Enhance Your Physical & Mental Resilience (HRV, Respiratory Rate, RHR)
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The science and practice of enhancing human performance for sport, play, and life. Welcome to Perform. Perform.

I'm Dr. Andy Galpin. I'm a professor and scientist and the executive director of the Human Performance Center at Parker University. And today we're going to be talking about how to control your nervous system. My favorite example of this actually comes from a TV show. Many of you probably remember the show The Office, at least the American version. And I'll never forget one of the classic scenes, one of the characters, Dwight Schrute,

was telling and bragging actually about how he had superior genes and he was able to, at his own will, raise his blood cholesterol levels.

And of course, the bewildered friends of his asked him, why would you even want to do that? And his response in classic Dwight fashion was so that he could lower his cholesterol. That had made me laugh and I've never stopped laughing at that. And it highlights one example, albeit admittedly, not sure why you would want to do that or if that's real or not. But it highlights the point of how can we actually have control over aspects of our physiology that most people think we can't.

Maybe we have some control, but it's subconscious or otherwise. And that's what I'm referring to when I say control your nervous system. There is actually a bunch of science behind this. Probably the most famous initial scientifically documented experiment came in 1970. There was a famous gentleman, I think his name is Swami Rama. I hope I pronounced that appropriately. But Swami was able to do a host of feats that still baffle most of us.

What eventually happened was he sat in a room with a handful of scientists and they placed what are called ECGs to measure electrical conductivity of his heart, as well as EEGs to measure directly into his brain. And he performed, again, this whole host of insane physiological feats without moving. Now, that part's critical, right? So when he did things like take his resting heart rate from 70 beats per minute to reportedly 300 beats per minute,

And he held that for several seconds and then brought it back down. He did that not by running sprints up a hill or anything, but by just simply sitting there and having the conscious ability to control that aspect of his physiology. Another really impressive thing Swami was able to do was actually shock the scientific team. They thought he was in cardiac arrest because his ECG stopped working. And what happened was he was able to bring his heart rate below 20 beats per minute at the same time, give himself what's called AFib.

And so the machine itself thought his heart had been stopped for like 20 seconds. I guess he signaled that, you know, I'm fine, I'm okay here. And then eventually brought it back up. Arguably more impressive was some of the stuff he was able to do with his physical temperature. So they had him on the same hand change the temperature by I think like six degrees Celsius or

in his same hand, again, only inches away. And so clearly demonstrating some, not only control of his whole body temperature, but extreme precision of where that temperature was going and where it was not. But nonetheless, that was documented and published. And again, to this day is probably one of the more famous cases of such incredible control of one's, what's supposed to be autonomic physiology. A decade later, and I'm going to highlight this one as well. I think it was 1982, actually.

A similar thing was done in a more extensive group. And so what actually happened here was a paper was published in Nature. Now, that's one of the most blue-ribbon, highest-esteem journals in all of science and physiology. And so, preeminent journal, it was published, and they looked at a bunch of Tibetan monks that lived in the Himalayas studying and utilizing a practice that's called TUMMO, T-U-M-M-O.

And they were able to do a bunch of similar things that Rami was able to do. I won't draw them out, but temperature controls, raising their body temperatures by like eight degrees consciously without moving. In fact, one of the things that they did was they put wet sheets on

on top of them and put them in very cold, if not sub-zero conditions. And these individuals were able to not only stay neutral with temperature, stay neutral with their heart rate, but they were also able to physically dry the sheets within like 30 to 60 minutes. And so you can go on and on. You can probably find many other case studies like this. And again, thousands of anecdotes and other stories throughout history. But I think one thing that I'm trying to highlight here that is inarguable

There is clearly the ability to run control over your physiology if you really take the time and attention. Is it tummo? Is it visualization? Well, probably, realistically, we've got tons of different options. And so what I'd like to do today is talk about just a few of them.

What do we know? What does it mean to control your nervous system? What can we do? What can't we do? And then what are a bunch of tactics and strategies so that you can have a more resilient nervous system? To start us off, I want to make sure we're all on the same page when I say nervous system.

The easiest way to conceptualize it is think about it in two large branches. The first is what's called the central nervous system. This is your brain and brainstem and spinal cord. And the second is what's called your peripheral nervous system. So this is everything else that goes out and comes back to the central nervous system. Now, focusing on the peripheral nervous system, that's where most of the action happens.

In this case, the peripheral nervous system is broken up into a couple of other categories, one being what's called the somatic system. This is what you can actively control. We're not going to talk about that much today. It's stuff you already know you have control over. What I want to focus more on is the other branch, and that's what's called the autonomic nervous system, the ANS. And so within the autonomic nervous system, we're talking about things like the parasympathetic system.

You may have heard of that as rest and digest. There are probably better ways we can describe it and the more interesting applications of it. But nonetheless, we'll just keep it simple right now and say that the parasympathetic is rest and digest. You also have the sympathetic. That is your fight and flight. And so most of us stop right there and we think, okay, parasympathetic, I'm relaxed, I'm lethargic, I'm down, I'm chill, I'm zen. Sympathetic, I'm fight, I'm flight, I'm up, I'm focused, I'm aroused, and so on and so forth.

Reality of it is there's probably more things like the freeze mechanism. There's also the enteric system that happens here. This is kind of like most specifically referring to your gut. But for the most part, again, for the sake of time,

We're going to focus on the interplay between the parasympathetic and sympathetic nervous system because that provides us the ability to have a lot of control over what our nervous system is doing. And as I'll show here very soon, that has a significant impact on how you're looking, feeling, and performing in the short and long term. And I'm highlighting that because, again, people don't necessarily realize how much control they actually have over those systems. They are autonomic.

but you have the ability to move them up and down. You can recalibrate them and you can consciously critically control them as I've given many examples of already. If we were to zoom all the way out, focusing on that autonomic nervous system, the ultimate goal is to not have too much time and attention spent on this thing. If it is firing and functioning appropriately,

It's running in the background. It is the software that's running your computer. You don't need to be worrying about it. It's making your life easier and better, but you shouldn't spend a lot of conscious control over it. That said, sometimes it gets a little bit out of whack and you want to have the ability to toggle it and recalibrate it so that you can bring it up or back down based on a particular thing you're trying to do. And so all we're talking about really in today's episode is

is what happens when it gets egging out of whack or is not as finely tuned to a particular thing that you'd like and what can you do about it. That is ultimately today's version of controlling your nervous system. Now to be really clear, because we could go in a lot of different areas here, I'm also going to qualify this talk even further. We're not going to be talking about stress management, emotions, or even really mental health.

In fact, I would encourage you to go listen to a recent episode of the Huberman Lab podcast, one of the ones that's in the essentials catalog, where they break down a bunch of different tools and tactics on overall stress management and neurological control. I'm not going to cover any of those things today. We're going in an entirely separate route. I'm also not only talking about downregulation. I know personally for many years, I had this connotation whenever I thought about parasympathetic

or recovery, or relaxing, or breathwork for that matter. I just always thought it's all about down, down, down, down, down. And it's not. In fact, I'm not only going to focus exclusively on breathwork today either. We're going to go well past those things. What I really want to get at is, again, fine-tune control, the ability to go down, but also go back up, and making sure that system is functioning how you'd like it to function. So what we will talk about today,

are of course the three eyes. If you're new to the show, what that means is how to investigate it, how to measure your nervous system, what that even means, what you should look for. The second eye is interpret. So how do you make sense of, how do you judge or evaluate that information that you got from that previous test?

And then the third one, which is intervene. What do you do about it? What are protocols? What are tools and technologies? What are things you can do at home? What are things that can be done at a higher level that will make those positive impacts no matter which direction you're going? So that overall is our game plan today. Talk about how we can control our nervous system in all those forms and fashion.

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And then two, we want to have some active control over it when we'd like. But we don't want to be spending our entire day mitigating and managing what's going on in our nervous system. So that goal is important because it lays the foundation of what we're trying to do. And so really you can bucket control of the system into two main areas. Number one is what we simply call read, right? You need to be able to read your current state. You can use this with technology. So you can buy something or use something that tells you what's happening in your own internal physiology.

Or you can learn what's called interoception or interoception, which means you can feel it yourself. Now, some people are really good at that. Some people are completely terrible at it. But either way, we've got to figure out where you currently are.

The second then step is to regulate. So know where I'm at, number one. Number two, move it. And when I say regulate, I'm going to break today's discussion up into two parts, what I call acute, things that move it right now. So you're feeling flustered right now. What can you do about it in this second? Are you feeling tired right now? You're losing focus right now. What are tips and tricks we can do that'll instantly change my state? And then the chronic ones are ones I refer to of what are going to move the baseline permanently.

Where we get confusion or oftentimes people that have tried things like this, where they've maybe been disappointed in the past is they're using things that are an acute stimuli and hoping it makes a chronic or permanent change. I'm really hopeful by the end of today's talk that you'll understand the difference and you can use the ones in the right form and fashion appropriately.

But that's what we're after. In either case, what we're really trying to do is make sure that we're widening the range of our sympathetic and parasympathetic experience rather than sensitizing it. What do I mean by that? It's not about just reducing stress. It's not about just down-regulating. It's the opposite. In fact, maybe not the opposite, but it is complementary. The analogy I like to give here is imagine driving down a road and you're going down a one-lane highway.

It's very likely for you to hit the guardrails on one side of the road when another car comes by because there's just not a lot of room to work. But if you expanded that highway from a one-lane road to a seven-lane road, you're far less likely to hit the guardrails. That's what I mean. When we become overly sensitized to the down regulation or the up regulation, we're driving on a one-lane highway.

We want to not only become better drivers, right? I want you to have more control so you're not weaving as much. That alone will help you reduce your likelihood of hitting the wall. But mostly what we're after is widening out that lane, giving you seven lanes so that when you do lose a little bit of control, you can feel it, see it, but you're not smashing up against walls. When I teach this, I like to use that highway analogy. That said, if you were to look at the research or talk to clinicians that work in this space,

you're generally going to see it described more as resilience. And what that means is you have the ability to experience high and low levels of changes in your autonomic nervous system without it having a dramatic impact on your lived experience. Whether this is your psychology, your happiness, your anxiety, your depression, your perceived stress load, or your actual physiology, your hormone health, your energy, your metabolism, your sleep, your recovery, your physical performance.

We want you all to be able to live a life that is your best, meaning you can handle things that challenge and change your body from a psychological perspective or a physiological perspective. And those things don't have dramatic consequences for you in the short or long term. So I feel comfortable in saying that most of us are better off with a more resilient rather than sensitive nervous system.

What does that technically and practically look like? I will give you some tangible examples a little bit later. But one thing you want to think about here is if you are somebody who feels like you are on constant sympathetic drive, you work out really hard at high intensity, you have a high stress personal life, a high stress place that you live, personal experiences, jobs, so on and so forth, then you might need to just focus on down regulation. That's fine. We have

hundreds of randomized control trials on people only doing downregulation work and it creating tons of positive experiences in their life. We've done this a bunch in my coaching programs. I've done this with my clients and athletes. No question that works there. But that's a little bit different and not always the best scenario when somebody is having issues on both sides, upregulation and downregulation. Because what can happen is if you're only ever paying attention to that downregulation size, that highway starts to get smaller.

All right, so what you probably want to do, and if you actually look at the research in this space more carefully, a lot of the interventions strategically implement both upregulation and downregulation. Even if somebody is highly stressed, has a lot of anxiety, or has other markers of overall dysfunction or problems in the nervous system,

you're going to see careful integration of both upregulation and downregulation. And that's because it works like a hormetic stressor. I've talked about this for many, many, many years. It's one of my favorite things to talk about. But effectively what you're doing is you want yourself to downregulate. Well, just telling yourself to calm down doesn't always work very well. Sometimes the easiest way to calm down is to actually give yourself a supercharge up

so that your body naturally swings back down as an equal and opposite reaction and the other way. So that is the framework with what we're going to talk about. Let's get right into how we measure our nervous system, what tools we can use, and then we'll go into evaluation and interpretations from there. With that all in mind, let's dive into our first I, which is investigate. How do you measure this stuff?

Well, there's no one answer here. I think it's easiest to describe this in three major categories. First one are what I call performance-based tests. So in the sporting world, you'll see groups do this where they'll take a vertical jump test every day. So you'll come in and every single day, you'll do say three or four maximum effort vertical jumps. And they look at the change. The assumption there being if your vertical jump is much lower today than it normally is,

then there's a strong likelihood your nervous system is a little bit fatigued. That is a very common and classic approach in the sport performance world. Others do it with things like grip strength. Again, simple test, easy to do.

There are reaction time drills. There's a ton of different apps and low or fairly inexpensive technologies to look at firing rates, fingering tap tests, how quickly can you move your thumb, lots and lots of different technologies here. Others I've seen, and we've actually explored this a lot, have looked at things like range of motion and flexibility.

And I've actually personally seen this one land pretty well. So a basic sit and reach test of your hamstrings and low back, a rotational test, a forearm or flexion extension test. I've seen all these in the field a ton. And I'll be totally honest with you, they're pretty good. We spent many years, probably over four years,

testing some of these things every single day. We stuck them directly up against other more scientifically validated measures, and they all came in pretty much the same. And so these are absolutely fine ways to measure it. It's obviously mostly used in, again, the sport performance world, and so they are hedging towards the performance aspect. If you're not jumping as high or moving as well, that's what they're concerned about. A totally different approach to this is more of a psychological assessment.

Again, you'll see research and I've seen now huge databases. You're talking about millions of data points stacked directly up against something like mood. How you feel today? And you'll be stunned, stunned on aggregate in large populations. Mood is a very strong predictor of overall nervous system state. How tired are you? So fatigue is another question. One we see often is called RPE. So rate of perceived exertion.

Just different ways to ask about how do you feel today? What's your effort feel like today? How interested in training are you today? Tons of different questions there. That's hedged more towards your subjective experience where the previous ones are obviously looking at objective performance, but there is classic overlap between both of them. The third one though, that is more objective and where the bulk of the published research is, which doesn't mean they're better by the way, it just means they're used more scientifically is

are in what I call the physiological markers. Common ones here are blood tests. I've spoke in season one. We had an entire episode on overtraining and overreaching. We also had one on how to interpret blood tests for high performance. In both of those, I talked about a number of different blood and salivary markers you can use to assess overall fatigue and readiness and performance.

We'll have direct links to those episodes in the show notes. You can go check them out and see what I'm talking about. But we're not going to get into that stuff today because we've covered a lot of it already. What we will get into for the most part are what I call the respiratory physiology markers. This is everything from resting heart rate to something called your heart rate variability or HRV to respiratory rate and CO2 tolerance.

HRV, heart rate variability, is the king here. Not saying it's the best, but it has the overwhelming majority of the research is on HRV. You don't see a lot anymore on resting heart rate, and that's because it's not very sensitive. We used to look at it a little bit more, and we kind of walked away from it. If you get really shot for a long time, you're overtrained or highly chronically stressed or have a chronic disease,

you will start to see increases in resting heart rate that are not being explained by a lack of physical fitness or cardiovascular fitness. So you can see changes in heart rate as a result of this autonomic nervous system being pushed into a direction, in this case, more sympathetic than you'd like. But it takes a long time. You're not going to see the resting heart rate move for several weeks.

before you would really notice and then the amount of movement is small. So it's hard to understand kind of signal to noise ratio there. So honestly, kind of cross off resting heart rate. Not a great marker. I don't know too many people that use it by itself or certainly use it as their first line of measurement. Now, heart rate variability is much more documented. Respiratory rate is growing. That's something we're learning much more about.

And CO2 tolerance is something that I have used a lot, but there's not a ton of research behind that either. I will share with you my personal experiences with all these things, but I want to spend most of our attention today on HRV because we have so much more information to go off of.

So let's dive into HRV. What is it? Why do you care? And how do we manipulate it? Heart rate variability is exactly what it sounds like. It is the variation in your heart rate. Let me use an example. Let's say your resting heart rate is 60 beats per minute. You would then assume that since there's 60 seconds in one minute, that your heart is then beating, in this example, every second on the second. And then if you sped your heart rate up,

to 670 or 80 or 90 or 100 beats per minute, you would simply shorten the time between each heartbeat. But that the time between each heartbeat would be the same. It'd be one second or half a second or three quarters of a second or whatever the case is. Well, in that particular case, there's no variation in your heart rate. That's not actually what happens. If your heart rate is 60 beats per minute, what's going to happen naturally is maybe it beats at 1.1 second and the next beat comes at 1.2 seconds later.

And the next beat after that comes 0.9 seconds later. And then it comes at 0.8. And then it goes to 1.3. And so there's variations. At the end of the 60 seconds, you'll still have done 60 beats. But it won't be a metronome. It doesn't happen every second on the second. How variable that is, is the marker we're talking about. It's a little bit counterintuitive, but the more variation, the more parasympathetic you are. So the more variation in your heart rate, the more down-regulated it.

If it becomes like a metronome, every second on the second, it's dialed in. That means you're in sympathetic drive. Now, as I said, parasympathetic and sympathetic aren't on-off switches. They toggle back and forth. So HRV is just telling us kind of where at on that entire spectrum we are. Generally, on average here, we want to spend more time in parasympathetic, meaning a higher HRV, and less time in sympathetic.

Most people struggle with spending too much time in sympathetic and therefore have a low HRV. Now you can have the opposite problem and we have seen that. I've coached people through that where their HRV is extraordinarily high and they're lethargic with no energy, no motivation and so on and so forth. But that's way more rare.

Generally, I would probably say 95 times out of 100, it's the opposite. We're getting people out of so much time in sympathetic drive and more in parasympathetic. A million explanations for this, but just as a practical example, you can imagine going from a

a high stress job sitting in traffic, even if it's not a high stress job, but it's a job. You're around people, you're performing, you're in traffic, you're listening to podcasts, you're coming home, you're watching TV. And it's just sensory input all the time that requires your attention and reaction. If you're managing children, if you're managing other stuff, and there's just not enough quiet time that used to be around us.

Plenty of other reasons to explain it, but that's a good way to kind of understand the idea here of why most people are probably in sympathetic drive. If you want to say that that means we're in a more stressed life than we used to be, I don't know. I'll leave that up to you. But just from a practical perspective, we have way more arousal coming in way more frequently than we probably had for most of our experience as a human species. So that's what HRV is. It's that variation. And that's what it tells us. It is a snapshot of

into the autonomic nervous system, specifically parasympathetic and sympathetic drive. It is only one metric. It is not perfect. There is not a single metric I will show you today that is perfect, but it does have a lot of research behind it. So that's roughly what HRV is. It is, at our best guess, 50% genetic and 50% lifestyle. Admittedly, I am not thoroughly impressed with that research. I think that number is going to change over time.

But it is inarguable that some point of it is not within your control and some part of it is. Why that matters? When we get to the interpretation stuff later, it's not VO2 max. I can't just look at your HRV and tell you you're good or bad. You have to consider the fact that a large part of it is not within your control. Tough to interpret. The numbers themselves aren't as specific as they are for other variables, again, like VO2 max.

There's also a age-related decline that happens in your HRV. So it gets lower as you age. That said, a recent paper just came out, I think actually last year, and it argued pretty strongly that the age-related decline in HRV is not inevitable. And if you maintain function and fitness through life, that HRV should not drop as much, if any,

but certainly not as much as you think. And so those are things that we are learning more about, but that paper just came out first time I've seen anybody even examine it. So we're gonna have to see where those things end up shaking out to be. Now, HRV is generally associated with better health. And you can look at this in a variety of different ways, but from a physical, cardiovascular, cardiopulmonary fitness perspective, it's generally pretty tied. It's not perfect.

Just because VO2 max goes up doesn't mean HRV will go up and the opposite as well. So they are related, but they're definitely not a one-to-one correlation. And it's, I'd say, a moderate correlation. So much so, we basically factor them in independently. I've seen plenty of people with smashingly high VO2s, and that will tell you almost nothing about their HRV and the opposite. Now, the research will show, and I have seen this personally in my experience, we've coached a lot of men and a lot of women who,

Women just tend to be a little bit lower with their VO2 max. Doesn't mean it's worse, but it is just a little bit lower of a score, meaning more sympathetic drive, right? Not worse. Now, that may actually not mean that, but that's a conversation for another day. But nonetheless, a little bit of calibration on what this thing actually is. We now know HRV influences, and I won't say directly and only causes,

Something like attention and focus has dozens, if not hundreds of things that regulate it. So we need to make sure that we're hearing this correctly, right? It is just associated with, and it does influence, but it's not the only influence of everything from attention to decision-making, emotional control, and then other things like what are called mental endurance. Now, this particularly matters because mental endurance under stress is resilience, right?

This is why we're talking about it, right? I want you to be more resilient to stress. In this particular example, can you maintain decision-making? Can you maintain focus? Can you maintain attention and memory skills in the presence of stress? Not just when you're baseline, not when you're fresh and okay, but what about when you become fatigued?

That's what a higher HRV allows you to do. And that's why we're going to press forward and give you tools to improve it, enhance it, or if it's already good, to maintain it. You could drown yourself in data, whether you want to look at systematic reviews or meta-analyses, but you'll find them. Heart rate variability is associated with an enormous number of health implications. Everything from

I'm being a little aggressive here, but basically every psychological or mental health metric, anxiety, depression, PTSD, and so forth, to things like cardiovascular disease, all-cause mortality, inflammation, hyperglycemia, hyperlipidemia, hypertension. I mean, pick your metric and you will find the meta-analysis

or systematic review that shows, man, a bad HRV is going to be associated with bad health outcomes. One example I can give you here is things like that hyperglycemia. Now that's high blood sugar, right? So think type 2 diabetes. Well, just think about it this way. If you were in a straight-up fight-or-flight situation,

You were fighting for your life. Your adrenaline would be up. When your adrenaline goes up, your body releases a bunch of glucose into the bloodstream. And it does that because glucose will then go to your skeletal muscle. It gives them short-term energy and it can prepare for combat in this particular case. It doesn't actually matter if you're fighting. General point is this. Stress goes up. Adrenaline goes up. Blood glucose goes up.

Well, if this is happening consistently throughout the day, you're effectively giving yourself stress-induced diabetes because you're constantly smashing your insulin system, smashing the pancreas because you're throwing blood glucose up and down and you didn't do anything with food.

This is why high stress and chronic stress management, one of the many reasons at least, why these things are associated with obesity. They are associated with inflammation. They are associated with high blood pressure and so forth. There's a direct physical reaction that happens from your psychology in this case all the way down to your molecular biology. And it has consequences across systems.

I can keep giving you examples, but I think you get the point by now. In fact, many of you may have already realized or known that bad HRV is associated with lots of bad health implications, and that's no good. What is less discussed and less understood in my experience is how it directly relates to resilience. And there's a couple of interesting papers that highlight this point, and so I want to dive into them in just a little bit more detail now. But if you remember

Your heart rate variability is driven by your autonomic nervous system. And one of the main things within that is called your vagus nerve. Now, when we hear vagus, we often think it's downregulation. But it's not just that. If you were to stimulate the vagus nerve, you could get arousal as well. Upregulation, excitement, so on and so forth. It is this toggle, right? It's this ability to go back and forth between them. Well, we have evidence now, molecularly, of how the vagus nerve can directly activate and change the immune system.

No surprise here, what happens when you are really cooked? You're shot, overworked, overstressed. Your immune system gets compromised, right? Why? Well, in part because of this. Now I'm not saying HRV caused that, but HRV would provide you that signal and says, hey, this is why you're not as resilient right now as you used to be. Vagus nerve, overused, overused.

altered immune system function and now you got sick or got more sick than you should have got because of that overall stress response you were less resilient to. Now another example of that is a really complicated study, but it was so beautiful, I wanted to point it out. What they looked at here was this resilience or what's called reactivity marker. And so what they found, just kind of getting to the end of the paper here, was when you were in the state of low HRV, sympathetic drive,

That gave you higher sleep reactivity to stress. Meaning when we expose you to the same stressor, you had a exaggerated sleep response. In this case, a bad sleep response. That's exactly what we're talking about. So the same thing happened to you when you had a higher HRV, didn't affect your sleep. Now, when we give that thing to you and you have a low HRV, it affects your sleep a lot.

That's higher reactivity. That is being less resilient to the same stressor. So same stress, big response. This is in circular, right? Because we also know at the same point, less sleep or worse sleep increases your risk of all kinds of problems. And in this specific paper, the problem that they're looking at was depression symptoms. So the lower amount of sleep increased the risk of experiencing higher depressive symptoms.

Many actual examples of this, but that really does, again, encapsulates what I'm trying to talk about here. It's not just up or down. It is being more resilient to everything that happens in your life. And our autonomic nervous system is a great tool to measure and pay attention to for that. So if that doesn't convince you, I don't know what will, but I'm assuming at this point you're all on board. So how do you actually measure it? Let's talk about different ways where you can actually investigate your HRV level.

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There's a ton of different cheap tools to measure. I have used historically something called Morpheus, and it is amazing for looking at changes in HRV over time, especially at a baseline. It's fantastic for improving your conditioning and knowing what exercise to do for the day. But the other ones I want to get into today function a little bit differently, and that is kind of more understanding and acute sense. What am I at right now? And if I go do something, can I see that change instantly?

So for that, actually, I like a device that's a combination of a couple of things. Number one, I use a chest strap, Polar H10. I have no affiliation to Polar. I buy it, and it's about $100 or so. This is the gold standard, and I like this the most because it is actually directly measuring EKG or ECG in the heart. Others, the ones that are worn like on your arm or on your wrist, are not directly measuring the heart. They're using a different technology or methodology, which doesn't matter.

And they're okay in some spaces. Some of them are very good. But for me, if I'm going to make a change, if I'm going to pay attention, if I'm going to coach somebody on it, I'm not going to try to save $30 and buying something that's slightly cheaper. $100 is pretty reasonable for most people to get to. And so I want the highest standard there. So for me, I've just personally had the most success with the Polar H10 strap. On top of that, I have recently been shown by a colleague of mine, Dr. Jay Wiles, who

W-I-L-E-S. Jay is phenomenal in this area. He does a ton of research and clinical experience in this stuff. He recently showed me an app called Optimal HRV. Again, I have no association to them. I pay normal full price for it. It's about five bucks a month. It's really, really cheap. It pairs perfectly with that Polar H10 strap.

So you can put the strap on, you can pull up the app and you can see your HIV in real time. So we can see it right now. We can go test something. We can go try something and we can see the response. It's very intuitive. So you're talking 100, 115 bucks.

or something like that, you could have yourself a nice HRV tool. One more time to be really clear, if we are concerned about HRV, we're going to go with one of those devices. We're going to measure it directly from the chest. We're not going to measure it from the finger or the wrist or anywhere else unless we absolutely have to. Now, it's been a long time since we talked about this, but earlier I brought up respiratory rate and I'm going to come back to it now. There's not as much research here.

but it is growing. And what's clear about respiratory rate is the information you get from it is different than what you get from heart rate variability. And so ideally, you're going to pay attention to both of these. Respiratory rate, like HRV, it is a non-specific but highly sensitive measure of your nervous system. In other words,

If your HRV is up or down, or your respiratory rate is up or down, something's happening. It's very sensitive to changes. You will see changes within a day. As I just described, you can change these things within minutes or seconds. If you see changes over a couple of days, it means something, but they're nonspecific.

They're not telling you, oh, this was your nutrition or, oh, this is your mental stress or, oh, this is hydration or bad sleep. You don't know what's happening. It's simply telling you something about the overall allostatic load, the total stress of the environment. So then you got to go work to figure out what's happening there, but they are both highly relevant. Why I like respiratory rate arguably the most here is because I have personally, and now I'm walking away from the research here. I can't show this scientifically yet.

But I have found it personally to be more sensitive. It'll show up fast, oftentimes, not always, but oftentimes in my personal experience, you'll see changes in respiratory rate before you'll see them in HRV, anything that matters, but not always. And so we really pay high attention to both. There's a really wonderful article in a technology journal actually called Sensors published a couple of years ago by a scientist that I just love in this field, Andre Nicolo.

called "The Importance of Respiratory Rate Monitoring from Healthcare to Sport and Exercise." And in that paper, they walk you through a ton of the research, what's going on here, the fact that it is a critical vital sign. It has been associated with everything from cardiac events and pneumonia to heat exposure and cold and exercise, emotional stress, cognitive load, and so on and so forth. You can go read about more of the details of respiratory rate there.

I've thrown this out a couple of times at the beginning, but I wanted to finally tie a bow on this as well. What does this have to do with CO2 tolerance? If you're not familiar with that, this is a similar metric. So when we're looking at respiratory rate and we're looking at resting heart rate and HRV, we also like to pay attention to CO2 tolerance. This is a different way of examining the state of your nervous system. Specifically, the way that we have defined CO2 tolerance is

This is developed, or rather was brought to me by a gentleman named Brian McKenzie. I don't know who created it initially, but Brian is the one who taught me about it. And the way that this works is it's effectively like a little bit of a breath hold test where you exhale continuously and you can see how long that you can continually exhale some small amount of air. It's a maximal effort test. In the show notes, we'll put a direct link to a video Brian has made that shows you how to go through the CO2 tolerance test.

And I like it. We've used it a bunch. I also feel like it tells us something similar, but slightly different than both HRV and respiratory rate. So while I told you earlier, we look at both of those, we also look at CO2 as much as we can. I can't get CO2 tolerance though from a simple test on a resting test. You actually have to actively do it. It only takes about a minute.

But because of that, people won't necessarily do it every day where I can check their heart rate easily, whether they're doing something or not. So that's the only reason why we don't use it necessarily every day. But here's the connection. The way that your physiology works is you will bring in oxygen when you take a breath in. And you're doing that because oxygen's primary job is to regulate metabolism. It's energy production, right? It's aerobic metabolism, which is what most of your body's doing most of the time.

When you breathe out, you're breathing out CO2. The difference between oxygen and CO2 is that carbon molecule. That carbon is a byproduct of any metabolic process. So whether you're breaking down carbohydrates or fat, whether you're using that resulting energy for exercise or digestion or immune function or cognitive performance, it doesn't actually matter. It all is going to net result in you leaving a little bit of the water left over, making some ATP,

and having a bunch of free-floating carbon. That carbon in your system is highly problematic. And so your body will immediately attach it to an oxygen molecule forming CO2. And so the way we say this is the net end result of all metabolic processes are water, ATP, and CO2. Now,

If you're in the case of, let's just say exercise, it doesn't matter, but let's just say we are doing that. The more metabolism you go through, the more CO2 is generated in your muscle. Your muscle then puts it into your blood and then transmits through your blood, goes into your lungs, and then you exhale and get it out. That's the entire cycle of life. Plants do the opposite. They breathe in CO2, pull out the carbon, and then they breathe in CO2.

keep it, hold on it to themselves, and then get rid of the O2. That's the relationship living beings have with plants in terms of oxygen and CO2. Why this matters? Again, you breathe in oxygen to regulate metabolism, but your CO2 levels are there to regulate your pH. It has nothing to do with your exercise performance. Your body will regulate blood pressure. It will regulate electrolytes.

and it will regulate pH over almost anything, and one could argue it will regulate pH literally over anything else in the whole world. That is because most of your body, the vast majority of all enzymes in the world, have to run at a very specific pH. Too acidic or too alkaline, they don't work. If they don't work and your heart can't pump and your brain can't operate, you die pretty quickly.

So your physiological pH levels are maintained at an incredibly tight number. Your testosterone can easily triple in a few minutes. Your adrenaline can go up many multiples. Your pH stays within an extremely tight window. It will move everything else around it to keep your pH at the right level. The primary way your body regulates your pH is by changing the amount of CO2 that it lets be in your blood. If CO2 levels get too high in your blood,

This will tell your autonomic nervous system to breathe more. You don't feel it. This is subconscious. You're just breathing more. You have no idea what's happening. Not an active process, autonomic nervous system. It does that. It gets rid of the CO2. It brings the acidic level down. If the acidic level is too low, meaning you're too alkaline, it will have you slow your respiration down. You'll hold your breath. Again, you won't even know this.

It'll let the CO2 levels increase more until it gets to the spot it wants, and then it'll bring your respiration back up. If you go start exercising, you start putting a bunch of CO2 in the blood, that's why your body makes you breathe more because it has to dump that CO2. In normal circumstances, the primary reason you get air hunger or you feel like you have to breathe, if I were to make you hold your breath right now,

It's not because you're running low on oxygen. It's because CO2 levels are rising. CO2 concentrations in your blood are the primary mechanism that drive you to feel like you need to ventilate. So it can be conscious. You can feel it. But most of the time, this is happening without you having any awareness at all of what's going on. If you are chronically breathing not enough, you are under breathing, which doesn't happen much, CO2 levels would be getting really high. You'd be acidic. What's more common is the opposite.

And there are papers on this, right? You can see it. If you are breathing too much, whether you want to call this over-breathing, like we tend to call it, or if you are actually truly into what's called chronic hyperventilation, this is a medically diagnosable condition. Chronic hyperventilation is over-breathing. What that really is, is you're putting too much CO2 out of your body into the atmosphere. So because of that, your CO2 levels in your body get too low. This is called hypocapnia, too low of CO2.

This is incredibly problematic because again, one, we are out of pH range now. We're not acidic, we're alkaline, we're the opposite. So because of that, your kidneys, somewhere within a couple of days or a couple of hours to a couple of days, maybe even a few weeks, can respond to that. They don't always, but they can respond to that by putting you into what's called metabolic acidosis. And it's doing that because it's, again, trying to reestablish some acidity in the system to make everything happy.

This then has a whole host of renal and kidney issues, hydration issues, and sodium, potassium, and electrolyte issues, and a bunch of other stuff that is just overall problematic. The other major problem with this over-breathing strategy is CO2 is a vasodilator. And so if you are exhaling too much of it and CO2 concentrations get too low, you get vasoconstriction. This means decreased cerebral blood flow. This means decreased blood flow

everywhere else. It also alters what's called Bohr's effect. In general, what all this is meaning, you don't have as much oxygenation. Not exactly what it is, but if that helps you conceptualize what's going on here, then that's fine. And so we're seeing problems in health, cognitive performance, physical exercise performance. All of this stuff can be a response to chronic hyperventilation or over-breathing, however you were to define those things.

That said then, if I'm seeing HRV is fine, resting heart rate's fine, but I am chronically over breathing, I still have some work to do. And it is indicating something is happening potentially from a stress situation that's not going to be necessarily picked up by changes in sleep or changes in HRV or changes in overall resting heart rate. Why this becomes really problematic is they can then turn quickly into what are called sustaining factors.

And so while something caused hyperventilation, which is a normal and healthy response, remember, I say I get scared right now. I want to go into sympathetic drive. I want adrenaline up. I want to start an anticipatory over-breathing strategy. I know CO2 is going to start increasing because I'm about to start doing something physically. So I'll start over-breathing. That's great. Normal reactive strategy there, healthy one. That's what we want. But if we're chronically doing that,

We're chronically over breathing because we're chronically in this sympathetic drive. We're chronically in this high stress environment. That can be sustained. It can turn into a habit. It can turn into misattribution. It can turn into lots of different things. We have increased that sympathetic adrenergic tone. We are ready and dialed and primed for the same situation, the same smell, the same thing we hear, the same thing we see to drive us back into that hyperventilation strategy.

we then can be causing the same problem and it can be cyclical, right? Because that hyperventilation itself can cause the same physiological problems. So it's hard strategy to break. So really important to pay attention to respiratory rate as well. I could go on, but again, for the sake of time, we'll stop right there. Important, highly correlated, highly overlapped with some of the other markers we've talked about, but it tells us unique information. Now, how do I measure this?

Most of the wearables you have will measure respiratory rate. I will give you fair warning. There is no industry standard, though, on how that's calculated. So just like HRV, don't put a ton of stock in the absolute number. You want to pay most attention to trends and things like that, but at least be consistent with the device that you're using. Use whatever you like. It doesn't matter what you get, how you use it. It's a very simple measure that basically every wearable has.

Either directly has or it can have. If they're not reporting it, they're measuring it. They're just using it to calculate other stuff. So that can be done in a bunch of different ways. Hopefully that gave you some more information about how you can calculate HRV, how you can calculate respiratory rate. You probably can infer how to calculate resting heart rate. And I gave you some tools on how to calculate and measure CO2 tolerance as well.

It's time for us to now move on to where we figure out how to make sense of all that information and determine how do we interpret it all. We're going to start off by talking about HRV. Anyone who works in this area will be squeamish when you ask them the question of what's a good one or a bad one. We all say the same thing, which actually to me is like a badge of honor that that person knows what they're talking about when I hear them say that. It's a hard thing to put a number on. I'll give you something though to get started. On most wearables,

Most men are going to be something in the 40s to 60 range on their HRV score. Women are a little bit lower than that. If you are older than say 60 years old, then maybe tink that down a little bit. That all said, I wanted to start off with a number, but I don't know what that even means. And that's because every device actually has a different calculation they use to measure HRV. So we're not even necessarily always talking about the same thing.

More importantly than that, though, there is a misuse of HRV in a bunch of different scenarios. So you should pay attention to it. I made a long argument of why it's important. It's relevant.

But I just started off by also saying the measurement itself is not the same between devices. So we want to use this as a measure of progress or regression rather than just comparing score to score, especially if you're comparing your score to your friends and you're on a ring and they're on a watch or something like that. The numbers actually, the calculation, the equation itself can be completely different. There's many, many ways to calculate HRV that are scientifically validated and the numbers are digits different, right?

than the other ones. So that's an important point to pay attention to. I've already also talked about the fact that it could be normal for you when you have an HRV score that is, let's just to put numbers on it, say 25.

Well, that actually might be normal for you. I don't know. If we look at your respiratory rate and your resting heart rate and your CO2 tolerance and your subjective feeling and your recovery and your performance and your cognition, and they're all great, well, then I might not be super worried about just your HRV. So we're never going to take it of itself, by itself, and only itself, and over-interpret its meaning.

If you are going to calculate it, please collect good data. What do I mean by that? However you're testing it, be consistent. If you're wearing a ring, wear a ring. Use the same one. If you're testing it with a chest strap every morning, use it in the same position. Don't take it seated one day. Don't take it lying down the next day. Don't wake up and go to the bathroom one day and then check it, and the next day you did it before going to the bathroom. Or you did it before breakfast and then you had coffee the next time and you had a giant pancake breakfast. You get the point here.

Test it under the same consistent terms, always. We want to pay attention mostly to trends over time. And the recommendation I'll give you here is to establish your own standard deviation. Here's what that means. Let's say you test your HRV for 30 days. And within those 30 days, don't do anything about it. Don't make any changes. On a piece of paper, in an Excel file, on your computer, just jot down the score on all 30 of those days.

Then ask it to run a standard deviation calculation. And this will basically tell you what your normal average number is and how far off, up or low, you tend to go within a 30-day window. This matters a ton because the amount of that deviation, number one, tells us something about your physiology that's maybe arguably more important than the actual number itself. Let me give you some mathematical examples. Let's say your HRV was 30 on your device. Whatever 30 is, whatever that means, it doesn't matter.

and you calculated it after a month, and it said your average is 30, and your standard deviation was 20. That means you swing all the way down to 10, all the way up to 50. That is a very large standard deviation. Other people, their standard deviation might be 3 or 5. And so you have to know what matters to you. If your standard deviation is 20, and you wake up one day, and instead of being at 30, which is your average,

you're at 27, that means nothing to you. That is nothing because that's such a low percentage of your normal deviation. The opposite person whose standard deviation is normally five and they wake up and they're seven high or low, then that actually tells them something's going on that their system is responding to. So if you want my honest answer of how to use HRV the most appropriate, this is what we're paying attention to. Typically, again, just a rule of thumb here, people that are more stable in their HRV are generally better.

If you have a score that is doubling every other day, we would immediately start thinking, all right, this person's hyperreactive. Whatever they're doing is causing a huge change in their autonomic nervous system. We need to create more stability here. That's how we become more resilient. That's how we become more predictable. That's what we're after. If you're so tight, no matter what you do, we're getting the same response every day. Then we know that system is actually quite stable. And no matter what insult hits you that day, work stress,

Environmental toxin, who cares? Your body is able to handle it. You're not hitting the wall on the highway. You're moving left and right, right? Your car is swerving, but you're not hitting the wall. So those numbers aren't changing. That's where we're bringing back that highway analogy. And that's what we're talking about when we're talking about nervous system stability. So we never make changes based on one day. We never use a cheap consumer wearable to tell us how to live our life.

to exercise today or to not exercise, to sleep today or to not sleep today. That is, and I think the people behind most of these companies would say the same thing. That's not the best way to use something like an HRV score. Interpret your numbers in the appropriate context, but regardless, we should be able to get better and maybe become more resilient in our overall nervous system responses to stress. Back to our highway analogy.

What causes people to be more stable versus less stable with their HRV is a bunch of different stuff, genetics. But, and then it's also the dumb stuff. It is an irregular sleep schedule. Once we get people sleeping just in a consistent time, HRV almost always goes up.

In fact, so much so it is very often the first thing I look at when somebody asks me about their HRV or we're going through their overall analysis of all their data and we see HRV is poor, my eyes go right up to sleep irregularity. If their sleep is irregular, then I honestly don't go much past that. When their sleep regularly goes up, HRV just goes up. So if you're like, man, I've been doing everything I've been doing now, blah, blah, blah, blah, blah, blah, my HRV doesn't go up and your sleep's irregular. Well, that's stop number one on the train.

Other stuff is honestly, sorry to be sound this way, but it's kind of what I call the dumb stuff. It's alcohol. It is lots of bad negative health habits. All this stuff will bring it down. So if you remove all those from the equation, it's probably going to go up. Another one I wanted to bring up here that people don't pay a lot of attention to, two things have stood out when I was diving back through some of our databases. One was wild changes in exercise within the same week.

So what I mean by that is if you're pretty standard throughout the week, and then you're the type of person who goes bonkers with your exercise on the weekend, we see this huge instability of HRV. So whether you do your 10 mile run on the weekend, or you do the multiple classes, or you like to play five hours of pickleball or whatever, and it is drastically different than your week, that will also explain a lot of instability with your HRV and your resting heart rate for that matter. So that one will sneak up on people.

The last one I'll bring up is actually nutrition related, feeding frequency of food. Specifically, we have had a number of people come in for sleep related issues, whether that is really bad sleep or just kind of suboptimal sleep, and they're eating one meal a day. Now, I'm not fundamentally opposed to one meal a day, but in our experience, this has led to really, really compromised HRVs. What has happened many times is these individuals feel good, okay, or great.

for 30 days or 45 days, maybe up to 90 days. But then you see the nervous system just starting to pay the price. I'm not trying to indicate that one meal a day is bad for your health. Again, I'm going on my personal experience and the data we have in our companies, and we've just seen it not go well. And we've at the same time seen people then who eat more frequently,

in terms of they were eating one meal a day and they change and go to two or three and the nervous system sends to recover. I want to be real clear here. I don't only mean their HRV score. That does happen. But it's other signs and symptoms as well. It's objective measures of say sleep quality, cognitive function, performance and so forth. They feel good, but their physiology in the longer term isn't responding how they think or hoping it really is.

If you are a one meal a day or fine, great. If you feel awesome, awesome. Keep doing it. I'm only bringing this up to where if you've made a change recently and you're like, what the heck? Why is my HRV going down? That I think is the most appropriate way to interpret it as this is maybe one of the things that happens with

lack of feeding throughout the day is it creates some potentially somewhat of a neurological or nervous system stressor that will alter HRV. So lots of other things I could bring up here, but those are the ones that I thought were most interesting. It's a combination of some of the stuff that is most well documented, the alcohol, the emotional regularity, so on and so forth, with some things I thought that maybe some of you would find interesting in that we've just seen behind the scenes that is not necessarily in the peer-reviewed literature.

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to save $350 off your Pod 4 Ultra. 8Sleep currently ships to the US, Canada, the UK, select countries in the EU, and even Australia. Again, that's 8sleep.com slash perform. We have a little bit of an algorithm we use when determining if a change in HRV matters to us. So how do you interpret this context? Number one, we always check to make sure we got good data. I talked about that earlier. If they don't, then I disregard it. But let's say they do. Most of the time they do.

So we've got good data, however you define that. Next question I'm asking is, are we talking about one day? Or has this been happening for more than three, ideally more than five to seven days? If it is acute, single day, second day, third day only, then I'm asking the next set of questions, which is, okay, what are we doing with your training right now? If we're in a phase where we're trying to cause physiological adaptations, I'm trying to stress you. So if your HRV is lower,

and i'm seeing signs of stress that's exactly what we're pushing for that's a good thing we're not changing anything this is one of the huge flaws of general technologies that just tell you what to do with your workout your nutrition based on today's score oh your hrv is low therefore take a day off that's a really bad approach because it doesn't understand what you're trying to do in the long term or even the medium term in this case so if we see an hrv that is low and it's been down for two or three days

And we're in a phase where we're in the off season. We're trying to build up change. We're in a caloric deficit and we're working hard. I don't care. You are a little bit stressed. That's the point. That's going to cause adaptation. We're going to ignore. That said, if we're in a phase where we're supposed to be peaking, I'm trying to feel good. Whether we're peaking for sports performance or you're simply saying, I need to be on today. I need to have a great day. This is a really important thing I'm doing in my family life or work life or something like that.

My HRV has been down for a couple of days and I got to get it fixed because I'm trying to perform my best right now. Then we're going to do what I call acute state shifters. And I got a whole category of these things to cover for you here in one second. But I'm going to give them tons of different strategies that they can pull out one or more of these acute shifters. And I promise you, these will make that HRV go up right now. They'll go up today. They'll probably be up again tomorrow and you'll be fine. We'll be back in the sweet spot. Going back up our algorithm a little bit. If we got good data,

And this has not just been a one or two day thing, but it's been here for five or seven or 10 days or longer. Then I'm going to ask the same follow-up question. Number one, are we trying to induce adaptation? If so, I'm not going to ignore it, but I'm going to watch it carefully. Not necessarily going to change your workout program today, but we are going to watch it carefully. If it is really suppressed, meaning it's more than two standard deviations outside your normal,

for more than five days, we're going to take action. We're going to do something, okay? If that was really technical for you, if it's a really big change and it's around a long time and you're really feeling bad, your motivation, your energy, you feel junky, then we're going to take action, okay? If we're in a phase where we're trying to perform our best,

And that's been down for a long time. Then we're going to go to what I call chronic solutions. So we have our acute solutions and our chronic solutions. And so ultimately, we want to make sure we're using the right tool for the right task. Now, I'm going to go through all those

briefly, but before we do that, I want to finish talking about respiratory rate as well, because it's a little bit of a different interpretation. I've given you some sample numbers earlier. I kept saying 14 breaths per minute or 15 breaths per minute, and I'm doing that because the literature will show you. The cutoff line seems to be about 16 breaths per minute. If you are over 16, there is clear and consistent literature tying that to everything from risk of a

or things like that, is tied to clinical deterioration, pain, emotional stress, cognitive load, and a whole host of things that you don't want to be anywhere near. If you are at 16, you're right on that line. I'm not trying to overly scare you, but if you're above that, I'm going to make the case that you, as long as our data are accurate, which is, again, a whole other question,

But if you are up there, then we have a case of chronic over-breathing, whether that is chronic hyperventilation, that's a medical diagnosis, not for me to decide, but you are over-breathing in my opinion, and we're going to want to bring that thing down. Most of the time I'm looking at, if you are in the 10 to 14 range, and then I don't see anything else, I'm good here. If you're 15, I'm asking a lot of follow-up questions. You're 15, 16, I'm probably going to ask us to do something.

If we have a bunch of other major issues, maybe I'm not too worried about it. But if you're over 16, then this is going to be one of our top tier priorities. Because of all the reasons I shared earlier about what happens when you're overventilating. Lots of short and long term issues. And so this is exactly how we interpret those numbers. Let's say you're at 16 or 17. Okay, very first stop on this train, I want to make sure your breathing mechanics are okay. Very simple first principles here.

If you are ineffective with your breathing strategy, whether you're breathing through your shoulders and your neck, or clavicular breathing, whether your diaphragm doesn't work appropriately, your intercostals are weak,

Your position or your posture is bad, so bad that it's infecting your breathing. Well, then you can't breathe well. You're going to have to breathe more often. This is simply, if you're weak in a spot, you have to do it more often. You can imagine being hunched over, touch your front of your shoulder to your knee and try to breathe. You can't. So you're going to breathe more frequently to get the same amount of air in. That's an exaggerated example, but you get the point. So number one, before I'm worried about some long-term intervention with you, I just want to make sure that it's not a mechanical issue.

Past that, we're going to look at breathing problems. And what I mean by that are everything from allergies to nasal blockage to clinical sleep disorders. If you can't breathe through your nose, there's a strong chance you're going to be hyperventilating. It's not a guarantee, but we've just seen that really highly associated. So step number one, the way that we're going to interpret this higher respiratory rate, okay, maybe it's a sign that mechanical breathing technique is not great. Nope.

How's your nose? Oh yeah, I'm stuffed up all the time. Hmm, have polyps. Can you breathe through your nose ever? No, never. Are you a mouth breather? Okay, great. Then we're going right there. I'm not going into anything else past this until we fix breathing out of your nose. Dehydration can do the same thing. So if you just notice your respiratory rates up one particular day, oh my gosh, and then you properly hydrate, it probably goes back down. Nothing to worry about long-term there.

After that, things get a little bit more work intensive. So it could be a CO2 intolerance thing. If you're highly sensitive to that CO2, your brain can sometimes get miscalibrated. It thinks there's way too much CO2 in the system than there actually is. So you're either hyper-stressed or hypersensitive. And so it starts asking you to dump and offload that CO2 way sooner than it needs to. You're intolerant or hypersensitive, one of those two. In that case, we can confirm that.

So we see your respiratory rate is elevated. We also then run that CO2 tolerance test on you. Oh, that's also poor? Then great. We don't need to do anything else with your respiratory rate. We fixed your CO2 tolerance and that respiratory rate will take care of itself. Other things to think about here if your respiratory rate is high, it could just be a long-term pattern. Remember earlier when I talked about how these can go from initiating factors to sustaining factors? We've experienced this a lot in our middle to later aged families.

Adults, right? These are often folks that came from high stress environments high stress careers Whether these have been lots of former surgeons military individuals Entrepreneurs things like that where they just had high stress for a long period of time The over breathing was appropriate because they were in a stressful environment and then they sell the company they retire They reduce their hours and then years later. They're still over breathing and

And in the cases where we've had years of data on people, we've seen this confirmed pretty well. That pattern just exists. You're just over-breathing and you don't know it. So that has happened a lot. You got to go break that pattern. One of the biggest causes of this has actually been pregnancy.

A lot of things can happen post having a child for women. And those patterns can be established and stay permanent unless you go back in there and actively reframe and rebuild a new pattern. Last one then here is what we would finally call general elevated allostatic load, whether this is physical or mental. Remember, allostatic load is that colloquial term for kind of like global stress on your body, no matter how it comes in or not.

I went through all that list for a bunch of reasons, but one of them is I want you to realize that that stress thing is at the last one. We don't look at respiratory rate and go, oh, you're stressed. That could be, but it could simply be the fact you can't breathe out of your nose. It could be something you're not hydrated. It could be the fact that you're just intolerant

or sensitive to CO2, or any number of reasons. And that is the pecking order. That's the strategy we go off of when we try to solve those simple problems first. And in our experience, you get through one through four, mechanics, breathing problems, hydration, and CO2 tolerance. Most of the time, your situation is solved. Whether you pick any of the metrics I just talked about today, heart rate, or respiratory rate, or anything else, or you pick something else entirely different.

I think most of us in this field would agree. You should not be overly fixated on one metric. There is no best number here. And there's problems with data and interpretation and normative values and so forth. Things like stress.

Things like recovery are multifaceted. You need multiple objective and subjective measures before you get too excited. Let's actually finally talk about what some of these interventions are and how we can improve overall nervous system resilience. It makes sense for us to start off with the acute changes. This is the stuff you can do right now in any given moment, and it will change how you're feeling and experiencing life. It will shift your state.

You already know this. This is what I call the 4x4 matrix. So picture on one part of the matrix your physiology, on another part your autonomic nervous system. What I'm going to share with you is how physiology can change autonomic nervous system and it can make it go up or it can make it go down. Autonomic nervous system can do the same thing with physiology. So it's a four-way street here. Really easy examples. If you want to make your physiology change your autonomic nervous system and you want to make it go up, just scream.

Yell right now. Flex your muscles as hard as you possibly can. You do anything like that with your physical body, that will cause your autonomic nervous system to change instantaneously. Heart rate will go up. Respiratory rate will change. Adrenaline levels. You pick your metric. Physiology directly increasing autonomic nervous system activity. You can also do the opposite. You could do a physiological double sigh.

You could do progressive muscle relaxation. You simply relax your forearm and this could cause a change in your autonomic nervous system. You get the idea. That is physiology to ANS. ANS to physiology is basically the opposite. You get scared. Big shot of adrenaline happens, this will physically increase your strength capacity, force production, and power output in your muscles.

and autonomic nervous system change you could do this with a supplement or a drug we could go down you could be more zen you could take again a medication it could lower your heart rate

And because of that, it can have a physical response as well. So you intuitively know the answer. You want to change and regulate your autonomic nervous system. You have the capacity and you already know the basics of it. I break these acute and chronic actions up into a bunch of different categories. For me, that looks like there are food-based solutions. There are supplements. There are thermal stressors. So temperature. Of course, there's breath work.

There are what I call brain distractions or brain alterations, basic rest or sleep. There's light things you can do like physical light. There's movement stuff, physical movement. And then there's what I call motivation. Tons and tons and tons of examples. Most of them though are acute. Let's take motivation for example. If you scrolled on social media and came across a phenomenal video

Cameron Haynes or Jocko Willink quote, you might get inspired. That could change your autonomic nervous system. That could change your arousal state right now. You're going to be low energy, lethargic. That could put you in more sympathetic drive. Your HRV will change if it is actually sufficiently motivating to you. You could read a story or a book or watch a movie.

You could do a physical warm-up, start training, do some hops. I mentioned earlier, flex as hard as you can. If I shine a bright light directly in your face. All these things would change your state in the moment, but none of those are going to make your chronic HRV improve over time. These are mostly short-term solutions. The chronic ones are a little bit more difficult. This is when we get into stuff like biofeedback training. If you have sleep issues, getting a chronic sleep improvement. If you are chronically under-exercised,

Start exercising more. If you are really off, particularly if you are low in caloric intake, you're hypocaloric for too long, this might have a chronic effect of bringing more calories back. And then there are things like, again, thermal exposure that can have a chronic effect, but most of that stuff is pretty direct and acute. Give you a really easy example. I've been doing a cold water immersion, cold water exposures for a very long time.

I do not use them because I think it adds a minute to my life. I do not use them to burn more fat. You guys can all debate whether or not you think those things exist. But for me, we have used it for stuff like this. We actually ran a bunch of experiments. We never published this stuff. We didn't take it through IRB. We just ran it with a bunch of our athletes. And what we found was if you look at somebody's HRV very specifically, and then you put them in a cold bath, cold water for two to five minutes,

How cold? I don't know. In American units here, somewhere between 30 to 50 degrees. It didn't really matter that much, to be honest. And you sat them there. Here's what would happen. Your HRV immediately post the ice bath when you got out would go down. No surprise. If you get in cold, really cold water, you get shot immediately into sympathetic drive. Low HRV. Remember, fight or flight. However, as quickly as 30 minutes post...

your HRV will be 10 to 20% higher, more down-regulated than you were before the cold. And that continued to increase for about the next three hours or so. And we ran this stuff by actually checking HRV like every 15 minutes for several hours. So we had 30 minutes post, 45 minutes post, 60 minutes post, et cetera, et cetera, all the way up to 180 posts. And we stopped measuring at that. And still 180 minutes post-cold water immersion, HRV was higher.

significantly higher, 25 to 50%, depending on the person, higher, three hours after the cold bath. And so while I know that most of us think about it as like that short-term thing, no, I don't have peer-reviewed

publications on this, but we saw this enough to where I was like, yeah, okay, great. And it also stacked up with what I feel. It's going to last today. Now, will this last weeks and months? I don't know. Don't think so. Probably if I had to guess, but it certainly will give you a nice acute bump. And by acute, I mean several hours and several days, right? If you hate the ice, you think it is terrible or you don't like it at all. Fine. I got 50 more examples I can give you. It's just one that showed up as really clear evidence to us.

Changing gears entirely. You can do this without moving your physical body at all, without suffering, by just doing what are called visual resets. Mentioned him a couple of times now, but thank you, Dr. Andrew Huberman. Some of his early podcasts on his platform, his show, talked a lot about this. But visual resets, I know his lab worked on it a lot.

are really compelling and really effective. Lots of ways you can do this. There are simple drills like eye circles. So you stand there and basically run a big loop with your eyes circling around. That will change your sympathetic drive.

Other ones that, again, my colleague Emily Hightower I know uses a lot are things like a smooth H. You can see this, and the literature is really clear here. There's lots of different cortical and visual resets, but this stuff is really fantastic and super effective. A different one entirely that I think a lot of you exercisers and strength trainers will like is

It's a modified Valsalva maneuver. The Valsalva maneuver is that intra-abdominal pressure that you create when you're doing things like lifting weights or having a bowel movement. This is exactly how you use it. Again, we're still talking about chronic or acute rather. This is something you're going to do right now. It's not going to fix your long-term stuff, but it'll give you that change when you're feeling like you need it right now. So you're going to hold your breath.

You can do an inhale and hold, or you can do an exhale and hold. It doesn't really matter. But you're going to hold and then create a bunch of intra-abdominal pressure. And what's really key about this is the pressure needs to be in a true 360 degree range. Here's the analogy I like in this one. Imagine you are a can of soda. So you're a barrel, if you will.

And the bottom of the barrel that's sitting flat on the ground is your pelvic floor. And the top is your diaphragm. So these are running parallel to each other. And then the barrel, or the can of soda, however you like to think about it, is everything from the front of your stomach to the side of your stomach all the way to your back. You want to create pressure against all of those surfaces. So imagine you're trying to explode that barrel.

Every way. You're trying to blow the bottom out. So blow the bottom into the ground. You're trying to blow the top up in the air. And you're trying to blow every side out each individual way, right? That's how we do it. It's not just a crunch. It's not a back extension. It's not anything else. It is a all quadrants vertical and horizontal. And you're going to do that and you're going to hold it for 10 seconds. In doing that, you're going to see your heart rate jump from, you know, 60, 70 beats per minute to 120. Okay.

It'll shoot way way way up in the air. But then at the end of those 10 seconds you exhale and actually that the literature suggests that it doesn't really matter how you exhale. Go slowly, go through your mouth, go through your nose, kind of let it all dump out quickly. It doesn't actually matter that much. In doing that, that heart rate will go from 110 or 120 all the way now down to like 40 or 50. So before you started the drill you were at 60 or 70 and now your new baseline is significantly lower.

Really effective. You can do it anywhere. It takes just a few seconds to do. It doesn't cost you any money at all. And it is particularly good at altering what are called baroreceptors that have specific action on that vagus nerve. And so you can do this. The magnitude of effect is actually really, really high. You'll hear in a second, but there's different technology you can use to directly stimulate your vagus nerve. But the magnitude of effect is much lower than something like this Valsalva.

So it's free, it's cheap, it's easy. You can do it a bunch and it has a big magnitude of effect. A couple of caveats here with this modified Valsalva though. If you are prone to orthostatic issues, you pass out a lot, you have low blood pressure, don't do this. Don't do this if you're by water or in a pool or in the ocean. Don't do this a whole bunch of times. Probably don't do this immediately during your workout.

All the caveats aside, right? You're going to create a bunch of intra-abdominal pressure. You're going to block a lot of blood flow, if not occluded entirely. Don't pass out. Don't fall into water. Don't drown. Don't do all that stuff. Another option, like I just mentioned, are what are called those vagal nerve stimulators. These are somewhat new. There are a handful of FDA approved devices that you can use. You generally have to have a prescription to get them though. You can buy a ton of these.

as normal consumers, and I have not been impressed with any of them. The data are, I would say, weak at best on them. I have personally used many of them and found, like, I got nothing out of it. The people we had try it got nothing out of it at all. The studies that are the most supportive are ones that are funded by the companies themselves. So that doesn't inherently mean the data are wrong or bad or manipulated, but you all know what that means. So for me, when it comes to these commercially available nerve stimulators,

Until we can see some more independent testing done and the data are more impressive, I generally don't like to use them. That said, if you had a different experience and you like it a lot, that's by all means, that's great. Use it. I have tried some of the clinical ones, the FDA approved ones, the ones that require a prescription, and those are far more powerful. Those have been effective. I specifically have used one called the GammaCore. You have to have a RX for it, as I mentioned, no affiliation to the company.

But it is quite effective. You'll notice it pretty substantially. Your data will change almost instantaneously if you're measuring it and monitoring it. Mostly when it comes to these things, these are coming from neurologists, people with severe migraines. This is generally the application. This is not something that we often think about as somebody who's trying to make their HRV score better today. So don't swing a sledgehammer at a fly, if you know what I mean. But these things aren't out there.

Hopefully that gives you a sense of a bunch of different tools and strategies I intentionally picked things all over the map. Cold water, to a breathing drill, to technology from free to a little bit more expensive, and a whole bunch of other things in between that can shift or improve that state instantaneously. We're going to transition now and finish up by talking about some of the things that will actually make improvements chronically.

So let's get you out of that hole and let's make you a more permanent, more resilient nervous system. Remember our goal. We want to desensitize. We want that system running in the background and for us to have the ability to have some control over it when we want. If you think about basic desensitization, the exact same principles apply here, which means desensitization.

You can already intuit a lot of the solutions. I'll give you some, again, what the science shows us, what we've experienced. But there's obviously many, many more things or an unending list of stuff you could try. Think about this from the perspective of the immune system. Now, I'll tell you a personal story. My daughter has an incredibly severe allergy to cashews. We put her through a treatment. It took us about 18 months, and she now eats cashews every day.

We were in a position for when she was younger to have to carry an EpiPen with us. If there was cashew dust in the air, there's a non-zero chance that she could die. It was that severe. How did that program work? Basic desensitization. You give them a very, very, very small load. Don't put anything else in the system that could irritate them. As time goes on, you give them a slightly higher amount of load until she got up to eating, again, multiple cashews a day.

If you look at a totally different system, another personal experience I had many years ago, I had an athlete who was struggling a lot with low back pain. I called a colleague of mine, a physical therapist, Dr. Quinn Hennock. Quinn was fantastic and he basically said, hey, you're dealing with low back pain, take her all the way up to the point of low back pain, go right below that line and then train a bunch.

Don't hurt her. Don't exaggerate it, right? Don't give my daughter a bunch of cashews and cause a huge reaction that makes the system worse, more sensitive, right? It's on high alert. No, no, no. Small doses and then build those doses up and desensitize the back pain. Worked perfectly well. The athlete has, it's been years that athlete not had back pain, chronic low back pain ever since. Completely different. And again, I'm showing you wildly different

examples here because I want you to understand, in my opinion, this is a ubiquitous physiological thing. This is not specific to HRV, specific to the nervous system. It seems to be just a renowned physiological principle. So it carries a ton of weight. This looks a lot of different ways. I'm just going to give you some samples. The research is going to show you most of the time practices in this area, you're going to start to see changes in three to four weeks.

You should feel noticeable changes, but it won't be a week. It won't be a day. Three to four weeks seems to be the number. The biggest impact seems to come around the six to eight week mark. Consistently dosing for that long. Past eight weeks, you don't see as much continued progress. And so what oftentimes happens is you can, whatever you're doing, you can kind of back it down from doing it once or twice every day to maybe two or three times a week. So you're kind of at a maintenance dosage from there. That's what my daughter is with her cashews.

She has a little bit of cashews a couple times a week, and that keeps her immune system totally at bay. As far as we understand it, if we were to do that, pull the cashews away for a couple of months, she might actually regress all the way back to the beginning. Again, some analogy that helps out there. If you were to think about this from a growing muscle perspective, nobody in their right mind would go do one workout and then go to bed that night and go, "Oh, my biceps aren't any bigger. This stuff sucks. It doesn't work. Strength training is a joke. It's fake. Woke up the next day, my arms aren't any bigger."

Like you just know that doesn't work, right? But yet we expect the same thing to happen when we do breath work. I've been doing it for two days. Nothing happened. My HRV score is the same. Sure. Of course it is. This is a system approach. This is a desensitization. You're reframing. You're building a new road here. It's going to take several weeks. That's where the benefit comes. If you feel better right now when you do it, great. That was an acute thing. But we're trying to get to chronic changes, right? So we want to be active now so that it can be passive later.

What that means is during these first four to eight weeks, it's work. It's a lot. You're going to have to dedicate 10 to 15 minutes a day of doing something that you're not going to necessarily feel that much better in doing. But if you do this appropriately, we reset this baseline, then you can be on to maintenance dosage and not have to actively do this so much. So there's a bunch of examples for you. I'm going to go through a handful right now. And again, I've intentionally tried to choose these from a wide variety of activities. So let's dive into them.

Very first one we're going to start with is exercise. You know about the hormetic stressor effects of exercise, right? You break it down to build it up. Not exactly what happens, but that's what hormesis is, right? Small insult, come back better. We saw this with cold. You get really, really cold, you dive into sympathetic drive, which then has this compensatory response into parasympathetic. Same thing here, same thing else. You can look across the research. I've got some papers specifically I pulled up that'll be in the show notes that

Strength training, low intensity cardiovascular training, high intensity intervals, all of it works. If you want to directly compare them, looks like high intensity interval training seems to be the best for this specific marker. Same time, if you're doing max effort, high intensity intervals every single day, you're going to run into a hole. You're going to run into a wall and it's going to go down eventually. So dose appropriately. We use a little bit of all of it. If we feel like somebody is doing way too much high intensity work, we're going to

we will pull it back and HRV will improve. Respiratory rate will come down. Resting heart rate will come down. I've seen that more times than I can count. That said, if you're not exercising at all or you're exercising a little bit or a moderate amount or you don't go that high of intensity very often, we will see the same positive responses by adding high-intensity training, whether that's higher-intensity strength training, higher-intensity interval training, or cardiovascular training.

Same thing. So this is just about the right dose for the right overall experience. Totally dependent upon your lifestyle and sleep and nutrition and blah, blah, blah, blah, blah, blah, blah, right? So not a one size fits all answer here, but pay attention to those things. So overall exercise wins. And this has been, again, documented so many times, I can't even count. Next one on that stop is breath work. Remember earlier, when you exercise more CO2, so you breathe more. So when you started thinking about it,

What is structured breath work doing? It's kind of like manipulating a little bit of a lower level amount of exercise. It makes sense. The same physiology happens. The same basic benefits. It's really consistent. The framework we use to think about it is in three basic steps. If we're going to implement a specific breathing protocol for somebody, here's how we do it. Again, for these particular purposes. Number one, before we actually put somebody on a breathing program,

We reduce arousal. I said this a while ago now, but this is actually step number one. Before you have to go through this meditation or intentional breathwork protocol, we just got to reduce the sensory input. We have seen this a lot. Go for a walk in nature, no podcast, no music, not as much time. You can't wake up in the morning, immediately go to your heavy metal music, work for 15 hours, come home, answer emails, and then fall asleep.

You can, because you burn a lot of energy. You're going to be tired, but that's going to keep you in a pretty high state of arousal. So I'm telling you right now, if you want to do breath work, you're into it. Cool. We've had a lot of people who just don't like it. I'd be totally candid with you. I'm not the biggest fan myself, personally. Always feels good, always works, but it's not like on my high list of things I enjoy doing every day. And so I would rather just be like, man, I need some recovery. It's easier for me to just reduce

physical arousal. Give me some more quiet time. No more sensory input for the day. That'll take care of most of it. If that's not enough, the next step we go to is more time doing nasal only breathing.

Close your mouth, breathe through your nose. Whether this means you tape your mouth closed while you're working, or you go for a walk and you're breathing only through your nose, or you're doing some or all or any portion of your exercise with nasal only breathing. I don't really care. It activates the diaphragm more. It tends to on itself slow respiratory rate down because you can't move air like you can. You will notice hyperventilation through your nose when you won't necessarily notice hyperventilation through your mouth.

you'll feel that, you'll hear that. That would be very different than it coming through your mouth. And we also know that nasal breathing is more parasympathetic on itself. So by doing that,

reducing arousal, and then forcing people into some nasal only breathing time. This basically takes care of all of our problems. If you like or want to still need to do more things past that, at that point, we will instill a specific breathwork protocol and it could look a bunch of different ways. But again, here are some samples. Intuitively here, just make your breath do what you want to feel like. What's that mean? Let's say you're trying to go up

More energy. You're feeling lethargic or lack of motivation and you're down and you're not breathing very much and everything, heart rate's low and energy's low. Think about it. What would your breath look like if you were at a high energy state? And then do that. Force your breath to do something. And as I talked about earlier, your physiology will respond to match it. This is hyperventilation. Breathe more. Any of you who have ever done hyperventilation breath work, you'll know within a few seconds, you're

tingling in your arms, you might start sweating, temperature goes up really acutely. So just do that. Just hyperventilate. If you're in the opposite and you're trying to come down,

Just don't breathe as much. Tons of protocols. Yeah. Extended exhales. Sure, sure, sure, sure. But the basic concept is slow your breath work down. That's as complicated as it has to be. If you want individual protocols, cool, fine, got it. But that is the top line strategy here. Most of the research and most practitioners who are effective at this are going to use a combination within one protocol. So you're going to do not just only extended exhales.

Not just slowing your breath rate down, not just speeding it up, but you're going to use a combination to develop that hormetic stressor. So if you want to truly downregulate, you can just simply slow your breathing down. But actually within one session, a combination of slower and faster and slower and faster will lead to that hormetic response. And if you finish, especially on low, it's been our experience and the research would support this,

you're oftentimes see more of a parasympathetic response than if you were to just do parasympathetic alone. So most of the time we're looking for a combination of up and down for the same reasons that we talked about with exercise in other words. Conflicts of interest here, I am a board member, no pay here for a nonprofit, called the Health and Human Performance Foundation. I've been a part of this group for many years. I was one of the founding members.

I'm bringing that up because that group, led by Tanya Bentley, recently published a phenomenal review article. We'll link it in the show notes. But I want to share with you what they found. They were looking directly at the relationship between breathwork for stress and anxiety. What do we know? In that review, they found, I think, 72 papers. And something like 75% or 80% of the papers found that the breathwork helped.

So just on a surface, if we want to say like, does breathwork actually help for anxiety and stress? I think pretty clearly the vast majority of time it does. But what was really interesting that Tanya did there is she started breaking down the papers and saying, well, what was true among the papers that worked and what was true among the papers that didn't? And can we glean anything from that? And the answer was yes. So here we go. There were a handful of things, in fact, five things specifically that were common among all those papers that showed it worked. And here they are. Number one,

They avoided fast only breathing practices. I know these are very popular. People love the max inhalation, exhalation stuff. They like hyperventilation breathing. If your goal is to try to reduce stress and anxiety chronically, pretty clear evidence at this point, that alone will not do it. Doesn't mean you can't hyperventilate. Doesn't mean it can't be part of your practice. But if your only practice is

is chronic hyperventilate or consistent hyperventilation probably not going to be effective for reducing your stress and anxiety long-term. Number two, the breath practice needs to be longer than five minutes. Number three, generally needs to be human guided. So people that do it by themselves initially, probably not the best strategy, whether you're physically in a room with somebody that doesn't seem to matter, but you need to have somebody coaching you through something at some point, especially initially. Number four,

It takes multiple sessions per week. You can't do this once in a while. You can do it and feel that acute effect, but it won't have that carryover chronic benefit. Number five, there need to be a little bit more of longer term practices. This is that four to six to eight week thing. So if we were to recap that, if you're using non-exclusively hyperventilation, you're doing it more than five minutes, ideally multiple times per day, someone that knows what they're doing has designed it,

and you're giving yourself four to five, six weeks, you got about a 70 to 80% chance that it will meaningfully and clinically improve your anxiety and your stress. That's some framework for breath protocols. Should work. Most of that will take care of HRV, CO2 tolerance, resting heart rates, and respiratory rate. The next big category I want to talk about are what are called biofeedback mechanisms. There's a lot of things here, tons of research,

I've actually been tinkering with this stuff for probably 15 years or so at this point. I want to categorize them for today's conversation into two main areas. One, what I'll call internal, and the other that are called external. So the internal ones are when you're trying to have that interoception. You're trying to pay attention to your heart rate. And I'm intentionally telling you to slow your breathing down. So that's an internal focus. External is when you're actually watching your physiology on some screen, and

and you're just trying to make that thing improve. So I'm not telling you how to do it. I'm telling you what I want the response to be, and you're using that direct visual feedback to make alterations. Both are great. They're a little bit different, and there's a lot of tools within them. So getting a starter with a handful that I'll call internals, and these ones are free or close to it. The very first one is any sort of hypoxic exposure. I've talked about that earlier. Hold your breath. The Valsalva Maneuver.

Anything like that. This will give you an acute change and I'll absolutely reset you. It will change your subjective feeling by simply holding your breath. If you want to cue that to some physical exercise, like the Valsalva, or you want to do jumping jacks or pushups or something, you'd be surprised. But a very short burst

of holding your breath combined with physical activity for a couple of seconds can change perception pretty immediately. And I'm calling this biofeedback because you're going to feel it. You're going to do it. I'm telling you to do something to your body. Ones that are more chronic though, which is what we're trying to get into now, there's a cascade of them. One that we've used a lot is actually a meditation app, if you will, called Waking Up. This is by Sam Harris. There are plenty of ways to learn

of meditation. There are many different strategies for it, but I'm highlighting this one because we've used a lot as well as because it is a progressive system. So you can kind of take it, follow the course. And if you don't know anything about meditation, the lessons are pretty simple and small and it kind of walks you through it. I've personally been paying for waking up for many years. We've given it to lots of clients plenty of times, but I've only recently learned you can try it for free for 30 days by going to wakingup.com slash Huberman. That's my friend,

Dr. Andrew Huberman's sponsored his podcast over there. So you can try it all there and I hope you enjoy it. It's truly phenomenal. We've used it a lot. And why, again, I'm saying that is we maybe sometimes someone's done breath work or they won't do breath work or they're not interested in meditation. We can just send them that and say, hey, this is the only thing we're going to ask you to do. And they can kind of get hooked on a little bit. They can gamify it. They can get there just focusing on paying attention to their breath, which is effectively what Sam is doing in that course.

It's biofeedback. They have no connection with their breath. They don't understand what's going on. They're learning to connect to their breath and it makes a big difference. That's why that's in biofeedback. Another super simple one is what Brian McKenzie calls gear one walking. So you're going to walk 30 minutes, 45 minutes. We have one client who we have walking almost two hours a day like this. And why we're calling it biofeedback here is you're breathing through your nose, but you're breathing at a very specific and intentional breath rate. Two second inhale, two

Two second exhale. That's a four second rhythm. What that matters is four multiplied by 15 is 60. That's 15 breaths per minute, right?

As I said earlier, 15 is kind of that respiratory line where we start to be concerned. If you're sleeping and you're breathing 15 breaths per minute, we think that's a little bit high. But if you're walking, 15 breaths per minute is appropriate. So in doing this, what we're trying to do is match an appropriate breath rate with an appropriate caloric expenditure. You're not having you do sprints or you're running where your heart rate's really, really high and you're under breathing. We're trying to retrain your baseline of saying, this is what 15 should feel like.

Now, when you go back and sleep, bring it down to 10 or 12 or whatever the case is. So it's a very intentional two in, two out. It feels very, very weird. It's nasal only. You can't listen to a podcast. You can't take work emails when you're this. You have to be in that space and you got to spend some time there, but it is quite effective. Third one here we'll talk about is the cold exposure. Now, what I didn't say earlier is how you can use cold exposure for biofeedback and retraining things like respiratory rate.

Common one we have used many, many times. Get in your cold, whether this is your shower or your bath or whatever you're doing. I'll give you the first, say, one to three breath cycles to kind of calm yourself down. And then past that, we're not sitting in here for a particular amount of time. What we're trying to do is take 10 breaths under control. We are using the cold to

to regulate breath. We are learning resilience. I put you in a very physiological and psychological stressful situation. Your hormones, your adrenaline, your heart rate will be flying up. And I'm asking you to control them despite the fact that they are wanting to go up. That is exactly how you build stress inoculation. That's walking you up to that line of low back pain but not pushing you over the edge.

You're not scared. You can get out any time. There's no danger here. But your body will be screaming at you that this is a... all those things. But you know it's not. You might panic. You might do a bunch of different things. Fine. Get out. No problem. That's the game we're practicing. Just like Dr. Harris in waking up. The practice is not how much focus you can have on your breath. The practice is when you lose focus, can you bring it back? Same thing here. We're using the cold.

to intentionally put you out of control. And then we're saying, can you practice regaining control? That's all we're doing. Now, the things I just mentioned, I call biofeedback, but they're not the true scientific definition of that. What we're really getting into this field is stuff more specific to HRV-based biofeedbacks. And so we'll cover those things right now.

A couple of examples. Many years ago, I had a colleague who was actually a sports psychologist who used biofeedback this way. He would put athletes in front of a computer screen and he would have an electrode attached to their ear that was measuring things in a pulse oximeter. And they would look at a screen and it was, say, a picture of a landscape or maybe kids playing at a park. And it was all in black and white. And he would not tell them anything, but he would simply say, make that picture turn into color.

And they're staring at a screen, they're like, what? And then all of a sudden, the screen would start filling in color. And then it would go away back to black and white. And it would take people a while once they realized, oh, wow, when I bring my heart rate down, I get more colors on the screen. And so they would bring their heart rate down and the colors would start filling in. Then it would get excited and then the colors would go away. And so they're not paying attention. He's not telling them, bring your heart rate down. Stop breathing as much. Exhale, extended exhales. He's asking for an external solution and they are figuring out internally how to get there.

Awesome, awesome, and then there's lots of different tools and technologies for that. But an awesome way of developing biofeedback that way. Really simple examples of stuff we've used for many years are things like a weight belt. You get 20 bucks on Amazon. You put this strap around your stomach and you can actually see increased proprioception in your core muscles. Lots of research on this. If you take a weight belt and you cinch it down really, really tight and you go to lift your weights,

There's been many studies show a reduction in core strength in response to that. You make it so tight, think of it this way, the core muscles turn off. They don't have to do their work because the belt's doing it. That said, if you put the belt on just kind of a little bit,

You can see increases in core strength. Why? Because it gives you a little bit of a tactile feedback. You know that you're not pressing hard with your core. You know you're not activating in all spots because you can feel the belt pressing back up against it when you're contracting hard. So because of that, it gives somebody a biofeedback reminder, a tactile feedback. Keep your core engaged, keep your core engaged. And so by keeping engaged more often, you get more of a training effect. Same exact principle can be applied here.

You can put people through a specific breath protocol or you can put a weight belt on them. Put a bigger one. A lot of the ones we'll use are like fat burning stomach belts. You know, the ones you put on, you're like plastic on them and they're there to help people think they're going to have a six pack. But what it's just doing is giving you that feedback. You don't necessarily have to give them a program. You can just say, hey, wear this for 20 minutes. Wear this for a couple of hours. You'll start to feel, man, I'm not breathing through my core. I'm breathing through my shoulders. I'm breathing through my neck.

So number one, we're starting to make improvement and progress in breathing mechanics. It also generally tends to slow people's breath rate down because you feel, you'll hear that belt crunching and moving and going back and forth. And you're like, geez, that's happened a lot. And you tend to just slow it down. Simple biofeedback, easy solutions, no complicated schemes at all. Very effective. For those of you that want more structure and specific protocols to follow,

This last one will get you really excited. There's a whole bunch of research on what's called resonant breathing. This is HRV biofeedback resonance. There's lots of different terms for it, but if you Google that phrase, this is what will come up. Same goal, trying to give you more ability to recognize and control your HRV.

A recent meta-analysis found very positive benefits for self-reported stress and anxiety. Other papers have looked at this and found positive benefits for cognitive function and depression. It has the same basic prescription of the other breathwork. You probably got to do it for about 20 minutes per day. It takes four or five weeks, ideally morning and night, morning and night rather. And so that stuff is fixed. But what is specific about this?

It's really, really clever. A lot of the research here came from a guy named Paul Lehrer, L-E-H-R-E-R, I believe, out of Rutgers. In general, this resonance is supposed to be consistent throughout life. Now, I don't know if more research comes out that that'll change, but that is, as far as we understand it, it seems to be about the same. So this resonance frequency is something internal to you in which your respiratory rate starts to match up with your HRV and your heart rate.

You're like, "What?" Here's what I mean. It's really, really clever stuff. It's just really fascinating research. I use that Optimal HRV app I told you earlier. It's five bucks a month.

The studies oftentimes will use another app called Pace Breathing. That is just simply an app that helps you watch the app and breathe in and out at the right time. All right. So on that Optimal HRV app, you can do this test that I'm about to take you through as well as the training. It's why I like it so much. So I can send people that polar strap. I can send them this app, say, do this resonance test. And then our training program is based upon the results of

Of this particular test. It's telling you how long to inhale and exhale. Remember earlier where I've said kind of like five in, five out, or six in, six out is a good starting place. That's true. But the individual response to people is different. And this is a phenomenal way to figure out which cadence is best for you. The test takes about 12 minutes. And effectively what happens is you start breathing.

at a breath rate of about seven breaths per minute. Now, depending on the study you'll find, most will actually start you at about six and a half. I think the optimal HRV, if I remember correctly, starts at six and a half. And then some have gone all the way down to as low as three breaths per minute, but most are going to start you at like six and a half breaths per minute and drop you to four or so breaths per minute. Here's exactly what I'm talking about. You breathe for two minutes at this specific cadence. Let's say six and a half seconds in,

six and a half seconds out. And you do that for a total of two minutes. While you're doing that, it's measuring your HRV. What it's trying to identify is when your HRV gets the highest. So you're breathing in and out at seven, a six and a half breaths per minute. And then you go from six and a half to six. So every two minutes, you lower your breathing rate by half a breath per minute. Now, for some people, when they go from six and a half to six, their HRV goes down.

And some people it goes up. And then you go from six to five and a half to five, all the way down. Like I said, someone's down as three. At some point in that spectrum, your HRV will be its highest. Where that lands is totally dependent upon the person. So let's say we do the test and my optimal HRV happens at six breaths per minute and yours happens at four.

That's called our resonance frequency. I now know you will get the highest HRV right now when you breathe at four breaths per minute. So then you're going to spend more time breathing at four breaths per minute where I'm going to do six. That makes sense, right? So we're looking at how can I actually optimize my inhalation exhalation strategy to get the highest impact on my HRV? Well, it turns out this strategy is highly effective. I'll go over more of those details in a moment, but

When we're defining high HRV, it's really actually important that the highest HRV score, like you're going to see on your wearables, is not what we're necessarily talking about here. There's three criteria that are used to determine best HRV score, and that RMSS thing is the lowest one. Highest on this is what's called low frequency power. This is another way of kind of defining and measuring your vagal nerve power.

This is primitive. This is a thing we're optimizing for rather than that actual HRV score. Another really interesting one is looking at your HRV amplitude. I've talked about that before. It's the difference between kind of your maximum heart rate and your minimum heart rate in one breath cycle. Remember, when you breathe in, heart rate goes up. When you breathe out, it goes down. And so let's say when you took a breath in, you went to 80 and you took a breath out and it went to 40. 80 minus 40 is 40. So therefore your amplitude is 40.

One thing that you'll see is people that are really well-trained physically have a really big amplitude. People can go like a well-trained individual, cardiovascularly fit individual might have a resting heart rate of 40 and they might jump from 40 to like 90. So that amplitude would be 50 or someone who's not very physically fit might go from 60 to 70. My amplitude is 10.

I know I'm throwing a lot of numbers and most of you are listening, so that's hard to follow along. But just the amplitude, the difference, your ability of your heart rate to go from really high to really low within one breath cycle is a positive thing. That is indicative of a really, really resilient nervous system. And remember, from the very beginning, that's what we're talking about today.

The HRV score itself, again, cool, it's on there, but it's the bottomless. So that's what we're optimizing for. And I needed to draw that little technical detail out there because I wanted to make sure that it's landing so deeply in your brain that we're trying to go after that resilience, not the score. And those other two measures, that frequency power and that heart rate amplitude are the things that are more important than just that HRV score. So more to be said about the resonant breathing thing, but it's just really phenomenal area that we love.

I wish I had something to do with those companies. I don't, but they're just phenomenal products. So I wanted to make sure you had some specific example of something you could go try that I personally used and that I like. Last thing I wanted to mention, and this is what some of you might deem to be outrageous, but again, full disclosure here, I have one of these things. I don't have anything to do with the company, but this is something that I've seen pop up a lot. I was

Just traveling around the country recently and saw a bunch of different professional and other groups using it.

I have one at my home, and this is a chair called the Shift Wave. It is $10,000, but it is phenomenal. You lay in this chair. It has haptic feedback, so it will vibrate. It has sensory control, what you're seeing, what you're hearing. It has a whole bunch of programs. It will directly measure your heart rate and HRV. And you can do guided biofeedback through, again, movement.

through light and sound and a bunch of different strategies. I've used it a bunch. We use it a lot with, again, special groups of individuals, and it's been really impressive. So those of you that just want to know what the best in the world are doing behind the scenes, I can't say that everyone's doing it, but I know some are, and it is really pretty awesome. And so there you go. Check out the Shiftwave chair if you'd like. If that is completely ridiculous, you'd like $10,000 for a chair, I totally get it.

And so we'll move on to our last couple of things that I just couldn't leave off the table. No good podcast can be done without talking briefly, and I do mean very briefly, about supplements. First and foremost, what we're talking about here mostly are acute benefits. Take caffeine, take a stimulant. You're going to change sympathetic drive, and you all know that.

But what's more interesting and I dove into a lot of was what do we know about chronic benefits? So if you're in that hole and HRV is way down for a long time, can supplements do much to bring you out of that hole and bring that HRV back up, bring that respiratory rate down or however we're defining autonomic control? The short answer is not really. Maybe they can, but there's not a lot of evidence to support that.

Closest thing I found was there was actually several review articles and meta-analyses on omega-3s. Benefit doesn't seem to be huge. We know a lot of positive benefits of omega-3s, but this doesn't seem to be a massive one. But there's some indication that there's some help here. So that was pretty cool. Other ones that we'll see, I actually found a study on watermelon juice. Now this may surprise you, but people don't realize that citrulline and arginine, the nitric oxide capacity in watermelons is pretty high. So there's a pretty cool study. They actually did it.

in combination with like an oral glucose tolerance test. And what they effectively found was it doesn't improve HRV, but what it does do is it blunts the HRV response when you dose them with something that should normally compromise it. It's stress inoculation. In fact, if you look at other things like ashwagandha, very similar types of research.

So it's not that these things will take your resting HRV and make it get better, but what it will do is it helps you not be as responsive to a stressful stimuli. That is the true benefit. So whether this is high intensity exercise or a psychological stressor, things like watermelon juice or ashwagandha may blunt how much of an impact those things make on you. So kind of...

stress inoculators, if you will, but they're not really recovering you from that hole, but worthy of mention nonetheless. A final one that I thought worthy of talking about was actually a review article on human studies that found an association between low vitamin D and B12 and low HRV. This was not a randomized controlled trial. This was not an intervention study, but it was interesting nonetheless. So I'll keep my eye out for more work in this area. Maybe we'll see that. Maybe if you take people...

who are low and getting vitamin D and B12, you will actually see a chronic improvement in HRV over time. Maybe you won't, not sure. I'd be willing to bet if you take and just give people who are normal in vitamin D and B12, those supplements, it probably won't do much, but we'll have to wait and see how the data pan out. So we've covered a lot of ground today. I think we should finish on a little bit of a wrap up.

Want to keep this stuff in proper context. Remember that hormesis. We want to stimulate, but we don't want to annihilate. You want to touch the boundaries. You want to desensitize, but we don't want to push people so far into an area where it actually creates a greater stress response, a greater protective mechanism. Small bump and uncomfortableness gives you a nice rebound. That's what we're looking for. But a huge trauma is not helpful or potentially even sends us backwards.

There are a couple of types of people in this world, in this regard. I call them big feelers, people that have that high interoception. They pay attention to themselves too much and they cause themselves way too much stress because they're hyper-focused on every little thing. In that case, maybe don't use that technology. Use more the feeling type of stuff or don't do anything. Pull them off of a lot of these things.

Then you have the dull knives is what I call them. People that just have no contact with their body whatsoever. Maybe you want to use more of these technological solutions to get more calibrated and more aware. Other big conclusion we talked about is overall, the first step is just reducing arousal. This is a free thing you can do. It's probably going to have multiple benefits across multiple areas of your life.

And so before we start worrying about specific protocols or supplements or anything like that, let's just start by reducing our overall stress cup. Number three, find things that work best for you. This is fill your recovery cup. This is something I haven't said yet, but it's really what I've been getting at the whole time. It's not enough always to just reduce stimuli. Sometimes you got to actively recover.

Most people don't think about actively recovering until they desperately need it. So not being stressed is not the same as fully recovered. Spend time figuring out what hits it for you. I know some of the things that land for me and they're not the same for my wife. They're not the same for my family members or some of the athletes I work with. What really fills your recovery bucket up? Spend time tinkering with that and then use it honestly quite often and as much as you possibly can. Final thing I'll say here is

Don't expect those acute solutions, whether it's the supplements or the thermal immersions or the motivational quote or the music. Don't expect those acute things to fix chronic problems, right? When you use the chronic problem solution stuff, probably looking at more than five minutes a day, ideally every day, if not multiple times a day, at least for the first four to six weeks, past that, you can back it down, maybe even as little as just a couple of times per week, and you should be in a pretty good spot.

Want to finish it up by giving some thank yous. As people have mentioned several times now, thank you, Dr. Jay Wiles. Jay, you were phenomenal. You were so helpful here. We had a lot of conversations and I deeply appreciate your help there. Jill Miller, I mentioned in your book, Body by Breath, covered a lot of these concepts. It was also incredibly helpful. Emily and Brian at Shift Adapt. And then somebody else, Martin McPhillamy, who I haven't had a chance to speak about yet, but has done a lot of great work in this area. So thank you so much for being here.

All you people, thank you so much for your help. I appreciate all of you for listening. I hope you have some new skills, some new things to try, some direct tools. Some may be more interesting to a few of you. Others may be less so. But either way, I would really love to hear feedback. Which ones did you like? Which ones have you had different experiences with? And if any of you do take the time to go try something,

Comments on YouTube would be a great place to fill me in on what worked, what didn't, and any other feedback you have. Thank you so much, and I look forward to doing it again.

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