but I've got my own methods of doing it, and we're going to see if they're any good trying them out in a proper laboratory.
Ben: So when you're getting the breathing signal out of the heart rate variability signal, all that you're doing is eliminating the potential influence of any type of special breathing protocol that someone might be doing and the effect of that on their parasympathetic nervous system?
Dr. Heathers: We wouldn't necessarily be trying to pull it out. In this particular context if we're trying to measure HRV the normal way, I'd be trying to match up the respiratory signal that's there, the amount of HRV that it actually gives us. This becomes conceptually quite sticky because most of the time we're talking about high frequency HRV. It's because it's an approximation of the respiratory modulated heart rate in the first place, but the problem becomes a problem of language there is that people start to refer to them as the same thing even though they're not the same thing, so sometimes you see it called respiratory sinus arrhythmia which is technically what it is. Respiratory as in breathing, sinus as in sinus node, the bit on the top of the heart that makes the cardiac cycle start and arrhythmia as being not particularly rhythmic overtime as having fluctuations, accelerations and decelerations, et cetera. I don't know if that's a really good answer, Ben. I rarely explain this out loud, it's an interesting experience.
Ben: So what you're basically saying is that when it comes to the relationship between someone's respiration and their heartbeat that it's not a simple linear relationship.
Dr. Heathers: Not at all.
Ben: And so the heart is going to decelerate and accelerate separately from the breathing, but a lot of the current heart rate variability apps or algorithms, research make the assumption that breathing and HRV are a little bit more linearly related?
Dr. Heathers: Here we get into an issue of measurement. I don't have a problem with a way that most general applications of HRV, especially for athletic training, are fine, and the reason for that is we're talking about two different types of measurement fidelity. The kind of stuff that I normally deal with is fine grained, and it doesn't necessarily have practical significance, but here's the nice thing. Really heavy duty deadlift workouts and half marathons and cluster sets of chin-ups have an absolutely massive effect on your body as you're probably well aware. These things really slam you, and when you're actually properly overtrained in the short term, you can see a very obvious difference in HRV that's much bigger than the measurement questions that we have to deal with when we’re talking about the fine grain details.
If you slam your stuff, it doesn't matter whether or not the measurement's absolutely perfect. It just needs to be good enough. You need to be able to say I'm in less good condition today than I was yesterday. That's your important piece of information.
Ben: Gotcha, okay. So I want to kind of use that as a segue into asking about what a lot of these things in the current self-quantification industry are actually measuring because there are claims out there with all these different apps and HRV tools that they can measure things like the strength of your sympathetic versus your parasympathetic nervous system or your approximate blood lactic acid levels or your readiness or your lack thereof to train. So when it comes to what the folks in the self-quantification industry are putting all these apps and stuff for quantifying heart rate variability, does HRV actually measure all of these things, or is that like blue sky thinking in your opinion?
Dr. Heathers: There's two answers to that. The first answer is the only thing that I'm really comfortable saying that HRV definitely does is it's a good measurement of the modulation of cardiac parasympathetic outflow. So if you are entirely at rest or entirely calm, you should be seeing a certain sort of signal, and when you're not in the absence of that, you should be seeing another signal. The interesting part there is that this question doesn't come up in research at all, and it comes up in device design and wearable computing and app stuff for the simple reason that it's easy to measure heart rate stuff, but your three examples were parasympathetic to sympathetic balance, right?
Ben: Right, that and a couple of others I've seen are blood lactate and readiness to train like green light versus yellow light versus red light, take an easy day.
Dr. Heathers: Right. I understand the third one, but my answer to the first two is substantially less positive. The whole idea of parasympathetic to sympathetic outflow is built on a piece of series from the early 90s by a group of Italian cardiologists who I had a fight with a couple of years ago because they're wrong, and they never really admitted it publicly. It's something that's been noted by people who are much more senior researchers than me. The whole idea of using spectral HRV to measure autonomic balance, it is just not supportable anymore. There's no particularly good evidence for it, and it doesn't work very well.
Blood lactate, I'm very surprised that anyone would try that for the simple reason that we've already got very good ways of measuring blood lactate. You take a finger prick, and you use a blood lactate monitor that have been portable for the last ten to fifteen years. I have one.
Ben: Yeah, but you still have to bleed, right?
Dr. Heathers: Yes, but you don't have to bleed very much.
Ben: But there's no research that you're aware of that draws a direct corollary between lactic acid levels and HRV?
Dr. Heathers: I think that's a very long bow to draw. I don't think, I'm turning over ways of my head that that might actually be possible. The two alternatives are that is decidedly ambitious or there's someone out there who knows a lot more than me about what they're doing. I don't think blood lactate, I don't think that's feasible from an HRV measurement, and blood lactate can be finicky.
Ben: Yeah, it was a study in the Journal of Strength Conditioning Research where they claim the HRV index is associated with blood lactate levels, and I don't have the exact research study on hand. It's a journal that I read, and I remember coming across that and thought it was kind of interesting, and I'm just curious what you thought about the relationship between HRV and blood lactate, but ultimately, the bigger question here, James, is would you as a lot of people are doing based on what you know about HRV, wake up in the morning and do an HRV measurement, and use that measurement to give you input about the type of activities that you should or should not be engaged in that day, specifically regarding hard training versus easy training or your potential for being in an overreached or an overtrained state?
Dr. Heathers: As a model for self-monitoring? If I was training harder than I was right now, which is not particularly hard, yes. The idea that in any point in time you can put a good finger on exactly how hard should I perform destructive physical activity today. I don't know, I'm 50-50 on that, but that's a separate question to have I woken up really seriously insufficiently recovered from what I've done there before. I think it's much more important that you pick up signals that you’re absolutely in the can than how should I go, medium versus extremely hard today, and there's plenty of research on this, and I've seen it in myself, it's particularly straight forward. If you are under-slept and overtrained and you wake up, you will see a good solid difference in your waking HRV.
Ben: Interesting. So is a high HRV always a good thing? Because you see a lot of people with HRV levels of 95, a hundred, often times even higher. In your opinion, is that exclusively good across the board?
Dr. Heathers: 95 or a hundred, what do you mean?
Ben: Most of the current HRV apps, they're kicking out a score that's based off of a smoothing of the… I believe is the root mean squared number where they're creating a scale of 0 to 100 for HRV, and most of the time what the prevailing thought is that the higher the HRV, the better, the more prepared you are to train or the lower amount of stress that you're in for.
Dr. Heathers: Okay, I just wanted to know what the number was. RMSSD incidentally is pretty good really. It probably has the best properties of being easy to calculate versus actually being meaningful. I quite like that as a measurement, and I'm glad the applications in general are using it because it's the easiest way of solving a complicated problem. But to answer your question, the vast majority of the time when people are healthy? It's a good thing. There are plenty of situations where it isn't, but you're very unlikely to encounter them on a normal athletic training basis. So if you're seriously properly overtrained, and have you heard of addisonic overtraining? They used to call it that because it has the same presentation as Addison's disease?
Ben: Yeah, right. Like really getting near to complete adrenal fatigue.
Dr. Heathers: Yeah. Basically your whole endocrine system is shut down. It's pretty much not there for you. Yeah, you'll have very low waking heart rate and reasonably high waking HRV. It doesn't mean you’re in good condition at all, but I think that's extremely uncommon. There's lots of people claiming to be overtrained that really aren't. You're far more likely to have less than more.
Ben: So if you had a really, really high HRV consistently on a daily basis and you weren't feeling good, maybe beneficial to go out and do something like an adrenal stress index and look at your cortisol and your DHEA levels, that type of thing?
Dr. Heathers: Yeah, I would definitely see an endocrinologist. If you train really, really hard for very long periods of time and you skip sleep, I don't think you really see a training like that and people who aren't polymonitored professional athletes or people who have physical jobs and training on top of that or some other concomitant sort of condition. It's pretty uncommon, but it does happen. It's probably more common in heavy-duty endurance sports as well than it is in others.
Ben: Yeah, but it would need to be accompanied by symptoms, like just having a consistently high HRV and having no other symptoms. Typically that doesn't indicate that you have something like Addison's or adrenal fatigues.
Dr. Heathers: No. If you have something like that, you will have many, many other fine symptoms. It winds simply with the fact that you have a particularly high HRV and isolation.
Ben: Now what about supplements? There are some supplements that are actually touted as being things that can increase HRV. In your opinion when it comes to things like supplements or medications, is there any research out there in terms of what may or may not increase or affect HRV?
Dr. Heathers: That question confuses HRV, the thing that we measure with the outcome of where you'd want to take the supplement in the first place. The idea of something that can increase your HRV because HRV is just a good thing. It isn't really tenable. The idea of something that means that you recover better from what you're doing that could increase HRV. I might be willing to accept that and that could work.
Ben: Right, so basically indirectly, let me give you some context too. The reason I asked for example, is as I mentioned earlier, I monitor HRV every day, and I have found extreme suppression of HRV by, and typically I'm around 90, 95, and I've measured it in the 60s to the 70s after using a Benadryl or a Nyquil type of supplement, right? Like an anti-histamine. I found that that significantly decreases HRV, and I was just curious if you had thoughts about chemical substances that can affect HRV like that and how something like that could actually be occurring.
Dr. Heathers: That is interesting. I don't actually know. I'm Australian in case anyone is not managed to pick that up. Does Nyquil contain pseudoephedrine by any chance?
Ben: But what do you ask? And by the way yes, it does contain pseudoephedrine.
Dr. Heathers: There you go. Well pseudoephedrine is a sympathomimetic.
Ben: So it increases your sympathetic nervous system drive and therefore decreases HRV?
Dr. Heathers: Yeah, interestingly enough people make amphetamines out of it traditionally, so they're pulled off the market in a lot of places and replaced it with something else called phenylephrine. Phenylephrine, interestingly enough, will transiently increase your HRV. Completely different method of action thing, but that's simply related to, this is quite difficult to explain. Let me try and get this right.
You're measuring your HRV in the first instance because you are or are not recovered from what you're doing. The stress to you or not. Your body is in the tank or it isn't. When you take different sorts of drugs directly interfering with the process of how the HRV is produced as an outcome of the system that it's from. So increasing or decreasing your HRV doesn't really mean anything in terms of what you're using the HRV to originally measure. Does that make sense?
Ben: It does make sense. It sounds to me what your saying is for example when we look at something like say meditation and the effect that has on HRV. All that we know once that we've meditated is that in acute state is affecting HRV while you're measuring HRV, and it doesn't necessarily mean it's having a lasting effect on your nervous system per say?
Dr. Heathers: Yeah, the whole idea of something having a direct effect on your nervous system, concepts get smashed together all the time, and people aren't particularly well concerned whether or not they're making any sense. Meditation for instance. If you're the kind of person who's continually tense, and not particularly mindful, if there's something that could be of great use to you individually, you may find a tremendous difference in your HRV, but is that because specifically of the meditation or the outcome of the meditation which is interfering with your ability to make yourself anxious.
Ben: Yeah, I hear you, and for example, I've said this before that if you wake up and you take your morning heart rate variability and you notice that it's low, and right there while you're lying there, you figure out that if you do something like meditation or box breathing or alternate nostril breathing or just relaxation that you can increase your HRV, all it shows is that you're good at increasing your HRV in that specific situation when you're lying in bed quantifying it, but it doesn't necessarily mean it's affecting your stress levels the rest of the day.
Dr. Heathers: Yes.
Ben: However what I would say is that, and this is how I would use something like this, James, would be if I am able to see that something like alternate nostril breathing like breathing in through my right nose, out through my left nose, and then in through my left nose and out through my right, I only have one nose. In through my left nostril and out through my right nostril. If I find that that affects my HRV acutely while I'm measuring HRV and that it's decreasing stress, then I know that even though I'm not measuring HRV like at a later point during the day when the lion is jumping out from the e-mail inbox in my computer or my children are annoying me, I can engage in that same practice, and I know that it's probably having an acute effect on my nervous system. We could safely say that, right?
Dr. Heathers: Yeah, you can. The problem with the idea of breathing to increase HRV in general is that when you breathe slowly, there's an awful lot of things that make you breathe more slowly, meditation is just one of them. When you breathe more slowly than usual you don't have normal respiratory sinus arrhythmia. If you remember from before, the normal modulation of the heart rate of breathing. When you slow it down, you get much, much more HRV. I mean lots, lots more. If you look at the two spectrograms side by side of someone breathing normally and relatively quickly than someone breathing slowly, there's absolutely no comparison whatsoever, that is simply because you are lining up your normal ability to buffer changes in your blood pressure that happen normally via what's called the baroreflex which is the blood pressure management system of the whole body. You're lining up your respiratory changes up with your blood pressure changes. So the colossal amount of HRV that you get when you breathe slowly is what you call an epiphenomenon. It's something that happens because of something else, basically in this scenario, and it doesn't really mean anything by itself.
So if heart works perfectly normally and everything's perfectly okay, and then you slow your breathing down, and you get a colossal amount of HRV, it doesn't mean that you're twice as healthy or twice as calm. It just means your breathing slowly. What it does on top of that, when it comes to acute stress management stuff, you gave a very good example there. There's been a ton of research of people in different situations where they're saying if you're particularly stressed at this point in time, if you can control your breathing at the point in time that you're actually stressed, is there going to be a relationship between you doing that and changing you ordonomic environment coming through to your behavior. A lot of the times, the answer to that is being yes in a number of different contexts, but why that's the case is actually quite a thorny question. Is it the fact that you're making people aware of what's happening to them? Is it the fact that you're knocking of the cycle where you hyperventilate and you freak out then you start to feel upset, and your removing people's ability to react to their own internal cues, or is it something more interesting where you're modulating your ordonomic environment at the time? This isn't simple. They're not easy questions, there’s lots and lots of stuff that's wrapped up in the answer to any individual question like this, and I don't mean to sound boring with that.
Ben: No, it makes sense. It sounds like though based on the research that you're planning on doing once we figure out a way to be able to separate something like the respiratory signal from the HRV signal, we'll never truly know how much of an effect something like breathing is having directly on the nervous system versus how much of an effect breathing is just having on the effect of the change in respiration on HRV, right?
Dr. Heathers: Well you're right on the fact that being able to separate them gives you a lot more information. Obviously right now, we can measure respiration via other methods, but then we run into a completely different problem again. That's the fact that respiration is surprisingly irritating to monitor. You can either put a mask on someone, which is not a particularly pleasant experience if you'd ever worn one. You can put a mask on someone which changes their respiratory mechanics, and most of them look weird and feel a bit silly, or you can have all these half measures of looking at the sides of the chest at any individual point in time which isn't the amount of air that's going to get to them at all.
There are a lot of measurement issues that come crunching up against each other when we start looking at the details of these things, and that's specifically why we're looking for respiratory information straight out of their recorded cardiac cycle on an ECG. That's because it a very useful thing to have.
Ben: Got it. What are you using when you measure HRV in your research? Because there's everything from the fingertip measurements to the Bluetooth enabled heart rate monitors that send a signal to the app. Like in a clinical research setting, what is being used?
Dr. Heathers: If it's a clinical research kind of setting, we use a laboratory ECG which is all wonderfully accurate and expensive.
Ben: And that's an electrocardiogram.
Dr. Heathers: Yes, exactly. Actually I think there's a place for just about everything because my primary ECG that I was using through the end of my PhD that's set up in the lab that we had it sitting. It cost about the same as a compact car does in America. It's not a cheap piece of equipment, but there are lots of other things that are a lot cheaper and a lot simpler, and the problem that we have when we're talking about the differences between psychological constructs especially an HRV, is the fact that both measurements are messy. HRV's a fairly messy measurement, and when you have something like a personality measure, you're trying to measure someone's neuroticism or their openness or how they react to new experiences, the measures that you take, you accept the fact that they're not very good. And when you have measures that are not good, one of the best way of addressing what you do is to have as many people as humanly possible in your study because your study runs the risk of being underpowered. It doesn't have enough people to make realistic, statistically meaningful decisions about what you're actually trying to measure.
So if it's the case that I can use a fingertip, smartphone mediated heart rate measurement, and I accept the fact that there's a couple of percent inaccuracy. If I can get twenty times as many people, that's a better idea than using the lab equipment. It's a tradeoff between your access to the sample that you're using versus how many people you're going to get in a sample. So I've done a bunch of research using the finger clip from the iFleet Monitor. Do you know the iFleet Monitor?
Ben: Yeah, I'm familiar with the iFleet.
Dr. Heathers: Yeah, I've worked with Simon, the guy that owns the company and designed it, et cetera, and we made a research version of the app, and I've got a few studies with hundreds, thousands of people taking HRV measurements at the same time. Now you could never do that with a laboratory ECG. It's not the fact that it's impossible, it's the fact that I don't have half a million dollars to run the study.
Ben: Yeah. Now, in your article that you were interviewed in for the Examine Research Digest, you did talk about a few new monitors or monitoring environments that are being developed, like some cool cutting edge technologies for either analyzing HRV or portable electrocardiogram, stuff like that. Can you talk about the few of the ones that you're excited about or that you think the self-quantification community will find really interesting?
Dr. Heathers: Would it be silly if I asked you which one because stuff like that changes?
Ben: Well some of the ones that I thought were interesting. So for example, there was one that can pull your heart rate straight out of a webcam picture.
Dr. Heathers: Yeah, that's actually a couple of years old now. This is a bunch of genius people at MIT realized that if you take a red shift of a video and you point it at someone's face, you can see their blood moving through the microvasculature in their skin, and what it means is that the normal measurement that we might get of a fingertip where we shine some light in and we get the reflection of the amount of blood that's inside, and we use that to measure the heart beat over time. You can do that straight out of a video. With the right magnification-slash-amplification, you can just get a webcam and turn the webcam on then you can turn that into heart rate over time. Now it's probably not accurate in the way that I've played with it. It's probably not accurate enough to get good HRV.
Ben: That's kind of cool that you can use your webcam as at least a way to measure well.
Dr. Heathers: Well, it's a couple of years old now. People use their smartphone cameras to do exactly the same thing.
Ben: Oh yeah. I guess if you could do it with a webcam, you can do it with a smartphone camera.
Dr. Heathers: It's exactly the same principle. It's just a different way of getting it. You got your finger right over the top of your camera, and it's being illuminated by the light of the back of the smartphone, and the red shift, it's changing as your pulse is propagating through your finger. It's going into the camera, and it's turning it into the amount of red present basically, and that becomes the vascular signal and that chops that into heartbeats. It's extremely clever. I wish that I had thought of it.
Ben: That's kind of cool. Now what about this thing called the SimBand. What is that?
Dr. Heathers: SimBand?
Ben: It's like this thing from Samsung that's a platform for developing software applications I believe that are associated with HRV. Do you know what I'm talking about?
Dr. Heathers: Yes, yes, absolutely. Of course. Sorry, you had me there for a second. The SimBand is a developer kit that Samsung makes, and instead if you're looking to do a biomedical wearable kind of build, putting hardware stuff, and there's lots and lots of little companies that are trying to do that, it is basically a one-size-fits-all measurement system for doing that, so you can add different peripherals, you can add different measurements to the environment. It's basically a test bed or a test kit for doing all sorts of biometric measurements, and they're all knocked together. It is for people who are developing sensor technology from scratch, so you might have different measures of PPG, and then you've got a normal ECG, so you got an electrical thing and a blood volume sort of thing or a light thing, a skin conductant sort of thing. It's an environment for the development of these sensors.
Ben: Right, I think that one's pretty cool too, and I'll put a link to this stuff in the show notes by the way. If you go to bengreenfieldfitness.com/advancedhrv, I've got a lot of show notes about some of the things that were discussing. The last one I wanted to ask you about James, and I know we're coming up on time here, so I want to respect your time, but there's also this research-grade ECG machine that apparently you can buy for a few hundred bucks. How's it pronounced, the Bitalino?
Dr. Heathers: Bitalino, yes.
Ben: How's that work?
Dr. Heathers: Lovely guys, bunch of electrical engineers from Europe. Basically it's simply the fact that your access to sensor tech stuff and PCBs and the general environment of how you get hardware built to measure physical things is now accessible enough that there's a little open source company that will make you research-grade, well, everything. There's an ECG and an EMG that measures muscle activity and a GSR and an accelerometer, etcetera, etcetera, and you have all of these different sensor environment, and they come in a little kit that you can break apart and you can stick together yourself, so you don't have to do any of the hardware development yourself. If I had one of these in the start of my PhD, I feel like I would've got a lot more done.
Ben: That sounds like something cool to just have around your office to test different things like EMG and muscle activity and even a home gym or a workout environment or ECG while you're at work during the day just to do a bit of self-quantification and see what kind of things in your daily regiment affect you.
Dr. Heathers: If I was a serious quantified-self kind of person that is the first thing that would be on my shopping list.
Ben: Yeah, pretty cool. It's on my radar now for sure.
Dr. Heathers: Yeah, more the fact that it's fascinating, that it's possible now than anything else 'cause I've had all of that equipment for years, but it was not a hundred and twenty Euro or whatever the hardware cost is. It's substantially more than that. The fact now that the access to these things is absolutely huge compared to how it used to be. It's not just stuff for researches anymore. It’s stuff for everyone, and that is a very good thing.
Ben: Well obviously there are all sorts of different ways that we could go with this in terms of all the different things that you're researching, but I think that we probably are right. You're making people's heads hurt. So if you're listening in and you want to look at the show notes and look at some of the stuff that James and I talk about, you can go to bengreenfieldfitness.com/advancedhrv. James, I have one last question for you, and that is this something that you personally measure frequently on yourself using an app or a smartphone or something like that, the HRV in terms of self-quantification, or are there other things that you find to be more important when it comes to quantification or do you just ignore quantification all together?
Dr. Heathers: The interesting thing about doing a PhD in this stuff is it leaves you with a great know ledge of it, not enough time to train sufficiently hard that you might want to monitor it too much.
Ben: But even not just for training, but just for monitoring stress.
Dr. Heathers: In general, I have about half a dozen different things that do this in my house, simply stuff that I've acquired over the years. I've had an idea for a while about something which works quite well, and it's the fact that immediately post exercise. You have a very interesting period where you go from having pretty much no parasympathetic activity whatsoever because you've been working hard, through to absolutely no sympathetic activity whatsoever 'cause you're not working at all.
So imagine me on a treadmill, I'm running, and then I stop dead. The heart rate response after that is a very, very good measurement environment that's been more or less ignored by the people who do commercial measurement stuff. Now if I'm measuring my response to exercise, that's the thing that I actually use because it's specific to the gym, and it's something that you've got control over. The relevant change that happens is something that you've done. You're not just waking up and hoping that all of the different factors that affect your HRV are lined up correctly. You go out, and you make sure you've got no HRV whatsoever by doing a bunch of exercise, and then you stop dead and you measure your recovery.
That's my little personal experiment thing. And as far as I'm aware no one makes a commercial product for that yet, but that's the one if I'm not convinced that I'm a hundred percent, that's the thing I measure in myself, and I have to kind of hack that together from equipment that I've got around. But for me, not very hard. That's my job.
Ben: And so what is it exactly, just one more time that you're actually measuring with that.
Dr. Heathers: If there's research on that, it's called HRR which is heart rate recovery.
Ben: Okay, heart rate recovery, got it.
Dr. Heathers: It's closely related to HRV without being exactly the same thing.
Ben: Yeah, got it. I'm familiar with that. That's actually a test that I occasionally do. I call it the five-minute burpee test where you do as many burpees as you can in five minutes with the exception that you have to stop if your heart rate exceeds 80% of your maximum heart rate, and then you can start up your burpees again once your heart rate has dropped down to that level and so what you're measuring is your ability to not only do exercise while controlling your heart rate but also the ability of your heart rate to recover quickly from heart exercise so you can jump back into it as soon as possible once you stop.
Dr. Heathers: Assuming you keep your pacing strategy the same that seem like a pretty good idea. For your recovery when your heart rate goes too high, I would suggest breathing through your nose very slowly with your mouth closed.
Ben: Which is tough to do when you're gassed.
Dr. Heathers: Which is extremely tough to do, but have you heard of breathing ladders?
Ben: Breathing ladders?
Dr. Heathers: Breathing ladders.
Dr. Heathers: Absolutely fascinating thing. Very simple kind of concept. You do one particular movement or one particular exercise, so kettlebell snatch or deadlift, fairly light one, something like that, and then you take one breath. And then you do two movements, and then two breaths, and then three movements, and then three breaths, etcetera and you load it. So doing twenty of these things would be particularly interesting. You don't open your mouth at all the entire time. And you breathe entirely through your nose, and you're recovery and rest is entirely dictated by how much you can slow your breathing down while it's not actually during the exercise itself. So say we've done five. If you take five breaths very, very fast, you're going to be back doing the exercise straightaway, but if you take them really slowly, you have plenty of time to recover. What it teaches you to do, this is from my perspective, someone who does mind-body research and breathing-heart rate research, and this is the holy grail of interesting phenomena being smashed together.
What happens is extremely strange. You get very, very calm when you do it right because you end up decoupling your perception of what's happening to you. Your chest is breathing, you want to open your mouth and gasp, but you don't let yourself. When you do that for long enough, you end up starting to ignore the physical symptoms that you have of sympathetic distress, and you find your ability to control the recovery that happens after the sensation of exercise gets really, really good. I have done these in a lot of different contexts, and the way that it feels is, I'm 100% convinced of this. I don't quite understand what's going on with it yet even though this is the stuff I do research into. There is something extremely unusual going on during breathing ladders.
If you've got any ideas or if anyone else's got any ideas, I'd be more than happy to hear them, but it's a fascinating mashup of normal exercise and the kind of stuff I research.
Ben: Yeah, so it's basically like a high volume workload that you do at a relatively low level of intensity where you're focusing on deep nasal breathing throughout.
Dr. Heathers: That's it, and the moment you open your mouth enough, either during the exercise or during the respiratory period, you're done. It's over.
Ben: That's really interesting. I actually did an entire workout like this a few days ago when I was feeling really beat up, and I was at the gym, but I wanted to do something. I told myself I was going to do the weight training circuit, but I did the entire circuit with the caveat that I was lifting at a slow controlled intensity and couldn't breathe through my mouth. And when I finished, I felt this deep sense of relaxation just as if I've done a yoga session although I lifted weights for a full hour, but I think it's the combination of, perhaps, I don't know if it's parasympathetic nervous system activation being coupled to that breathing, like the deep nasal breathing or the fact that barrel receptors in your chest can detect shallow chest breathing and cause a cortisol release that's been shown in research. Maybe it's like low cortisol, less sympathetic activation, that type of thing. It's really interesting.
Dr. Heathers: Your speculation is literally as good as mine on this because I have absolutely no idea. What I do know is the state of mind that you've just described is totally 100% the same as my experience with doing that.
Ben: If I can find any research on it…
Dr. Heathers: It's a very unusual state of mind that you get, and I wish that I understood more about it. It's one of those things that's very high on my list of stuff to find out when I have my own laboratory.
Ben: Yeah, if I can find any research on it, I'll put it in the show notes for folks listening in, but in the meantime, we should probably wrap. So first of all if you're listening, go to bengreenfieldfitness.com/advancedhrv where you can see everything from a very nerdy picture of James. It looks like some kind of a… what's it called when they take your photo after you've committed a crime?
Dr. Heathers: Mugshot?
Ben: Yeah, it looks like a mugshot. Along with all the articles that we've referred to, some of the research, some of these cool things like the Bitalino for measuring your ECG and your AMG, some research on the effects of fish oil on HRV. I'll link to that research article on HRV and about lactic acid, and some other things. So check all that out over at bengreenfieldfitness.com/advancedhrv, and also leave your questions, your comments and your feedback over there. I'll also link to some of the easier previous podcasts and articles we've done on HRV in case this stuff is really making your head hurt. You need some of the more elementary information before being able to understand some of the stuff James and I have talked about. But, James, thanks for coming on the show, man.
Dr. Heathers: You're most welcome.
Australian HRV researcher Dr. James Heathers (pictured above) is one interesting dude.
On a professional level, he is a Ph.D and an Endeavour Research Fellow in Electrocardiology at Poznan University of Medical Science, where his research revolves around measurement issues in heart rate and heart rate variability.
On another level, he has an extremely interesting and thought-provoking blog, where he writes about health, science, medicine and bioethics, and has articles on topics such as medical sensors embedded in tattoos, how drinking affects sleep quality, how peptides are used for doping by professional athletes, and much more.
In our discussion in this podcast, James and I take a deep dive into HRV, and our topics include:
-How James went from being an experimental psychologist to instead being immersed in HRV research…
-Very interesting ways to use HRV that tend to fly under the radar, including computer gaming and cognitive performance enhancement…
-Whether HRV can really measure the things that the self-quantification industry often claims it can measure (e.g. sympathetic outflow, or blood lactate, or ‘readiness’)…
-When a high HRV may not be a good thing…
-Which supplements and medication affect HRV…
-The main areas of research in HRV now that James is most excited about, including something called HRR and breathing ladders…
-And much more!
Warning: if you know nothing at all about HRV, you will probably need a good intro to HRV prior to listening in, because this particular podcast is a bit more advanced, and skips over the basics of HRV. The good news is that there is over three years of HRV articles and podcasts on BenGreenfieldFitness.com, and here are the most popular and useful:
Other resources we discuss during this episode:
–Bitalino (a second-generation research grade ECG machine that you can buy for a few hundred dollars)
–The SimBand (Samsung has released a research platform for developers called Simband, who can now use the platform to build their own software applications without having to build their own hardware)
–Video magnification of HR using a webcam (a lab at MIT developed a method of pulling your heart rate straight out of a webcam picture)
Do you have questions, comments or feedback on HRV? Leave your thoughts below and either myself or James will reply.