Stress Adaptation and Heart Rate Variability (HRV) with Dr. Mike T Nelson

Logan Christopher: 00:18 We continue our conversation with Dr. Mike T. Nelson. If you missed the previous episodes, there you can find the topics of metabolic flexibility and fasting. And now we dive into stress, adaptability, and heart-rate variability right after a short commercial break.

So, I want to shift gears a bit into talking about stress and heart-rate variability, which is something you're quite [crosstalk] on.

Dr. Mike T. Nelson: 01:08 Sure.

Logan: 01:09 I believe you did some research papers on that. Is that right?

Mike: 01:12 Correct.

Logan: 01:12 Yeah, so for people that are not familiar with heart-rate variability, how would you explain that?

Mike: 01:18 Yeah, so heart-rate variability is a noninvasive way to get a marker of stress on your nervous system. Most people are familiar with what the average heart rate is, and if you polled, most people, they would say, Hey, your heart rate at rest should be just like a metronome. Right? So, very little to no variability.

What we find in research is that's actually very bad. There was an old Chinese proverb that said that if your heart beats like a metronome, your days you have left to live are limited or something like that. So, even hundreds of years ago, they've kind of known that this is a thing and you can go back in time, too. Galen was one of the early physicians who had looked at variability in heartbeats when listening to people he took care of and all sorts of stuff. But it wasn't until probably about the ’60s that we were able to have the equipment to actually measure it.

Initially, HRV was used to measure the status of the Russian cosmonauts. So, when they started putting them up in space, they were like, Oh, how do we know if they're going to be healthy or how do we know if something goes wrong? Because the communication, the radio waves were very, very limited on the amount of data that they could move back and forth.

So, what they did was they found this heart-rate variability and found a way to actually measure it, so they would have the cosmonauts do a little heart rate strap and they would send back literally three to four bits of data from one right after the other, which is called the RR intervals. And then, they would process that basically back in Moscow or wherever they were monitoring them and they would translate that into their heart rate variability score, which would give them a marker of how much stress they were under.

That very similar methodology is still used now, and when I started doing research on it, it was probably almost 10, 12 years ago, the equipment we bought to use was probably $12,000–20,000. It was in the tens of thousands of dollars and you had to come into the lab, and I had to write this little silly MATLAB program to transfer this and to take it and drop it into QBOs, and there was a monkey motion to get the numbers out of it to process it. So, it was kind of a pain in the ass.

But starting about seven years ago, they had phone apps that would start to do this via your smartphone now, which is like a microprocessor in your pocket, and there's many of those programs now. You can literally wake up in the morning, put on a little heart rate strap or some type of finger sensor. It'll take 60 seconds in the case of ithlete to measure. And the accuracy in most of them, I would say, not all of them, but the ones that have published research shows that it's actually really good. It's probably almost equivalent to some of the bigger, fancier pieces of equipment.

And the nice part then is you get a daily measurement that takes just a few minutes because if you're training, you have other stressors you're doing. Maybe you want to do a seven-day fast or whatever and just some crazy stuff like Logan is doing. Just start slow. You can then see how your stress level is changing from day to day, and that to me is the most useful, because a one-time-point measure of stress, yeah, even if it's the morning, not that useful. But now can I see how it changes each day. Oh, I did something different in my nutrition. Oh, I did some different training. Now it becomes useful to try to help figure out what's going on with how your body is responding to all the different things that you're doing.

Logan: 04:47 This just popped in my mind. Are you aware of any researcher correlating this to the stress hormone cortisol in the body?

Mike: 04:53 There is some. The hard part is that they don't line up quite as neat because they're looking at stress response, but a little bit different. So, cortisol is, in my opinion, a little bit more of a long-term-ish management of stress, right? So, if we all of a sudden run, walk through the woods and we see a bear, yeah, by all means, cortisol is definitely going to go up and then it'll come down. But most of the changes that we're going to see immediately are modified by the nervous system itself.

So, related to heart-rate variability, we'll see that the parasympathetic side, the kind of, quote-unquote, “rest and digest” branch of the autonomic nervous system, that will actually go and change very fast. And then, we'll have the sympathetic portion of the nervous system, the stress kind of fight or flight, and that will also change very fast, too.

I tell people it's like having a break in the gas pedal on your car. I push down harder on the brake. That's more parasympathetic activation. The car is going to slow down, right? More rest and digest. If I jam harder on the gas, it's going to be fight or flight, and that's going to make the car go faster, but the engine is going to be under more stress.

So, there are associations between cortisol and HRV. Most of the time acutely they'll look at specific nerve trafficking. They'll take a tiny needle, which I've had done, which is not a lot of fun, and they jam it in one of the nerves, and they actually listen to the nerve traffic, and then they can do different things like maybe put you on a tilt table and tilt you up and down, and do different things and monitor HRV at the same time, and see how there are kind of correlated to that.

Logan: 06:37 Hmm. Interesting.

Mike: 06:38 Yeah, and my comment on that, too, is that a lot of people get mad at me for talking about HRV and then they're off doing four-point cortisol tests all the time. I'm like, Wait a minute, yeah, I don't know how much the saliva cortisol test is associated with things. I think it's an okay marker and gets you in the ballpark, but even if it is a hundred percent nuts accurate, you're still talking $100 to $400 a test. How often are you really going to be able to do that? I can give you an app on your phone that costs very little to almost free. Now you can do it daily and see how things are changing, which to me is a lot more interesting than just these single-point measures.

Logan: 07:14 Yeah, absolutely. Yeah, and then, it speeds up the feedback loop because you can do that. Rather than like once a quarter, -

Mike: 07:21 Yeah.

Logan: 07:21 - once a month, you can do it every single day, which is important.

Mike: 07:24 Exactly. Yeah, it'd be like learning, right? It'd be like, Hey, go squat and I'm going to tell you how your farm looks like four months from now. Oh, okay, that sounds like a horrible idea. Or I can pay a coach to tell me on each rep how I'm doing. Hey, that sounds better if I'm going to learn.

Logan: 07:42 Yeah. I mean, are you familiar with the concept from Chinese medicine or Ayurveda, the pulse diagnostic?

Mike: 07:48 What exactly is that?

Logan: 07:50 Holding different points which would correspond to the different meridians, and being able to feel the difference in the pulse on those points and how that would map to things. I was just thinking about it, so it's like the most simplified version would be just counting the pulse, right, which is something doctors do that, but now our science is getting to these things. We can measure heart rate variability and I'm not sure … I don't know a whole lot about this subject. I’m certainly not a master of it by any sense of the word because that's a very deep thing. But yeah, being able to feel these different things. So, it's interesting to see if our technology continues to kind of map more of those things that ancient Chinese masters have been doing for millennia.

Mike: 08:29 Yeah, I mean, I think there is something to it at a high degree, right? I mean, if you want to go back in time and look at the history of HRV, just look up “history of heart-rate variability.” The main author is Billman, B-I-L-L-M-A-N. He does a really good summary of just the principles and everything, and my guess is that people probably figured this out hundreds or maybe thousands of years ago. Like I said, there's some data to support that and that they were feeling variability. They may not have known what it was as a concept, though. So, in theory, you can feel differences in variability possibly and that can be a marker for stress.

There’s some old thing called the Coca Pulse Test. I think it was by a chiropractor from the ’60s or ’70s maybe—I might have got that wrong—that said to try to pick up food allergies and different things, to eat a specific food and then measure if your heart rate went up or down.

I haven't seen any data that's said that is a useful thing or not, because now you get into the thing of, Oh, let's say I did that and let's say I used heart rate variability. Hmm, if I became a little bit more stressed or less stressed, is that, quote-unquote, “good or bad”? Right? I could do a biopsy of my right bicep after I did a bunch of curls, and look at the muscle fiber and go, Oh my God, that's horrible. Never do that again. The muscle’s completely destroyed. Or I could do it four days after it's healed, and like, Oh, wow, it's a little bit better.

So, I think that's where it gets messy to try to determine, Is that something that is useful or not? And, again, we always want to say it's good or bad, but physiology is kind of dynamic, so it depends upon when does it happen and what is kind of the long-term outcome of that?

Logan: 10:18 Yeah, this is where the terms “eustress” and “distress” can be useful.

Mike: 10:22 Correct.

Logan: 10:22 There are some things that are just plain bad like if I whack you in the head with a hammer, that's not really good. I mean, there's a healing response and maybe it will come back a bit stronger to be able to protect from that, but not so much like it's not a useful thing, whereas doing any sort of exercise, you're stressing the body in order for that to trigger adaptation, to trigger mechanisms within the living body to come back stronger from it. So, yeah, that's a very good point there.

And we know with our food, there's a whole thing about, oh, you shouldn't eat lectins in food, now people talking about this, and, yeah, there may be some cases where you should be avoiding or cutting down on these, but we also see that these are the plant stressors. They go in their body and stress things in order to make our body better adapt and come back healthier from doing so.

Mike: 11:08 Yeah, I would agree with that as that. Is that—I'm going to butcher this, but was it a xenohormedic response I think? Or something like that it was.

Logan: 11:15 Yeah, something like that.

Mike: 11:16 Yeah, there’s actually a technical term for it. Yeah, I would agree. I mean, I like the concept of eustress and distress. To me, that's most useful and, yeah, I mean, all things being equal, I would say a marker of health is to have the most amount of metabolic flexibility you could.

All things being equal, they had this robot a while ago called EATR and it was an autonomous scavenging robot that could use all sorts of different things for fuel. To me, that's kind of the apex of what humans should be like, Oh, I can eat red meat and I'm fine. Oh, I can go eat some of these lectins and I'm fine. Right? You should be able to eat a wide variety of things and still be okay.

Again, that doesn't mean I'm only going to survive on ginger root extract the rest of my life or whatever. People get kind of crazy with one particular thing, but having a good variety of different things, we get different beneficial compounds from them, and then ideally having a response from them be pretty good. Right? You can handle fats pretty good. You're going to handle a long fast and you do good. You can handle eating two bowls of white rice and you don't end up passed out in an insulin-induced stupor under your table. It doesn't mean you want to do all of those things all the time, though, and that's where people get stuck.

Logan: 12:31 Right, so adaptability. I like the term “antifragility” because I think it really [crosstalk]--

Mike: 12:35 Yep, that’s my favorite word with that because you're getting better with stress, right? I can drop a Tupperware bowl on the kitchen floor, and it'll bounce around and not break, but it didn't get better from that impact. And so, a lot of physiologic living systems like humans, I go to the gym and I do exercise, and initially, we measure you may be the next day. You're actually a little bit worse. I'll give you a couple of days and you recover, and then you're actually a little bit better. So, you actually became better because of that appropriate amount of stress.

Logan: 13:12 Yeah, in the very first episode of this podcast, I was defining health. Most people think of it as the absence of disease and I don't think that's a very good definition. Instead, it's the great antifragility or great adaptability to stressors.

And I did a thought experiment a while back of what would ideal health actually look like? And a whole bunch of things like, of course, you need to get all the micronutrients the person needs and whatnot, but this person wouldn't be lacking in stress. They’d actually be under a whole bunch of different stressors, but with the ability to handle those stressors and come back better from them, in which case, they'd actually be getting better over time, not worse.

Mike: 13:48 Yeah, I one hundred percent agree. When I do presentations, I show a picture of—have you ever seen a huge vehicle called the Unimog?

Logan: 13:57 No, I don't think I have.

Mike: 13:59 I just saw a picture of it next to a Land Rover and it dwarfs the Land Rover, and a Land Rover is not a small vehicle. It's much bigger than a Hummer H2, and I believe they used them towards the end of World War II. So, I actually got to hang out and find warm air in Baja, and I am standing next to it and the top of the tire is just under my armpit. This is a huge vehicle, but they use it for a lot of races in Baja and across the desert because it has super-high clearance suspension and it has all these things to literally absorb and handle a massive amount of stress.

So, I always think of physiology is similar. What amounts of stress can you take on and sort of absorb, and get back to baseline or homeostasis faster? I would agree that that to me is a much better marker of health, and indirectly we have all these markers that are literally that.

What is heart rate recovery? Hey, let's stress the piss out of you with exercise and see how fast your heart rate gets back down to baseline.

What’s an oral glucose tolerance test? Oh, let's give you 80 grams of glucose and see how high you go and how fast you get back down to baseline, without going hypoglycemic on the other end, right?

What is performance? How fast can you change directions, whether that's a sprint, change of direction in a football game, changes of the direction of a heavy deadlift off the floor? Right?

So, we have all of these kinds of indirect, I would say, markers of that concept already.

Logan: 15:37 Absolutely. And, of course, there's many of them because the human body is very adaptable and can try a lot of different things out.

Mike: 15:44 Definitely.

Logan: 15:45 With the heart-rate variability, just to kind of close the loop on our idea there, so if you're observing that every day and making changes just because you have, let's say, less variability the next day, then that doesn't necessarily mean that thing is bad. It means you're more stressed. That could be stress in a good way versus a bad way.

For instance, the exercise thing, once again, the next day, if it was a really hard workout, you'd probably have a lot less heart-rate variability. That's not necessarily saying it's a bad thing. You have to look at the trends over time.

Mike: 16:15 Yeah, and that's where people would go kind of awry, like recently there's a bunch of people who have their undies in a bunch because HRV and research wasn't necessarily absolutely predictive of acute performance or even over a short multi-week training study. Again, one of the studies did show they got to the same result by using HRV versus not using HRV, and I won't go down that whole rabbit hole.

But all you have when you look at HRV is a measure of stress only on the autonomic nervous system. I would argue the autonomic nervous system, if you want to measure one thing for stress, that's a really good thing to measure because it controls a lot of stuff in the body, but, like you mentioned even with cortisol, it's not absolutely everything. All right?

A lot of people are obsessed with, Hey, what is the one metric that can predict performance? It's probably a performance, right? I mean, doing a vertical jump can get you close and some stuff for reactive strength, things of that nature, but non-performance metrics, and we know they're a real thing, but the physiology is not quite that simple like fatigue is a multifaceted thing. And everyone listening to this knows this, right?

How many people listening to this have gotten up one day like, Man, I don't feel very good? I'm supposed to go to the gym today and do heavy deadlifts? When you get there, you kind of get through your warmups, and you're like, oh, I'm feeling a little bit better. You should. You pulled a 10-pound (PR 17:40) out of nowhere. Right?

It happens. It's probably not going to happen all of the time, but you're not going to do that every single day. Right? I can take my little Jetta and drive to Cub Foods and redline it. I can get there faster, but I'm not going to be expected to do that every day and expect that the engine's going to last 250,000 miles. So, there's always a cost somewhere associated with it.

And what you said is also true. There may be some days where I want to see a worse, quote-unquote, “HRV score” the next day, right? I'm maybe trying to reach something that's a little bit higher, so I need to and impose enough stress that it may take me 24, 48, 72 hours or longer to get back to baseline from that stress.

Again, that's not inherently a bad thing. However, if I don't realize that and I don't know that, and I tried to repeat that thing again three days later, eeh, I may get away with it, but if I do that enough, it's not going to be quite so good. So, to me, my little, quote-unquote, “golden rule of HRV” is it's only telling you the status of your autonomic nervous system at that point in time when you measure it, which is now only the first thing in the morning, the measurement.

And, to me, that's still super useful, right, because I can see how much stress my body is under. The hard part is it could be from a whole bunch of different things. It could be from poor nutrition. It could be you had an accident and your dog, unfortunately, died the day before. You got in an argument with your spouse or training was harder than you expected. Right? It could be a lot of different things. All of those are going to provoke a pretty big stress response.

And so, that's the tricky part about HIV. It’s kind of trying to figure out, What are kind of the main things? What are some of the main drivers? And then, I use that to kind of autoregulate performance long term because I can look to see, okay, if let's say their lifestyle is good and not much is going on there if we just simplify it and I really start pushing them hard on training.

The first kind of cycle I do with new clients is I just push them by adding more volume each week until they tell me that they hate life and their HRV goes in the tank, because within one cycle, I have a really good idea of about how much volume and how much stress their body can handle.

And, again, this is done in an intelligent manner. I don't want huge load spikes or anything like that, but some people get up to doing five, six, seven sets of training a day and maybe training five to six days per week. Most people aren't nearly close to that high. But, by looking at HRV, that gives me an idea because I'm getting that response of their specific physiology, so I have some data to know, Okay, ooh, getting kind of close here. Ooh, might kind of go over the edge there.

And then, I'll actually use that. So, if I'm programming, say, for a powerlifter to peak for a big meet, we may take then nine or 10 weeks, push all the volume up super high. Ideally, we want to see HRV is starting to tank maybe two weeks out, and then I'll run a very long taper to make sure we have enough time to replace, kind of resolve all of that stress so that they have a little bit of super-compensation on the day that they're being tested.

Logan: 21:03 Yeah, that's really good stuff. I have a question with HRV. I imagine you've been doing this for yourself for quite a long time.

Mike: 21:09 Yeah.

Logan: 21:10 Can you do it without measuring it? Do you pretty much know where you're at?

Mike: 21:14 What's funny is I've been trying to do that for years, so I've been doing my own HRV daily for seven years. I mean, I've literally probably only missed a handful of days, and people are like, Hey, you dumbass, don't you know anything about your own body? Why the eff are you still measuring HRV?

And the answer is, most of the time, I'm pretty close, but—and I stole this quote from Simon who runs ithlete and I agree with him—10 to 20 percent of the time, I'm not even close at all. And the thing that people forget is that some stressors are unconscious.

For example, I recently was down in South Padre, Texas. We drove down, did a bunch of kiteboarding. It was super fun. Stayed in a slightly different place. And my HRV was the highest it's ever been before we left. Even traveling down, everything was looking great, and I get there. I go out and ride. It was super cold out, but not a big deal.

And then the next day—every day I took my HRV for literally the next nine days—it just was on this roller coaster, headed downhill, and I'm like, What the hell? I'm playing with different things with sleep and recovery, and training, and trying to figure it out, and it still kept going down. I'm like, This is so weird.

At the end, I was left with, huh, I wonder if it's from kiteboarding and trying to do jumps, and just massive amount of neurologic input to your eyeballs and vestibular, and that kind of stuff. We’ve changed almost everything else we can.

We stayed in a place that had two open bedrooms. I'm like, Let's just try the other bed for just the hell of it. Boom. The next day it goes up like eight points. I’m like, What? Try it again. Next day, it goes up eight points. Again, maybe it's all negative associations with one bed versus the other. Maybe it was one had kind of a foam mattress on it and it does tend to accumulate a lot more heat and things like that. I don’t know. But, within two days, I felt way better for some odd reason.

So, if I hadn't been doing HRV, what I found in the past was I would tend to just bury myself in a hole because I'm like, No, that can’t be good. You're feeling off today. There's no reason you should be off. Just train harder, you pussy. Or if I look at the number and go, Huh, okay, this is a lot lower than normal. Eeh, I feel a little off today. There's probably something going on. I don't need to necessarily figure out what it is right away, but I know, okay, I'm just going to do some music cardio today. I'm going to move my strength training until tomorrow. Right? So, yeah, it's been interesting. I'd say most of the time I'm pretty close, but there are some days where I'm super far off. It’s interesting and maddening at the same point.

Logan: 23:56 Yeah, in the next seven years, maybe you'll be able to dial it in a little bit further, but, yeah, it's interesting.

Mike: 24:02 Yeah. It's a … I don't know. And then, I go into the whole thought process of like, Oh, do I want to be conscious of all the stress I'm under? I don’t think so. That doesn't sound like a good solution either. So, yeah.

Logan: 24:14 Yeah, and I think that's a really good point. We don't, aren't aware of all this stress, like I talked about EMS. Sure, there seem to be those hypersensitive people that can notice things and some of them may be crazy as well, but the average person doesn't, but that doesn't mean it's not affecting them down to a cellular level. That can be causing things that's going on. So, there are all kinds of hidden dangers or stressors out there that may be having an impact. Who knows what was up with that bed that could have possibly been it? And it could have been something else and not even related to the bed.

Mike: 24:46 Totally. Yeah, totally. It's the analogy of the … a buddy of mine tells a story of the barking dogs in the room. The dog doesn't know why he got locked in the room. He just keeps barking, and one day the door opens and the owner lets him out. So, now he just goes, Every time I bark, then if I get stuck in a room, the door will open, right? Just the simple association.

And I have a couple of friends who are kind of very proud of how sensitive they are to things, and I'm like, Hmm, that's interesting. If I need a human guinea pig detector for stuff, assuming you're accurate, but, man, as a way if I wanted to live my life, I don't want to be that sensitive to stuff. That sounds like you kind of went a little too far in the wrong direction, in my biased [opinion].

Logan: 25:30 Being a canary in the coal mine has its drawbacks.

Mike: 25:33 Yeah, that canary is …

Logan: 25:36 Yeah. All right. There’s so much more we could discuss here, but coming up at the end time here, where would you like people to go if they like what they heard today and want to check out more about you?

Mike: 25:47 Yeah, the best place is probably just the website, which is MikeTNelson.com, M-I-K-E-T-N-E-L-S-O-N. At the top of the main page there, there'll be a way to get on the newsletter, which is free. Most of my content, similar to Logan’s, goes out over the newsletter, so that's where you'll be able to find most of it. I've got articles and a bunch of other stuff on the site.

And I do have a certification for people, especially trainers, who are looking for nutrition and recovery aspects. They can find that at FlexDiet.com, F-L-E-X-D-I-E-T [dot] com. There’ll be a way you can get on the waitlist and on the newsletter there. Usually, we release that … yeah, right now we've been doing it about quarterly per year, so it's kind of a mashup of metabolic flexibility and flexible dieting, along with a bunch of other stuff.

So, those would be the two best places.

Logan: 26:38 Excellent. Thank you so much. And, like I said, Mike has a new podcast, so you want to mention -

Mike: 26:42 I do.

Logan: 26:42 - that as well. Not Another Fitness Podcast.

Mike: 26:45 Yeah, Not Another Fitness Podcast. I had a little podcast contest and I had a lot of really good ideas, but I was like, Oh, that one kind of makes sense because that’s the reason I did it, do it for a long time. But these are little daily ones. They're some daily kind of shorter concepts that are five to 15, maybe 16 minutes long, and then, I’ll be having a few more interviews probably coming out next year, if we can get a few more funds.

And, eventually, I'd like to be at the point where I can go out and fly out, and visit people and hang out with them in person, and get some good info that way, too. But, yeah, we'll see where it goes. But, right now, it's just mostly pure information as another way of trying to get better, like yourself, information out into the world, make it a better place.

Logan: 27:30 Excellent. Thank you so much, Mike, for joining me today. I hope everyone enjoyed this and as always, I’d love to hear your feedback.

Mike: 27:37 Thank you very much. I appreciate it.