I think what it comes down to is each person has a certain amount of training in a week. I think it's a weekly basis, right? Because that's kind of the cycle we live in. There's an amount and a type and an intensity of training that you are individually going to respond the best to.
And if you go above it, not so great things are going to happen. If you go below it, you're not going to get the outputs you want. And that amount is not easy to find. And it changes on a weekly basis. It's not the same week in, week out.
And so the more that you can hone in on that. core how much volume do i need and how much intensity do i need if you can get that right week in and week out you will see continual improvements and that work will turn into result if you don't answer that correctly bad things happen you either waste your time because you're not getting as much out of as you could or you do end up over trained in which case we see injuries and we see burnout and lots of things that are going to have negative health consequences so i think ultimately what you said is i want to use information to make sure that i'm getting the most bang for my buck best result for the amount of work I'm putting in. And that's where I think data can play a really powerful role is it's information that you can use to make much more granular decisions around rather than just guessing, oh, I should go do 40 minutes today.
Should you? Or I should do 200 minutes this week. Is there anything to support that other than just throwing stuff at the wall and seeing what sticks? And I think that's what intrigued me so much about HRV is it felt like I could open the black box and get some real answers other than like test. train for eight weeks, remeasure, see what happened.
I don't want to wait eight weeks. I don't want to potentially lose the gains I could have made across that time period. So for someone like yourself, that's again, wanting to get as much out of their time as they possibly can.
Yeah. Data can play a really strong role in that because it can answer questions that can't be answered otherwise. Hey everyone, welcome to the drive podcast.
I'm your host, Peter Attia. Hey Joel, thanks for coming out to, uh, to Austin. Um, and, uh, you know, been, uh, looking forward to this discussion for some time. We've not met before, but had, uh, what seems like an endless stream of email communication. So I always appreciate your, uh, your willingness to not just respond to all my questions, but the thoroughness with which you do so.
Um, this is a topic that as we were discussing just a few minutes ago, I think, uh, everybody has heard of it. People have a vague sense of what it is, but Once you get beyond a very superficial description of it, most people, I think, don't really understand it. And certainly most people don't understand how to use the data. And I would absolutely include myself in that category. So the topic, of course, of heart rate variability is near and dear to your heart.
Maybe before we dive into the weeds of this stuff, maybe just give folks a bit of a sense of your background and kind of... What brought you to the study of this and over what period of time? Yeah, I mean, it's really interesting to me to see the growth of it because I've been using it now for 20 years.
And the story of it, it's really fascinating to me because I was in my early 20s and I had just graduated from University of Washington. I'd interned there and done strength conditioning and then was progressing to the Seahawks to work with the same coaches. And there was a track coach named Randy Huntington. And most people probably never heard of Randy.
But he was the USA track and field jumps coach. He coached Mike Powell, who broke Carl Luce's long jump. In 1993, right?
Something like that, yeah. So Randy was around for a long time. He was a tremendous coach, and he was from my area.
And I just kind of was talking to him one day, and I asked him some general advice. You know, as a young coach, what would you suggest and resources and all sorts of stuff? And he writes a phone number down for me and says, you need to call this guy. And I was kind of like, okay, you know, whatever you say, Randy.
And so I called this guy, and this... thick russian accent answers the phone and says his name is val and i still don't really know what i'm calling this guy for i just know that randy told me to and so he says i'll be in your area i'll meet you at the airport and i still i'm like okay right like i'm just kind of playing along and i'm not really sure what the the whole point of this is but randy says call this guy so i call this guy and he just says i will show you the technology and i'm again kind of like okay uh and so i go down to the sea tech airport And I see this kind of big Russian-looking guy with a trench coat. I mean, it looks like he could be straight out of a movie. And he, like, introduced himself, and he's like, lay down on the couch. And so...
I hope you're now out of the airport, or... No, I'm in the hotel by the airport. Okay, all right. So, you know, and so again, I'm kind of, I'm just in the dark of what is going on. And he says, lay down on the couch.
And so I lay down on the couch, and he's like, take your shirt off. And I'm... i'm at this point i'm looking around like is there some kind of practical joke like is randy just mess this is when you have a lot of faith in randy this is my lot of faith in randy and paid off um and so he does this big briefcase and he pulls out this big laptop and he starts plugging in wires and all this sort of stuff and he pulls out these electrodes he starts putting them on my chest and he does basically an ecg he's asking me birthday and weight and all this sort of stuff and he's like don't move and so i sit there for two and a half three minutes and i see all this stuff on the computer happening and i'm again still just completely in the dark right what what is this guy doing to me like i have no idea um after about three minutes he's like finished you know sit up and he starts kind of telling me about my recovery status and my readiness my metabolic profile my central nervous system starts talking about all this stuff that didn't really make a whole lot of sense of how he would know and he was he was like you know you're much more strength oriented and your cardiovascular system is not very good which is accurate at the time maybe didn't take a computer to see that because i was definitely on the strength side but he started just telling me the story of hrv and heart rate and variability and this was again 20 plus years ago it was not something that people were aware of and i had never of course heard of it and the idea that you could take something out of a laptop connected to my body and have any idea of physiologically what i was as an athlete or as a human being was you completely new and seemed foreign to me and i immediately was like i need this because it seemed to me like there's so much of a black box when it comes to fitness right like sometimes i do a workout and i get better sometimes i do workouts and i don't why like what is what is the right magic answer here to always get the workouts that i want to see are the results and so he started talking about the story of heart rate variability and this is really fascinating because you don't read this when you look at the western literature so you know as you you've probably know it goes back way 1700s they're aware of b2b intervals chinese have used pulse medicine a long time but the russians were pretty ahead of the game as far as application of hrv so in the 19 late 1950s they were aware that from ecg you could pull out these btb intervals and get something more than just heart rate and so when they would send the first human being in space yuri gargarin they were able to send back the ecg and some respiratory data and see fundamentally what happened to people when you shot them into space, which they really didn't have a way of gauging without this.
And so they saw as soon as he went into space, his HRV went way up, probably because you have changes in blood pressure, you have less gravity, so you don't have to have as much muscle activity. And they started using this literally all the way back in the 1960s, which is pretty fascinating because you didn't really see that in the Western literature for decades later, really, in a meaningful way. Then in the 1980s, they were dominant as far as... all the Olympic sports, right? They just crushed us.
Now they had a very elaborate drug program, they had a very elaborate training program, they had, you know, a lot of different things that gave them the advantage. But in the mid-1980s, they started basically figuring out, can we use this tech for sport performance? And so they put together an engineering team, and they started collecting data on thousands of Russian athletes of all levels, from their school-aged kids all the way up to the Olympic athletes, and they collected just populational norms. And they started building a system that was meant to monitor training and, you know, be used for this purpose.
And they, you know, don't get me wrong, they had really high volumes, but they did blood monitoring like weekly or monthly. They were constantly testing. And they, you know, from an organizational standpoint, their communist structure gave them a very hierarchical way to organize this sort of stuff and monitor it. So anyway, they spent years working on this platform.
And then before they could finish it, the Soviet Union collapsed. And kind of the whole team that was involved in this. just dispersed and left left russia and just by chance a lot of them had been involved in track and field different sports they end up reconvening in the track meet eugene and kind of just talking about this past project and they decide that they want to get together and keep working on this because they never brought to fruition and they did and that was ultimately the first system that i think was available i mean it was the first system that was available commercially with with the intent of being used for sport and fitness and that was what i was being introduced to at the time um this was the result of this project being finished the problem is they wanted 35 000 for it and it was you know it was a very research heavy medical type system that was not easy to interpret and i didn't have 35 000 but i convinced them to let me help them introduce it to teams across the u.s and gain some exposure for them as we worked at a deal and i started using it but it gave you 12 or 14 different metrics of heart rate variability it required you like said connect electrodes to people before you'd measure them. And really, it was that introduction to it where I started this whole journey.
And, you know, 20 years of looking at data and coaching people and trying to understand what the data was telling me and how it aligned with all these other metrics has really just led me down this path of how you get to heart rate variability today. And it's, you know, it's certainly been a large change, but it's kind of that crazy journey of starting one day in a laptop, you know, in a hotel next to the airport. Now it's on everyone's phones and watches and everything else.
But I spent, like I said, 20 years coaching with it, and that's really the difference is I was a coach. I opened a gym. I worked with lots of fighters and athletes and different teams and military groups using data, looking at HRV.
you know the whole the whole nine yards so it's uh it's been a long time but it's really fascinating to see it grow so let's talk a little bit about the the actual measurement um so in in the example you gave when you were first introduced to it it was done off an ekg um i i assumed three leads would be sufficient there's six back then okay but you can certainly get it from three obviously yeah so would we say joel that that's still the gold standard for how to measure hrv yeah Absolutely. I mean, if you're talking about medical grade research quality, you want the cleanest signals, you want the most signals, ECG, three lead, six lead is by far the way to go. This might be a little too in the weeds, but given how technical this topic is, do you want to explain how an EKG works? Because I think it will be relevant to distinguish between what an EKG is doing, what a chest strap is doing, what an optical sensor is doing on the forearm, on the wrist or on the finger.
These are all going to be basically the tools the technology companies are using to measure HRV. But as you and I have discussed and, you know, gone deep on this, there's a total difference in the fidelity of the signal depending on where the signal is acquired. Yeah, exactly. And given that our audience here is an appreciative audience for nuance, I think it might be worth explaining from the gold standard all the way down how these signals are acquired, what's happening physiologically.
and electrochemically that's enabling the capture of the signal? Sure. I mean, you can kind of group these into two things, right? One is the electrical signal of the heart itself, right?
And that's what we're measuring with an ECG or EKG or the chest strap. You're literally measuring the polarization, repolarization of the heart as the chambers are beating. And you get this electrical signal that gives you the QRS complex, right? And we're honing in on where those beat-to-beat intervals are.
Because ultimately, to get HRV, we need the exact amount of time from one heartbeat to the next. because that's what we're quantifying so if you have an electrical signal you get a very clear clean signal that you can pull out those exact beat to beat intervals and that's where we fundamentally get heart rate variability from if we're talking and is it all i mean is it always done r to r because that's the cleanest signal yeah it's always an rdr so you just have to be able to identify where is the peak of the r interval right the more accurately you can identify here's the peak of the r wave here's the peak of the r the more accurately and if my memory serves me correctly because it's been so long right so the p is the polarization of the atria uh and then the q r s is the ventricular is it the repolarization or the contraction it's the contraction yeah and then the t wave is the repolarization exactly so you're basically the r wave is giving you if my memory serves me correctly i'm sure there's a cardiologist listening who's going to scream right now but that's the peak electrical signal of the contraction of the ventricle. Exactly.
Yeah. I'm not a cardiologist either, but from my memory, that's correct as well. But yeah, you're getting this exact electrical signal that's showing us where that peak is happening.
And because it's a high resolution and it's electrical, we can pick that out pretty easily, especially the more leads you have, the more you're going to be able to get that. The difference between that and an optical sensor. And tell me, by the way, if I'm wearing a polar chest strap, which is what I wear when I'm on my bike.
I have a chest strap. How is the fidelity of that compared to an EKG? It's pretty close, honestly. It's very close. As far as picking out the actual peak of the R-wave, it's going to be within a millisecond, which is more than enough.
Now, obviously, if you have a full six-late EKG, you're going to get even more, but you don't need it for HRV. As long as you can identify that peak of the R-wave precisely within one or two milliseconds of what it's actually at, and that's where the gold standard is, is from the ECG. and just to give folks a sense of that a millisecond a thousandth of a second is what is the unit that hrv is typically being measured in so if a person is looking at their hrv and they're seeing a number that says 60 milliseconds you're saying with a chest strap you would put a plus or minus of one or two milliseconds exactly on any reading that comes out as long as it's a good chest strap now the caveat is good skin contact and those sorts of things if it's moving around or it's not in the right place you can lose some of that which of course you have a better chance of getting the signal correct with actual electrodes, right? And so that is really the gold standard.
And that's how it was done for decades. And that's how most, you know, 90 plus percent of the research has been done with either the EKG or with chest straps, because that's really been the gold standard of how it's measured. The use of these PPG or optical sensors really has only been the last, you know, five, six years they've been around. And traditionally, their accuracy was just questionable. but it came to it and they don't get the same electrical signal they're measuring changes in blood volume through the skin basically electrodes shine electric or shine the led light down into the skin it reflects differently based on the blood flow flowing through the the arteries below it and so you're getting the pulse and they actually call it pulse rate variable it's not really heart rate variability if we want to get technical it's pulse rate variability but it's showing us the same thing it's showing us that cardiac cycle now there seems to be a big difference between the wrist, and the forearm.
So, um, on my bike, if I'm riding indoors, um, well, actually I'm doubling up. So I'm wearing, we're going to, people are going to be like, what is wrong with this Peter guy? He has so many stupid devices, but it'll all come to full circle with through this.
When I'm on my bike indoors, if I'm outdoors, I'm just wearing my polar chest strap because it pairs perfectly with the system, with the bike system I'm using outdoors. Indoors, I ride with my Morpheus. chest strap and my Wahoo optical sensor. The reason is I'm using two different programs.
The Wahoo sensor on my forearm, which is optical, is pairing with my computer and that program I'm using there in ERG mode. But the reason I'm using the Morpheus chest strap is I'm using the Morpheus program on my phone. So it's not, but the reason I bring all that up, Joel, is to say they're perfectly in sync.
the chest strap, the gold standard, and the optical sensor on my arm, never off by more than a beat. And I can see them in real time concurrently. Conversely, when I'm rucking, when I'm putzing around, I wear a Garmin GPS watch that measures heart rate.
It's a very high-end watch. It's about a $700 watch. It is categorically a piece of garbage.
I would call it a random number generator for heart rate. can't come close to estimating my heart rate. There are times I look down and it says I'm at 170 beats per minute when I know I'm below 100. Conversely, there are times when I'm probably at 160 beats per minute and it says I'm at 110. So as far as I can tell, it serves absolutely no purpose.
Occasionally it's accurate, I'm sure, but it's so inaccurate so often that I find it i would never rely on it i'm using it for gps sure i'm almost annoyed that it's a feature that is there they're both optical sensors why the difference yeah one is location as you mentioned right to get a good resolution you need good blood flow below the surface and you need the lack of movement the biggest problem with ppg sensors optical sensors as a whole is they get what are called motion artifacts and any kind of movement starts introducing noise into the signal because again we're not getting electrical signal we're just getting this blood flow going beneath the surface that we're using leds to detect right for heart rate when you start moving around you get lots and lots of motion artifacts and it just becomes much more difficult for those sensors to detect it accurately particularly in like acyclical movements anything where your arm is moving around at random higher heart rates darker skin colors lots of things throw off ppg sensors so my darker skin is obviously a disadvantage presumably just in general tattoos you know all of these things so Optical sensors in particular struggle with higher intensities, higher movements, higher heart rates, all those sorts of things. Now, my optical sensor on the bike, even though admittedly I'm not really moving, my upper body isn't obviously moving. Is it superior because it's less movement or is it superior because it's on much larger blood vessels? It's both, right? So there's a company called Balance Cell that we use.
It's done a lot of research on this because they produce the sensors and they've looked at any location, bicep, arm, calf. I mean, all of this. the above anywhere where you can have the least amount of like even your wrist you have bone movement right even if you're not really moving your wrist can still be flexing and extending and that in just that wrist movement will cause motion artifacts you get much cleaner blood flow on the forearm you get just much less movement and torsion as you're moving so you get just a much better overall signal on the forearm in general you're going to get from the wrist and they've you know they've looked at accuracies of garments and whoops and or like you don't get very good accurate data at all as you've seen when you're doing exercise and even when you're doing somewhat cyclical exercise you can still get as you've seen completely garbage numbers that make no sense because the center just can't pick up the the blood flow very accurately and like i said tattoos dark skin makes it far worse so in general you know it's the this test trap is always going to be the gold standard but if you're going to wear an optical sensor the forearm where you can get good blood flow is going to be by far the best place to be able to put it and you can even manipulate where in the forearm you tend to get the best signal the best results.
Yeah. I don't know if I'm doing it correctly, Joel. I tend to apply it right beneath the antecubital fossa where I know the artery is running. Yeah, that's what you want. And I'm sort of like assuming that I'm going to get the best signal there.
And I also put it on pretty snug. I mean, I was just doing that, not thinking about motion artifact, but it sounds like that you would encourage that. Yeah, exactly.
You want a good enough skin contact that can read. smash it in there. Yeah, I'm not using it as a katsu band.
Yeah, exactly. I'm not doing BFR. If you're using a forearm pump, then you probably have it a little too tight.
But yeah, the more secure it is, the more... So it's almost like there's really three. I know you said there's two buckets. You could really say it's anything on the chest.
amazing gold standard always going to be good as long as anything on the forearm i think we've established if you do the forearm right at least heart rate to heart rate is comparable we'll talk about the hrv variability and then anything below the forearm is yeah i mean nonsense it's not great it's definitely not great especially if you're doing if you're lifting weights if you're doing interval training if you're doing anything high intensity you're doing change of direction it's it's garbage you just get very poor data and you know like i said i wouldn't i wouldn't rely on it it might be accurate sometimes and sometimes it'll be way off the one that seems to be i wouldn't say accurate but the most accurate the less accurate is is the apple watch and i think what they're doing since they can actually have ecg um i think they're just interpolating a bunch of data so when they see bad data they just kind of replace it with what they think the data actually should be i see so you're saying the apple watch might be a step ahead of other risk-based devices based on sampling and algorithm yeah exactly i think they're probably you can detect when the junk data is there you don't have to display it the other ones do but they have enough previous data to know your heart rate didn't go from 110 to 160 in two seconds right so i think they'd start building out yeah it's odd that garmin tolerates that for lack of a better word because i'll see it do that right i'll see it go from 100 to 150 and i'm like yeah it's stuck a lot of times that's not even physiologically possible why yeah why wouldn't you sample that out yeah or ask a second order question yeah great great point um okay Let's now talk about the very confusing subject of how one calculates heart rate variability, because let's again reiterate what we're talking about, right? So if anybody has seen an EKG, everybody watching us has, you've got your little P, Q, R, S, T, and you just line up a strip of those and you. Imagine you were doing this in the olden days.
You'd have a set of calipers. You'd literally measure across R to R to R to R. So let's pretend we have a minute's worth of data, Joel, and a person's heart rate is they're laying down and resting.
So they're at 60 beats per minute. So the approximate beat to beat interval is one second. On average, sure.
Yeah, on average, or 1,000 milliseconds. What's happening at the physiologic level that makes it such that there is variation? And how is that measured and calculated from the raw data? And let's start with the gold standard and assume you have an EKG. Sure.
Yeah, as you mentioned, you're starting with this gold standard of okay, we can accurately pinpoint where are these are our intervals. And so we pull out what are called the RR intervals, not surprisingly, and we'll plot those. Now, from there, you do what's called correction basically you have to filter data there for filter ectopic beats which are beats that don't actually arise in a single atrial node you fill out if there is any noise in the signal or anything like that and you end up with this clean set of rr intervals and let's so let's say i gave you 60 of them sure and it's again it's a person who's at rest so um on average it's a thousand milliseconds between them but i'm going to give you 60 numbers that vary from 900 to 1100 milliseconds exactly okay So this is where things get interesting, because when we talk about HRV, we just usually give a number, and that number can be different. But a better way of thinking about HRV is just a framework to assess variability, because there are multiple ways to calculate that. There's one category called time domain, where we literally just do some math.
The most common one is RMSSD, root mean successive squared differences, where we just do some basic math, and they get that number of milliseconds of RMSSD. There's... There's SCNN, there's PNN50, there's all these different, call them time domain, where they just are taking that time series, doing some math on it, and giving you a number that represents the average variability. So let's talk about the RMSSD because it appears to be the most common one.
It is the most common for multiple reasons. What we're, again, measuring is that average variability across that time span. And what that represents is the input of the vagus nerve, the parasympathetic system, and its input into that sinoatrial node of the heart.
because fundamentally the autonomic nervous system is is governing that heart rhythm and primarily what happens at rest is that parasympathetic system via the vagus nerve and the way that it works is it's innervating that sinoatrial node in the heart and it's pulsing in beat with respiratory processes so as we inhale that vagus is inhibited and you get kind of this acceleration of heart rate actually i should back up if you were to cut out the autonomic nervous system you'd have roughly an intrinsic heart rate of about 100 beats per minute somewhere in that range everybody basically does so if you just and just let's be back up even a little further i think there's a lot you and i would take for granted here um so sort of nervous system 101. We have two nervous systems, broadly speaking. We have one that's under our control and one that is not. So most of what you and I are doing that people can watch the movement, speaking, all of these things, that's voluntarily under our control. But what most people can't see when they're looking at themselves is how many things are happening without any input. And thank God for that system.
That system happens to be called the autonomic nervous system. Without it. We would forget to breathe and we would die. Our heart would stop beating. So all of these vital functions from respiration to heart beating to regulating blood pressure to digesting have to happen via a nervous system that we never think about.
That system is further subdivided into the two terms you've already brought up, a sympathetic system and a parasympathetic system. And you've already alluded to one of the most important nerves in that parasympathetic system. called the vagus nerve which is a cranial nerve so originates from a very primal part of the brain and we won't necessarily get into all the neurotransmitters involved in these things but what you're basically describing is that the heart is under the influence of both of these exactly an example that gets to your point is after a patient has undergone a heart transplant for as an extreme example that vagus nerve is transected their heart is no longer under that control.
And therefore, it's just going to have... And you'd see heart rate variability basically zero in that scenario, because it would just be like a metronome. Yeah.
Okay, so didn't mean to interrupt, but I think that might be just helpful context for people to sort of understand what we're talking about, which is you're talking about, even though that person's heart is beating at 60 beats per minute, there's still a very fine interplay between what the sympathetic nervous system is doing and what the parasympathetic nervous system is doing. nervous system is doing. Yeah, we should probably even back up a little bit more that the whole reason that we need this autonomic nervous system is to keep us physiologically within these normal ranges that we have to be in to be able to produce energy and stay alive, right?
So if our blood pressure goes too high or too low, if our blood glucose gets too high or too low, if our body temperature gets all of these things happy within physiological norms, and we'd call that homeostasis, that the internal environment has to be controlled at all times. regardless of the external environment, right? So whatever temperatures we're in, whatever we're eating, whatever we're doing, we have to be able to regulate internally and stay within these physiological norms that are necessary for survival.
And that fundamentally is what the autonomic nervous system is doing. It's keeping us alive and it's trying to match the internal demands with whatever we're trying to do given the external environment, right? So like you said, people have heard of probably these two branches, the sympathetic, the fight or flight, or the parasympathetic which people call rest and digest now that's a good terminology to understand but it makes us only think of this yeah it's not nuanced it's not nuanced enough it also makes us think the sympathetic isn't doing anything unless we're fighting stress right and it's not really like that and these things aren't binary they're not switches that turn on or off a better way to think about these is dials that the brain is constantly manipulating and fundamentally what the autonomic nervous system is doing is twofold one is it's sensory A lot of information has to go up to the brain to process what the internal environment status is. And then the brain has to make decisions and push motor action down to the different organs to make sure that they're doing what they need to do, given the state of the body, given its external relationship with the world.
So fundamentally, the more important, the more we can regulate our internal environment and match the demands of our external environment, like the healthier we're going to be, we're going to be more adaptable, we're going to have better overall function we probably would just say it's broadly better health and so the interplay between that sympathetic and that parasympathetic and making sure they can do their jobs appropriately is a really big piece of making sure that our bodies are going to stay healthy as we age because i would say fundamentally if we look at aging as a whole we lose adaptability right we lose the ability to respond to workouts as quickly we become more likely to become injured when we get sick it takes longer to get over that and that's just the body's ability to regulate itself decline with age so anyway with that said At rest, we should have very little sympathetic activity going on. And we can talk about this in terms of waking versus sleeping. Those are different things.
Yes, I want to talk about that. We have a pretty low level of sympathetic just sitting down or laying down. Yeah.
And at rest, that parasympathetic dial is going to be higher because we don't need this additional energy that the sympathetic system can drive. So at rest, we're primarily measuring that parasympathetic input into the heart. And as I mentioned, it...
turns on and off with our respiration it's called respiratory sinus arrhythmia and as we exhale that dial turns up just slightly and as we exhale it turns down just slightly but mostly what's happening is we are inhibiting that bagel input as we breathe in and we're letting it function correctly or not correctly but we're disinhibiting it as we breathe out and as we exhale and so you're seeing just this pulsation type effect of that vagus nerve on the heart rate accelerating and then slowing down and then accelerating and then slowing down so you're seeing that input pulsing with our respiratory cycles and so when we measure hrv regardless of how we do it we're ultimately trying to understand that tone we call it bagel tone that input of that vagus nerve into the heart rhythm and that's what we're trying to then gauge as a functional marker of what our autonomic nervous system specifically the parasympathetic nervous system is doing How is it responding to the world around us? How is it responding to what we've done in the last 24, 48 hours? What is its resting tone? How much input does it actually have? And from that, we then try to gain all the other insights we can talk about.
And then just to close the loop on the measurement thing. So the most people are using devices that are probably calculating the HRV on the RMSSD algorithm. Yeah, it's a transformation that's basically run on the data.
And if my memory serves me correctly, I mean, we could figure it out, right? Root, mean, square, the standard deviation. Successive squared. Successive squared, so standard deviation. So you're basically going to say average or mean value is 100, you know, mean value is X, standard deviation is this, and then you probably do a sum, square, square root of.
Exactly. Yeah. Yeah.
Okay. So you get your number. Now, the only one I would say that's different is Apple Watch, actually.
They use. what's called sdnn which is just the standard deviation of the btb intervals why they do that uh i'm not sure that's when it's historically been used medically and they'll usually measure it for 24 hours and they'll just kind of look at like do you have any autonomic variation does the parachute method system function well at all and it's kind of a gross measure it's not nearly as nuanced because we're not measuring vagal input at a particular time we're just measuring across longer periods of time and maybe that's why they did that it seems to me that that would also introduce a bit of noise because you're combining being at rest with being active. Yeah, exactly.
And you would, I mean, I don't know if it's the right word, but you'd be penalizing people for being more active because the more you exercise, the more sympathetic tone you have during exercise, the more you're crushing the variability. Correct. Yeah. And what's interesting is Apple is just kind of measuring randomly for the most part. It just kind of measures when you don't know.
And you can, you can do a manual measurement, which we can talk about and you can actually check it, which is a better way to do it. But for whatever reason, they've just used this metric that nobody else. uses, and then they kind of measure it periodically when you don't know what's happening. And so the number you're just kind of getting in there, if you're not actively measuring it is just kind of like, I don't know where it comes from.
So a couple of things that I remember from a, an AMA that I did on heart rate variability a couple of years ago, and we'll link to it here in the show notes so that people can go back if they want a real primer on HRV. Um, the reason we did, uh, uh, sort of an AMA on that was, you know, a lot of people had questions about it. I don't, frankly, I don't think we went into nearly, um, this level of detail about it.
We talked much more about the mortality data and things of that nature, but that was one of the first things that stood out, right? Two things I remember more than anything, Joel. The first is there was a relationship between, in the research literature, what was measured as HRV, and we should talk about what that means, and all-cause mortality, and even disease-specific mortality.
And the second thing that really stands out is a graph that I'll never forget. that shows on the x-axis age, on the y-axis HRV, and what the curve looked like. And I couldn't believe how steeply it declined, right? And I think what it was plotting, if I'm not mistaken, was kind of mean or median HRV with a band of plus, call it the 80% or interquartile range or something like that. But it was an unmistakable trend, right?
which is like a 50 year olds HRV is less than half of a 15 year olds. And it just keeps getting further and further crushed as we go down. I suppose that speaks to what you said earlier, right? Which is one of the hallmarks of aging is this sort of lack of resilience. And we see it on every level, but this is just.
a very notable example, which is even at the level of the autonomic nervous system, we lose the ability to recover from insult. And life is an insult. Everything in life is an insult. The world around us is insult to us all the time.
It's just we can respond much better to it as we're younger. Yeah. Do you have a sense, by the way, of what it is physiologically at the cellular level that is resulting in this profound reduction in HRV as we age?
You know, it's interesting. They've They've looked at this, and I don't know that we have a great answer for the exact physiological mechanism. We know it's tied to mitochondrial density, mitochondrial function. We know it's tied to elements of the immune system.
We know it's tied to hormonal status, and we obviously see decreases in all those things as we age. So there's probably— You just have to wonder which ones are causal and which ones are the response. I don't think we know that, but we definitely know that we can increase our age of beer. We can at least prevent the decline. most effectively through cardiovascular fitness.
We see people with higher VO2s have higher mitochondrial function. They have higher VO2 that leads to, or at least correlates with greater HRV. So we know that cardiovascular fitness in general seems to be the most closely tied to average HRV.
There's also a pretty strong genetic component, which we can't ignore. We can talk about that. But yeah, if you look at the hallmarks of aging paper, which I'm sure you've seen, they kind of take these buckets of things, right? They say, oh, as you age, you get dysbiosis, you get the... deregulated nutrient sensing, you get senescent cells, you get stem cell exhaustion, you get mitochondria, they list all these things that happen as we age.
And they kind of look at this prism of what's the output. And if you read that, they say, okay, the output to the major things are loss of resilience to homeostasis and lack of a stress response that's appropriate given the world around us. So yeah, where that cause and effect and which ones, you know, causing the other is tricky to say. But I think fundamentally aging is this progressive loss of adaptability.
And there's multiple pieces that obviously but we're measuring that as you mentioned is you know one of the things that we want to gauge of hrv is how much of that resilience of that adaptability are we losing as we age that's something we can influence through lifestyle and training and everything else that we're trying to do here to prevent that slow down one of the things in that ama that i didn't get a great answer to was how much genetics played a role on this but from our Patient population, because even though that's not a huge N, we've got years and years of seeing these data in patients where every single one of them is using some sort of device. And by the way, it's even devices we haven't talked about. Like if you look at, you know, really high end things like, you know, like mattress covers and things like that, like the eight sleep will now measure that quite accurately. So from every form of wearable and out, you've got. Endless streams of data and there's an unmistakable difference between people I mean there are some people who and let's just talk about this in RMS SD We should talk about the other numbers because they you know, you have to do this apples to apples Yeah, but if we just talk RMS SD, you know I've got patients who live at a hundred and a good day for them a good day for them quote-unquote They're at 120 and a bad day for them.
They're at you know, 85, but you know if you follow them for five years their average hrv is going to be 100 milliseconds i've got other patients whose average hrv is 15 milliseconds and a good day for them is 25 to 30 and a bad day for them is 10. um how could that be explained by something other than genes it isn't i mean there's i've looked at a bunch of this research just to understand it's all over the map depending on what paper you're looking at depending which metrics they calculated they they say genetics is somewhere between like 15 and 70 something percent of hrv there's just such a wide range in the research of what you see you know where the exact number falls i'm not sure but you definitely see a very strong genetic component to it why i don't think we truly understand that but as you mentioned i see people who don't work out at all and they come into the gym or they you know whatever you look at their numbers you're like you have a very high hrv that you would not expect because you clearly don't have a very high level of cardiovascular fitness but i'll say kind of as a whole you start Talking to those people, they tend to have a healthier family history. They tend to have better health markers. I think there's something to that and that higher age rate probably still correlates to a health benefit, even if it doesn't necessarily come from exercise-derived means. It's just a genetic thing that they have that probably confers some benefit.
Would you... Put HRV in a comparable bucket to VO2 max in terms of the following, you know, amount of it that is genetically determined, amount of it that is modifiable, and the role it might play in understanding overall health status. So for VO2 max, I know the answers to all those questions, right? There is a genetic component.
It's not huge. It's probably closer to that 15%. So. than 70 percent uh it's highly modifiable but difficult and the fact that it's highly modifiable but difficult to modify is why i believe it is you know you've probably heard me say this the single greatest predictor we have of mortality um and if there's a better one out there i'd like to hear it but i haven't seen one and i think that's because I always talk about VO2 max is like the integrator of so much hard work. Yeah.
It's like you can't get there. Yeah. You can't you can't cram for the test. Exactly.
If your VO2 max is in the top one percent, you weren't born there. You you you blood, sweat and tears your way to that. And all that work does so much good for you. Yeah.
OK, so let's use that framework to evaluate HRV. You know, how genetic is it? How modifiable is it?
And are the. Do the modifications you have to put into it then speak to, hey, if somebody improves their HRV by 50%, how confident are we that that moves the needle in terms of what actually matters, which is not the silly number, but actually the outcome of their life? Sure. No, I think it's more genetically based, just from what I've seen, and probably a bit less modifiable. I would say it's less predictive in the sense that if I have somebody who's got an HRV of 110, to use your example, or whatever, or and then i have someone who's got vo2 max i know is i don't know 70. i can pretty well know that person with a vo2 max of 70 is pretty aerobically fit and they've lived a pretty solid lifestyle and had to done the work and the training to to get that level i'm more confident that that person as long as you ever be benefited and affected from that that i'm confident in somebody who has no workout history that just has a high hrv i don't know that i can say with the same comments at all just because they have a higher hrv that they would have the same prognostic value in all-cause mortality so it's it's a it's a metric that we aren't gauging output from right we're just measuring this internal physiological state and i think that confers benefits someone has higher hrv but i can't necessarily just look in that number instantly say oh this person's really healthy or this person's really fit necessarily because you do see that much stronger genetic component now if i see a coupling if i see some of the higher vo2 and i see higher hrv chances are you know that's a reflective of all the things we just talked about a healthy lifestyle and a lot of hard training and physiological changes that come as a result of that and we're more confident that those numbers are going to line up with all-cause mortality i think a nice way to interpret that joel would be the following um as much as people are worrying about their hrv and people really do worry about it you should worry more about your vo2 max because you have more control over it and it's a better predictor of all-cause mortality And I think that what gets measured gets managed, right?
And because HRV is so ubiquitous and it's so spit out, and basically you're at the point now where if you go get a Starbucks, they'll tell you your HRV that they've somehow inferred from the pressure your lips put on the cup. I'm being facetious. Everybody is inundated with these data, and it is creating a lot of stress. Yeah, I think we want to look at output measures.
VO2 max is the best output measure. We can look at something like heart rate and zone 2. Heart rate recovery. Heart rate recovery.
We can look at actual. output measures because at the end of the day i fundamentally think that's what matters we need to as we age we need to be able to continue to move and we need to be able to continue to be able to respond to our environment around us and output is where we can see those metrics how much what's the metabolic cost for us to move around yeah right as if we can maintain movement as we age we can be highly active if you look at people you know just that you know around you they're healthy and older a lot of them they're very active they move around they have hobbies they have friends they're social they do things they love and that's a big part of keeping them healthy and resilient if we don't have the metabolic capacity to move we've declined a lot faster and so again vo2 max and heart rate at different speeds that correlates the ability to move and maintain that as we age that's far more predictive i think than just an internal metric that you know is important but doesn't does not have the same predictive power it's so funny um do you have kids i don't so um anybody who's got kids especially young kids will appreciate this comment but um I've become so much more cognizant of a metric I would love to introduce to the world that ties into what you're describing called spontaneous movement, right? So I'm an old guy, and even though I'm fit for my age... Like, I don't waste a lot of movement, right?
So I'm already at that stage in my life where I actually think of myself as quite lazy, right? So I love to exercise, and obviously I'm not lazy when I'm doing that. But, like, if I'm walking through the airport, I'm just walking. I will use the stairs and not the escalator and all that stuff. I get it all.
But, like, if you're with my kids and my two boys are six and nine. The amount of spontaneous explosive movement is something I don't remember doing as a kid, although I'm sure I did it too. But it's really a remarkable thing.
And we also have a puppy. So we have this puppy that also is bouncing off walls. But when you see older dogs, that's done, right? Like a 14-year-old dog is not, even if it's in good health for its age, it's not bouncing off the walls.
Whereas that puppy can't. stop moving. And the same thing, like when I look at my boys, like everywhere we go, they have to race. Everything is a race. They're sprinting there.
So if we're walking somewhere, they're doing sprints to and from us the whole time. And I just think, A, there's something beautiful about that. But I think it speaks to this idea of youth, right? Youth is about movement.
It is converting the chemical energy of our food. into the electrical energy that powers muscles and spontaneous locomotion seems to be this so i don't know at some point like i would love to know like is there a way to take that as another output metric which is gps on somebody exactly what is the drive to spontaneously move for no apparent good reason we talk about we lose hrv right but we also lose sympathetic drive too we lose some of that ability to turn that sympathetic dial up as we get older too and probably it's as we've lost both of those capabilities the ability to turn that synthetic dial up and crank out more energy and produce adrenaline is that what you think explains the fall in maximum heart rate is it just purely a lack of loss of contractility the heart loss of contractility the muscular system loss of hormonal release as a result of the sympathetics i mean you're just losing again this adaptability this ability to turn those two dials as necessary to meet whatever demand you're placing the body we can't turn that sympathetic dial up as much we don't have that spontaneous energy that you just described to get up and sprint because that's that that was way slower and it probably can't go up as high yeah so it's like we were born with a zero to ten rheostat or dial on both of them and as you age that ten goes to a nine eight seven six five and yeah you can still move them but you just can't move them as much i would call like autonomic range and that really kind of represents what is our body capable of from an energetic standpoint how quickly can we turn that dial up and then conversely how quickly can we turn that dial back down and crank up that parasympathetic side to restore homeostasis and get our bodies back to normal and it's when it's interesting if you look at um i've looked at the paper where they looked at different navy divers that were going through this qualification school which is kind of their equivalent of of seal training and you know hell week and all that and they tried to pick out what are the variables that separate the people that are really good at this and succeed and make it through versus the ones that don't and they measured hrb throughout the process and essentially find what i just talked about is this autonomic range where they could really crank up the sympathetic system when they needed to and then turn it off as soon as the stressor is over and respond in the other direction with a much higher parasympathetic response that ability to use those dials quickly and in the right combination seems to be a really key thing to get adaptability and as we said if you age if both those styles lose their range and they lose their coordination to some respect then we have much less resilience much less adaptability and we should mention too as you pointed out the vagus and the sympathetics they do influence behavior in a lot of ways there's a whole thing that's outside my lane in the psycho social aspect of this and you can look at the polyvagal theory by stephen porges but fundamentally the brain regulates emotion through autonomic function in some capacity and the vagus is related to social behaviors it's related to cognitive control in in different scenarios it's related to all sorts of stuff they call it fight flight freeze you know all these things related to how our autonomic nervous system is influencing our emotions. And if we don't have that autonomic range, we probably have less drive to get up and move around as a result of that, as those nerves in the autonomic system changes what it can and can't do.
I mean, I don't think that should ever be underestimated or understated. I think, again, just even looking at a sample size as small as our patient population, I think we see that a lot. I An individual that, if you just look at them from a movement and exercise perspective, has a very difficult time relaxing.
and relaxing sounds like such a silly word but i mean that in a sort of a clinical sense right like if they can't let their rib cage down if they can't properly generate intra-abdominal pressure if they can't go through a sequence of movements that generate some amount of motor control and compensatory relaxation contraction um i think there seems to be very high association between that and emotional stress and psychological stress um and and and actually pain as well so i think we see Chronic pain and again you could argue well, where's the chicken? Where's the egg if you're in pain? Does that lead to more emotional stress?
Does that lead to an inability to regulate relaxation within the body which further exacerbates pain? It's a very vicious cycle It is yeah And you see like a sleep as we get older older people need just as much sleep But they have a harder time getting this much sleep and sleep is very much tied to that vagus nerve and the parasympathetic Nervous system. So it's again if we get worse quality sleep we get less adaptability. It's it is chicken egg, but fundamentally that's why we want to regulate ourselves correctly that's where exercise i think the biggest thing exercise does is improves our body's ability to regulate itself it improves the use of those dials because we are exposing the body to aerobic training that we know has some broad correlation to that and we're giving the body a stress it can adapt to in a positive way if we do it in the right amounts and that's the caveat there before we leave the measurement thing i want to go on to another one or two of those measurement um and so at morpheus what do you guys use to measure so we use rmssd and then we use log natural transform and a multiplier that sounds like a lot of math but essentially if you look at the data of rmssd and you look at like a normal bell curve it's skewed it's non-normal it's all the way to the left so you get these normal ranges of i don't know 20 to 80 or 100 like you said but then you can get elite athletes 180 200 and see this big bunch of data on the far left hand side it's kind of hard to interpret so and i'm not a statistician i didn't create the formula but essentially to normalize this data and make it look more naturally distributed more like a normal bell curve you do this log natural transform use the multiplier and more if it ends up on a scale that looks more like a hundred point scale so people with lower hrv are more like the 50 60 people with more moderate 60 70 higher 70 80 you know elite athletes are going to be 90 to 100 it's more of a scale that we have a more familiar relationship with i would say and the data is more normalized from a uh from a standpoint of a bell curve so it's just an easier to interpret but that's the reason for it so do most people when they start using morpheus and they're also using like whatever other device they're using that's just a purely rmssd device how much discordance are they typically seeing between them really depends on what other what they're using there can be a big difference between the device that they're using the numbers they're getting but the trends should generally line up.
If you're seeing Morpheus increase as a whole, you should see the other one increase as a whole. You should see the directional change matching, but the actual numbers will be somewhat different depending on where you're at in that spectrum. So let's now talk a little bit about Morpheus. I've alluded to it a couple of times. So it's a product I've been using for about a year and a half, maybe close to two years.
But before I talk about my experience with it and why I... use it, right? Like I'm, you know, everything I do, I do for a reason.
I'm a very deliberate human being. Um, so there's a very particular use case that is pretty narrow for how I use it. I, I, I, I'm, I know that I'm not using it to its full potential, but tell folks what this is about your, your involvement in this. And that's obviously how we got to know each other. Yeah.
I mean, when I started using the old system, I had to wait for people to come in the gym to measure them. And so I realized I was getting a pretty small snapshot of what their life story was because I might measure them two or three times a week. sometimes they come in the morning sometimes they come in the afternoon and i realized the limitations of that this is back in you know 2007 or 8. and so i wanted to create something that people could use their phones and that we could get way more data from and that was my first system bioforest hrv 2011 and that was really one of the earliest hrv apps out there where we could you know take your phone you could do a recording and you could get your hrv on your own you didn't need to come into the gym and one of the limitations of that was all i could look at was your HRV.
I didn't necessarily have any idea what else was being tied to that. And so I could look at the change and ask you a bunch of questions and maybe try to figure out what those changes were coming from. But I wanted to create something that also tied in training and sleep and subjective markers and other metrics so that as a coach, I just had a more complete story of what was happening.
And so that was really the genesis of Morpheus. And I started that in 2016, 2017. So quite a few years ago. And basically what we're doing is we're measuring hrv and then we're tracking activity sleep workouts all that sort of stuff you can use the morpheus device for a lot of that or you can use other devices so if you're using an apple watch to track your activity your sleep or garmin we'll pull that data in but what we're trying to do is take that hrv this is this is something we should definitely talk about there's a lot of apps that give you hrv and then you can either say okay i'm going to interpret what this means myself and i can try to figure out what these changes are it's a physiological metric or you can say the apps are giving me a recovery or a readiness or some gauge that's based on that now this comes back to every apps doing this completely differently right where we have a lack of standardization across not just the hrv measurement but then how that information is interpreted to generate recovery or readiness or some sort of number that the person in the app is saying oh my recovery is 80 percent or my readiness right these are just numbers that we are creating as a way to try to interpret the data and then some of those apps i think do a reasonable job with it some of them don't but i created morpheus in this idea of the recovery score based on what i had seen using hrv for 20 years or maybe 15 years at that point it's just a metric of what's appropriate for you on a given day what is your body more likely to benefit from and so we should probably talk about again what is recovery what is readiness because those are metrics that morpheus gives you and aura gives you and whoop gives you and garmin gives you like a body battery or every kind of app has their own gauge of that but then the question is how accurate is it what does it really mean and i think that's where a lot of confusion also comes in because we're trying to take metrics and turn them into something that's not a physiological measure but something we try to create yeah i mean look i used an aura ring for many years uh probably haven't used it in a year, a year and a half, there's better devices I can use to track my sleep now.
And the recovery score, as you said, even if you believe that the score is accurate, and there's no reason to believe it necessarily is, more importantly, it's not something you can act on, right? So let's just say you believe the number and you say, okay, my recovery score is 80 today. And I certainly believe that if it spits out a 90 versus a 70, you know, your whooper aura, there's probably a difference there. There's, you know, you're probably better off on the day you're 90 than the day you're 60. But how do you operationalize that information?
And so when I was introduced to Morpheus, it was actually someone on my clinical team that said, you know, we're having a hard time giving people real instruction around zone two, because most people don't want to do what you do, Peter. Nobody wants to check their lactate levels and go through this. And I get it.
I mean, I never fault somebody for not wanting to do a finger stick every time they do a workout. And truthfully, for some people, just relying on RPE can be challenging. So this person said, hey, look, the Morpheus app, and we'll talk about how it works, you know, because I also appreciate how the measurement is taken.
The Morpheus app gives you. target zones for heart rate every day and if you use the cutoff between what it's calling zone one and zone two that's a pretty good proxy for what your zone two is on that day yep so i bought the system um and started using it and i should show you the data because i have recorded every single workout i have ever done for the last year and a half and i record the following I record the heart rate predicted by Morpheus for what my zone two is, the heart rate I largely end up at by RPE. And sometimes they're close.
Usually they're quite close. Sometimes they're quite far. So sometimes Morpheus tells me to be at 138, but I'm kind of gassed out at 131. And sometimes it's the reverse. Sometimes Morpheus says you should be at 133, but I feel fantastic and I go to 140. But the power was for the interval and what the lactate is. And I have to tell you, Joel, I, I cannot put in words how impressed I am with that system and how remarkably accurate it is at predicting something that is very difficult to predict.
Um, so kudos to you for doing that. Um, what I find amazing are the days when, and I had one of these days a week ago. Morpheus said I should have been at 140 or 139 for zone two.
I got on the bike and I did not feel great. And I sort of said, I think Morpheus got it wrong. I'm going to ride to this wattage.
And my heart rate was about 132. And I checked my lactate and it was 1.1 millimole. I was nowhere near my limit of where I could have been that day. Now, again, we could get in the weeds on maybe that's fine. Maybe that's all I needed that day. And maybe I should have just been.
following how I felt. But if I'm really trying to get the right training effect, I was under training a little bit on that day. So I'll kind of pause there because I want to kind of let you sort of interpret what I'm saying and what you think of like, why is it about that? Because you spit out three zones, zone one, zone two, zone three. And I think you call them recovery and conditioning.
Yeah, it's just terminology, right? It's just a way to gauge low, moderate, high intensity. Does it surprise you that, because I haven't told you this story before in all of our communications, we've never talked about this particular issue. Does it surprise you that the heart rate that is on the cusp between your first and second training zones happens to correspond to this lactate of two sweet spot? I mean, that was really the intent when I designed it.
And I think probably that's the difference in Morbius, I would say, is when I designed it, it was as my experience as a coach for many years of testing lactate, of VO2 max testing, of HIV testing. i took synthesized a lot of information that i gained and a lot of knowledge inside again to create this structured system of low moderate high intensity you can call them whatever you want to call them that's basically what those zones are the biggest thing i realize is as people's autonomic nervous system changes intensity and heart put our heart rate changes and you learn this over time when you see today 140 is doing this and tomorrow 140 might be doing that based on changes in the autonomic nervous system and so when i created the algorithm was just based on a lot of data collected over a number of years of what i'd seen in the gym what i'd measured what i didn't look back at the data and so that was the end result of morpheus was trying to translate changes internally with how we can then turn that into smarter, more accurate, precise training. And that's what you're seeing with Morpheus. So it's awesome to hear that it's accurate for you.
And some people, it's always going to be much more accurate than others. But as a whole, Morpheus is by far the best way to translate, you know, again, changes internally with changes we should be doing in the gym. Yeah.
I mean, basically for our patients now, we almost never bother with them checking lactate. It's basically RPE, if you can manage it, if you really have a sense of what... zone two feels like great.
Um, but if you want some guidance, look, take the Maffetone formula, one 80 minus your age, great place to start. Once you're getting a little more nuanced, if you want more guidance, use Morpheus and, and, and go to that, go to that heart rate. Um, again, tell folks how I get that number every morning.
What am I, how is it spinning out that number for me? It's I have to do a measurement, right? Yeah. I mean, you have to measure your HRV and then we're looking at other things that you've done in the past 24 hours. If you're recording it.
um and then based on your fitness level so we ascertain your fitness level by looking at your resting heart rates by looking at your average rgb by looking at some of your heart rate trends when you're training and we say okay peter's roughly at this level of fitness peter's autonomic nervous system is responding in this way which again correlates to how it's going to react today if i'm fatigued then it's going to take more energy to produce the same level of power output and then we estimate like you said what for you is this cutoff between low low intensity moderate intensity and high intensity and a way that people can think about this i would say is muscle fiber recruitment so low intensity is primarily slow twitch muscle fibers doing the majority of the work and specifically zone two we're talking about where they're mostly oxidizing fat as much as possible kind of this moderate intensity we're starting to recruit some of those moderate threshold fibers and we can talk about what that means but we're starting to recruit some of those those faster twitch higher threshold muscle fibers and then higher intensity we're starting to really recruit all the muscle fibers and the highest intensity muscle fibers and so as morpheus is looking at this it's basically saying okay roughly this heart rate we think this is the level of intensity that is going to correspond to these low medium and high and then it's giving the ability to just plug in morpheus and say i want to do zone two morpheus says okay based on what we've seen this is where we think your zone two is for you today and other zones the same thing yeah and again i just want to reiterate this is why it's very valuable like It's actually giving me the prescription every single day. When I got it, I was a little surprised because I didn't, you know, I sort of bought it sight unseen. I was just kind of told it's valuable, but I didn't understand the nuance of the thing shows up. And I realized, oh, every morning I need to do a two and a half minute lay down in bed before I get up.
Still test measuring my heart rate. And I guess you can do that. Morpheus at the time came with a chest strap and an armband. I think now it's just a chest strap, right?
So you put the chest strap on in bed, you lay there, you answer a couple of questions. So it wants to know how many hours did I sleep the night before? So I pull that data off my sleep tracker, my eight sleep.
And then I, what's the quality of my sleep? I'm pulling off that as well. And then I think it's saying, how sore am I subjectively and how good do I feel?
Yeah, the subjective markers. Yeah, which again, I think those are actually. reasonably validated markers for training performance.
Um, and then I measure, I lay there and just kind of do nothing, meditate usually. And it measures my HRV and heart rate. And then it spits out, here's your HRV, here's your heart rate, here's your, um, basically your recovery score as a percent. And then here are your target training zones, which then come up again, when you train that day, it's already. loaded into the app.
So your training zones change with every day. So one of the things that surprised me, Joel was like, wait a minute, I'm used to having to measure HRV over the course of a night. What is the difference between what my aura ring used to tell me by measuring over eight hours of sleep versus this thing that's telling me in two and a half minutes in the morning before I've gotten up? Like, how do you think about that? Yeah, this is I think this is probably the most important.
part of HIV because there is so much confusion on this. If we look back historically, all the data that's been used, these all-cause mortality studies and all the different pieces of literature out there, 95% of them are from spot HIV measurements, that we are measuring at a specific time, and you're doing this in standardized conditions as much as you can to get a baseline. Because we want to know where is your outnumbered nervous system right now. Same time every time.
Same time every day, the same conditions. Because what I want to know is, last 24 hours, how many people are in the hospital? You did something yesterday. You did lots of things, I assume.
You ate food. You maybe worked out. You maybe had alcohol or maybe you didn't.
You did mental stress or maybe you didn't. put your body in a situation where it had to respond for for the majority of the day to do something and then you went to bed and we want to see the result of that we want to see this stress and recovery cycle that you went through yesterday because that tells us where your body's at right now how is it responding because we'll look at changes over time and understand how your body is is adapting the world around you and that's what most hrv has been built on is we measure in standard conditions we see where you're at today and that informs us about what happened over the last 24 hours and maybe slightly beyond and the analogy is if i was going to weigh myself i'd want to weigh myself first time in the first thing in the morning in standard conditions i wouldn't want to have a meal and then go weigh myself i'd want to have very standard ways of measuring so i can see the changes because ultimately it's you changing against yourself that's the most informative so we wake up we measure hiv we see where you are and we see where you were what your averages have been what your variations have been and that tells us where you are today and that helps us make a decision about what are you ready to do right now what's the most appropriate for you to do right now one thing i'll say is if your hrv is high or low we can talk about what those mean yeah it doesn't mean that you can't train hard it just might mean that like that might not be the most beneficial thing for you and there might be a cost associated with that if i wake up my hrv is way outside of normal you can't say oh i can't work out today you can you can it's just a question of is that what your body needs but anyway if you sleep yeah to be clear I don't think I've I mean, I don't think I have never once not exercised as a result of what that said. And there have been days when I've had abysmal scores.
And it's told me like my rate of what my heart rate range on what it has told me is never above about 141. There have been days it's been as low as 121, which for me means like my recovery was 35 or 40 percent. That's a night when I didn't sleep and something was dramatically off. You'd still do the work.
You still do the workout, right? You just. are aware of what the cost of that workout will be you might make adjustments tomorrow or through your plan um so anyway now that's what we're getting when we're measuring at the end of sleep right the morning time we're seeing what was the result of our sleep what was the result of our workout so yesterday everything else we did if we're measuring hrv overnight hrv number one is always higher at night because the parasympathetic system is that dial is already turned up quite a bit because you're sleeping where it's the highest for most people joel they wouldn't see the reverse because like my rmssd hrv overnight is lower than the log normal transform i get out of morpheus yeah more because if you look at the actual rmssd data you would see that you'd be higher and i know morpheus is different can we see that in the app can we you can't right now we've honestly when we first came out with bioforce and morpheus there weren't so many other apps to compare against so it wasn't as big a deal to not show the raw number um so we chose not to but now i think we probably will just because people do want to compare but anyway overnight that dial of that parasympathetic system was already higher so we're getting less of a responsiveness to see what actually is changing at rest we're not measuring at rest the second thing is if you have arrhythmias if you're an athlete who has very high hrv you don't have as much variability we're not really gauging the true responsiveness of the 24 hours before we're measuring more of what's it doing during the recovery recovery period which you know has some correlation obviously but we're not really seeing where are you at the end of that recovery period where are you ready to go today for this you know next period of stress and if you do here's the biggest thing is if you do something if you do a workout in the evening if you have a few glasses of wine if you're doing something very mentally challenging the first part of your sleep you're just responding to that and so your hrv is not reflective of this whole process it's just reflective of hey you just did an evening workout and your hrv is still suppressed for the first half of your sleep responding to that workout so we don't get a true picture of where am i at right now and how is that correlate to what i should be doing for the next you know 12 to 18 hours as i'm awake across the the next day so i think we're just we're probably getting a much better gauge of sleep and how our body responding during sleep but we're not really getting this true picture of how did our body go through the whole process of life sleep recover next we don't see that picture as well because we're not measuring at the end of sleep we're getting this average across it so i don't think it's telling us really the same thing and it doesn't have the same utility for telling us From a workout perspective, what's the most appropriate thing for us to do?
Might be a silly question, but it occurred to me now as we were talking about this. The one fundamental difference from one day to another in that morning check for me is there are some mornings I wake up and I have to pee so badly. And there are some mornings when I don't.
And there's a part of me that's wondering as I'm laying there doing my test while needing to pee, is that putting a little more sympathetic tone? Into this am I getting a skewed measurement would I be better off going peeing coming back waiting a few minutes I go to the bathroom get up. There's not it's not that bad of it big of an issue if you just go up with a bathroom you come back and you reestablish and part of that's actually measuring how well can you reestablish that if that significantly impacted your hrv it probably was on the lower end to begin with but it does bring up a point i should mention people with really high hrvs i don't think this becomes an issue at least in more peace until you're in the 90s or resting heart rates in the low to mid 40s your your hrv is already very very high that laying down you're taking some of the responsiveness away if you start getting those categories you probably want to get seated the challenge for most people seated they get And see they move around you introduce more motion artifacts.
It becomes more difficult But we really want to have as much range that dial available as possible because we want to see how the nervous system is turning That dial and so if you're very high like I said, I would say someone who's resting hurry. Yeah, I'm never above I'm in the low 80s is as high as I yeah I think at that point laying down is still a good way to take it But if you get up in the 90s mid 90s, you really want to maximize that potential responsiveness and that's where a seated measurement makes more sense but that's a fairly small percentage of the population that's going to be you know up in the ranges rmsd you're talking 120s 130s 150. we get up in those ranges you probably want to take it seated you also would say you've what's when i bought the morpheus a couple years ago you had an armband and a chest strap that came with it so i still use the armband as my morning check because i can i just that way i don't have to move them back and forth it always sits right there and then i use my chest strap when I'm exercising. You've gone to just a chest strap.
Is that because you think you're going to get better data and it's just better to have people using the chest strap for both? And should I do the same? I mean, it's two things. I don't think the data, as long as you're measuring consistently and you have the chest or you have the armband placed correctly, that's not any less accurate. I don't think the problem we ran into as people, as you know, we're trying to use our armband to train because it's more convenient.
Like, oh, the armband is like goes my wrist and their workout data was, was just not as accurate. The second thing is you're going to have to be able to do this. It looked like a watch, but it wasn't a watch.
And so we had a bunch of confusion with people just putting it on their wrist and not sure what to do with it. It just created a lot of confusion. So at the end of the day, I said, look, the chest strap is giving us the best data.
Unambiguous. It's unambiguous. If people really want to wear an arm vice device because they just don't want to put the chest strap on, we work with the rhythm, the Scotiary Rhythm 24, because it uses the exact same sensor that Morpheus used in our original armband that you have.
And so if they want to do that, they can measure it that way. But from a... accuracy perspective from both the HRV and the workout, it just made sense for us to standardize that use the chest strap and make it as, as universal as possible rather than trying to sell two devices, which people were ultimately somewhat unsure of. Yeah. Um, okay.
So let's talk a little bit about the question that I'm sure is on everybody's mind, which is, uh, I've been doing this for a while and I get that at the individual, you know, for my data, my, I see my up and down level. And I know that, Hey, when it's higher, I'm generally going to perform better and I can push a little harder when it's lower. I'm probably not going to perform as well and maybe need to make that a little bit more of a less hard day.
But then you get this question of, hey, what can I be doing to improve the quality of my health in a way that is measured by this output of HRV? Sure. I mean, this is where HRV is driven by genetics, fitness. primarily cardiovascular fitness is the biggest thing we see in Corley and drive it.
And then obviously lifestyle. So doing things in your lifestyle that make that sympathetic dial come down when you don't need it and doing things that turn on that parasympathetic dial when you're not using this is going to put you in your highest level of your particular range, right? From a lifestyle perspective.
And that's where I think most people underestimate the lifestyle impact on HRV and train everything else. They don't realize if you're stressed out from work. six, eight, 10 hours a day, you're running around chasing your kids, you're doing all these things in your daily life, that's a pretty significant impact on your HIV, because that sympathetic dial will be turned up for hours on end, maybe not the same degree, of course, of the workout, but hours on end. So a lot of it comes down to just the stuff we know in everyday life that makes us healthier, right?
Eating healthier foods, making sure we're getting enough sleep, managing our mental stress effectively, doing things that allow us to relax and turn that parasympathetic dial back up and that sympathetic dial back on. down and then build vo2 max you know use strength training to so do you think it's more impacted by peak aerobic fitness or by uh base aerobic fitness so would you say it's more impacted by a higher zone two or a higher vo2 max i mean they both contribute exactly how much um you know i couldn't say because we don't we measure we tend to measure aerobic fitness from a peak standpoint for the most part so that's probably standardized more standardized what we would look at but i think training frequency matters, which is where you get zone two, right? You can't do VO two Mac training five, six days a week. We do a lot more zone two. We do a lot more frequency and volume of that.
And I think that translates, uh, more than likely into a higher VO or into a higher HRV, even if you didn't go out and do a bunch of the zone two or the VO two max type work. Yeah. Um, and then tell me a little bit about sort of the, um, And like what as far as OK, so one of the advantages, I think, of those overnight tests, again, whether it's aura, whoop, eight sleep, any of these things is people have noticed how much of an impact alcohol has on overnight HRV. Sure.
It's probably one of the most profound changes you see in response to alcohol. And I would argue that a big part of the movement we're seeing around people drinking less. can be attributed to those devices, which is giving people visibility into, oh my God, like, you know, I didn't realize that alcohol could have such a profound impact on this.
Is that something I... I guess that would kind of be out of your system maybe the next day, or would that still be there in the morning? It would depend in the sense of if you had alcohol close enough to bedtime, it can impact your sleep, which impacts your recovery, which will impact the morning measurements.
You'll still see some remnants of it for sure. But yeah, you'll see that more directly in the overnight stuff. I think as a whole, what we see is people become much more aware of things like alcohol, things like excessive stimulants or God forbid smoking or just years of massive amounts of chronic mental stress.
Those things impact much more than I think people realize. As an example of this, we were measuring a college soccer team across a couple of seasons and we would see that during finals week, they would look far worse than during tournaments, even competitive like. playoffs just because that stress of being you know in a finals week where you're studying and you're not sleeping and you're you know we're stressed out and what will give me a sense of the range that you would see what what what would you see in an like give me an average athlete where this would be their morning hrv under these circumstances this is what it looks like when they're over trained you this is what it looks like when they're in the tournament this is what it looks like in finals yeah again there's a lot of variability there um but from a college standpoint most soccer athletes that we would see these are female athletes to be in the low mid 80s on a you know normal basis and this again this is morpheus system that's you can't compare each other numbers um but they'd be in the low to mid 80s kind of as a normal range we shouldn't drop into the 50s 60s sometimes even seven there were 70s sometimes down the 50s which is in morpheus that's the stress yeah that was the stress of finals week it's two three four days of not getting much sleep and you know studying a lot and just working out very less or very sporadically probably compared to normal training sessions you just see the impacts of life being very very significant that people don't necessarily expect that because they feel like oh the workout's the most impactful thing well it is in a way but it's also only an hour maybe two hours it's the rest of your life that also adds up to a huge amount of stress if you are very very stressed and if you're going through your life you know in that kind of type a i'm always turned on i can't turn off my stress that has a very big impact i think um you know sapolsky who i know you've had on the show talks a lot about the mechanisms like you see that play out pretty um frequently when you look at hiv data i don't utilize the morpheus system fully because i only wear it during my zone two workouts so i don't wear it when i'm doing my vo2 max workouts because i'm already wearing that polar system because it pairs with the garment and it pairs with the other power meters and all the other stuff I'm using. Um, I guess I could double up. I, can you wear two chest straps?
I mean, you could, so you probably could, the polar should be able to connect to the Morpheus app directly while you're training. Then it would have to pair to two apps. It should be able to, if it's got two Bluetooth radios, which it probably does. You probably could do both.
That would be good to know. Yeah. Um, but I don't wear it when I'm strength training.
And, um, so, so I realized that I'm failing to give it. all of the data because that's another, you know, I don't wear it when I'm rucking. There's a lot of time I'm active, but I'm not wearing it.
So how much am I missing out on in terms of the fidelity of what it might be telling me? And I want to because I want to talk about the algorithm and how it's able to because, you know, one of the things you and I spend so much time on is I can't make sense of how it's coming up with the numbers, even though they end up being right. yeah most of the time yeah like the more data you give it obviously the better it's going to be um exactly how much you're losing and you know it's it's hard to say but we're we're measuring the output with that hrv change and with the numbers that you're putting into it so we know the output of where you are we can't always ascertain how you got there if we don't have all that data the workout sort of uh things but as long as we have that consistent hrv measurement every morning in standardized conditions you know we're still able to get the vast majority of what we're trying to get which is what are you most likely to do when you work out right now so that is the most important thing that's by far the most important thing to make sure that every day you see my heart rate my heart rate variability how long i slept how sore i am and my desire to train yeah that's the vast majority because again it's telling us where you are right now the readout state the readout right now it that's the output we know the output this is where your body is is at right now if we can reverse engineer that from the input we can have some more insight into that but you're not like losing a bunch of accuracy because you didn't get that we want the output we want that as standardized and accurate as possible so i would say as long as you're measuring consistently every morning the same context same conditions it's going to be more than accurate enough for what you want to do okay great and again my use case is quite simple which is mostly just predicting that zone too but i have a feeling a lot of people listening to us will immediately you know resonate with that use case because i think for many people there's still a little bit of ambiguity on not the concept of what zone two feels like but the day-to-day variation again is really significant that speaks to the body's dynamic you know i think we we can do a zone two test and look at lactate and all these things if we just take one test we don't realize how much the body changes on a daily basis and so if you just okay i took my lactate test six months ago i'm just using this static zone two you're missing that dynamic change that the body is going through on a daily basis the body is not static i measure blood pressure i measure testosterone i measure like Like all these numbers change constantly.
Like the body doesn't sit still. And I want to make another point, which is people, again, might be listening and saying, you know, Peter, man, it's too much data, dude. Just go out there and do it. And I'll give you the counter argument to that.
When I was a competitive athlete and I was training 28 hours a week, I had the luxury of junk miles. I didn't always have to be perfect, but I'm not a competitive athlete. I'm a competitive father.
You know. I'm running three businesses. Like I don't have the time for nonsense. Every minute I'm training, I have to get the training stimulus right, or at least as close to right as possible.
So when I'm setting out to do zone two, I got to do it. And if I'm out there trucking along and my lactate's 1.1 or 2.9, I'm missing the training effect I want. So the more insight I can get to narrow that down. the better because I'm only going to give three hours a week or four hours a week to that training. I'm not going to put 12 hours into it where if I do 12 hours and I screw up three of them, who cares?
I still got nine. So that's why I know that there are people watching this saying, dude, you're a psycho. And it's like, no, I'm just efficient with my time.
And I don't want to waste my time. I think what it comes down to is each person has a certain amount of training in a week. I think it's a weekly basis, right? Because that's kind of the cycle we live in. There's an amount.
and a type and an intensity of training that you are individually going to respond the best to and if you go above it not so great things are going to happen if you go below it you're you're not going to get the outputs you want and that amount is not easy to find and it changes on a weekly basis it's not the same week in week out and so the more that you can hone in on that core how much volume do i need and how much intensity do i need if you can get that right week in and week out you will see continual improvements and That work will turn into result. If you don't answer that correctly, bad things happen. You either waste your time because you're not getting as much out of it as you could, or you do end up overtrained, in which case we see injuries and we see burnout and lots of things that are going to have negative health consequences. So I think ultimately what you said is I want to use information to make sure that I'm getting the most bang for my buck, the best result for the amount of work I'm putting in.
And that's where I think data can play a really powerful role is it's information that you can use to make much. more granular decisions around rather than just guessing oh i should go do 40 minutes today should you or i should do 200 minutes this week is there anything to support that other than just throwing stuff at the wall and seeing what sticks and i think that's what intrigued me so much about hrv is it felt like i could open the black box and get some real answers other than like test train for eight weeks remeasure see what happened i don't want to wait eight weeks i don't want to potentially lose the gains i could have made across that time period so for someone like yourself that's again wanting to get as much out of their time as they possibly can yeah data can play a really strong role in that because it can answer questions that can't be answered otherwise Yeah. And I think it only gets more significant as we age. You know, when I was 40, my recovery capacity was so much greater than now.
Never mind 30, 20. That's obvious. But even the difference between 40 and 50 is significant. And I know there are a lot of people listening to us right now who can relate, right? They're sort of like, hey, I'm getting a little bit older. I don't feel as great as I did.
So it's a question of time and age. And I think the further we get along that, the more this type of system. Again, for me, I can't say enough about it.
Yeah, I think age reduces your margin of error. Yeah, exactly. That's what it comes down to. I mean, I'm 44, and you can do a lot of things wrong in your 20s and maybe in 30s, and you can still get a lot of benefit out of it because you're so resilient. Your metabolism will adapt.
But like you said, the older you get, the less you can do that. And so you have to be much more acutely aware of what your body can and can't do. And that's part of what HRV can help you understand. You said something maybe 20, 30 minutes ago, and I jotted a note down because I didn't want to… derail us at the time, but I'll come back to it now. So, um, when I'm doing my VO two max sets, the thing I monitor for every set is heart rate recovery.
So as soon as I get to the top, cause I do those on a Hill. So as soon as I go to the top of the Hill, I hit a timer, I hit the lap timer and I count how many beats does my heart rate go down in the first 60 seconds at the completion of the interval. And that's a great proxy for how I'm doing.
Um, um, So I've got kind of my normal range should be 30 to 35 on a really good day. I'm 40 to 45. And a week ago or so, I had like one of the worst days I've ever had where I was like 19 to 21 in a minute. That's all I could recover. I mean, I was smoked.
Now, I didn't sleep the night before. So I think, you know, I made an Instagram post about it because I thought it was just a great sort of illustrative teaching point. You said something that made me wonder about another test.
Would there be any utility in right after a VO2 max interval doing an heart rate variability test to see how much sympathetic tone can I dial down and how much parasympathetic tone can I dial up after what's probably a peak, you know, a very high sympathetic, low parasympathetic exercise? You can do that, actually. I mean, it's very.
specific. Like you can't move around if you want to get some standardization to it. So yeah, you could, you could do a 10, 15 minute recovery period. Steven Seiler, the guy, what if I just did it right at the top?
Like literally, would that be too much? Probably, probably. I think honestly, I think heart rate recovery is illustrative of what you wanted to get to because what we see is heart rate recovery is driven by what the reactivation, the balance of those two, it's turning the sympathetic down as quickly as possible and turning the vagus, the parasympathetic up as fast as possible.
So heart rate recovery is already giving you that. information without having to get as granular as pulling out the art you don't have to get that level of detail you can just see the heart rate drop and that drop is being caused by the increase in heart rate variability and what's really fascinating is they used to think and this is pretty new research I was going through we used to have this idea that when your heart rate increased above 100 beats per minute that there was really no vagus input there was almost no parasympathetic and they figured that because They would look at acetylcholine as essentially they could block it into the heart and they'd say, oh, we block acetylcholine from vagus and heart still pumps just fine during exercise. Exercise must not be vagus driven at all. But what they found is that. the vagus might actually be turned up a bit during exercise in some sense because it can increase coronary blood flow by increasing vasodilation in the coronary artery and so hrv is probably not our part the vegas i should say is probably not completely completely off yeah no it's probably not completely off it's this it's this ratio it could be turned up but the sympathetic system has turned up so much more and it's using a different mechanism we don't see the heart everybody pie obviously but it's probably more ready to turn that back up even further as soon as that sympathetic system starts turning down and we're dropping our you know our adrenergic hormone levels or catecholamines all these things are dropping pretty quickly and the faster we can turn that parasympathetic up the faster our heart rate comes down the other thing that's interesting is they've looked at heart recovery in terms of it represents to some extent the balance of the aerobic anaerobic systems that contributed to that exercise so the more aerobically driven something was the faster our heart rate drops because in a lot of ways higher heart rates are driven by that sympathetic and by the anaerobic pieces of metabolism what do you see in young exceptional athletes i mean i i wish i had tracked this metric when i was a teenager like i wish i know how much my heart rate recovered then um back when my peak heart rate was 205 to 210 uh what what do you see in these young collegiate athletes 60 from near max so yeah i trained combat athletes ufc fighters fighters for many many years and they have to go into the octagon or cage ring depending on what they're doing and they have to fight for three five minute rounds the five five minute rounds probably is a ten minute round which is crazy um and so we would use heart rate recovery between rounds that's a really good because it's one minute between rounds yeah that's exactly and they would sit down between rounds so we could standardize that and so i would use that drop as a very good gauge of how well conditioned is this athlete how Ready to go out there.
Give me an example of what you see on a fighter They would come out of the previous round at what I'd want to they come out 160 180 Depend I mean could be depends what the round was around was right in the round was slower It's gonna be much lower, but most of the rounds are between like 160 180 Depending on their their age or anything else you make a drop by 50 to 60 I would want them to get to 130 s between each round We would simulate this in sparring rounds key to leading up to the fight. We wouldn't measure during a fight, obviously Yeah, but if they're doing a simulated fight round where it's three fives or five fives I I want them to be able to drop in the 130s between every round. If we started seeing their first round, they weren't coming down below 150, 160. They're not in good enough shape. They're not in good enough shape.
They were going to fatigue every time. And that just told us they were having to rely so much on the anaerobic piece, they were going to fatigue. Because at a sport like this, where you have to be really explosive, but you have to also have the endurance, it's about the ratio of energy utilization that matters so much.
If you don't have enough anaerobic, you're going to lack power and speed and ability to finish. but if you have not enough aerobic you're not going to sustain that explosive power for very long and so it's really tricky to get that ratio right and you see the fastest most explosive hardest hitting athletes often fatigue the fastest because they're generating that from the anaerobic side and they're relying on that and that's great if they can win and they can knock the person out or submit them but if they can't and you get in the later rounds that's where they're going to really struggle versus somebody else who's more aerobically dominant so that's a really hard part about that sport is getting that ratio correct and training the right side of it but the heart rate recovery was such a great way to see that and so like i said i would want to see inspiring at least you know there are going to be higher heart rates during competition from the psychological stress but we want to see them drop the 130s again this is seated going from standing seated but they should get a heart rate back in the 130s between each round ideally before they go for a fight if they could do that and they were fighting a high level pace you knew they were in pretty good condition and they'd be ready to go out and go if they weren't doing that especially if the early rounds they're like i said round one they're 150 160 you know they better finish the fight quickly they're gonna be in trouble yeah oh that's so interesting um i want to go back to kind of what we were talking about on the the trailing average of hrv data so again i i think the so i'm glad to hear that my failure to utilize morpheus in every moment of the day isn't really impeding its fidelity i kind of know that because again as i said it just it's so damn accurate in what it predicts it's like a shaman. But what amazes me and what I'm sure you have the patience of a saint, Joel, because I email you so much, it must be infuriating. But what amazes me is how sometimes the data I see, I don't believe it. And you're always like, yep, but you got to look back at what it did seven days ago and six days ago and five days ago.
And so walk me through kind of the. The arc of the HRV over time and how, you know, the undulation of the HRV matters as much as the HRV on a given day. This is this is the part that is totally news to me. And again, I think the proof is in the pudding, because at least for me, this seems to really work. Sure.
Yeah. I mean, again, we're looking at not just what is your number, but what is your number in relation to where you're usually at? and we're looking at how much does our number move today versus what's like a normal movement for you and again we're looking at just this manipulation of dials by the autonomic nervous system so what morphs is doing is looking at your seven days and seeing okay what's kind of your normal baseline number itself but also what's your normal level of variability across those different time periods and then we look at standard deviation and so if we see big changes greater than one standard deviation away from your average away from your baseline we know that that's the odd number in your system responding to a greater input it's it's responding to more stress and it's having to make bigger dial adjustments and that tells us that you've been paying a higher cost because you put your body under more stress if we were to probably illustrate to just isolate like let's say we put our body our body's in kind of a normal rested state let's say and then we do a single workout and we allow it whatever necessary time it needs to recover during the workout obviously the body turns up that sympathetic dial It turns down that parasympathetic dial. We produce more force, more energy, more power, blah, blah, blah. And then after the workout, like we talked about, the sympathetic system starts to come down.
The parasympathetic starts to come back up. Now, depending on the workout you did, that could happen in very different timescales. And Steven Seiler, again, who really popularized polar training, he was just showing some stuff.
If you do like zone two and below aerobic work, that recovery happens. pretty quickly within a few hours we'll see that parastimic system turn on and it'll come up above your baseline to maybe 110 120 percent of what your hrv was at rest so morpheus you know if you were i don't know a 70 if you were if you were to theoretically remeasure it you might be a 74 75 you would see a noticeable uptick above baseline because our body has been able to shift very quickly into that restorative phase by that vagus nerve firing more forcefully and turning up the parasympathetic. So we see, again, suppression during the workout and the curve starting to come back up.
During lower intensity workouts, we'll see it pretty quickly come up above baseline. And then kind of as your body went through that complete cycle and restored homeostasis and did what it wanted to do, it would then just kind of settle back down to where it started. And so you'd see this curve, this very clear curve. Now, in a much higher intensity.
But the amplitudes aren't as big. The amplitudes aren't as big, exactly. In a much higher intensity, higher volume, even lower intensity. It's easier to don't do it three hours in heat, right? That's a much bigger stress.
You see the same curve, but it would play out over a much longer time scale because it would take much longer for the body to restore back to where it was and then to get everything where you started with from an HIV standpoint. So we'd see a much bigger depression, a much lower drop. and then we'd see a much longer time scale for it to come back up to normal and then we might see it come up above normal for some period and then restore but i'll say there's a big difference in the individual as well people with higher hrv and people are more fit they're more likely to see this increase above baseline somebody who has less autonomic range they can't quite turn that paracetamol up as much they might never get up above baseline they might just kind of spend time getting back to that base on hrv you never really see the peak above baseline and then they're restored afterwards so it's an individual thing based on fitness but we should generally see suppression of hrv an increase of hrv and then kind of a back to normal hrv it's that process now the tricky thing comes is we have so many other things influence it alcohol influences it mental stress influences it sleep influences it so it's overlapping influences that will get to where you're seeing but that's the core thing of our body response to stress by dropping hrv and then by recovering hrv and then be by coming back to whatever that normal range is.
Yeah. And that's why, again, I think it's not intuitive enough to just look at the HRV that given day. You can't just say my HRV was X today. And there's a one-to-one map between what my HRV is on a given day and what my training output should be that day. Exactly.
Because you need to know the first derivative, the second derivative, and frankly, even the, the arc that it's on. Yeah, it's, it's, it is, it's, it's, it's an all cause. you know metric that's not just looking at one input it's looking at everything and so interpreting that output is not always the easiest thing in the world and again if you kind of look at this like oh up is always one thing and down it's always one thing it's a little more nuanced than that because it's again it's this responsiveness of okay it's going to drop after pure stress that's going to come back up it might come up way above baseline and then kind of drop back down to normal you know this curve is not always the most intuitive thing to understand and and that's part of the challenge i think with people just kind of looking at it and say oh it's this i'm going to go do that Yeah, I mean, it's certainly not intuitive to me, which is why I annoy the hell out of you and pepper you with all these questions.
I want to change gears to talk about something that I've alluded to a couple of times in the past, which is a phenomenon that we see in patients taking this new class of drug. I mean, it's not really a new class of drug. It's been around for a decade, but a class of drug that has gained a lot of popularity in the past probably two to three years, which is the GLP-1 agonist, the dual agonist with GIP as well.
Again, we don't have an enormous and overwhelming body of evidence on this. You know, we don't have that many patients in our practice, and we frankly don't have that many that take it. But certainly over the past three years, you know, I have to think we've seen two dozen patients on these drugs. And again, in all cases, we have overnight information on heart rate and heart rate variability. And so the unambiguous sign that we see is that resting heart rate is going up.
Hmm. And it's going up an average of 10 beats per minute with a range of about 8 to 12. And again, this is unmistakable. It's not subtle. And when they come off the drug, usually within a month, it goes back to normal for patients who do indeed go off the drug. We're also seeing a compression of heart rate variability.
So we see heart rate variability come down, although that's less predictive. But... i now realize we're kind of using the standard we're not using like a morpheus we're using kind of the aura ring or whatever and you know maybe those data just aren't as accurate yeah um so my first question for you is if there's something going on in a drug that is predictably driving heart rate up would you expect it is also driving heart rate variability down do those tend to move in that generally speaking yeah generally speaking you'd see that now just as you mentioned that my thought would be it's it's strong appetite suppressant correct the vagus is very tied to appetite so if you think about this if we were to turn up that sympathetic dial our hunger gets turned down we don't really want to be hungry while we're in the middle of some stressor right but after that period of stressors over theoretically we've burned energy we need to restore and eat and so the vagus is very connected to the gut and to hunger centers and it feeds up into the medulla and it's controlled hypothalamus there's a very strong vagal relationship to hunger and a desire to eat So I almost wonder if suppressing the vagus and decreasing HRV and increasing heart rate is a byproduct of how this is inhibiting appetite. Yeah, interesting.
That would make sense. And so it's an interesting question because it then leads to another question, which is if I told you that I'm going to change you in a way that your heart rate is 10 beats higher and your HRV is 10 milliseconds lower. You would say, well, whatever you did was negative. Sure.
I mean, there's a cost to that, right? Do we think that that could be the case here? I mean, again, we're really wildly speculating, but this is, you know, I get asked all the time, Peter, are these drugs safe?
Are these drugs good? What do you think of them? And I always say sort of the same thing, which is, look, clearly for some people, whatever unknown exists around these drugs is worth it, right? Like if an individual, you know, goes from being...
250 pounds to 200 pounds and having a hemoglobin A1C of 7% to 5.5%, that is so positive for them that I think it justifies whatever unknown exists around these drugs if there's no other way they're going to achieve that benefit. But I'm really more interested in these marginal cases of people who don't have diabetes and want to lose 20 pounds, which by the way, might not. really matter in their overall health. It's cosmetic.
And are they taking too big a risk? That's kind of a question I'm interested in. And that's why I keep coming back to, if it raises your heart rate that much and lowers your heart rate variability, is there, is it, is it doing so, is that, are we picking up a signal that is just a niche representation of appetite suppression via the vagus nerve, or is it actually playing a role in the parasympathetic sympathetic dials i would imagine it's got to be i mean to move it that large 10 beats is a fairly significant amount i would can't imagine that's not having an actual effect on our ability to regulate ourselves effectively we're probably in a more sympathetic state all the time which is going to have a cost now if it's a few weeks or a month you know maybe that cost is relatively small i don't know um but if it's weeks or months and these they're they're living on this drug yeah there's i would suspect there's a real cost to that. And to your point, if it's the benefit is they lose a bunch of weight and all their blood markers improve and we see health outcomes, maybe it's certainly worth that cost.
But maybe somebody, like you said, who cosmetically wants to lose weight and they have an easier time on the drug, it's doing that, you know, is that a net benefit? I mean, it's hard to say because we don't have long-term studies on those drugs. But I would just kind of say in general that, yeah, if we see these noticeable decreases in HRV and these very noticeable increases in heart rate, that's a real sign that the body is, is that autonomic nervous system is being adjusted in an artificial way.
And that probably is not a good thing in the long run, specifically if it's for a long time. Yeah, I don't know where the companies are at in terms of their post. surveillance, meaning post-marketing surveillance studies, and if this is a metric that they're tracking or interested in. But again, given the popularity of these drugs, there's no shortage of opportunities to kind of measure these things. Yeah, it'd be interesting to see.
Also, I'd be curious to see what happens when they come off. Do we see a big rebound? Does their heart rate stay suppressed?
How does it change? Again, our sample size is so small that I want to be very careful and note that everything I'm saying is, again, it could be nothing. It could be that you know it's just a very small n and you know 25 people is not enough but the thing is in the 25 people i've never seen an exception so that's you know when you don't need statistics to measure things you kind of need to pay a little closer attention it's pretty hard to modulate uh appetite that significantly without suppressing the vagus to some extent yeah it's so closely connected but we do see everything come back to normal when people are off the drug um and i'm trying to remember it's been a while since i've looked I feel like it's within a month, maybe even less. It might be within two weeks.
Everything is going back. And the half-life is very long on those, so it would probably just take a few weeks to clear out. And I don't think I have enough insight to contrast the two most popular drugs, semaglutide and terzapatide.
But again, I don't think these drugs are going anywhere. And I would love to better understand this. My guess is there are a number of people. on these drugs that might not be aware of this because either they're just not tracking it or they are but they haven't they haven't noticed it you know i some patients will say this after a few months and i realized they kind of forgot when i told them this in the first place um but anyway wondering if you had seen anything about that or heard anything about it but yeah i mean you see it like i mean adhd medications for example got it you see a very suppressed hiv in a very elevated uh sympathetic arrest and heart rate you see in several type of things like that any sort of strong stimulants, obviously those are not stimulants, but people who live on caffeine and Red Bull and are constantly shoving coffee, like to constantly turn that sympathetic dial up is to me a kind of sign that the sympathetic system isn't working the way that it should by itself, probably because you've overstimulated to begin with through stress and the lack of ability to turn that off. And we see people reach for stimulants and artificial ways of turning that sympathetic dial up once their body's not doing it the way that it should.
And so... you know we see people kind of self-medicate with stimulants to get that sympathetic response when if they had been able to manage stress more effectively they probably would have a normally normal functioning sympathetic system that wouldn't need that artificial stimulus to turn it up let's take a step back and now just talk about where you think hrv belongs in the hierarchy of health metrics um we've talked about so many different types of health metrics and we've talked about how output metrics tend to be preferable you know we can sort of think of them as functional metrics um you know i like an oral glucose tolerance test more than a hemoglobin a1c one is kind of functional it actually is a test it watches how you do something vo2 max strength those are more functional tests than maybe resting heart rate or muscle mass right muscle mass is great it's predictive as is resting heart rate but when you actually put the work out um hrv is obviously a readout state what where do you think on the dashboard of health longevity, uh, where, where do you, where do you place it? You know, I think it's important to monitor as you're going along, but I would say if all your other metrics are telling you you're healthy and you're going the right direction, nine times out of 10, it's, we tell you the same thing.
The, the point where I would be more, uh, aware of it is where it's very low and you don't have a reason for that. You'd want to figure that out. We've had people have with me as they had no idea about, and they go to the doctor and they're on, have some serious heart condition that they need to be aware of. But I would just say long term, it should line up with VO2. It should line up with your metabolic markers.
It should line up with all of this stuff. It's easier to track because we can measure it on a daily basis. I think that's probably the advantage I would say it has is you're not getting a VO2 max test every day, obviously, or every week, every month. You know, you're not doing lactate tests.
You're not doing these markers that are more output based that are really important frequently enough to get feedback of whether or not you're going in the right direction. So I think we can look at HRV in a more... granular daily basis just kind of say am i going the right direction and that's probably more of a utility than a great predictor of you know something and we can look at those daily changes to help us make more informed decisions we can't do that with vo2 max or with you know more invasive tests so it's a more uh you know narrow data point but it gives us something we can use more actionably than these longer term tests i think are better actual measures of outcome and if we see our hiv training down significantly that is a warning sign we're doing something wrong our body is not adapting the way that it should be and we need to make adjustments whether it's the training or or lifestyle so i think it's used differently right like we use vo2 and we use uh those sorts of output measures as are we going the right direction and we have some prognostic value specifically from them we use hrv to say you know are we more likely to be making improvements in the short term or are we heading the wrong direction where if we keep doing that for a long period of time we're going to either see the benefit of the cost depending which direction we're going so i think they're different is there a number joel on the um the log normal transformation you're doing on the rms sd a number below which if it's consistently there you think that you know i would i would want to inquire more 50s 40s i mean those are those are pretty low numbers for for a more just for folks listening that's not the rmssd number right the rmssd number might be far far lower than that yeah exactly yeah so you really do have to be specific of what we're talking about the systems um but yeah i mean this is a you know and one but i was at a guy there was a guy named mel siff who you probably aren't familiar with but he was a very well-known sports scientist he wrote a book called super train i was at his house with the original uh hrv system i was using and i had all the metrics this armist he was like five and he just looked really bad you know i said then he'd had a heart attack and i said mel this looks really concerning he was you know he kind of brushed it off and he died of a heart attack uh you know a few months later and so you know if you're really seeing this super low rmssd or morpheus numbers like it's definitely an indication that that autonomic nervous system is not responding well to the world around it if it's really really low you know there could be a legitimate medical concern that's driving that so if you're you know morpheus 40s 30s and you're just not getting up it's probably worth looking into and it's something to definitely be concerned about and do you see the opposite where really high numbers or a sudden change from low to high can indicate an arrhythmia or something like that yeah yeah absolutely you definitely do see these these kind of weird numbers come out you know that could be arrhythmia that could be medication that could be who knows you see some of these these things jump around from or anomalies that you just kind of like, oh, it's an artifact. I don't know what happened.
And then sometimes you do see a medication or you see weird stuff with COVID and you definitely see some weird stuff in the data that you want to be aware of that, you know, you probably wouldn't pick up otherwise. I would say HRV is more of a leading indicator and kind of how you feel and some of those symptoms can come days later. So you'll oftentimes pick up something that looks weird and then two days later you get a cold or you get the flu or you get some sort of thing that explained it. Joel, this is awesome. I honestly, I feel like I know much more about this now than even after I did the AMA a couple of years ago.
And I learned a lot to sort of prepare for that. So I appreciate it. And again, you know, I apologize, because on some level, this for some of the listeners probably sounds like a bit of a Morpheus commercial at times. But, you know, obviously, I have no affiliation with Morpheus at all.
But I point to it because, again, I'm a big consumer of data. I test. every device out there extensively. And I view it as the, you know, the stickiest device I've ever found for this use case. And so I do hope that people check it out.
I think I just bought it online. It's a, you buy it direct to consumer, right? I don't think you buy it on Amazon or whatever.
So, you know, I would encourage people to, if they want to take this to another level, that they should check out Morpheus. I appreciate the work you're doing, Joel. I think it's, um, it it's, you know, you're, you're the curiosity and inquisition with what you bring to this is fantastic.
Um, I, I benefit from it greatly. And, and those are my patients who use it also as well. So thank you for both, you know, all the work you're doing and obviously coming here to talk about it. Yeah, no, I appreciate being on here and be able to speak to your audience. I think the biggest thing I've learned after, you know, 20 plus years of coaching is we're all different.
Um, and as much as it may be easy or, or a tractor to say oh this is what somebody else is doing let me just try that let me just do the same thing if you can spend the time just copycatting someone else's workout and really dig into your own physiology how you respond to training how you respond to diet how you respond to different food intakes really learn how your physiology works you know you will reap the reward of that in the long run i think that's where you know tools like hrv and sleep monitors they build awareness and whether using morpheus or or whatever else using that data to really be your own coach and really understand your own physiology and your own biology. That's the ultimate way to get better results and have the health outcomes you're looking for. So I appreciate the opportunity to talk about that.
Thanks, Joel. Thank you.