Busting The Lactic Acid Myth & Sauna Hacks For Enhanced Endurance (SSOF Ep 105)

James de Lacey0:00

As far as the Strength Conditioning Blueprint, Adam, that I post there, is free. You just got to sign up with your email. So free in a sense that it's not monetary value. You're just giving up your email to me, so I can, for example, I just sent out an email before this to let people know to join this livestream to ask questions, etc.

So yes, that is free. I'll be doing blueprints for the other martial arts too. Obviously, the Sweet Science of Fighting Underground training app is not free. That takes—well, that costs money because it's essentially pay for me putting everything together, etc., etc. So that is there. So I think that covers everything.

But let's dive into this lactic acid myth. If you have any questions throughout this, just throw them in the chat and I'll get to them as well. So there's a few papers that I'll reference throughout this. Some of them I'll probably forget to reference. I'm sorry if you want any of the references as well. Just shoot me a message. I can also send them through.

But I'm going to—I've tried to synthesize everything so it makes sense in kind of like a logical order, almost like a story, starting with what lactic acid actually is initially. And when we define lactic acid, it's not really a thing, funnily enough. So lactic acid in lactic acid form virtually doesn't exist in the body. It's two separate ions.

So you have the lactate and you have hydrogen ions. The hydrogen ion is the acidic part of it, and that's what makes it the acid. And then you have lactate. And when people typically refer to lactic acid—lactate—it's usually used in a negative connotation, and it's usually talked about as in we're trying to flush lactate out of the body, or we're trying to remove lactate, or we're trying to reduce as much lactate as possible while training.

We don't want to get too lactic within training. I mean, I've even said some of these things in the past, right? So I've been wrong on a lot of this too in the past. Unfortunately, we don't get taught a lot of this within, I guess, physiology within our study. It's just stuff you got to go do a deep dive on your own.

So I'm trying to present this to you—helps me with learning it and helps me pass it on to you as well. So when we talk about lactic acid, we refer to it as lactate from now on. That's what it really is. And it's typically that lactate and hydrogen ions are associated together, and that's typically seen as the rise in lactate from exercise. You see an associated rise in these hydrogen ions, which is creating this acidic environment. I'll dive into that in a second.

So how does lactate even increase with exercise? So with muscles contracting, they use a certain form of energy, and that is ATP. I'm sure a lot of you have heard about adenosine triphosphate, or ATP, term often used within all sorts of different things now. The glycolytic pathway is one pathway—oh, here we go, question from Chris.

Actually, I'm going to dive into this now. He says, "James, I have a major lactic acid buildup problem below both my gastrocs and on the inside of both legs. I have quite flat feet, and within 20 seconds of mat jogging, they're on fire. Help."

All right, so I'm going to dive into why it's probably not a lactic acid problem. This is what this will cover. Sounds like almost like compartment syndrome, to be honest. You should probably get that checked out. It sounds very much like compartment syndrome.

But on what you're saying about lactic acid, that is one of the things that often comes up when people talk about, "Hey, it's—I get this buildup and burning sensation, it's lactic acid." However, it probably isn't lactic acid. It's definitely not lactate. It could be the buildup of some of these acidic metabolites from, I guess, energy creation. But regardless, I'm going to take you through why this might not be the case and why it probably doesn't matter, and why it's actually probably a good thing.

So we have the glycolytic pathway, which is using blood glucose, muscle glycogen. So think carbohydrates, right? Carbohydrates and sugar. And it's a pathway that doesn't use oxygen. So forms ATP and forms pyruvate. But also, this pyruvate is shuttled into the mitochondria, where with oxygen you create a ton of ATP. That's the general idea.

However, as exercise intensity increases, the mitochondria can't keep up with all the pyruvate that's being produced. And that's when you get kind of this overspilling of pyruvate that then gets turned into lactate. And we get the associated hydrogen ions.

Now, the old way of thinking about this—and I actually just watched a video from a very influential, I guess, influencer—that's probably why influential on this—and there was a lot of old school, I guess you could say, false things in it. And it's around this idea of the aerobic and anaerobic energy systems and aerobic and anaerobic, or lactic thresholds. And we all know this idea around anaerobic thresholds, lactic thresholds that we often get told about, that, "Hey, we need to increase our anaerobic threshold or our aerobic threshold."

And this was actually talked about a lot in this video. But a lot of that has been kind of disproven since then. So if we go into it, so the aerobic threshold is considered that first inflection when blood lactate increases. It's also known as—I think a more, a better term for it is onset of blood lactate. So when you get that first rise, typically from like 2 millimoles per liter to 4 millimoles per liter. But again, there's no absolute number. It's just that first increase.

As exercise intensity increases, the mitochondria can't keep up with the excess pyruvate, which I talked about before, from the glycolysis, and is converted to lactate. Now, multiple factors may contribute to this increase in blood lactate. We're talking about central factors, oxygen delivery. We talk mitochondrial capacity, which is a peripheral factor. We covered that in the previous podcast too. Ability to clear and utilize lactate by other cells throughout the body. And that is taken from a really good paper called "Lactic Acid: Friend or Foe" in 2016, if you really want to look that up too.

So we have the—what they call the aerobic threshold, or the onset of blood lactate. Then we have the lactic threshold, or anaerobic threshold, which is when essentially it starts to skyrocket. I'm sure a lot of you have seen those graphs of anaerobic threshold stuff, where you just see the graph kind of curving upwards and skyrocketing as exercise intensity increases.

And at that point, that's called the maximal lactate steady state. Essentially, you're able to maintain that lactate level at a certain, I guess, work effort. Now, it is thought that once we go from that—once we go past these points—we go from aerobic to anaerobic. And that was actually in a video that—

I watched the other day, which is quite funny. And if you've been listening to this podcast for a while, even or any of the videos, you know that that's just not true, just from muscle oxygenation data which I shared before. Essentially, if you're doing a 30-second sprint, that is highly aerobic because of the oxygen being used within the muscle to create that energy. You don't just have pure aerobic or pure anaerobic, you don't just cross some kind of threshold and suddenly you've gone from aerobic energy metabolism providing you energy and then suddenly you go into anaerobic energy metabolism.

Instead, with these thresholds, you're essentially, the metabolism can't keep up with all the pyruvate, so you just creating more lactate, and then lactate essentially rises. Now, the presence of this rise in lactate is associated with the rise in those H and those hydrogen ions which I shared before, which brings us to the lactic acid hypothesis of fatigue. And I think this is where most people, or most the information that you're probably consuming, sits.

This idea that—I mean, I used to talk about this too, and I was wrong about this for sure, and I'm trying to share, I guess, more developed information around this. So the idea is that as we exercise, the exercise intensity increases, we build more blood lactate and then more hydrogen ions with that. These hydrogen ions make the environment, the muscular environment, more acidic, and then this acidity reduces the contractile function of the muscle. And therefore, we cannot produce as much force. Therefore, we start to fatigue.

That is the general consensus that was put forward many years ago but has been disproven, and there's major problems with this theory. Now, regarding just fatigue, I don't want to make this like a fatigue podcast because there's so much to go down the rabbit hole with that. Plus, we're not entirely sure the main mechanism of fatigue. There are a lot of theories around it, but we do know that this increased acidosis or acidic environment probably isn't a major one and is likely a very, very small part of the fatigue problem.

Because a lot of the studies done on this increased acidic environment for fatigue done in imposed anaerobic environments or post environments where essentially they're artificially removing oxygen from some kind of skinned muscle, and typically in rats or animals. So they would gas it with nitrogen instead of oxygen, they would use an ischemic cuff, known as like blood flow restriction—you're just tightening it up and stopping the blood flow going in—or they're doing it at cold temperatures. And we don't even see acidosis causing fatigue or much fatigue at all at normal temperatures.

And as an example, we see a paper by Pate, Paty, or Pate and his colleagues in 1995. So they tested muscle at 10 degrees Celsius and 30 degrees Celsius, and they showed that at the 10 degrees C, it did reduce maximum contractile velocity—so the speed and force—under acidotic conditions. And we're talking acidotic conditions of like 20 millimoles of lactate per liter. And when we're talking 20 millimoles of lactate, that's like an absolute bloodbath. Think about like the hardest session you've ever done where you're trying to crawl out of the gym—like, that's the intensity we're talking in terms of the acidic environment.

But at 30 degrees C, which would be closer to normal body temperature, this minimal effect of this reduction in pH—and if you remember your pH scale from school chemistry class at school, obviously seven is neutral, below seven becomes acidic, above seven becomes basic or alkaline. So a lower pH had minimal effect, indicating that pH plays a less important role in fatigue.

Another example around this idea of fatigue and lactic acid or lactate is a paper by Nielsen and his colleagues in 2001 on skeletal rat muscle. So they saw a reduction of force from essentially, they were just like twitching the muscle over and over again, right? And they found that potassium concentration increases from these contractions, and then you get a buildup of this potassium as potentially one of the theories around fatigue.

But when they added lactic acid—so in this case, it was the hydrogen and lactate to these muscles—they actually saw a recovery, a huge recovery in force generation. I'm talking like back to normal baseline from adding lactic acid. And that indicates lactic acid actually counteracts the force-depressing effects of potassium in this case. So are we seeing that lactic acid and lactate is actually protective of fatigue? That's something to think about there.

So what actually happens with this increasing blood lactate through exercise intensity? And it's an awesome paper from 2006 from Simon Kaye out of a university in Auckland, my old university there. I've had quite a few researchers and faculty members on the podcast from AUT, so yeah, awesome research coming out of there. Dr. Eric Helms was one of them who was on recently. Definitely, I'm sure a lot of you might know Bret Contreras, the glute guy. Met him in Auckland through my studies there. So there's some good guys that come out of there and some really interesting research.

But essentially, he's done a review on the lactic acid myth, and turns out lactate might actually be ergogenic, a.k.a. performance-enhancing, which sounds counter—sounds like it doesn't make sense, right? So lactate, it's actually a fuel. It's a fuel for the body during, and it's actually a preferred fuel. It's not a waste product that a lot of people talk about.

So there's the lactate shuttle theory—oh, I can't remember who actually created that. I'm sorry, it's the original theorist on this. But regardless, essentially lactate is shuttled into an oxidative fiber, so slow-twitch muscle fibers, where it can be metabolized into pyruvate. And then that pyruvate is then, again, as we mentioned at the very beginning, is metabolized in the mitochondria, creating out energy.

Now, it's important to note that lactate may also be shuttled to the heart and to the liver and kidneys, where it can release more glucose into other places, such as the brain. So it's not just used for the muscle to create energy, it's actually used to help, I guess, deliver more fuel from the liver, liver glycogen, and kidney, then also used in the brain, also used for the heart. So it's a preferred fuel source in that area. And that is taken from Gladden and Takahashi 2016. It's a good paper too.

So this accounts for approximately 75% of lactate removal, with the rest being used in the liver and kidneys to release more glucose. So a lot of it is used in the brain and the muscles, et cetera. So lactate becomes the preferred energy source for the brain and muscles at higher intensities because it's fast and efficient.

Which brings us back to the idea of this aerobic, anaerobic threshold. So how most people see this is you want to keep lactate as low as possible as long as possible. And I had talked about this in the past, and I was definitely wrong on this too. So keep up with the podcast and stuff because I'll keep iterating on things.

But essentially, the general premise was that we don't want to see a rise in blood lactate because it's associated with fatigue. So we want to increase—typically, it's done when people talk about these aerobic, anaerobic thresholds—they're measuring them against heart rate or against power output for a certain activity. So a typical graph you might see, down on the x-axis, you might see heart rates or you might see watts, and then on the y-axis you might see blood lactate levels from 0 to 20.

And they essentially want to try and push the rise in blood lactate further to the right as much as possible. So instead of seeing this inflection of blood lactate at 160 beats per minute, they want to see it 170 beats per minute, or instead of at 300 watts, they want to see it at 400 watts. And the theory was, okay, I'm delaying when I'm going to go, quote-unquote, anaerobic, which means I'm going to be able to resist fatigue longer and operate under these thresholds so I don't have this increase in blood lactate.

That was—I mean, that still is what a lot of people talking about and what a lot of people are saying when it comes to improving conditioning.

Now, this is why right now there's a big push for zone 2 cardio. Zone 2 cardio has gone—I mean, I guess it doesn't help that the big podcast influences, longevity crowd, have pushed it a lot. I mean, for longevity, this isn't about longevity, but for longevity, sure. But we're not talking about longevity. We're talking about maximizing combat sports performance.

So the big push in zone 2 is so you can use fats, you can oxidize fats or use fats for fuel instead of glucose. So intensity is going to dictate what kind of fuel you're going to use, whether that's fats or sugars. But by doing a lot of zone 2, you're using more fats and reducing the glycolytic rate or reducing the use of sugar, and then you're lowering blood lactate. Okay, that's the general premise.

But does this even matter for performance? That's the big thing, right? We only care about if we do this, is this going to make us a more fit, quote-unquote, fit fighter? Am I going to be able to last three, five, however many rounds, and we're going to be able to—which I think is most important—repeat high intensity efforts?

Well, it turns out that this probably doesn't even matter for performance when we talk about our maximum lactate steady state or lactic threshold, as it's often called. Again, remember, it's that big inflection in lactate as it quickly rises as exercise intensity rises. So this study by Beneke and his colleagues in 2000, they found that this lactic threshold does not predict the power output, or what they call it, workload relative to body weight.

Or the essentially time to exhaustion. So the performance time at that point, at that lactate point. So for example, you could have two athletes with identical maximal lactate steady states. So let's just say it's 5 millimolar per liter, right? That's the point before it inflects up. They train, they stick at that level, and they just have a constant workload. You'll see that the two athletes have different power outputs relative to body weight, but they'll also have different times to exhaustion.

And as an example, in this one study, numerous athletes terminated a test between 20 and 30 minutes. So instead of this number being predictive of when someone should essentially cap out, doesn't really tell us much. There's no correlation between these, and it means that lactate potentially is not the limiting factor in performance. And the authors concluded here that the speculations from previous studies of high performance reduces blood lactate at maximal or anaerobic threshold, maximal lactate steady state, and the increasing work intensity could not be verified.

So essentially they're saying that if we shift this anaerobic or aerobic threshold further to the right and we're able to have lower blood lactate levels at higher heart rates or higher power outputs, it doesn't mean, it does not mean, for being able to before for time to exhaustion in these tests and also the power up relative to body weight. So what does this really, what does this even mean then for us as combat athletes?

I think this paper put it really, really well. This is the Lactate Friend or Foe paper I referenced earlier by Haller and his colleagues in 2016. They said, and they use this term, performance predicts performance. And what this means is your performance numbers are going to predict your performance more than physiological markers. So as an example, a study of elite endurance runners, maximal sustainable speed on a treadmill, so this is performance speed, predicted 5K running performance better than VO2 max, running economy, VO2 at lactate threshold, onset of blood lactate quote unquote aerobic threshold, or maximum lactate steady state quote unquote anaerobic threshold.

So at this point, it's almost like this risen blood lactate exit doesn't really matter for performance. We're not trying to shift this, I guess I'm going to call it like an imaginary aerobic and anaerobic threshold, because they're not aerobic or anaerobic. You don't go from aerobic to anaerobic or the other way just because of an intensity. Intensity dictates what you're going to use as fuel, and lactate is going to be your main fuel source, especially as intensity increases.

Now I've got an excerpt from Dr. John Babraj's book, really, really good book on high intensity sprint intervals and high intensity interval training. Hoping to republish that and be able to essentially sell that on the site for you guys as well because more people need to definitely need to read it. And I mean, he wrote this over 10 years ago and this is, you could say it's ahead of his time. It's ahead of his time still because people are still talking about a lot of this stuff I talked about previously.

But taking a quote from his book: so lactate is also not just an important source of energy during maximum high intensity exercise, but also when working at lower intensities or when recovering from higher intensity exercise. This makes it essential for getting the most out of high intensity training as you will need to use it to fuel your sprints and to increase the speed of your recovery. And we talked about the speed of recovery when lactic acid was added to the muscle, those rat muscles that were fatigued, it brought force generation back up. So that kind of supports that point.

The reason people who do more physical activity can perform longer and harder is not because they're able to withstand lactic acid or that their bodies produce less lactate. And that's what we just talked about before around that paper showing that shifting this anaerobic or aerobic threshold further to the right to higher power outputs or higher heart rates does not mean anything for performance.

What happens is that as you train, your muscles adapt. Okay, I'm just going to read it as is. What happens is that as you train, your muscles adapt to be able to more readily use this fuel source. So essentially you're just improving your muscle's ability to use lactate as fuel. The strenuous effort causes a greater production of lactic acid, and this combined with small rest periods, so this is in relation to sprint interval training, that do not quite give your body enough time to replenish other fuel sources, forces your body to more efficiently use alternative sources of energy. And alternative sources of energy means lactate.

So that's, I think that's everything I had for this lactate myth. So to sum it up: lactate is a preferred fuel source. It is not a waste product. It is very useful for providing energy to the working muscles, especially under high intensity environments. It is quick and is efficient, but it also uses energy during low intensity activity as well.

It is not something to be scared of, and it's not something that is going to cause the burning sensation and burning things when you're doing exercise. It's likely other acidic metabolites. Again, this acidic environment is not a negative. Acidic environment may actually be a protective mechanism around fatigue, so bear that in mind too.

We also have these ideas of aerobic and anaerobic thresholds that are not real because, one, we're not just going from aerobic to anaerobic just because the mitochondria are using or turning this pyruvate into ATP does not mean that we're not using any anaerobic or glycolytic pathway to produce energy. We are always producing lactate even when you're sitting here watching this, driving, whatever it is, you are producing lactate right now when using it as energy.

You're just not producing much. As we get into more intense exercise, blood lactate will rise. It does not mean you are suddenly anaerobic. Just means that the aerobic metabolism cannot keep up with all the pyruvate that is being produced, and a lot of that gets turned into lactate, which becomes a more efficient fuel source to be used.

And again, shifting these aerobic and anaerobic thresholds doesn't mean anything for performance because it's not about trying to stay less lactic or producing less blood lactate. It's about being able to use this fuel source efficiently. And when we're using this fuel, to use this fuel source efficiently, we likely have to be in higher blood lactate environments more often, which would be our sprint intervals. Our Zone 2 conditioning likely isn't intense enough to provide the adaptations we want, and athletes that are more well-trained are even less likely to see the benefits from Zone 2 type conditioning.

There are likely better ways to target central adaptations that are slightly more intense that are going to get you that. And then we have the whole idea of central and peripheral adaptations, which I touched on in the last podcast.

So if you have any questions on that, throw them in the chat. Chris, I hope that answers your question around your lactic acid buildup problem and your gastroc. I'm honestly, that just sounds like compartment syndrome. Flat 20 seconds of muscle joing fire, yeah, definitely sounds like compartment syndrome. I've had athletes with that issue. It can be a surgical thing, so definitely go see someone.

And since you're in New Zealand, ACC bro, just make sure you write on the form that it was a sudden pain or you got kicked there or something happened suddenly and then you should be good. That's just for learning purposes only. That is not anything, that is not advice.

I want to cover as well saunas, this little sauna hack. I got to jazz it up. So, oh, did I not open the page that I wanted? Okay, hold on a sec. I'm opening these.

So there's this huge push to everyone getting in an ice bath, right? Everyone loves ice baths, and there's a time and place for ice baths. I've covered it before in the podcast and on the channel where ice baths are typically more useful maybe within higher or more condensed training periods when you're preparing for a competition, where the adaptations you're trying to achieve from training probably not as important as being as fresh as possible for technical training.

The sauna is something else, and there's some really interesting research around using the sauna to enhance endurance, which makes it a, it probably makes it a really good thing to use either out of camp during, like, to say a more voluminous or lower intensity, I guess, training period. And also helps you become heat acclimated, which is another benefit. So you could potentially use it in camp too. There's a couple of different, I guess, use cases in there.

So if I jump into some of the research, there is a few papers. This one by Scoon and his colleagues in 2007, they essentially took competitive distance runners. They did 12 sauna sessions in 3 weeks, so that's like four sessions a week for 30 minutes in there, and it was around 90 degrees Celsius directly after approximately 50 to 60 minute endurance session. And they found that after those 3 weeks, an increased plasma and blood volume and a 32% increase in time to exhaustion test, which is pretty insane.

And they found that this increase in blood volume, so this would be the delivery aspect of, I guess, our conditioning, was associated with this rise in time to exhaustion. So literally just sitting in a sauna, and this was compared to, this was a crossover design, so this is compared to no sauna. So it's pretty interesting that just sitting in a sauna after endurance training can enhance time to exhaustion in these endurance events.

Now there's another paper as well. I'm just trying to pull it up here. I've got the right one. I think this, yes, this one. And this one's...

Middle distance runners, there's one in cycling. I'm just going to make sure I have it here. Yep, well-trained cyclists. They essentially did 10 days training plus sauna, 30 minutes of sauna, again similar temperature. They found an 18% increase in blood plasma volume, so same thing, increased blood plasma volume, 10% reduction in resting heart rate, and 133% reduction in 60-second heart rate recovery. So that's pretty interesting after just during this one, after endurance training.

Another one in middle distance and cross country runners, they found their improved speed at 4 millimoles per liter of blood lactate by 4%. So from what I was just talking about before, that would be potentially like an aerobic threshold if we're going to use old terms on that. But essentially at a certain blood lactate level, they were able to increase running speed. They're also able to reduce submaximal heart rate while running by seven beats per minute. So essentially your efforts were easier, and that was just after nine sauna sessions directly after exercise over three weeks. That was compared to a control group as well.

So it's an interesting concept. It's definitely something you could look to do maybe the beginning of a fight camp or even just during an out-of-camp period. The important thing is it has to be under, it has to be after low to moderate intensity training. So whether that's your easier conditioning, whether that's a more technical training session within your technical training and getting in the sauna for 30 minutes after, looks like around 3 to 4 weeks and looks like around 3 to 4 sauna sessions per week for 30 minutes at around 85 to 90-ish degrees C. That seems to be the general consensus for improving your endurance.

Now, the reason I say that it should be, it needs to be after low to moderate intensity conditioning, because if you start doing it after high intensity conditioning, remember anything you do that is, I guess anything you do like this, is an extra stressor on the body. Being in a hot environment is stressful for the body, even though I mean you probably feel it if anyone's been in the sauna, especially after already being hot, it is a stressor.

So there's a study in competitive swimmers. They actually did I think it was 4 by 50-meter sprints in the pool, and then they sauna directly after. But they found that it reduced swim performance the following morning. So using the sauna after, say, an intense sparring session or very hard conditioning may not be a good idea because you're just adding more physiological stress on top of the stress you just imposed on yourself.

So just bear that in mind. If you're going to implement something like this or play around with something like this, sauna directly after low to moderate intensity exercise, 3 to 4 times a week, 3 to 4 weeks, and then you should see some improvements in endurance. Plus you become a little more heat acclimated, which is nice, especially if you're, when you're fighting, you're often under bright lights depending on what you're doing, hot rooms, et cetera, et cetera. So just something to bear in mind too.

Also, some interesting research around recovery. So essentially getting into a far infrared sauna directly after endurance training, participants were able to jump higher compared to a group that did not sit in the sauna. So that's another interesting tool for the sauna there. I mean, that was far infrared, so it's a little different I think to a traditional sauna. But yeah, that covers almost everything I had for you.

4 minutes into this pod. If there's any questions, shoot them through for anyone listening on the replay. I'm going to, if you subscribe to the Sweet Science of Fighting YouTube channel, not the podcast version, I'm going to have proper videos of a lot of the stuff up to really try and essentially distill everything really, really down to fine details in those videos as well. So it's in podcast format, then it's going to be in YouTube video format, and there's a couple of ways to consume that style of content.

I think eventually I'll put some articles up on the website, but the way Google is currently going, I'm sure some of you have seen it searching, it's a show, and they don't like small publishers. They want to shovel more money in their own pockets and in the big publishers' pockets. So video it is. Also make sure you follow on Instagram. I'm going to create reels and all the stuff too. I've been creating quite a few reels that have been doing well, so jump on there as well.

But I believe that is everything I want to cover. So make sure you subscribe to the YouTube channel. Also leave any reviews. Reviews help a lot, whether it's on Spotify, Apple, whatever it is. Reviews help podcasts a lot. And if there's anything, any topics you want me to cover, just let me know. Just shoot me a message on Instagram or wherever, through the email, and I will see you on the next podcast.