Welcome to part one of our three-episode limited series with the one and only Dr. Stephen Seiler.
Way back in the year 2020, our producer Jana Martin and Dr. Seiler recorded three podcast episodes before she left Colorado for Spain.
Recently on a rainy day, while digging through the backup server, we were shocked to find this gold mine of recordings with Dr. Seiler. After dusting them off and pulling them out of our archive, we are excited to share some great original content created by Dr. Seiler. Over the next few months, we’ll be releasing these three episodes right here on the Fast Talk channel.
On the first episode, Dr. Seiler joins Jana and Chris Case to share his background as a researcher and tell the story as to how he landed in endurance sports research. Then, he will talk about the amazing organ that was central to his early research (and obviously important to athletes)—the heart.
We think of the heart as just being a pump, but it’s also an electrical device, a muscle, and a stressometer for the body. In this show, Dr. Seiler takes us through each of these roles in a way that only he can.
So, ramp up that pulse and let’s make you fast!
Rob Pickels 00:04
Hello, and welcome to Fast Talk, your source for the science of endurance performance. I’m Rob Pickels, and normally I’d say I’m your host, but not today. That’s because your host is going to be Dr. Steven Siler as he begins the first of a three part limited podcast series. Way back in the year 2020, our producer Jana Martin and Dr. Seiler recorded three episodes before Jana left Colorado for the Siren Song of Spain. Recently, and likely on a rainy day, Trevor and I were digging through our backup server and we’re shocked to find this Goldmine that we didn’t even know existed. So we’re excited to dust these off out of our archive to share some great original content created by Dr. Seiler. Over the next few months, we’ll be releasing the three episodes right here on the fast talk channel. This is the first episode and Dr. Seiler joins Janna and Chris Case to share his background as a researcher and how he landed in the endurance sports world. Then he’s going to talk about that amazing Oregon, which was central to his early research and pretty important athletes the heart, we think of the heart as just being a pump, but it’s also an electrical device, a muscle and a stressometer for the body. Dr. Seiler is going to take us through each of these roles in a way that only he can. So ramp up that pulse, and let’s make you fast.
Trevor Connor 01:28
Listeners it’s here, our guide to polarized training featuring Dr. Stephen Seiler training for endurance sports can be hard, way too easy to do too much for too long and pay the price. Our frequent contributor Dr. Stephen Seiler is widely considered to be the modern pioneer of polarized training. We are excited to offer you the largest and most comprehensive body of work on this topic. All this content is free through September 8. See it now at fasttalklabs.com.
Dr. Stephen Seiler 02:01
Hi, this is Dr. Stephen Seiler. Welcome to my own podcast, the fact that I am even saying that makes me feel like maybe I’m having some kind of a midlife crisis. Because it’s feels like something I should say no to do my own podcast, I have so much respect for it. I’ve been a guest on a lot of them in the last few years, maybe about three or four years ago, I didn’t even know what a podcast was. And then I started being invited to speak on them related to training and the things that I kind of do in my research. And in the process, one of the early people who invited me or groups that invited me were the guys from a podcast called fast talk. And in the last few years, I think I have ended up doing about five different sessions with them. And now they have somehow convinced me that I should try to do my own podcast, and they will kind of be in the background and help me out with it. And so, as I’m speaking to you, Chris Case is in the background. Hi, Chris. Hello, Dr. Seiler, and we have some technical support can that technical support person, please introduce herself.
Dr. Stephen Seiler 03:20
Hi, there, this is Jana. So I am venturing into a new thing here, I don’t know how it’s gonna go. If you’re listening to this, I guess that’s a good sign. Because that means I didn’t just throw this audio into a big trash pile. But I am going to stick to what I know, in this podcast, I’m going to try to talk about the training process, particularly endurance training, we may venture into other aspects of it, I will try to stick to what I know best within that, which is the physiology part, the endurance physiology aspect of it. But along the way, I have learned that, you know, the training process is highly integrated. So there’s some psychology there, there’s some biomechanics, there’s some nutrition. So it becomes a little tricky to just speak about one facet of the training process, but but I won’t venture too far from where I feel like I have something to say. And if I do, I’ll certainly only do so with the help of some experts, some other whether it’s coaches, athletes or other sports scientists that I’ll try to pull in to the discussion. So that’s my plan. And for me, I guess it’s interesting or it might be useful to know my background. I’m a professor in sport science. I am an American as you can probably hear from my voice you may also be able to hear that I am from the south. I grew up in Texas in Arkansas, and so I did my bachelor’s in Exercise Science at the Univer versity of Arkansas Razorbacks, I did my master’s degree there as well. And then I went to a rival University, the University of Texas the Longhorns and joined the Ph. D. program there and did a PhD in exercise physiology and, and exercise biochemistry. And then my life kind of took a turn. And I, as I’ve said several times, in many podcasts, I ended up in Norway, because of a woman and I’ve been here for 25 years. And now I’m a professor at the University of augur in a city called Christian song, Norway, which is on the very south coast of the country, kind of the Miami Beach of Norway, I like to say, and so my career has been split between the United States and Norway. And I think that’s actually been pretty important for my pathway for the things I’ve studied, because it has the influences and impulses and the science, from both places, from Scandinavia and from the United States have kind of become somewhat intertwined. And I don’t think I would have had this particular career if I had not moved out of the states into Scandinavia. So it’s kind of been a very specific, you know, meeting of different traditions that have made a big difference for me and the things that I’ve ended up having an interest in. But the very first thing that happened to me that kind of started me down this path was way back in high school. And I, you know, I discovered that look, I like science, I like sports. But these two things don’t go together. And then I finally discovered through a couple of articles in a book, and that that they did go together. And Sports Science became a term that fascinated me. And so it wasn’t long after that, probably 17, I realized, okay, this is what I’m gonna do, gonna study sports science. But at the time, I was playing American football, you know, and, and I was skinny, I wanted to get stronger. And so strength training was definitely the first area of sports science that I was interested in. And I even went to the Soviet Union at the age of 20. It was still the Soviet Union. This was 1986, the period I think they call it Glasnost or Perestroika, so they were kind of opening up a bit. And there was a delegation from the American institution called the National Strength and Conditioning Association. And I managed to get onto that study tour as one of three students in a group of 50 and went to Moscow, and studied the Olympic lifts and strength and saw kettlebells for the first time in 1986, before they were even a thing in fitness training. And I was, you know, fascinated, and then I came home, I worked at a fitness center, I was a personal trainer, or fitness center trainer, I even was the coach the strength coach of Scottie Pippen back in 19. Yeah, it must have been about the same time, right this summer before he became a Chicago bull. And so that was the start. And then I ended up starting to my big goals to become a strength trainer or have a job at the Olympic Training Center in Colorado Springs, that’s what I saw is kind of the, the mecca of Sports Science at the time, for whatever reason. And I can even remember doing an English assignment on creating a CV and introduction letter and so forth to that effect. And so I was moving down that path. And then towards the end of my bachelor’s degree, I’m walking through the Human Performance Laboratory at the University of Arkansas and, and I walk past this little small laboratory with some strange sounds and some professor with special goggles on and a very bright light. And under that bright light is a is a big lab rat. And that poor lab rat is being operated on, it’s basically being subjected to open heart surgery, and that heart is visible. And I see it beating about 300 beats per minute. And I asked the professor if I can just step in and look a little bit watch and he lets me in. And so we began talking and I’m just, you know, kind of mesmerized by this procedure and he he’s actually interested in diabetes and, and how diabetes affects heart function, how exercise can ameliorate or reduce diabetic consequences. And so anyway, I ended up becoming his graduate assistant. And I actually helped make a lot of rats diabetic. I did studies on rats, you know, diabetic rats had them run on treadmills saw the profound effect it had on them the positive effect it had on these diabetic rats, but I just did not want to study diabetes. So I said I would like to be your student but I want to study training. I want to study it. interval training. And so that’s how things started for me is I made rats run on a treadmill, I made one group of rats run steady state continuous ketamine, regular low, or moderate intensity endurance sessions, I made another group of rats do intervals 10 times two minutes, I remember it, because I actually did the same protocol just to see how it felt to see what the rats were feeling. I wanted to, you know, really connect to them, you might say. And then we had the third group of rats that of course, were the the cage potatoes that did nothing. And so then I won’t make a long story out of it. But I tried to figure out how to measure the changes in their heart function after this training period, and I was able to do that and got pretty good at operating on a heart that’s about the size of the first digit of your index finger weighs about a gram. And despite that size was, you know, able to do a lot of little surgical things to be able to measure the pressure and the blood flow coming out of the heart, the cardiac output and so forth. And so that started me down this path. And then I ended up doing a PhD, where I said, Well, I want even more control, I want to be able to look at the heart in an even more isolated way. And that’s what I ended up doing, I literally learned how to remove the heart from the rat, and then put it on are connected to this kind of an artificial circulation, where I could manipulate different variables like exposure to free radicals or the pressure and so forth, and then look at the function of that heart. And that was my PhD work, I actually looked at what we call free radical stress. The in this was a big topic, oxidative stress. It was a big topic back in the 90s. It’s still a big topic, but I think we’ve learned a lot about it. That makes it our understanding of it different than it was at that time. But at any rate, got my PhD, had knew a bit about the heart studied, I had, you know, literally, Lance Armstrong was being tested in the lab. But next door, other labs were doing chemical warfare suits studies looking at heat stress, because this was the time of the conflict in Iraq. And so there were military studies going on. So there was just a beehive of different kinds of research being done in the same laboratories or in the same environment. And it was really stimulating, I was part of some of these studies, I was fairly well trained at the time in cycling, and then I went into rowing. But when I was trained for cycling, I had eight muscle biopsies and participated in different studies and so forth. So this was the kind of crucible that I grew up in as a scientist or as a young scientists working with a lot of different people. And then I moved to Norway, and left rats, no rats haven’t touched a rat, since 1995. And I think that was a good thing. Because even at the end of my rat tenure, as a PhD student, I was to be honest, kind of thinking, Wait a minute, wherever I gotten here, I wanted to work at the Olympic Training Center. And now my research is more medical than it is sports science. And that happens a lot in our research training process. As we we go down these these rabbit holes, and sometimes we go so far down, and that we forget where it was we wanted to go in the first place. And that I think happened to me to an extent, but the training was outstanding. And I felt like I learned a lot about the exercising body from different perspectives. And then I moved to Norway, and the perspective in Norway that I embraced was that back to the whole human, the the athlete the systemic approach of trying to understand the training process. But I took with me some of that cellular level. And Oregon level, you might say research, but the heart was really in focus for me because that’s what I had studied most. And if you study the hardest, there is a connection to endurance, obviously, because we have found that endurance performance is strongly connected to cardiac performance to heart function. And so I guess I would like to start today, talking about different ways of understanding the heart, different ways for us who are coaches, who are athletes and maybe young sport science students, that the heart can be actually conceived or perceived. evolved in at least four different ways that are all, you know, each has their own research areas, its own lingo, and has its application to understanding different things we experience in training different situations we come up against in our daily prescription of exercise, our interpretation of heart rate and things we see, and things we may experience along the way. So what are those four ways of experiencing or understanding the heart? Well, I think the first and perhaps the most obvious, or it is definitely the most popular, according to a little poll I did with my Twitter responders is about 58% said, when I gave them four choices, they said they see the heart is a pump. And that makes sense, because that is what the heart fundamentally is for the body. It is a pump for moving blood around this set of pipes, this this vascular system that we have, and from very large pipes, and then branching out and branching out and branching out until we get all the way to these tiny capillaries that provide oxygen and remove waste from every single cell in the body, there literally has to be a a vessel passing in very close proximity to every single cell in our body for this aerobic system to work. Now, because the heart is a pump, you can measure it, you can think of it pretty much like a plumber thinks of the plumbing in your house, it obeys the same basic laws, that means that you think about flow, the flow of the fluid through the pipes, you think about pressure, and you think about resistance, that the pipes can get backed up, there’s resistance that tends to keep the flow from boil flowing. So those are the basic terms. And those are applied to the plumbing in your house. And but they also apply to the heart. Now, one of the things just as an example, for the pump to work, you have to get the fluid to it, there has to be a loading of the pump, bellows or piston or whatever it might be. And in heart performance, we call that the preload, you got to get blood returning from your body to the heart at a high enough rate, or else you get problems. And one example of that would be if you’ve ever, I don’t know, I used to sit in on the church pew as a kid. And while the preacher was speaking, and then suddenly we would have to stand up and seeing and I can still remember getting dizzy when I would just pop up after an hour of struggling to stay awake. And then suddenly, we have to stand up and seeing you with a you know, with all our might, and I would get dizzy. Well, that was because of what’s called orthostatic intolerance, the blood had kind of started collecting in my lower body and my legs because they’ve been still for a long time. And then when I first stood up, there was this little transient period where I didn’t have enough return or flow to the heart. And so then I didn’t get enough blood flow to the brain, and then you get dizzy, the body quickly adjust these valves help in there’s constriction of the muscles around the vasculature and the legs and, and things work themselves out pretty quickly. But that is an example of orthostatic intolerance. It also happens if you stay in for a long time. But this idea of loading the preload that fills the heart, and then the pressure that the heart beats against. Well, that’s kind of fundamental to our understanding of the exercise process. And these relationships can even change for example, you can be sitting on a bicycle, and you’re riding down on the drops. Well, now your your body angle is kind of lowered so that it’s easier for blood flow to return to your heart. And then if you stand up, you stand straight up. You may notice I do all the time that I’ll suddenly have an increase in heart rate, just a few beats. It may even slip back down a bit after a minute or two. But initially, even just changing my body position can change my heart rate. Now why not because I’m pushing differently on the pedals. But it’s because there’s this very transient change in the return of blood flow to the heart and the heart. I was super sensitive to that so called preload. And if it doesn’t get what it needs, it accelerates, it beats faster to try to compensate. Because the heart has these two mechanisms of increasing blood flow. One is the rate and the other is the so called stroke volume, which is just how much blood is pushed out of the heart each beat. In those two, they’re kind of interconnected, they tend to, in very rapid situations, they tend to compensate for each other. So so things like body position make a difference. Another thing we’ve just been in a hot summer, at least part of the Northern Hemisphere, it’s been summertime. And if it’s hot, you can also experience something that’s related to this Pope concept of the heart. And that is that your heart rate is drifts up in the heat. Why is that happening? Well, it’s happening because the blood flow that the heart is distributing has multiple functions. And the obvious one that we’re interested in is endurance athletes is that oxygen delivery function. But the heart blood flow is also a radiator. Just like in a car, it is a way of moving hot blood that is collected heat from the deep musculature and moving it out to the radiator, which in the car is in front and it’s receiving when but in on the body, it’s your skin. And so if it’s hot outside, then that forces the brain to make some selections to make some decisions about distribution of blood flow. And some of that blood flow that we would like to go to the muscle ends up having to be rerouted to the skin in order to deal with the heat to remove heat and keep the brain and keep the body at an acceptable temperature. And as a very narrow range of temperature that the brain is willing to accept, it’s between about 37 and 39 degrees. So that’s, you know, two degrees is the working range that the brain is willing to let the body deal with. And often it’s even less than that. So hot day, the heart rate goes up because that so called preload, that return of blood flow to the heart is going down a bit. And we get problems. And another issue that you might be interested in, related to this pump thing, which I think is kind of the coolest part of it is that how in the heck does the heart which is the size of a fist, you know, look at you make a fist, look at it, take your fist, put it in the middle of your chest, imagine it’s built up behind your ribcage, that’s your heart. And that’s about how big it is. And that little sucker, that little pump can move amount of blood every minute, that is equal to if you turned on the faucet in your kitchen full blast, it often will be able to pump more blood per minute than your faucet can drain out per minute at full blast. That’s pretty amazing when you think about it, because it’s a pump it’s beating. And so how the heck is that happening? It’s almost inconceivable to me until you understand that the heart kind of uses a vacuum effect. It functions both as a kind of a piston. But also it creates a vacuum effect inside the ventricle that helps to just make that blood flow almost just never, it never really just stops inside the heart and then gets squeezed out it just almost gets. It’s like a merry go round where the blood flow just swishes through the heart and never loses velocity. And that way it makes it possible for blood flow to be really high. Now, I’m really getting nerdy with you now on this pump stuff. But that’s what happens when you study the heart for years and years is you get pretty darn fascinated with it when you think of it as a pump, but it’s a lot more than a pump, plumbers, you know, can connect and I even had some people on Twitter that they replied and said, Well, seeing that as I’m a plumber, it stands to reason that I see it as a pump. And that makes sense. But the heart is more. The heart is also a really sophisticated and sensitive electrical device. It’s quite strange to say this because it doesn’t necessarily make sense. But if you take a heart and remove it from the body, meaning there’s no nerve connections, as long as it’s at the appropriate temperature and has you know, pressure and so forth, it will beat automatically. It has a feature that’s called Auto rhythmicity. This is complicated. It has to do with membranes and leakiness of ions across channels and I’m not going to go too deep into it but the heart itself with no nervous stimulation still has its own intrinsic rate, it will be in this. The proof of this is heart transplant patients. Because heart transplant patients, they are given a new heart from a donor. But that heart that they that is put into their body, there’s so long the aorta and the vena cava connections are all sewn together. But there are no nerve connections that are rejoined. So that heart is sitting in it with no sympathetic or parasympathetic nervous stimulation that that direct channel that normally would control heart rate. It’s just not there. And yet, that heart works fine, keeps them alive. And there are heart transplant patients that have actually run marathons. Now not fast. But they’ve run marathons. How do they do that? Well, the temperature of the body helps to increase heart rate, the circulating hormones of the body helped to increase heart rate, it happens slower than it normally would. But it happens. And something called the muscle pump, just the movement of the muscles helps to bring blood back to the heart and that it helps to drive heart rate. So heart transplant patients with no electrical connections to their heart, are proof positive that this the heart has this amazing auto rhythmic function. However, in a normal heart in our hearts, if you read if you’re listening here and you’re not a heart transplant patient, then you have nerves, the sympathetic cardiac accelerations and parasympathetic, so called vagus nerve that are connected to the heart to the pacemaker area and can control can both reduce heart rate and increase heart rate depending on the need. So it’s a sensitive electrical device, and that electrical signal is very carefully and accurately distributed across the muscle of the heart in the healthy heart. So that the timing of the contraction that pumps that blood out is perfectly timed. Because it’s an electrical device. That also means that sometimes it goes wrong, the electrical activity, the electrical pathways can become blocked, or you can develop rogue so called pacemakers. The normal sino atrial no the pacemaking function of the heart can be disturbed by areas of tissue that take over and interfere or confuse this normal sinus rhythm. And there are different examples of that.
Trevor Connor 27:57
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Dr. Stephen Seiler 28:31
Now, somewhere in the background as I’m speaking and I don’t know if he’s falling asleep or not, but Chris Case, are you there?
Chris Case 28:39
I am here I am awake.
Dr. Stephen Seiler 28:41
You’re awake, the same task? Well, you know, Chris, you wrote a book on the on the heart as an electrical device, I guess you say I mean, the haywire heart corrects is a deep dive into these different kinds of arrhythmias that people experience and particularly your interest was in as I understand it, in reading the book, the issue of whether or not endurance training, years of endurance training, actually can make these electrical disturbances, these arrhythmia problems more prevalent. Is that a reasonable summary?
Chris Case 29:22
That is correct. Yeah, I was a co author. So Leonard Zinn was one of the other authors and then a cardiac electrophysiologist from Louisville, Kentucky. Dr. John Mendiola, was the third author. And yeah, in combination, we wrote this book about all facets of heart arrhythmias in endurance athletes. And as you said, yeah, it’s the science may not be entirely conclusive, but we were working with the data we have there are some definite patterns and trends that you see when it comes to endurance athletes and the prevalence of have certain heart arrhythmias in them. So yeah, that was the basis of the book.
Dr. Stephen Seiler 30:04
Yeah. And I think you sent it to me at one point. And part of the reason you sent it to me was because I’ve had atrial fibrillation. Right. So I, unlike 98% of the people in my twitter poll, who did not see the heart is an electrical device, there are only 2%. That said, that was the main way they see it, I definitely see it as an electrical device, because I’ve experienced atrial fibrillation and PVCs. Another kind of all the arrhythmia rhythm disturbance, but I’ve been in the hospital twice with atrial fibrillation that wouldn’t go away. And then I had to be put under anesthesia, and basically shocked out of it the same way they you know, when you watch on the movies, someone’s getting shocked, except they did it, you know, I guess it’s a lot nicer if you’re not awake for the, for the experience. So I’ve experienced atrial fib, it’s no fun, it’s scary. It’s it’s, yeah, you feel like your hearts up and your throat and you definitely lose, you know, the heart doesn’t work the way it should know, lucky for me, I, you know, I was lucky enough that I knew I was able to go into the research, I found some case studies. And I found that with my particular situation, let’s you know, everyone’s different. But I was able to find a way to actually auto convert that I was able to get myself out of these atrial fibrillation, situations by very carefully going out into the forest with my heart rate monitor, and just starting to jog very slowly and slowly increasing the intensity is almost as if I was able to kind of recapture the rhythm. And the way I would know it was because my heart rate would actually my heart rate monitor would actually start working again, that I would actually start getting a heart rate once I was back in a normal rhythm. So I have experienced this. It’s scary. Some people have to have surgical procedures. But it does remind us that the heart is also an electrical device. And we use that electrical device concept or aspect of the heart. For example, if we use heart rate variability, because heart rate variability is essentially trying to use the fluctuations in parasympathetic and sympathetic nervous system stimulation of the heart, and the very minut differences in heart rate from beat to beat to say something about recovery, about parasympathetic control, and so forth. So this idea of the heart is a stress ometer. And the heart is an electrical device, they end up kind of going together quite a bit. The haywire heart is a great book, if you want to get a bit of a deep dive into that interconnection into how the heart works. I was looking at it again yesterday. And I was like, wow, they they know a lot of stuff about the heart. I was impressed and I don’t know case. I don’t know how you obviously had a doctor on the team. So that helps. But I bet you did some serious digging into the research when you were writing that book.
Chris Case 33:19
Yeah, absolutely. A lot of PubMed searching a lot of reading of the of the literature, a lot of speaking with scientists, also speaking with people that have experienced this some pretty grave case studies of people. There’s a spectrum of arrhythmias out there. Some are pretty benign, a lot of endurance athletes will have experienced PVCs or PAC in their lifetime, these little flutters these little things that make you think, but don’t really have consequences don’t disturb function too much. And then the far end of the spectrum can die from this stuff. There are serious consequences that can come from some arrhythmias. So yes, a lot of research went into that book. It was really great to have Dr. Mann droll on the team as well. He’s not only an electrophysiologist he specializes in seeing patients that are athletes with arrhythmias and he also has an arrhythmia himself. So he sees it from I guess you could say three different perspectives. So yeah, it’s it was a fun project to work on. That’s for sure. I learned a lot.
Dr. Stephen Seiler 34:23
Right. Well, and I guess another thing is, you didn’t have a psychologist on board but but my feeling was when I developed these arrhythmias, this atrial fibrillation is that I, I was really depressed. I felt like my life as I knew it had fundamentally changed because I lost a bit of control of my own body. It was It no longer answered the call in the way that I had been accustomed to. It wasn’t my, you know, I wasn’t the warrior athlete. Suddenly I was a patient in a hospital. And that was tough to accept. It was tough, you know? think that a lot of particularly, you know, when athletes develop these kinds of arrhythmias, it is jarring at first, and I’m sure you experienced some of that in the interviews you did. But at any rate, I’m not trying to sell your book. But I think, certainly for those of us who, as we’re getting older, we’ve been doing endurance sports a long time, there’s a fairly big percentage of us that have experienced some kind of something related to that electrical nature of the heart. That can be a little Yeah, kind of wakes us up makes us think what’s going on?
Chris Case 35:33
Absolutely. Yeah. You know, Leonard Zinn, famous in the cycling industry, for his his tech books, he was the first person that I knew that experienced the arrhythmia, you know, out on his bike, doing a climb, starts feeling these weird sensations, these flutters in his in his chest. And it was great to have him as a co author, because he was walking through the many stages that one goes through when they’re faced with a situation like this as we were writing the book. So he went through a phase of denial, he went through this phase of yet quite significant depression. Oh, my God, I’m not the person I used to be I am. My heart is malfunctioning in some way. What am I going to do about this because my heart, you might not realize it all the time until you’re faced with a situation like this, that for an endurance athlete, specifically, the heart is absolutely critical. And if it’s not functioning properly, it affects your mental health, your physical health, your well being, it’s somewhat defines us as, as people sometimes. And he went through a lot of struggle, and he continues to go through an evolution, because he has an arrhythmia that doesn’t allow his heart, you know, he can’t allow his heart rate to go over a certain point or else, it becomes so bad, the rhythm gets so disordered, that he has to pull over to the side of the road, get off his bike, sit there, wait, sometimes call somebody to come pick him up, and so forth. So it really has had an impact on his life, he is no longer the athlete he used to be. So can have very significant consequences.
Dr. Stephen Seiler 37:18
Well, now we just this sounds really gloom and doom now. But
Dr. Stephen Seiler 37:23
no, but it’s fair, it’s part of it. But I think it’s just it is worthwhile to say it usually works well. And it’s just the heart is a an amazing device, that that is the pump, it is an electrical device, and it is a muscle. And that’s that third way of looking at the heart it is muscle, and like a biceps, or a quadriceps, the myocardium is a muscle that can adapt to a change in load, it can get stronger, it literally get bigger with training. It’s also if you have this spectrum, we always talk about fiber type, you know, you got your slow twitch fiber type and your type. You know, that’s your type one, and you have type two a and you have type two, B is usually the old nomenclature, well, if you are going to position heart muscle on that, it would be like type zero, it is the ultimate slow twitch muscle. It’s so far, you know if type one muscle was your idea of a really good endurance muscle type one, the slow twitch muscles are quads that have been trained forever in cycling, they are useless as endurance muscles compared to that muscle, which is the heart. It is amazingly adapted for exactly what it does, which is to beat millions of times to never, ever stop. And so as a muscle, it is just packed with mitochondria. It is immensely tight with capillaries within that muscular network, the muscular myocardium. So it is beautifully designed to purpose. Now, when a muscle is super aerobic, it usually also means it’s not very good at anaerobic conditions. And that’s for sure true with the heart. It is not designed to handle a period without oxygen. And it even you know, normally the heart actually takes up lactate and can quickly move it back into the mitochondria and convert it to power of gas and then turn it into or use it aerobic ly. So the heart normally takes up lactate it just doesn’t produce lactate at all and it has really no capacity for doing so. So it’s not it’s not designed to go without oxygen at all. And this obviously makes it pretty sensitive to any kind of oxygen availability. problem. And what do you call those? Well, they we call them heart attacks. Usually, when the hearts own blood flow, the heart has to steal some of its own cardiac output through the coronary arteries. And to oxygenate itself, because it can’t just pull oxygen from the ventricle, it has to have its own very clear and well working coronary tree of vessels to to oxygenate itself. And when any of those become blocked, then we got big problems. So the heart as a muscle is what makes us susceptible to typical kinds of heart disease associated with clogging of the arteries, the where we get this plaque buildup in one of these major coronary arteries gets blocked and you get your heart, you get that classic heart attack, which is just some region of the heart has become deprived of oxygen sufficiently that it it’s starting to die. And you get all kinds of various signals related to kind of referred pain, pain down the arm and things like that, that may be a signal of a heart attack. So the heart can also go wrong. But But the other thing about that idea of the heart is a muscle is it it is adaptable, that it if you go back to the pump, you’ve got pressure, the heart has to squeeze against more resistance, it has to do that at high heart rates. And we have and also high volumes of blood returning to the heart that kind of stretched the ventricle. This seems to be a signal for adaptation in the same way that if you were to do bicep curls on your biceps, the biceps would show some so called hypertrophy. Well, the cardiac muscle can also have a very limited hypertrophy, or a very proportional hypertrophy to the increase in volume or the increase in stretch that is happening. And so you get this nice response. And there’s been a lot of research done showing that elite athletes, high performance endurance athletes tend to have larger hearts. Part of that is genetic, but part of it is training. And the way you can show that part of it is training is that you can actually, there’s studies done on elite performers when they’re well trained using ultrasound echocardiography. And you can measure the thickness of the SEPTA wall, the ventricular walls of the heart, you know, they’re like maybe a centimeter thick, and they can slightly they get thicker, a little bit during training. And the the diameter of the ventricles gets a bit bigger, meaning that they have a bigger space, they move more blood, the stroke volume is higher. But what they can show is that if you take people who are highly trained, and then they d train, let them be trained for six months, maybe they were finished with their Olympic career, they did some nice echo Cardiography studies when they were at their peak, and then they managed to bring them back into the Cardiography lab, six months later, after they’ve stopped training. And lo and behold, just like a biceps, when you quit doing the curls, their cardiac muscle will actually shrink a bit. It gets smaller when we stopped training. So this means that that hypertrophy, or that increase in the heart muscle size, for most of the time, is highly adaptive, it is functional, and it’s reversible, meaning you stop training, heart size goes back down. But you do occasionally you get these discussions about the athlete’s heart. And even you know, over 100 years ago, there were people that tried to say all this training, it’s bad for you, it’s gonna cause the heart to, you know, wear out get tired, and, and so forth. And it was compared to heart failure and other conditions where the heart muscle also gets bigger, but in a non adaptive way, it’s failing. And so there’s a clear distinction between a heart muscle that is failing, and then that the true athlete heart which is adapting to load and growing in a very appropriate way to the demands of the pressure and flow that that are going through that heart and stretching it and creating resistance just like any other muscle. So the heart is a muscle needs oxygen, super slow twitch, no real anaerobic capacity to speak of. It does a great job of sponging up lactate actually from skeletal muscle. So it’s one of the ways that the beating heart is actually helping to mop up lactate as we produce it during high intensity exercise. But it’s super sensitive to oxygen availability. So so if you know if you despite all your good intentions of exercise, if you have coronary blockage, well then then that can create problems for the heart. And then the other issue is this thing about kin the muscle of the heart get tired, does the heart muscle fatigue? Because we know other muscles do that biceps curls. If I keep doing curls even with a light weight, eventually, that bicep says stop. It fails, it ceases, it loses its ability to produce force. Do we have heart muscle fatigue? Does the heart for example, after a marathon, or after a triathlon and Ironman Triathlon, it may last 12 hours? Is that heart muscle weakened temporarily? Is it less able to pump? Is it not as strong. And there’s obviously been quite a bit of research on that I was even involved in a study where we, we used rats, again, we made rats run until they dropped. And then we remove their heart and studied it in isolation. Using that isolated heart process I was talking about, well, we we could not find any evidence of fatigue when we remove the heart from the rest of the body. And this is a pretty big issue because one of the things that is tricky when you’re trying to measure something like muscle fatigue and heart is that the hearts force development is so entwined are intertwined with things like dehydration, the amount of blood volume, you know, and as we, at the end of an Ironman Triathlon, you do typically partially dehydrated so acutely, it can look like the heart is not it’s fatigued, it’s not pumping as well. But but that can be partially because of the fact that it’s not, there’s not enough pre low that venous return, that there’s differences in that circulatory system that are actually explaining some of this. So as far as I can tell the idea of exercise induced cardiac fatigue, there may be some, but even within 24 hours, those small normally, even after a marathon or a triathlon, within 24 hours, the small residual actual muscle fatigue in the heart is generally resolved. So it appears that in the healthy heart that doesn’t have any kind of oxygen availability issues, it is super resilient, it essentially is not getting tired, like skeletal muscle. And I remember when my daughter one time said, you know, she equated fatigue and the heart rate going up as her heart was getting tired. And I said, well, not really, you know, it’s not so much that your heart is getting tired, but it is mirroring other parts of your body that are getting tired, it’s responding to that. And that kind of brings us to that last way of looking at the heart, which is the heart can be seen as a kind of a speedometer for the body, or maybe more specifically a stress ometer. The heart is kind of aggregating, it’s responding to pretty much any kind of stress that you experience Good grief, when I was asked to give a TED Talk and walking out on the stage walking out on the stage physically using just about nothing of energy, my heart rate was 120 beats a minute, my stress ometer was going through the roof, and my heart was displaying that if you’re out in the heat, your heart rate goes up heat is a stressor. If you are fatigued during a cycling session in your in your four hours into a long ride and you’re becoming dehydrated, your muscles are becoming fatigued, you get this cardiac drift. So the hardest function is a stress ometer there it’s sensitive to any kind of change that makes your body perceive a kind of fight or flight response or changes the balance between the internal cost and the external work that you’re doing. So it is a good stress ometer it is a pretty good speedometer. And that’s one of the reasons why we use heart rate as an intensity control device. We try to use heart rate and calibrated appropriately and be able to say well, you know, 65% of max heart rate is low intensity and 85 is I mean the threshold and 93. Well, I’m getting close to max and that’s high intensity interval training. And for the most part that works, but there are some caveats and we have to understand some things that are influencing how the heart kind of responds to different kinds of stress. But in general, if heart rates are higher than normal, then that means your body is stressed. It may be because of impending exams it may be because your your job is tough or you’re afraid of losing your job. It may be because you got kids home, instead of being in school. It may be because you’ve trained, you know done a heavy block of training, but all of those things can end up creating the same response. And initially, that is usually an increase in heart rate. And that’s kind of in keeping with that famous general adaptation syndrome that Hans Salya described, which is, you know, when a stress is imposed on the body, you initially get this alarm response. And then you get a resistance where the body adapts, and but if the stress goes on too long, then you can get a exhaustion phase and, and that’s where reading heart rate can become tricky, because eventually, if you’re training and you are loading the body, day after day, you can actually experience that the heart demonstrates this exhaustion phase where, for example, maximum heart rate actually declines. So instead of an increase in heart rate to the increased stress, the heart basically tells us now, our systems are failing, our body is no longer able to mobilize that response. And now the brakes are going on, and maximum heart rate is going down. This happens, for example, to Tour de France riders after three weeks, particularly the guys that are doing the, you know, the domestics that are having to shuttle bottles back and forth are doing a lot of work every day, they’re not they’re not being protected. They’re the ones that will often say their maximum heart rate goes down 20 beats in the course of that three week event. So that’s an example of the heart is a speedometer, a stress ometer. And it also connects to that electrical device issue, you can get a rhythm is not only because of how you train or that but but also during periods of heavy stress. In my case, when I developed atrial fibrillation, I was also under a lot of psychological stress, going through a divorce, going through some different things in my life. And that all added up to too much. And now I’m back to normal. I’m not experiencing atrial fibrillation. I’m not experiencing all the psychological stress and I’m able to go to maximum heart rate during races and so forth. And but there was a period in my life where I was very stressed psychologically. And that’s the period when I was experiencing atrial fibrillation. So for me at least, it’s an example of the fact that it’s more than just training stress, it is a combination of stressors that may kick us into some kind of electrical disturbance. And that’s that implicates the feeling that the stress ometer function and the electrical function they’re, they’re connected. So that’s some of the stuff I wanted to talk to you about today. And in future podcasts, we’re going to be talking about other aspects of the training process. I will probably be bringing in some some guests that can help us along the way. But the goal will always be to dig into development, dig into physical performance development, and have some fun with it. Think about how we can do it at different ages under different conditions with different constraints on our lives. So stay tuned, and we’ll speak again soon.
Rob Pickels 53:19
That was another episode of Fast Talk. Subscribe to Fast Talk wherever you prefer to find your favorite podcast. Be sure to leave us a rating and a review. The thoughts and opinions expressed on Fast Talk are those of the individual. As always, we love your feedback. Join the conversation at forums.fasttalklabs.com to discuss each and every episode, become a member of Fast Talk Laboratories that fasttalklabs.com/join. To become a part of our education and coaching community for Stephen Seiler, Jana Martin, Chris Case, and Trevor Connor, who wasn’t on this episode at all. Well, I am now I’m Rob Pickels. Thanks for listening.