In this episode, I’m speaking with Dr. Mike T. Nelson, a self-described research fanatic who has more than two decades of experience studying and obsessing over how the human body works.
Dr. Mike has a Ph.D. in exercise physiology, a master’s degree in mechanical engineering, and is an associate professor at the Carrick Institute and a university instructor at Rocky Mountain University.
He’s also the creator of the Flex Diet and Physiologic Flexibility Certifications, has published research in both physiology and engineering scientific journals, and has even been asked to share his techniques with top military agencies.
Today, Dr. Mike and I go deep into the research and practical applications of heart rate variability. HRV has gained popularity as a performance metric, but after listening to our conversation, you’ll have a much broader understanding of HRV, how to apply it to your life (whether you’re athletic or not), and ways to improve your HRV score.
Table of Contents
In this podcast, Dr. Mike and I discuss:
- What, exactly, is heart rate variability (HRV), how it’s different from a standard heart rate measurement, and why it’s so important to understand
- How HRV relates to your “rest and digest” and “flight or “flight” responses
- What HRV really tells you about your body versus its popular use as a performance metric
- Why HRV isn’t just for people who work out—it’s an eye-opening data point for anyone who wants to learn more about their health and response to stress
- Ways to practically apply your HRV readings into your daily life and workout schedule depending on your personal goals
- Athlete-specific ways to use HRV, such as HRV-guided versus traditional periodization, how to apply HRV if your progress has plateaued, and how to achieve long-term success
- Is HRV a reliable predictor of longevity? Plus, we discuss a well-studied (but surprising!) co-metric that is an amazing predictor of longevity and mortality
- Dr. Mike’s opinion on HRV devices, how accurate most of them truly are, and the best time of day to measure your HRV
- The role genetics might play in your HRV score and why some people simply have higher (better) HRV readings than others
- The top 6 factors that can negatively impact your HRV
- The difference between acute and chronic stress and how HRV helps you find the “sweet spot” of stress that actually improves your health!
- The 3 primary ways to increase your HRV even when nutrition, sleep, and training are dialed…along with some out-of-the-box methods Dr. Mike has seen in his clients
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Transcript
Ari Whitten: Hey, this is Ari. Welcome back to the Energy Blueprint podcast. In this episode, I’m speaking with Dr. Mike T Nelson, who is a research fanatic that specializes in metabolic flexibility, heart rate variability, and human performance. He spent the last 20 years of his life learning and studying and obsessing over how the human body works. He has a PhD in exercise physiology, also a master’s degree in mechanical engineering, which relates to biomechanics as well.
He’s an associate professor at the Carrick Institute. He’s a university instructor at Rocky Mountain University, and he’s the creator of the Flex Diet and Physiologic Flexibility Certifications. He’s also the research and human performance science advisor at Tecton, who are the makers of a unique ketone ester supplement.
He’s also an advisor to the company Rapid Health. He’s published research in both physiology and engineering peer review journals, and he’s even been called to share his techniques with top military agencies.
As you’ll hear, he is an absolute wealth of knowledge, and in this episode, we are talking all about the very important metric that, as you’ll hear, relates both to day-to-day management of your stress, of your fitness routines, and much more, but also, maybe more importantly, it also relates to your long-term risk of early mortality as well as your longevity outcomes. This is a wonderful and important metric that we can use to get a picture of our overall health status and a predictor of how long we’re likely to live.
Heart rate variability is an incredibly important metric. It’s something that I personally measure every day and use and believe in, and I recommend you guys all do the same. This is a deep dive into the science with somebody who has an extraordinary wealth of knowledge on this topic. I hope you enjoy this podcast with Dr. Mike on heart rate variability. Mike, welcome to the show.
- Mike T Nelson: Welcome. Thank you so much for having me here. I really appreciate it.
Ari: Yes, I’m excited to get into this with you. I’ve been following your work for many, many years, and it’s nice to finally connect with you.
Dr. Nelson: I’ve been following your stuff in the past too, so nice to finally “meet” in person, I guess, or virtually. [chuckles]
What is HRV
Ari: Cool. We have a lot of different topics, as we were just chatting about, that we could potentially talk about. I wanted to focus this podcast all about HRV, heart rate variability. First of all, to just help people get into this world with us, can you give people a high-level overview of what HRV is in simple terms and explain why it’s an important metric?
Dr. Nelson: Yes. At the simplest level, everyone is familiar with doing your average resting heart rate or getting your heart rate during exercise, and that does provide you some information. It’s definitely useful. However, if we apply more advanced mathematics, we can do something called a variability analysis, and we’ll explain what that means in just a bit. What that allows us then to get is a status of your autonomic nervous system.
If your listeners are probably already familiar, autonomic nervous system has two branches. We have the parasympathetic branch, which is just like the brake on your car. If I push down harder on the brake of the car, so I increase parasympathetic tone, I’m going to push harder on the brake, and the car is going to slow down. We know heart rate generally slows down. This is more of the rest and digest branch of your autonomic nervous system.
On the other side, we have the sympathetic side, which is more of the stress side and fight, flight, freeze, and a bunch of words associated with that That’s like the gas pedal on your car. If I push down harder on the gas pedal, I’m going to induce more stress on the car and the engine, but everything is going to speed up. I’m going to get more performance from it. The main part about doing heart rate variability is it allows us a really nice marker for status of the autonomic nervous system. Are you more on the sympathetic side? Are you more on the parasympathetic side?
This is, not an on or off switch, but more like different dials or a volume indicator. The analogy doesn’t work so much anymore because people don’t spin records anymore, but the old school– where you had the Tech 12 records. Imagine you have the one record on the left side, one record on the right side. The blend is how far are you? Are you really on the record on the left on the parasympathetic? Are you really on the record on the right on the sympathetic? You can be anywhere in between there. Heart rate variability gives us a really nice way to see where you are at that particular point in time. You get more information than just the average heart rate.
Ari: What is this useful for, practically speaking?
Dr. Nelson: How I think of it, when I initially got into it, I was hoping that it would be a really good metric for prediction of performance, i.e., “Hey, I did this measure this morning and it says, ‘Yes, go balls out at the gym. It’s going to be amazing,’ or, ‘Ooh, today’s definitely a rest day.'” You can use it for that, which we’ll get into the details of that, but prediction on one variable, as you know, for performance historically, isn’t very good.
Maybe [unintelligible 00:05:40] there’s a whole bunch of ways of auto-regulating and God knows I’ve probably tried all of them from the tap test to sticking this little thing on my finger that would zap the muscle of my thumb and measure twitch response and all this stuff. It gets you in the ballpark, but it wasn’t as good as what I had hoped.
What I’ve realized over time is that HRV is better at measuring the cost of everything you’re doing on the system. It’s not necessarily performance prediction, maybe, but if you had a really hard training stress, a hard training day, and then maybe you’ve got a bunch of other stress, you’re drinking four cups of coffee, your sleep is a disaster, your spouse is mad at you, whatever, all of those things are stress on your system. That will show up in your heart rate variability measurement.
I find it’s more of response of the system. How I explain it to clients is we have the training program and all the other stressors in your life, that’s the stimulus that we’re looking at. I really want to know what is the response of that system? Because as you know, everyone will be a little bit different for that. Different levels of fitness, different levels of outlook, et cetera.
Over time, if you have that stimulus and response day in and day out with clients or yourself, it allows you to titrate and go, “Oh, wow, if I really pushed it hard on the rower for 500 meters, yes, that really tanks me. Where I could lift heavy for two hours, that didn’t really tank me as much.” I could literally go down my list of clients to the next client and it would almost be the inverse of that. It allows you to then customize things over time and then get more specific with what you’re going to do for recommendations.
Who is HRV relevant for?
Ari: Is this only relevant for athletes or for people who are really into fitness, or is it relevant for people outside of that?
Dr. Nelson: Anyone can use it. When I first started, I was like, “This would be good for athletes,” because that’s probably what it was done. My initial foray into it was the Omegawave system, which was a Russian system. It’s been around for a long time, but at the time I didn’t have $30,000 to spend on this mythical black box that only a few people in the world had.
When I started studying my PhD in HRV, lo and behold, a few years into that, a guy was able to make an app for $10 that would accurately measure HRV. I was like, “Oh, this is great. Now I can have more clients do it.” You can do it on a daily basis because a one-off measurement isn’t really that useful. It’ll tell you where you’re at, but that can change day to day. What you really want is a measurement done first time in the morning to see where you’re at.
I just wanted more data. I just started taking general population clients, everyone. I just said, “Hey, if you want to work with me, you have to do HRV,” because I wanted more data. What I realized was that everybody can use it, but you have two different populations. If you have more of your high-level athletes where their main stressor in their life, hopefully, is their training. The rest of their life is, hopefully, pretty good. Again, this doesn’t always happen, but their training is the main stressor. Nutrition is good. Sleep is good. Everything else is pretty good.
The general population is the inverse of that. Their training may be stressful, but it’s probably one of the only stressors they control in their life. They’re sleeping four hours a night. They’re driving back and forth. They’ve got kids. They’ve got all these other stressors pulling at them. Their training stressor is definitely usually not their main stressor. In that case, the more general population, I’ve used it to try to get them to realize the cost of everything that they’re doing to themselves.
The perfect example is sleep. I loathe having sleep discussions with clients because nobody wants to be told, “Oh, those one or two hours I watch Netflix at night, I just need to shut up and go to bed earlier. I’m not going to put my kids up for adoption. I’m not going to change my job. I have all these other things going on.” If you’re sleeping four hours a night, unless you’re a DEC2mutant, you just need more sleep. It was a very difficult conversation.
One day I just gave up. There’s a client who was complaining, he’s like, “Hey man, I’m paying you all this money. I’m not getting the results I want. I’m trying to do this stuff. I’ve got all these stressors.” We’ve had this conversation multiple times. I just went back in old school Excel and drew a graph, put on “Hours of sleep in bed,” this is very primitive, and, “Stress.” You see sleep time in bed goes down, stress goes off the roof and I just sent him the graph and said, “Hey man, what do you think is going on here?” He looks at and he goes, “Oh, holy shit. You’re telling me when I’m not sleeping, my stress goes up?” I’m thinking, “Yes, man, we’ve had this discussion for three fricking months at this point.
I realized at that point that seeing the actual hard data of their physiologic response to it from them as an individual was probably the first time in their life they ever were made aware of the cost of everything that they were doing. That’s when I realized, I’m like, “Oh, HRV is a really good driver for in all these other habits we want to do with general population clients.
Let’s say they go to bed a half hour earlier. Great. Now you’re sleeping five hours a night. It’s probably not going to repay all your sins of stress, but we could see, “Look, your HRV is getting a little bit better, even though you still feel like dog crap,” and they’re like, “Oh, okay. That trade off I made of going to bed a half hour earlier, I don’t feel better, but I can see that physiologically I am getting better.” You can give them a little bit of a win.
Then a lot of times they’ll come back and they’re like, “Oh, I am starting to feel better now. I’m thinking that I rearranged some stuff. I can go to bed a half hour earlier again.” It becomes this sort of game you can play with them because you’re getting a marker of changes in the system, even if those system changes are sub-perceptual for a while.
Ari: In athletes, you mentioned that using HRV is not as predictive of performance as one would hope, but that it it’s more of a gauge of how much of a price we’ve paid for stuff we’ve already done or how much we’ve taxed the body perhaps with recent workouts or a particular kind of workout. How do you recommend someone- an athlete or just somebody who’s into fitness, a general person who wants to exercise regularly and to get fit and healthy, how do you recommend they leverage this technology? Is it necessary? Is it necessary for them? Is it helpful for them? If it is helpful, what can they do with this information that’s helpful for them?
Dr. Nelson: That’s a good question. How I use it is the high level discussion like we had, “Hey, this is a cost of everything that’s going on in your system.” Then I also use it on a day-by-day decision basis. In terms of prediction of performance, it’s okay for some endurance performance. I’ve had athletes who have had a horrible HRV score and gone out and set PRs, national records, that kind of thing.
If you think back to what we said, “What is HRV?” that makes sense if they’re doing a sport like powerlifting, because when you are more red you lose fine scale variability, you become more on the sympathetic, that gas pedal side of the equation, your body is just hanging out in that stress cycle. Now, if you’re going to go and do something that is a large amount of stress, like lifting heavy weight hopefully nine times, okay, that makes sense. I probably want someone temporarily on that side for that level of performance. If you purely went by what the HRV said, you’d be like, “Oh my God, it says it’s red, you shouldn’t lift at all,” too bad your competition’s today, you don’t have a choice.
In context, it can make a little bit of sense. If we back off from that extreme example, most clients in general have them some type of programs. Let’s say they’re lifting five days a week. They’re doing something five days a week. Monday, Wednesday, Friday, they’re probably lifting. Tuesday, Thursday, Saturday, I’ll have them do some type of cardio. Say their cardio is more moderate zone to relatively easy, if their HRV shows that they’re really stressed on Monday morning, I’m like, “Great. Let’s just flip Monday and Tuesday. Let’s take the easier day Tuesday, which is easier cardio, let’s do it today, Monday, and let’s do the higher stress stuff tomorrow.”
The overall scheme of the program didn’t change, the total volume in the end of the week’s going to be the same, but we’re going to prioritize the thing that’s heavier stress when your body is showing that it’s a little bit more recovered. The issue you can run into though, is if you have a client who maybe only has– Monday and Thursday is the only time at noon, bro, they can get to the gym. At that point, I probably don’t care.
If you skip Monday, unless you can move it to Tuesday, but if you can’t because of schedule, now my option are, two sessions a week down to one. I’m probably going to say, “I don’t care what your HRV is. Just go to the gym because you’ve got all this time in between to also recover.”
That’s where I think people run into issues is– because I get all sorts of crazy emails from people that are like, “Oh, so you’re telling me ethylene [unintelligible 00:15:18] two days a week and you’re telling me HRV is bad that she shouldn’t go to the gym and not train.” I’m like, “No, I’m not saying that. I’m just saying that if you have the choice, take something that’s going to match your stress level. That may be pushing your schedule out by a day. Maybe Sunday is a flexible day. Maybe you can just take an off day on Monday, shove your whole schedule out by a day and you get everything in over the course of a week. Perfect.”
It’s looking at trying to match what the overall stress is to that individual day, and then also tracking the long-term changes week to week, month to month. If I have someone who’s a little bit higher level athlete, and they want to do a powerlifting meet, we may stress the ever living crap out of them up to three to four weeks before a meet and then remove that stress for a taper and then do their performance.
It can work on both sides. I think the hard part is people– I understand why. They want the easy answer. I want this little guy to pop up out of the device and tell me like, “Today’s the day, go for it, bro,” or, “Just go back to bed.” You can get there, but you have to look at the overall context and see what’s actually going on.
Ari: There’s another layer of complexity here, which is that exercise can be thought of- and I think this is more of the frame that you were just presenting it, more in the frame of an athlete who is training for high performance, it can be thought of as a stressor, the workouts you do are part of the stress load on your body. There’s another frame which is, exercise as a stress reliever, as something we do to de-stress and that makes us feel better when we are stressed.
Maybe we’re also talking about different kinds of workouts. Maybe one is really in the context of an athlete training super hard and doing really intense workouts that are very taxing. On the other hand, maybe one is just going for a bike ride or a jog or a more casual lift at the gym, or something like that. How would you incorporate that? Let’s say somebody is stressed out, but they see their workouts more as a form of stress relief.
Dr. Nelson: With that, again, I’m going to look at what is the cost of that session? I’ll pick on CrossFit for a while. I love working with CrossFit athletes, I think they’re great, because most of the time you just have to spend your time just telling them not to do stuff, which is easier than trying to motivate people.
Ari: Just stop doing half of the stuff you do in CrossFit?
Dr. Nelson: Yes. The intermediate person who’s pretty good at their gym, but gets their butt kicked at the next level, historically, every time I talk to him, the aerobic base sucks and they’re like, “I just love doing CrossFit. It’s the best stress reliever of my life.” Their respiratory rate’s fricking 17 overnight. Their HRV is okay. The resting heart rate’s high. We usually have to have this chat of like, “Okay, that’s cool. On the mental side, if that’s what’s going to hold you together, by all means, please go do that. However, you then are also telling me you want to be more competitive and you want to get better at this thing.”
Now it’s a different conversation versus, “I just go to the gym three days a week. It’s my stress relief. I don’t really care if I make a lot of progress or not.” “Okay, fine. Great. Whatever.” Now if you’re telling me, “I want to make progress at this thing,” then I’m going to keep showing you data that says every time you go beat the shit out of yourself, you’re wrecked for 48 hours.
Your options now are, we can modify that, we can add some things in, we can work on your recovery, we can work on your breathing to mitigate those things and still let you go ham at the local CrossFit and see if that’ll work, many times it can, or you’re going to have to modify said workout to some degree. Usually, they’re like, “Well, I don’t like that.” I’m like, “You have associated progress with you crawling out of the gym and making sweat angels on the floor. If you want to do that, that’s totally cool, I don’t care, but you can’t want to make progress at the same time when you’re clearly going backwards.”
that’s usually what I call the come-to-Jesus talk of like, you can do these things, and there are freaks who can handle that and do perfectly fine, they usually are very competitive in that sport and do well, but if you’re not one of those freaks, you have to make some concessions somewhere else.
Ari: Is this where you break out another one of the pieces of paper and you draw one of those fancy graphs that you alluded to earlier?
Dr. Nelson: Yes. I literally just keep sending them graphs of HRV the next two days, and then we have some marker of performance that they can do, because as much as I love CrossFit, it’s really hard to see if you’re making progress or not when everything is changing all the time. We’ll have some agreed-upon CrossFit WODs or a 2K on the rower or some metric that we will reassess over time to see if you’re making progress.
At the end of the day, it’s a client’s choice. I’m just helping you get to your goals and do whatever maximizes your life. If you’re okay with your 2K never getting better, and that’s what you need for sanity relief, cool, man, I’m fine with that. That’s cool. If you’re like, “Oh, my times aren’t getting better. Everyone’s beating me in the local WODs,” and you’re overrunning your system and redlining it all the time, now something has to give, we have to make a decision somewhere here.
HRV-guided training versus traditional periodization
Ari: What are your thoughts on HRV-guided training versus traditional periodization?
Dr. Nelson: Ooh, good question. I think it’s better, although the research I would say is super mixed on that. The research I would say would say for endurance athletes is probably better. With strength athletes, it gets muddy and messy really fast. My argument is, all things being perfect, we could give you the perfect, seven-stage Russian periodization program that we say is “optimal”, or I could give you more of a flexible framework that we’re going to change based on your biofeedback. The Soviets would call this cybernetic periodization and they had all sorts of fancy words for it.
Pretty much any time you can intelligently take and incorporate feedback from your own body, you’re going to do better. That would be my argument because I’ve seen when I’ve worked with a lot of people, not so much now, but especially in the past, who had ex-coach who was a famous person, he or she followed their periodization and they just burned them into the ground. The person was super motivated because they paid said coach who’s top person all this money and just torch themselves, and then I get them and have to figure out why they got so messed up.
In pretty much every single case, it was like, “Well, I felt bad. I was starting to have issues. My sleep was getting disturbed.” There’s all these warning signs, because their body is saying, “This isn’t a temporary thing. We’re going to push you for a couple of weeks and pull back. We are running into issues.” You’ll run into overreaching, which, Bill Kramer’s definition would be, take two weeks off of training. If it comes back, you were overreached. If it doesn’t, you’re probably have overtraining syndrome, which, in hindsight, isn’t very useful when that athlete is in front of you.
My argument is, you don’t even have to use HRV, just use some intelligent system of monitoring what signals your body is telling you. Measure your output, measure some level of performance. It can be very simple. It can be just weights lifted, density, volume, whatever. There’s many ways to measure it. Then what is the feedback your body is constantly giving you? Then you have to decide as the outfit, as a person, “Okay, this is worth it. I’m going to really push it today because I’ve got two days off and I have to travel,” or, “I’m going to pull back a little bit.”
My argument is if you’re prioritizing for the long game, most of the time, I’m going to have athletes pull back or do less. If it’s general population, they might need to do more. Usually there, I’m trying to push them to get to a true level of an RPE of a 10 and to push them until they realize, “Oh, okay, this is the max.” Now we have a reference on those end points and now we can play in between.
Ari: I’m interested how you conceptualize it, but there’s almost two contexts. Maybe there’s more, but there’s at least two contexts that I can think of to talk about HRV and to think about what we want to do with that metric. One is pretty much everything that you’ve been describing here, which is working with individuals, especially, people who are training, people who are into fitness, people who are athletes, and how do we use that HRV tracking to understand how much we’ve taxed our body and to optimize our training accordingly?
There’s also this other body of literature that has linked HRV with health and longevity and mortality outcomes. I’m interested again, how you would conceptualize the distinctions here. One context is taking an individual and looking at, “okay, whatever your baseline HRV is when you feel good,” and then monitoring the day-to-day fluctuations and adjusting what you’re doing accordingly, “Maybe I need a little less hard training, a little more recovery, a little more sleep, et cetera.”
Then there’s also, what is objectively your HRV? Where does that put you relative to population scores, what we know about objective HRV scores, and how that correlates to mortality outcomes and health and longevity, the bigger picture of that. How do we not just use these day-to-day fluctuations to optimize what we’re doing, but how do we actually go from this level of HRV up to this much higher level of HRV, which indicates that we’re at a much lower risk for various bad mortality outcomes, or another way of thinking about it is that we’re likely to live a longer life?
Dr. Nelson: Definitely. I get a lot more of the latter case right now than I ever have, which is cool. It’s great. People are looking at more longevity stuff, which is awesome. You’re a hundred percent correct. HRV is highly associated with longevity, especially cardiac mortality and risk and everything else. It’s associated with all sorts of stuff. The bugger in all of it is what measurement system did they use? What sort of algorithm did they use to get the score? Because even in the consumer area, not all of those devices agree.
For example, I have an Oura ring. I do lots of Oura analysis on my own clients. I work for Rapid Health Optimization. I do Oura sleep analysis, HRV on all their clients that come through there. I have a Garmin that gives me HRV. I have an app that uses iFleet and the first thing in the morning to do HRV. Those three HRVs, even if I put them on the same scale, they all don’t agree. They will generally move in the same area.
Each app has their own, I’d say happy range of what HRV is. If I’m just looking at Oura, for example, and somebody comes in and they’re like, “Hey, I heard HRV is this great thing for longevity. My baseline is 14,” which happened the other day, I’m like, “You definitely would do better with a higher HRV because that is very low.” On Oura, if I were to back-of-the-envelope calculate it, most people, I want to see 30 to 50, probably in there.
The hard part is once you start getting 50 to 70 and above, there isn’t as much benefit because it’s this logarithmic scale or the inverse of it, actually, because people would be like, this happened two weeks ago, “Bro, my HRV is 77. I want to get better before longevity.” Homeboy was training twice a week.
I’m like, “In my opinion, instead of doing some aerobic training, go lift some weights and your HRV is perfectly fine. We could cheat and do some hacks to get you to 90, sure, no problem, but I can’t show you any data that says that’s going to be any more beneficial. I can show you a ton of data that says being stronger, having a big aerobic base is going to help you. You have the headroom in order to do it because your HRV is higher. We can erode from that and hedge our bets on some of these other things.”
Again, it depends on where they’re at. Then the other part that makes it hard too is, I’m sure as you know, the data on aerobic health. VO2 max is an amazing predictor of longevity and mortality. The hazard ratio from the lowest interval to elite level athlete is 5.0, I think. Smoking is 1.2 or 1.3. If you stop smoking, you decrease your risk by 20-30%. It’s astronomical.
Aerobic training, most people respond relatively well to that compared to strength training. Strength training, people definitely respond, but I find there’s just a lot more variability. We know that aerobic status is highly associated with HRV. One of the main things that somebody comes in and they’re like, “Yes, man, I really want to get my HRV up,” and it’s 20, the first test I’m probably going to have them do is some type of surrogate aerobic test. Of course we’re going to look at their lifestyle. We’re going to look at their nutrition and sleep and all these other things.
How I frame it to them is imagine you have a– I have this glass here. This cup, as much water as I can put in it, that’s your current HRV. Most people have a cup that just has a shit ton of holes in it. They’re sleeping five hours a night. They’re drinking eight cups of coffee. They’re chasing their kids around all day. Their breathing is a disaster. The only green thing they ate was a fricking Skittle for lunch. Their cup just has tons of holes in it. They’re just a losing water left and right.
Step 1 is, “Hey, let’s plug all the holes in your cup. Let’s work on some of these stressors.” Great. We get all that, we get all their cups sealed. Now, the next step would be, “Let’s make your cup actually bigger to hold more water.” Usually when making it bigger, I’m looking at what type of capacity can we enhance your system? Usually the first thing I’m going to look at is going to be aerobic training. Let’s run a VO2 max test. Let’s see where you are. Don’t need to use a fancy metabolic cart. You don’t need to be a complete nut job like I am and have your own metabolic cart in your house. You can do a 2K on the rower, a Concept2. You can do a Cooper run test for 12 minutes.
Usually when I explain it that way, they’re like, “Oh, okay,” because most people want to work on capacity things in a cup that’s just completely full of holes. The reality is you want to do both because you’re back to recovery and what you can handle again. You probably can’t handle a lot of hard aerobic training if your lifestyle is a disaster. Plug the holes first and then let’s get you a bigger cup overall to hold more water.
Ways of measuring HRV
Ari: I know that you were just speaking to this to a large extent, but let’s delve deeper into the different tech that can measure HRV and some of the key distinctions there, because we can measure it with devices, for example, rings or watches or devices on the fingertip. We can measure it with a chest strap, heart rate monitor. There’s also time of day and maybe variability from day to day in when we might measure it.
Some of these rings, for example, are tracking it throughout the night while we’re sleeping and then giving us a score based on data collected during the night versus a snapshot in the morning. Take us through some of the key distinctions in how we actually measure it. What are the more or less valid ways of measuring HRV?
Dr. Nelson: For years, I was very much a critic of what’s called the PPG model. If you’ve got a ring or a watch where it flashes a little piece of light into the skin, it’s looking for basically the blood flow that’s coming past, because we know the heart beats in very rhythmic fashion. If you were to measure this, you’ll see this little pulse wave come by and that represents a heartbeat.
For years, I had heard people saying, “Oh, we’re going to have tech that’s going to measure it on your wrist,” and I’m like, “Trying to get it off your wrist is a horrible place because of different colorations in the skin. The watch may not be next to the wrist. It’s moving around. You’ve got artifact. You’ve got to pull it off of this pulse wave.” To their credit, most of the tech places have solved that, and it’s actually pretty decent. In terms of taking the number, getting an accurate heart rate variability, I would say it’s possible.
In the past, I would say, you only need to do electrical signals because we can pull the waves off. Even doing that is not as easy because the people have seen the EKG. You’ve got the QRS, the R wave is that pointy thing in the middle, and that’s the depolarization electrically of the heart, so when it’s contracting. You’re looking at the electrical signal directly and you have to pull off what’s called the RR intervals. You have to find that little peaky R wave thing. You’ve got to measure that within probably two to five milliseconds. You have to be super accurate. You can’t get a bunch of noise doing it.
Even electrically, it’s a little bit of a pain in the butt, but they have solved that issue. Now they’ve solved the issue of getting it off the wrist or the ring. That’s why Oura went with the ring because it’s easier to standardize that distance to the blood vessel. The vessels there generally are more reproducible from one person to the next. They can get a higher quality signal in order to do it. They’re primarily looking at recovery. I’d say that’s probably, in most better devices now, a non-issue.
The main issue right now is two factors, is, one, not everyone is using the same algorithm even in the background to calculate the number. Most of them use something called time domain, but even within that, there’s a little bit of discrepancy of what type of measurement within the time domain that they use. You can’t take the same number from your Garmin to your Oura to your Apple Watch, even on the same person, and get the exact same thing.
What you mentioned too, is also a big deal, is when are you grabbing the darn data and over what timeframe? I like Oura. If you look at the research on it, they can sample up to 256 times a second. They’re very accurate with heart rate variability. They do a good job. They basically took a lot of engineers that worked over in Finland from another company, so very knowledgeable on that side.
The downside is it’s collecting over the course of the night during sleep. If you look at most of the research up to that point that had been collected, you either have people in a hospital-type setting where you had them hooked up to an EKG where you could run these long data collections overnight, or they came into a lab, they did the measurement and away you went. We don’t really have, up until recently, this large swath of data being collected overnight. Now, unfortunately, sleep movements, patterns, all that stuff will make a difference.
Then the biggest question I get on devices that are capturing it during sleep is if you have a very low heart rate, your heart rate’s hitting the high 30s, low 40s at night, your HRV, even if it’s done accurately, may not move all that much. The emails I get from people are, “I don’t know, this HRV on Oura– I went out to the bar last night and went to a show, I had three drinks and slept five hours and got up. My HRV really wasn’t all that different.”
I’m like, “What’s your resting heart rate?” “37.” I’m like, “It’s probably not going to move much when it’s that low. There’s something called parasympathetic saturation, which in just English means that at rest, you have a huge amount of vagal tone. You’re super far on that parasympathetic side because your heart rate is so low.”
Ari: Just to be clear for listeners, you’re referring to somebody with extraordinary cardiovascular fitness.
Dr. Nelson: Most likely, yes. They’re almost all crazy endurance athletes. You do run into a few freaks who don’t do a lot of endurance training who end up in that boat, but they’re usually low 40s. You don’t run into them a whole lot. That’s probably because aerobic qualities are highly genetic, meaning there’s a huge genetic component onto that. Some people, like all things, just win the lottery and do pretty good.
They have this super high vagal tone at night and it doesn’t change much because they’re measuring it lying down. What do you have to do with those people is you have to have them probably measure it seated or standing first thing in the morning. What you’re doing is you’re forcing a little bit of sympathetic tone because you have to stand up. Your heart now has to work against gravity, but because you’re measuring it in a perfect world, standing at the same position every time, those differences wash out over time.
The moral of all that story is if you have a very low resting heart rate, your HRV may not move around that much in correspondence to acute stressors. It will still go up and down and we will still see changes, but there’s much more of a lag and a delay and you don’t see as much change.
The other part too is that when is the device actually capturing the measurement? Garmin will measure overnight, which is okay. Oura will measure overnight. I still don’t know when the Apple Watch does an HRV measurement. I can’t find any reliable source that tells me when. Every time I try to use an Apple Watch for HRV, as far as I understand, the tech that they have is pretty accurate, but from what I’ve heard is that they just start measuring it at random times, which is completely unuseful because what if you got up?
Ari: I have an Apple Watch and I don’t think it even gives an HRV score after sleeping. To get an HRV score, maybe this is the older generation, I got mine a couple of years ago, but you have to go into the– I forget the name of the app, but you do a two-minute or three-minute breathing session. Then that is when it takes the HRV.
Dr. Nelson: The older version you could do– it’s called the Command and Measurement and you could get it. The new one, which I don’t have, but I’ve heard it just– they try to put it in the background, but then companies try to spin that and everything else, like your stress score and all this other stuff. They don’t cross-check it for movement, which drives me insane, meaning, of course my HRV is going to be dog crap when I’m training really hard or doing intervals. I’m stressed.
My argument to these companies, which I’ve lost I don’t know how many consulting gigs in the first meeting, is literally like, “Here’s what you do.” Usually they come to me and they’re like, “We got this algorithm done. We’ve got all this stuff. We heard you’re the HRV expert. Here’s what we’re going to do. We’re going to measure it at this time. We’re going to do it again at noon. We’re going to give them these five-point aggregate stress score.”
I’m like, “You’re just going to confuse the crap out of people. They’re going to hate the thing and not use it, not trust it.” They’re like, “Well, why is that?” I’m like, “Because what if they had two cups of coffee before their HRV goes off on the timer on their device and takes their measurement? What if they were training? What if they were moving? At least cross-check it to the accelerometer to see what they’re doing for movement and then decide when to do your measurements or at least you’re doing it at rest.” Then they’re like, “Oh, that’s a pretty good idea.”
Ari: Then they’re like, “You’re fired.”
Dr. Nelson: “You’re fired,” yes, basically is the next thing.
[laughter]
Dr. Nelson: Overnight is okay. Any other time during the day, again, it’s highly context-specific. If you want to do a command and measurement that can be useful. Apple Watch can be useful for that but outside of that it’s– Again, it’s all these device companies want to have their own proprietary thing and it is getting better. WHOOP, finally put a step count in, shocker. Apple finally went to a step count a couple of years ago but WHOOP still has strain which no one can tell me what the hell that means. It’s some aggregate of HRV and something else. It just makes it very confusing for consumers and coaches too to compare across devices.
Ari: You mentioned a few minutes ago the genetic component in endurance fitness. I’m curious if there’s a similar genetic component to HRV scores because in my personal experience, my wife, who trains much less than I do, and she’s a genetic freak in many different ways. She has six-pack abs. She’s had two kids. She has six-pack abs even when she barely works out and eats whatever she wants, she grows muscle. She has to not train upper body because she grows muscle so easily that it’s actually– Like she has to avoid doing exercise for her upper body.
I’m very jealous of her in a number of ways.
Dr. Nelson: I’ve never had those issues. [chuckles]
Ari: With HRV, when I do mine, I’m on the Apple Watch. This is also true in some certain other technologies. I used to have the iFIT app and I’ve done it with the chest strap as well. It was also true there. I would be maybe 60s, 70s, 80s in terms of my HRV score and she would be off the charts always. She’s now in her late 40s and she’ll have HRV scores that are the equivalent of like a high-level 18-year-old endurance athlete. Can you explain that?
Dr. Nelson: There isn’t a lot of hardcore research that’s looked at genetics in HRV. However, I’ve had the same question because I’ve tested, God, hundreds, probably thousands of people now over 15 years, and I’ve seen really high numbers of people that are like, “What the hell? Your lifestyle is a floating trash bin fire and your HRV on iFIT is 91.” The weird part is I started cross-checking it with resting heart rate because we know if you drive your resting heart rate down, that increases parasympathetic tone that gives you a higher HRV score.
Some of these people, resting heart rate, seated first thing in the morning would be by most general physician standards, okay, be 65, and their HRV would be 94. I’m like, “Oh my God if my resting heart rate hits 65, my HRV is probably in single digits on iFIT. It’s horrible.” Anecdotally, Most of those people, when they exercise, tend to be more on the hyper-responders. Anecdotally, most of them, even if they didn’t train it, have a really good aerobic base.
My hypothesis is, I think a lot of it is associated to aerobic base, which we do have some studies. You can look up the Heritage Study that was done at the University of Minnesota, who did a bunch of this stuff. When I did my PhD there, one of my professors, Art Leon, was the main guy on the Heritage Study. He was telling us that they have these people come into the lab. God, they probably started this study maybe 20 years ago.
They were looking at fathers would bring their kids in because it’s obviously direct genetic relationship. They wanted a wide swath of people. They would take people that were recreationally trained too. He’s like, yes. We had the Harley biker guys who put their cigarette out on the way into the lab who would score sometimes higher than athletes who had been training. It’s just crazy. Now, again, these are the outliers. That’s not everyone.
There’s also the story of Lance Armstrong who got tested in Cole’s lab in Texas. Supposedly the story goes, walks in, goes up to the tech. He’s like, “Yes, I bet I have the highest HRV your lab has ever seen.” The assistant goes to the Cole, the lab director, and he’s like, “Hey, this kid out here, he says he’s got the highest VO2 max we’ve ever seen. What do I do with him?” He’s like, “Well, hook him up.” He puts him on a metabolic cart, tests him, and I think it was high 50s or something like that, 55 or something like that. Just crazy. Not world-class elite, but for someone who just walks in the lab who hasn’t really trained a whole lot, pretty high.
There’s a huge, I think, genetic component to it. My guess is it’s probably more related to aerobic and high HRV, but there’s probably a lot of other genetic stuff there that we just don’t understand, don’t have any idea about. No one’s really looked at either. That’d be my guess. I don’t know what your thoughts are.
Ari: I have no idea other than [unintelligible 00:45:20] [crosstalk]
Dr. Nelson: It’s crazy because I’ve definitely seen it. Other than aerobic stuff, that’s the only thing that was relatively consistent but I can still list off a bunch of people where that didn’t fit either.
Ari: It doesn’t really fit for my wife. She can mostly just be hanging out, working out super inconsistently for months. She’ll still be doing some stuff. She’ll be doing surfing and yoga and tennis, but compared to me where I’m doing all those same things plus training like three times as often as her doing strength training, doing endurance training, doing all kinds of stuff, and she’s just way higher than me all the time. Older, too. HRV typically goes down with age as well.
Dr. Nelson: Has she ever done a VO2 max test? I’d be super curious.
Ari: No. I’m afraid of the results of how depressed I maybe if I was to do that test alongside her.
Dr. Nelson: Because some of those people I have tested, and their VO2 max is pretty damn good. I’m like, “What the hell? How did you win the a genetic lottery on everything.” [laughs]
Ari: I think she did. The times I can think of it are like if we go for a bike ride together or times we’ve gone backpacking in the mountains together carrying a heavy backpack up very long hikes, 10-mile hikes up mountains and stuff, she’s always out ahead of me. It’s depressing. I don’t even want to talk about it anymore [chuckles].
Dr. Nelson: That’s similar to my wife. Her HRV generally is pretty good, adds muscle pretty easy, got a medal in Finland for grip training, trained like eight months for it. I’m like, I have to drive my resting heart rate into low 40s to have like a 75 on athlete.
Key factors to lower HRV
Ari: Exactly. Let’s talk about a couple of things. In terms of day-to-day management of HRV, what are some of the key things that people should be aware of? I know you’ve mentioned some of these things in passing, but some of the key factors that people should be aware of that are likely to lower their HRV?
Dr. Nelson: The big one that’s surprising to people is actually alcohol. Some people I’ve noticed over the years are more sensitive to it than others. Most people, you start getting above two drinks, most of the time, that’ll mess with your HRV. Even if we’re doing a command and measurement first thing the next morning because alcohol will actually mess with circadian rhythms and sleep and all that stuff, which can throw Oura scores off.
What’s crazy within that is even the type of alcohol can make a big difference. My hypothesis at first was if you’re drinking more clear alcohols or higher quality alcohol that’ll make a difference. I can’t find any specific pattern to it at all. I can tell you one person drinks whiskey, can drink tequila just fine. I can find another person who drinks tequila, it messes them up, whiskey is fine. There’s definitely an individual pattern but as a group we can’t really find too much with that.
The other part that is surprising I think to some people is psychological stress will definitely show up. I had a client who was doing pretty good, everything was good, working with him for quite a while. His HRV just kept going down and I’m like, “What the heck is going on? We’re going through all his nutrition, going through everything, and I can’t figure it out.” It was a big enough change where I’m like, something’s going on. Then he mentioned he had some psychological stress, had some death in the family. I’m like, “Yes, that can definitely change your HRV.” He’s like, “What? No way.” You just never thought of it. That’s a big one that people tend to miss.
Ari: This was like an athlete who was more looking at it in the context of HRV as a reflection of their training. It was news to them that there could be some other factor outside of that that would have a big impact on it.
Dr. Nelson: Yes. Correct. A big one is breathing mechanics and rate. We’ve been able to do some hands-on stuff using RPR and some other techniques to get pretty big changes in HRV overnight just by getting better breathing mechanics overall, which that makes sense, but probably not something most people would think of right away.
Ari: Tell me more about that. What do you do and what are you assessing as far as breathing mechanics and how do you alter it?
Dr. Nelson: The biggest thing I look at is someone– I can do hands-on work here in Minnesota. They can come in, lie down on a table, and I just look at their breathing pattern. I’d stand off to the side. I’m like, “Hey, we’re going to do some stuff. Take a few breaths.” All I’m literally looking at is where is their ribcage expanding and where is it not. Most people, the ribcage will do– if they’re lying down, it’ll do this move up and move down.
You’ll see more air go into their belly, but you don’t see a lot of expansion into the upper part of the lobes. You don’t see lateral expansion. If you flip them over on their back, you don’t see the ribcage in the back moving much at all. They’re just stuck. A lot of people complain that their neck is real tight, their traps are tight. They’re using more accessory muscles to pull up on the ribcage. Obviously, they’re still using their diaphragm, but not as much.
We’ll do some stuff called RPR, Reflexive Performance Reset. There’s different targets you can work on the body that will neurologically work on different muscles. As weird as it is, working on the back part of your head and your neck actually works on your glute max. That’s from when kids are learning to develop when they’re on the ground, they have to lift their head up as their leg is going to go into hip extension. There’s different areas that you can work on. Sometimes it takes a while.
Then the goal is I’m trying to see, can they get more lateral expansion. If their back is real rounded like this because their pelvis is tilted real forward, can their back go back and flatten out into the table? I’m just watching mechanics. Usually, when we can get the top part of their ribs to start moving pretty well, they usually are like, “Oh, I feel a lot better. I feel more relaxed. Breathing is easier.” Then their sleep is usually better.
I’ve had countless clients who are like, “I can only sleep like six and a half, seven hours a night. Even when I go to bed, my brain’s still racing. Do a bunch of that.” They’ll send me a text the next day. “Oh yes, I slept 10 hours last night for the first time, I think, in my life.” Just because breathing is tied to your body’s ability to down-regulate. If you’re always stuck on that sympathetic side, you can’t down-regulate, you can’t get into deeper levels of sleep. Obviously HRV is highly associated with that too.
Ari: Are there any other factors that jump out to you as big variables that could affect people day-to-day? I assume sleep deprivation, the Netflix example you gave earlier, and obviously training, of course. Probably for you speaking to mostly athletes, it goes without saying, but to my audience, which is going to be a very mixed bag in terms of people who might be super into fitness and be already training at a high level. Some segment of the audience that maybe they’re very reluctant to go to a gym or they only started recently going to a gym.
Dr. Nelson: Yes, training can make a big difference and it’s highly individual. For me, I can tolerate a lot of volume lifting, even at a moderate intensity. My HRV won’t move around that much. If I do a lot of 90% of 1RM, so super heavy singles, and I really push it, maybe a little bit, but higher intensity work, intervals will definitely drop it. Too much aerobic stuff, in my case, will drop it even if it’s moderate. If I just start accumulating too much volume, that can do it over time.
I’ve also noticed the other big thing that people forget is, especially now with a lot of fasting and things like that, I like intermittent fasting. I think it can be useful. It’s probably a whole another podcast, but it is a stressor on the body. Cold water immersion, same thing, same thing with sauna. I’ve lost track now of how many– Had a CrossFit athlete two years ago, could not figure out what the hell is going on with their HRV. We went through everything like, “Oh, your nutrition’s good, everything’s good, performance is dropping. That could be because we’re pushing pretty hard.”
Finally, I’m like, “You have to be doing something different. What’s going on?” She’s like, “Well, I started doing Wim Hof breathing before I do cold water immersion every morning.” I’m like, “How long are you doing Wim Hof breathing?” She’s like, “Oh, I do it for 10 minutes before I do cold water at 35 degrees for five minutes or something like that.” I’m like, “Yes, that’ll definitely drop it.” She’s like, “Really?” I’m like, “Yes, those are all high sympathetic stressors.” Again, they’re not bad. I like cold water immersion. I think there’s time and a place for breath techniques, 100%.
When you’re biasing them on the sympathetic side, you can definitely do too much. Same thing with sauna. People get highly competitive. It’s usually guys who are like, “Oh, I just started at 185 for 20 minutes because of whatever podcast.” “Have you ever done sauna before? You live in Minnesota for Christ’s sake. Are you ever even outside when it’s hot?” “Oh, how’d you feel?” “Oh, it was miserable. I felt horrible.” I’m like, “Yes.” [laughs] Those are the [unintelligible 00:54:59] [crosstalk]
Ari: There’s an interesting paradox here. exercise could be listed in the examples you just gave to us.
Dr. Nelson: Oh, yes.
Ari: Another sympathetic stressor, obviously that can drive down HRV, but there’s really what we’re getting at is the famous expression in pharmacology, the dose makes the poison. Yes. Conversely, as you’ve already explained, exercise, and this is also true of things like sauna and cold water immersion and breath holding, many people also report that these things raise their HRV over time. One of the best methods to raise your HRV is, of course, exercising, increasing your fitness. We have this paradoxical thing of we’re listing exercise as something that can tank our HRV and exercise is also the thing that’s likely to raise our HRV over time. Just explain that phenomenon to people.
Dr. Nelson: It’s a concept of acute versus chronic. You’re correct that the worst thing you can possibly do is to– I call it being the sea slug. You’ve ever heard the story of the sea slug? It’s this little critter that floats around in the ocean and once it finds its little rock, it attaches itself to its rock and then it eats its own brain because it never has to move again. It doesn’t have to do anything.
We know putting people into space, like we chuck people into microgravity, probably one of the worst things for human physiology, period, because there’s not even the loading of gravity on the system now. Massive muscle loss, massive bone loss. There’s cosmonauts who went up early on who still never got back 20 years later, bone mass in their heel. We know that if you do too much stress, that acutely it’s going to be hard to recover. Yes, you can run into overreaching, overtraining syndrome. It’s very hard to do that, but you can.
I like the concept of eustress versus distress or just eustress, E-U-S-T-R-E-S-S. What that means is stress you can generally recover from in a shorter timeframe. Distress would be stress that takes you much longer to recover from. Again, if we use the example of a competitive athlete, just because it’s very easy. If I have a powerlifter, most of their training leading up to a meet is going to be eustress. We want to have stress. We want to be able to recover because we want to go back to the gym and do it again.
Now, as we get closer to a meet, we might add more and more stress. We might have some time off, but the day of the meet is generally going to be a distress. For athletes, most competitions, especially like Olympics or whatever, that’s going to be a distress. Do I care about that? No, because you can take the next three, five, two weeks off after. It doesn’t matter. We’ll have plenty of time to recover from that stress.
In training, if we do a distress session and it costs us like seven days of training, that’s probably pushing it a little bit too hard. For most people who are not high-level athletes, how I explain it to them is, “If you go to the gym on Monday and you wreck yourself so bad, you can’t show up again until Friday. Do you think if you didn’t do quite as much, but you got another session in on Wednesday, you would do better?” “Oh yes, I probably would.”
Again, in a perfect world, which this doesn’t exist, is you would exercise just enough to “trigger the maximal adaptation,” and then you would leave. Now, nobody knows exactly what that is, but in theory, that’s what you would do. What you find out is that it’s this linear plateauing curve where it’s hard to determine where you are at on that. HRV, again, is a good proxy. If you go in Monday and HRV is a little bit lower Tuesday, I’m probably not that worried if Tuesday is an easy aerobic day. If it’s back to baseline again on Wednesday, cool, we’re probably pretty good. If it takes till Thursday before HRV is good again, I’m probably going to modify your Monday training, even if you’re general population.
The fastest thing to correct the ship is to change the stimulus that you’re already doing. Long-term, yes, you’d be better with better nutrition, better breathing mechanics, more sleep, all those things. 100%, you’re going to be much better. In the meantime, I don’t want to burn all the wheels off of the car before we make it to week two. I’m going to modify and pull back on the stressor.
Last part is, consequently, with some people, if their HRV never drops the next day, I’m like, “Bro, we’re going to crank some stuff up. Send me some videos. Maybe your RP is too low. Let’s add more volume. We probably want to push until we get some of that stimulus that says, hey, I had enough. The body’s saying, no, this is good. If it is, that’s probably the best proxy we have right now for finding what is “the optimal amount of stimulation.”
Ari: That’s what I was going to say is like the best tool we have available for doing this self-experimentation to figure out, what is our optimal dose of training of different types of exercise, of the amount of sauna, and intensity of sauna and cold plunging and whatever else we’re experimenting with. We can use HRV basically as a way to guide the dosing of that and to give an objective indicator of when we’re overdoing it.
Dr. Nelson: Even in high-level athletes, it may be sub-perceptual. Even in general population, it’s just harder to determine. Again, back to the weird emails I get, people are like, “Oh, you’ve been doing HRV for 15 years and measuring every day on your own body. Don’t what the hell is going on by now? Why are you still measuring it?” The answer is, I have a pretty good idea, but there’s still those days that come up often enough, like maybe three, four times a month, where it catches me by surprise. It’s like, oh, something changed or my perception of my stress wasn’t as good.
This happened today, all my metrics generally were pretty good. Nothing weird. Man, I was just super tired. My throat was a little scratchy and I debated, should I go to the gym? Should I not? I got to fly out to do some stuff this weekend in Denver. I just decided, even though my metrics were good, I know I have to do a thing to perform on Saturday. That’s the highest priority.
I’m going to take the day off, just do some walking. My wife helped me with some RPR, go to bed early, eat the same amount of calories, not cutting my calories. If I feel good, I’ll train tomorrow before I leave. Where in the past I would have only followed the data and be like, “Screw it. I’m going to do it anyway.” There’s this fine line of using the data to inform your intuition, not necessarily to 100% replace it.
How to improve your HRV
Ari: A couple last questions here. One is, given the context that we talked about earlier, as far as the link between HRV and where you stand on that number relative to the rest of the population and long-term health, mortality, longevity outcomes. If somebody was interested in optimizing their HRV long-term and going, let’s say, from mid-50s to mid-70s or from 30s to the 60s or whatever, what would be the top three or four things you would tell them to focus on?
Dr. Nelson: The assumption here I’ll make is that their nutrition is pretty good, their sleep’s pretty good, their lifestyle stress is pretty good. Obviously, we talked all about those. Those things have a massive difference on it. I get these weird cases of exactly that. Nutrition is pretty good. I’m pretty good with my training. Everything else is good, but my HRV is always super low. Hey, what the hell is going on? A couple of things to look for when you get to that level.
Number one is, I’m going to have you do some type of VO2 max tes. If it’s really low, that’s by far away going to be our first thing. Number two, if you have Oura, I’m going to look at your respiratory rate overnight. If your respiratory rate is high, which can occur even independently of resting heart rate. I had a guy today just looked at his, it was 17.5. If you’re 15 or above, that’s going to be probably one of my big targets because that increased respiratory rate is telling me that your body has a problem regulating CO2. You’re basically over-breathing at night when you’re sleeping, and that’s telling me that you’re in this constant sympathetic stressor because of that, because those are two-way streets.
If we just start breathing real fast, you can do this on yourself. Heart rate will go up even at rest, the HRV will start going down. You’re pushing the body to be more sympathetic. After that, I would like to look at their blood work to see is there anything weird. Is everything good? Magnesium is probably a big one to look at, any mineral deficiencies, that kind of stuff. I do run an at-home test on omega-3. You look at EPA, DHA, prick your finger, bleed on a little piece of paper, send it in.
There is some pretty good data showing that levels of fish oil, EPA DHA, we look at red blood cell content, is associated with heart rate variability. That’s usually a pretty easy win, just adding more fish oil, eating more wild fish, that type of thing.
After that, you get into the really what I call weird and wacky stuff. There isn’t much data, but I’ve seen over and over. If you have a history of concussions or you have poor coordination between your visual and vestibular and proprioceptive system, that can absolutely tank your heart rate variability. In my case, I don’t really see very well in 3D. I have a monovision because my right eye sits up and out too far. When the brain goes to fuse those two images, it can’t. I dropped from binocular to monocular. Now my brain is running all these workarounds all the time to figure out where I’m at in space. That is a sympathetic stressor.
The last one is any type of scars, especially midline scars. I use a Dolphin or it’s a microcurrent. We’ll go through, usually zap the scars. A lot of times their HRV may go up 10 to 12 points on an iFIT scale and stay there for 3, 4, 5, 6 days. I don’t know why. If you go into the different philosophies of, it’s interrupting the meridians, it’s the scar tissue, it’s maybe related to polarity. I don’t know.
I’ve known that midline scars in general will do that. For women, C-section scars, a lot. I had open heart surgery when I was four and a half. I have a huge midline scar. The first time I had that procedure done, my HRV went up 12 points overnight, which is wild. That ends up in this weird boo-boo, wacky land. I’ve done it enough on clients now that it seems to be pretty reproducible.
Ari: Interesting. Last question I have for you is how do you recommend practically people track this as far as what specific devices and time of day one should measure it?
Dr. Nelson: If you want a general rough ballpark of where you’re at, I think Oura and Garmin will do pretty good for that. Assuming you’re not a super low resting heart rate. If you really want the next level and you really want to dial in your training each day, so you want to make a daily change, I’m still a fan of using the iFIT measurement or some app to do a single point measurement first thing in the morning.
Ari: With a chest strap?
Dr. Nelson: With a chest strap. There are some finger sensors that are okay. Just ask them for their valid data. They can be okay. Most of the research data is done on that single-point capture in the morning. That also gets you out of sleep affecting it as much. Of course, if you didn’t have real good sleep, it’s still going to affect your score, but the score isn’t tied to your sleep at that point. They’re independent of each other, so it’s a little bit more cause-effect, not associative. That’s what I would do.
I would pick the same system. I would pick the same time you look at it and keep everything the same as much as possible. If you’re doing that single-point capture, you have to do it either seated, standing, or lying down. Again, vast majority of people are going to do seated. Rare people are going to do it standing. If you change that position, of course, it will change your HRV.
I had a client a couple of years ago now. Couldn’t figure out why your HRV all of a sudden got much better. I said, “What’s going on? I can’t figure this out.” She’s like, “Oh yes, I realized if I take the measurements lying down, I get a better number. I started doing that two weeks ago.” I was like, “We can’t do that. You get a different number now.” [laughs] Just be consistent with it.
Again, know that if you’re using Oura or Garmin, it’s going to give you a ballpark. Also, don’t forget to look at the average of where your HRV is at. Yes, the daily score is important, but is your average, is it trending down, neutral, or up? That was a big mistake I made early on was I put too much emphasis on the daily measurement, not enough emphasis on the trends over time.
Ari: I was just going to ask you as a last question, if you could go back in time and give yourself one HRV-related piece of advice, what would it be?
Dr. Nelson: The biggest mistake I made was not looking at the trends. How I figured this out was being an idiot. That was probably 2014. I was running for a Strongman event. It was in Minnesota, so it was coming up in spring, so I didn’t have access to any of the stuff outside. He hit me. He’s like, “How do I get ready for medleys here? I can’t do anything.” “Oh, I’ll put 225 on the trap bar, and I’ll do sets of 25, and this will be my conditioning.”
What you realize real fast is the first set’s not so bad. The second set sucks. The third and fourth set are absolutely fucking miserable, like miserable. I look at my HRV the next day, and I’m like, “Oh my god, my HRV went up eight points. My god, it’s a fluke.” Do it again. Goes up seven points the next day. Son of a bitch. Do it again. Goes up six points. An idiot in me goes, “Hey, maybe I found some secret Russian squirrel recovery technique, but for whatever reason, when you do this, your HRV gets better.” I started doing that two or three times a week and I realized that by week three and four I’m like, man, I don’t feel so good. I’m sleeping 10 hours a night to function. I’m drinking like four cups of coffee. What the hell is going on? Then I thought, “Hey, dumbass, maybe you should look at your average HRV score and not be so hyper-fixated on each particular day.”
What I realized when I looked at the average, it was like a double black diamond ski slope. It would have these bumps that would go up. When I looked at it closer, what I realized was the next day HRV would go up six, but 48 hours later it would drop 10. There’s only been one study I’ve seen on this where if you push something really in the “lactic area,” your HRV the next day generally is better. 36 to 48 hours later, it generally just goes off a cliff.
Ari: Interesting.
Dr. Nelson: I don’t know why that is. I’ve been able to reproduce it in a whole bunch of clients now, just not even telling them what I was doing because I’m evil that way sometimes. “Hey, you want to try a weak experiment and see what happens?” I got myself into that area by one, ignoring what my own biofeedback was telling me. Then two, not looking at the trends of the actual data and just being hyper-focused on each day.
Ari: Mike, you are an absolute wealth of knowledge. It was a pleasure to finally connect with you. I really enjoyed this interview.
Dr. Nelson: Thank you so much. That was fun. I appreciate all the really good questions.
Ari: I get the sense that you could probably talk for five or six more hours, at least, on HRV alone. We could probably do a 10-part series on HRV. With that in mind, I know that you have a full course on the subject. Let people know about that and let people know where they can continue learning from you, follow your work, buy your courses, and how they could work with you personally, whatever you want to tell them.
Dr. Nelson: Oh, yes. Thank you so much. We do have a course. If you go to miketnelson.com, go to Programs, it’ll be listed there. I need a sexier title. I just called it the HRV Education Course [chuckles]. It’s about eight to nine hours. All the feedback on it has been really good. We try to make it practical. We don’t spend much time beating you over the head of, ooh, frequency domain of total power. No, nobody cares about that. They just want to know, what do I need to know about it? How does it work? What are different case scenarios? It works for whatever HRV you’re using. We did it primarily using iFIT for illustrative purposes, but the principles are all the same.
Then most of my content goes out through the daily newsletter. If you go to miketnelson.com, there’ll be a little button on the top to go to Newsletter. You can just hop on there and, hit me a reply from there, and I’ll send you a cool free gift for listening to this podcast. We also have the Flex Diet Certification, the Phys Flex Cert, and then also the Flex Diet Podcast. If you like podcasts, you can listen to that one also. Most of the stuff goes out through the newsletter. That’s probably the best source.
Ari: Is it possible for people to work with you directly one-on-one?
Dr. Nelson: Yes. I do some one-on-one. There’ll be a little spot on the website you can apply for programs. I usually only work with 12 to 15 people at a time. I’d have to look to see if there’s even an opening now. There may or may not be. I’d say still apply because if there’s a waitlist, that’s where I’d take people from first. It’s been pretty fun. I’ve been doing that since 2005. I’ve been doing it online since 2011. People of all types, from highly deconditioned people, post-cancer, to competitive athletes. I get all the, we’ll say, the weird and difficult cases, which makes it fun [chuckles].
Ari: Mike, awesome. I really enjoyed this, and I definitely want to do some more podcasts with you. I know in addition to HRV, there’s a whole bunch of other topics we can talk about, and I know we have some shared interests in a number of areas. I’m really stoked to have connected with you and started this friendship and have someone to have these conversations with that clearly is a wealth of knowledge. I look forward to many more future podcasts together.
Dr. Nelson: Yes. Thank you so much. This is really fun. I really appreciate you having me on here and all the great questions. That was awesome. Thank you so much.
Ari: My pleasure.
Show Notes
00:00 Intro
00:23 – Guest Intro Dr. Mike T Nelson
02:53 – What is HRV
07:41 – Who is HRV relevant for?
21:13 – HRV-guided training versus traditional periodization
31:26 – Ways of measuring HRV
47:32 – Key factors to lower HRV
1:02:19 – How to improve your HRV
Links
Click here for a special price on Dr. Mike’s robust (but highly practical!) heart rate variability course if you want to incorporate HRV into your health routine. Dr. Mike has been studying heart rate variability for over 15 years and is one of the foremost experts on this topic…if you want to learn HRV, this is the course I recommend.
Click here to get access to Dr. Mike’s exclusive video on Top 4 Ways To Dramatically Increase Your HRV
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