Myth Busters—Why We Can’t Talk About Lactic Acid

Ouch, it burns! But what causes that burning sensation in our muscles when we work out? Dr. Inigo San Millan and Caley Fretz reveal new science on lactic acid and "the burn".

Chris Case Fast Talk Podcast
Photo: Brad Kaminski

Ouch, it burns!

But what is “it” — the root cause of the pain in your legs when you smash it up a hard climb? For the longest time, we colloquially called “it” lactic acid. It turns out that was wrong.

Coach Trevor Connor and Caley Fretz examine the chemistry that occurs in our muscles while riding and racing. They talk to Dr. Iñigo San Millán, who is the former director of the University of Colorado Sports Medicine and Performance Center.

Best of all, they give you practical advice for your own training to help make that burn go away—or at least make you faster even if it hurts.

Trevor Connor, Caley Fretz, and Dr. Iñigo San Millán

Episode Transcript



Welcome to fast off the velonews podcast, everything you need to know to


Dr. Iñigo San Millán  00:12

teach muscle fiber training, which is


Dr. Iñigo San Millán  00:20

slow twitch muscle fibers. So that’s why the whole concept of the zone two and the base, it’s very important because you’re not going to prove much the interest rate high intensity high intensity, the promise first, and I continue to improve because they improve for the glycolytic capacity capacities of fibers and they increase exploitation outside. improvement. People get stuck there.



Coach Trevor, I have a story for you. This morning, I went on a bicycle ride. I spent an hour and 20 Yeah, not that long before work. caught up with a couple a couple guys that ride pretty fast. Got about 15 minutes in first sort of hard section first on section we call it my legs. They filled with so much lactic acid. Just burning, burning like fire. Like they were on


Dr. Iñigo San Millán  01:23

fire. It



was the worst thing ever. I’m just wondering if, if you could tell me how I could buffer that lactic acid a little bit better. Can you tell me how to do that, Trevor.


Trevor Connor  01:32

So this is a test of the sensitivity of our mics because I’m not sure they can pick up the sound of my teeth grinding right now.



That was a fake story. Welcome to another episode of fast doc. I am Kaylee frets, man of the fake story. I’m a senior editor here at felonies across the table, as always from our favorite coach, Trevor Connor. And the topic of discussion today is lactate, or lactic acid, which doesn’t really exist.


Trevor Connor  02:01

So this is the Mythbusters I have been waiting to do. This is one of my cringe moments. So boxes, whatever you want to call it. But we are going to spend the next however minutes explaining to you why lactic acid does not exist in the human body.



And why my whole little fake story at the beginning there was absolute nonsense, because my legs do not burn because they are full of acid.


Trevor Connor  02:30

Well, they do a little bit sort of relax, just don’t burn.



But let’s get into it. So Trevor, why if lactic acid is not a thing that we find in our bodies? Why have I heard about this for the entire two decades? That I have been an athlete? Why, what why Why? Why is this the thing that consistently comes up again, and again, we have an entire plethora of products designed to decrease lactic acid we have. We have coaches the world over teaching you how to training you how to reduce your lactic acid. While these things if lactic acid ain’t a thing.


Trevor Connor  03:17

So this comes down to inertia. And let me tell you, we’ve been hearing about this for longer than 20 years. The researchers and I can’t remember the name, who discovered it, discovered what they thought was lactic acid back in 1907. And I believe they won the Nobel Prize for it. But that was at the time that we were well it was fine. acid base chemistry was in its infancy back then and we didn’t really understand fully, or they didn’t fully understand how it worked back then. So you can you can forgive them for getting lactate and lactic acid mixed up. But that stuck around for a long time it became part of the common language. And then in the 70s you had two researchers This was Fitz and mispronounces. butthole. Allow ski allow ski, h o LL. O s Zed. Why? Tell me how you pronounce it? I



don’t know what is that is?


Trevor Connor  04:12

Yes, I believe they were Canadian. And they found a correlation between the rise of lactate in your blood and a drop in pH. So they said There you go. ph drops, which means that the Bloods becoming more acidic, so it’s lactic acid. Again, and we’ll explain why you have that correlation, but it’s not lactic acid. This to me is a sign of people who are keeping up with the science because when I hear people talking about lactic acid, I just go read current physiology book.



While we’re here to, we’re here to make it so you don’t have to read you just put your headphones on and listen to us. There’s the whole idea. So lactic acid myth. This is a myth. This is definitively a myth. This is Not one of those things that is controversial. Well, lactic acid is is definitively not in existence correct?


Trevor Connor  05:05

Well, I’m gonna prove that exists in the world just doesn’t in any physiological quantity exist in our body. Let me tell you, I wrote an article about this back, what was it 2012 2013. I have never been so attacked for an article. And my favorite part was it turned into this argument on the velonews website between me and a researcher who studied redox reactions. And we got a little hot and heavy into this debate. And then all of a sudden, a third person pipes in and all he writes is nerdfighter, a whole bunch of exclamation marks and that ended, he won.



No one wins a fight on the internet. That was back in the good old days when the Wendelin is calm had comments, I think, well, maybe the battle days. But thankfully, the comments are no gone. So explain this to me. Explain yourself, Trevor, if this is if this is something that you are so sure about. Explain to me why. Why? Why? Just tell me again, why explain to me why, like the acid is not found in a physiological sense.


Trevor Connor  06:09

So forgive me, this is the five minutes of this podcast where I’ll put you to sleep. And then I hope our promise the rest of this is going to get a little more exciting. But I do need to explain a little bit of acid base chemistry. And when I was doing my chemistry classes, this was the part of chemistry I went, Damn, this is complicated. What I’m about to explain to you is a simplification. But to help you understand lactic acid versus lactate, not as a definitive This is how acid base works. If you want to understand that go look up bronsted Lowry acids and the different types of acids and all about hydronium and various other things in acid that I’m trying not to remember from my chemistry days. So yes, this is my qualifier to all you scientists out there simplification. Basically, what an acid is, is a chemical that has a hydrogen that can easily disassociate, so detach from the molecule. This isn’t quite chemically accurate, but I’m going to use this to make it easy to understand. Don’t think of that molecule as the acid think of that hydrogen ion. It’s called an ion because it doesn’t have an electron. So basically, this is a atom floating around that has no electrons, that hydrogen ion can become very, very damaging, because it’s going to go to other molecules and try to steal electrons. That’s rude. It’s quite rude and quite selfish. But that’s what hydrogen does. So basically, an acid is just something that can release a whole bunch of these hydrogen ions into a, a liquid. And then depending on how easily it disassociates, those hydrogens can be more or less damaging. The thing is, something will eventually take up those hydrogen ions. That’s your base. So a base chemical will then grab that hydrogen bond to it. And then that reduces the acidity, because now you don’t have this hydrogen ion floating around that your base I’ve now explained to your your acid and your base. Where I’m going to with this is, as soon as an acid releases its hydrogen ion, it’s now essentially become a base because it can take up a hydrogen now. So every acid has its base compliment. And when we’re talking about lactic acid, you have lactic acid, which is the acid because it still has the hydrogen ion. And then you have lactate, which is the base that can take up the hydrogen ion. So they are and I’ve had in that argument we, we had on the web, I’m sure it’s still up there, if anybody wants to go up, take a look at it that scientists said, well, it just nomenclature, there’s no difference between lactate and lactic acid. So you can just use them interchangeably. Not really true. One is bonding to hydrogen, one is releasing hydrogen. Those hydrogen ions have a huge effect on our ability to exercise and can be very damaging. So one’s almost lactates almost protective against acidity, or it is protective against acidity, or lactic acid can contribute to acidity. So there’s your chemistry lesson any any sound like a professor, any any questions, or Tomorrow,



I will be failing this exam a while so if they’re so they’re both inside you. Well and lactic acid, so isn’t lactic acid then technically in there, it’s just sort of balanced by lack tape.


Trevor Connor  09:50

So here’s the other part of of acid base chemistry you need to understand when you are talking about in an acid base pair You have what’s called a PK a value. So this is the pH of a fluid. Or what pH of a fluid is required to have half of the molecules exist in the acid form half of the molecules exist in the base form. So it’s basically, when you’re thinking about, since we’re talking about lactic acid here, what pH? Would your blood have to be for you to have half lactic acid, half lactate following me, yep, the and remember, the lower the pH value, the more acidic the PK, apart from chemistry. Okay, good. The PK a value for lactic acid and lactate is 3.67. Which, so that’s why it’s so great, which is quite acidic. So human body, your typical blood pH and in a resting state is around 7.4.



When you are, which is just a hint, basic,


Trevor Connor  11:03

I believe so yes. When you are all out killing yourself, you’re getting that burn in your muscles, your pH of your blood will drop to around seven, you know, the lows will drop to around 6.9 7.0. You drop much below that, and you are now getting into serious dangers like pH that you could die from. That’s no good. So human body, our blood won’t see much below seven, you have to be at 3.67 just to have half lactic acid half lactate. So at the pH is that our bodies operate at lactic acid essentially does not exist or it’s zero point, some bunch of zeros 1% lactic acid, the rest is lactate. So it’s physiologically it does not exist in the human body.


Dr. Iñigo San Millán  11:55

All right,



I got you know, I’m following along. Basically, it’s not so much that lactic acid, as sort of we’ve described it here doesn’t exist entirely. It’s just that it’s in such a small quantity. And it’s just the broader point is that it’s not what we’re talking about, right? When we’re talking about the burn and etc, etc. Like the the actual, the things that are happening inside you when you’re exercise. This flush of lactic acid, as it’s been described, to many athletes, does not exist,


Trevor Connor  12:27

right. And here’s what’s going to annoy you even more. And I won’t go too deep into this, but I’ll put references, excuse me, for a couple studies up on the website that show that lactate concentration. So when you go in and do that lactate test in a physiology lab, and they show the rise in your lactate as you you get higher and higher wattage is that elevated lactate isn’t even a measure of fatigue. And it’s not even a measure of hypoxia.



So why why does it correlate relatively well with ability? The ability to ride quickly?


Trevor Connor  13:09

So that’s the question that we want to get to let’s hold off, though on that question for a bit. Because there’s a few other things to understand about lactate, which does exist in your body. To help you understand why we still measure lactate, that is the physiology labs are not ripping you off. That’s good to know. They’re not measuring this going. Fools they there, they got lactic acid in there, not the case. There is actually good reasons to continue doing these lactate tests. But before we can get there, I need to tell you a little bit more about lactate.



I see on the board. lactate is a fuel slash transporter.



This is



our This is our magical what we’re going to talk about next board that is sitting in front of me.


Trevor Connor  13:53

So there is a professor Brooks who really turned around the science on on lactate and lactic acid. And so before he came around and did his research, everybody said, well, it’s lactic acid. And lactic acid is a dead product, you build it up, you fatigue, you’re done, you now have to clear it out in the next day, you’re gonna be really sore.



So that’s the that’s always what I had heard prior to discussing this with you about seven years ago.


Trevor Connor  14:21

So that’s all been thrown out. And like I said, a lot of that was Professor Brooks. And what he has discovered is that lactate actually serves a very important purposes in our body. And I will tell you one of the biggest compliments I got when I was having this whole debate about that article, and just thinking, Oh, geez, why did why did I write that? One of my professors from CSU actually emailed me an email he received from Professor Brooks, with a copy of the article saying, finally somebody got it right.



That was well done, Trevor,


Trevor Connor  14:55

that went took it from like the worst article I’ve ever written to Wow.



Thank you. So hopefully you get another email after this podcast.


Trevor Connor  15:05

Not gonna hold my breath, but it’d be nice. So, yes, lactate is a fuel. It is not a dead product, our bodies use it a lot. As a matter of fact, it is the primary fuel of our hearts. Our livers also take it up. during exercise, our slow twitch muscle fibers will take it up and use it as a fuel. There are a lot of uses for it. So there’s again, I’m not going to go down too many rabbit holes here, I’m just going to touch on a few. lactate chemistry and physiology is actually remarkably complex, really fascinating, remarkably complex. So we’re only going to skim it in this podcast. But there’s what’s called the lactate shuttle and the Cori cycle. And these are processes by which your body essentially uses lactate to transport energy. So when you break down glucose for fuel, that’s called glycolysis. At the end of that, the old textbooks tell you that the end product is pi rebate and then pi rebates used. Pyro VEDA is taken in into the mitochondria, and it’s used for the Krebs cycle. And I’m sure everybody’s remembering their high school biology for all this,



remembering might be a slight overstatement.


Trevor Connor  16:19

They nightmares of these terms,



I remember that that term exists. Yes.


Trevor Connor  16:24

So what we’re actually discovering is no, Pyro vape might not be the primary end product, it’s actually lactate. And lactate is really good for transporting across membranes. So it’s really good for transporting out of cells into cells into the mitochondria to be used for fuel, it actually transports better than glucose. So our bodies actually like to get this fuel into the the the lactate form, and then send it to where it’s needed. So it gets pumped out of the cells. And this even happens at rest. This is one of the mistakes people make is they think we only produce lactate when we’re going hard. sitting in your chair right now looking bored out of your wits for what I’m saying and not moving. You’re actually producing lactate. I’m intellectually invigorated ran out, Trevor, I wish that lactate gets pumped out into your blood, it’s taken up by your heart, it’s taken up by other tissues that can use it for fuel. And that’s it’s also taken up by your liver and your liver converts it back to glucose in a process called gluconeogenesis. And that’s the Cori cycle here. So it is think of lactate is is great way to transport your fuels, particularly your sugar based fuels.






follow up question?






How is it produced? We’ve said a couple times now that when you when we go when you go hard, we produce lactate. That seems like an important piece of the puzzle here.


Trevor Connor  17:51

So you do produce more and more when you when you go hard. So as I said, when your body breaks down glucose, that process is called glycolysis. The end product of glycolysis is either provate or lactate, and used to believe that the Pyro date was the dominant, I’ve been reading a lot of research recently that saying actually no lactates the more common form. So when you are going easy. Your body likes to burn fats when it’s going easy. It’s also using a lot of slow twitch muscle fibers when it’s going easy. So twitch muscle fibers are not big producers of lactate because they don’t rely on sugar, they rely on fat, so you’re not producing a lot when you’re going to use E. As you start going harder you recruit more and more fast twitch muscle fibers. They are big users of glucose. So glycolysis is getting ramped up. They’re producing a ton of lactate. Remember I said the lactate generally goes into the Krebs cycle, which is where you burn fat. That’s also where you use oxygen. fast twitch muscle fibers don’t really rely too heavily on the Krebs cycle. They don’t rely too heavily on oxygen. So they have all this lactate build up that they’re like, what do I do with this? Meanwhile, right beside them all the slow twitch muscle fibers to go in over here. I’ll take it send it my way. And that’s that’s that that lactate shuttle is talking about. So the fast twitch muscle fibers will pump all the lactate out of the cell. And then the slow twitch muscle fibers will take the lactate up and happily use it for fuel. Liver will also take it up to produce more glucose. So yes,



that’s why is it a waste product of those fast twitch fibers using glucose?


Trevor Connor  19:32

Well, the fast twitch muscle fibers since they don’t rely too heavily on the Krebs cycle and oxidative metabolism. They can use the lactate but not nearly as rapidly as they’re producing it. So it’s not a waste product for them. They’re those cells, those fast twitch muscle fibers are saying I can’t really use all this so I’m going to pump it out. But there’s other tissues in the body, particularly your slow twitch muscle fibers, your liver, your heart that can take it up and you it.



All right, I’m with you, when you’re with me.


Trevor Connor  20:03

Yep. So that’s we jumped a little bit ahead. But that’s great. That is why you see more and more lactate production when you’re going harder and harder and harder, even when you are exercising and going hard, and a lot of lactate is being pumped out into the blood. And so we said, you know, lactate levels rise when you’re going hard, that’s actually beneficial. So we thought lactic acid is a sign that the body is not able to function well. But actually pumping the lactate out, a helps get those hydrogen ions out of your cells, your cells can keep working. It also helps drive ventilation makes you breathe harder. We actually have sensors for it. And then there’s an effect called the bore effect, where lactate has been shown to potentially help your your blood the hemoglobin in your blood to release Oh, to see your muscles can take it up. So lactate is not this end product that’s shutting you down. Actually, this production of lactate is showing to help your body go longer.



So I guess the the the follow up question of that, for me is can you produce too






is that is the original analogy of the original lactic acid analogy of you just your legs are filling up with lactic acid and they hurt a lot and it shuts you down. Is that eventually somewhat true? Or is it something else entirely?


Trevor Connor  21:30

Really good question. And that’s kind of what we were just getting at with our conversation we just had, when you are looking at the level of lactate in your blood, you are not just looking at production, it is the ratio of production to clearance. So that’s what I was saying. Even you are resting when you’re not moving, you’re producing lactate, you are just clearing it out as rapidly as you’re producing it. So you maintain a very low base level. As you produce more and more clearance might not be able to keep up. So when we talk about lactate levels, we talk about millimoles. at rest, you’re generally going to be below one. Once you go over to you are considered to be at the start of what’s your threshold range. Some physiologists out there say you are at what is commonly called your anaerobic threshold, or now we’re talking more about FTP. When you’re at about four millimoles. You have somebody like Chris Froome, he probably can’t go much above six. A really good sprinter can hit like 19 2021 because they have those big fast twitch fibers and produce a lot. And I remember early as a coach, I was working with this Master’s athlete who got tested at a lab in the city where he lived. For some reason this physiologist just had him do an hour at a steady state. So his threshold power was right around 300. So this physiologist had him do an hour at like 260 watts. Not sure why not a test I would ever do. But it had a really interesting side effect. He spent the entire hour at 12 millimole. Hmm. And I contacted the physiologist and said, Okay, that’s ridiculous. You didn’t test this right? He went No, actually, I see this all the time and masters athletes, I go, Well, you can’t have that sort of level, it goes, No, you don’t get it. A lot of these masters athletes do nothing but 30 minutes of intensity. So they have this enormous ability to produce lactate, but zero clearance ability. So it’s not so much that they’re producing tons and tons of lactate is just building up in their blood and their body doesn’t have any ability to get rid of it. And that’s why he could ride at 12 millimoles and not feel like he was dying. So the clearance part of the equation is really, really critical and and we talk later about ways to train, we’re gonna actually talk about ways of improving clearance. We already talked about the when you’re going hard or when you’re exercising the slow twitch muscle fibers will take up lactate, we’ve already talked about how the heart will take it up. kidneys will take it up, liver will take it up there’s a lot of tissues that will take it up. If you’re going really hard and you’re not getting enough blood to those tissues, they can’t take it up and that’s one of the things that affects clearance. Your body has to transport the lactate in and out of the muscle cells of all tissues, and the transporters are called MCT. There’s a lot of different types of MCT but we’re just going to talk about two transporters. One is MCT one and one is MCT for MCT. One is the transporters that’s used by tissues like the heart and your slow twitch muscle fibers to absorb the lactate take it out of the blood and pull it into the cell. So slow twitch muscle fibers have a lot of MCT one MCT takes the lactate and pumps it out of the cell. And there’s a lot of that in your fast twitch muscle fibers. When we talk a little bit later about training, training affects the quantity of MCT. One and MCT form, we’ll talk about what types of training effects each short version is fast, hard, high intensity training, builds up those MCT for so you’re pumping lots of lactate out into the blood, but it’s the slower, longer endurance rides that build up the MCT one so that you can take up the the transporters and maybe Actually, this is a good point, we talked with Dr. nego saw Milan about this, and he explains a little more the MCT one and the MCT. Four and why it’s so important not just to do high intensity work


Dr. Iñigo San Millán  25:52

wacking is produced mainly in the fast twitch muscle fibers. And lactate cannot be leave the cell, you know, by itself. He needs a transporter and you know, transporter shard the MCP force, right now those four spurs are stimulated by training high intensity, and by a lack of production itself, because it can relate geofences to post transporters. So therefore, lactate is exported out of itself by those transporters, right. Now, that doesn’t mean that you’re going to clear the lack is still is there, I will tell you that the muscle fibers in the muscle used to that need to get about out of the muscle, right? So we have two ways. One way is to take it to the bloodstream and from the bloodstream goes to pretty much every organ in the body. And that’s what we use for fuel. Right? Right, probably the major Oregon is the lever, right. And that’s where through the Cori cycle is we can produce glucose through gluconeogenesis from lactic, that’s one way the problem without pathway is that it takes minutes. So here we are producing lactate by the second during an activity right into building up building up those up, and he’s taking a minute to consider it. So that’s not going to worry about making it so we wouldn’t make a nation that is local, inside the muscle where we can oxidize that lactate or clear that lactate back to fuel in a matter of seconds. Right. Now, this happened mainly in the oxidative muscle fibers, which are the type one muscle fibers, right, which are which are adjustments of usually to the to the to the fast twitch muscle fibers. Now for that we need another transporter that transports lactate into this slow twitch muscle fibers and not the MCT one transporter, right. And that’s something that should have been placed. That is the MCT one. And there’s one enzyme in the mitochondria that a lot of federal lack mvh. Right that house, converting that lactate by to pyruvate. And therefore fuel for the tortoise shell, right. And part of shell to shell anti shuttle and all that anyways, well, what I mean with these is that in order to have that conflict developed, you need to trade, you need to stimulate those, that regulation that that regulation, that conflict and the habits mainly that the slow twitch muscle fibers, so you need to stimulate them as well. So what we see is that people who just do high intensity, high intensity, definitely they’re going to stimulate those MCT force. So they’re going to stimulate beyond also the glycolytic capacity of the cell, they can stimulate the capacity to export market outside the town. Right, which is necessary first step. However, if they don’t do that, the more that the slow twitch muscle fiber training, which is more like visual to they’re not going to stimulate the capacity to pour that lactic back into the slow twitch muscle fibers and clear up. So that’s why the whole concept of the zone two and in the bay interface, right? It’s very important because, you know, you’re not going to prove much. And that’s what we’ve seen for so many years. You know, I mean, you can trust training, high intensity, high intensity, the promise first, and I continue to improve because the improved for the collectability capacity of those fibers, they fire better that turrible works better. And they important they increase the lactate explication outside of those cells, right? And that’s where we’re seeing that we might have, we might see we see like a flat improvement, where we see people get stuck there, but then people don’t improve more and he gets back and they get back and it’s not until they don’t start working those slow twitch muscle fibers and all the components are electricians capacity, which is the mitochondria lakia to accomplish. And then we’ll see that until they start re improving. And that’s where we’re like we should a combination of both. That’s where it will be, she’ll be improvement in electric trains capacity and fat oxidation, which is also tells us that there saw a new quarter to improve a mitochondrial biogenesis. Because the type one fibers are the ones with the highest mitochondrial function, okay, by stimulating the fibers, we are not just proving that like excess capacity and oxidative addition to the mitochondrial biogenesis.



That’s good explanation from from Dr. Indigo. He’s always good. We always like Dr. Annika send Milan.


Trevor Connor  30:38

So since we’re talking about lactate, and we just heard from an ego saw Milan, and I also mentioned Dr. George Brooks, I think it’s worth mentioning that the two of them are actually working together right now. They just published a series of papers showing that lactate is involved in cancer and really coincidental so I’m looking at my screen right now and and on my Twitter feed just came up a new paper or at least Dr. salon just re posted it, a paper that he and Dr. Brooks wrote called re examine cancer metabolism. lactate production for carcinogenesis, could be the purpose and explanation of the Warburg effect. And he thought my explanation was a little heavy,



what’s the Warburg effect,


Trevor Connor  31:25

don’t go down.



Okay, we will get on that rabbit hole,



whatever we want here. Here


Trevor Connor  31:29

we go lactate producing lactogenic. cancer cells are characterized by increased aerobic glycolysis and excess lactate formation, a phenomenon described by odo Warburg 93 years ago, which still remains unexplained. That is the best summary of it I think I’ve ever seen.



There you go.



Why does this matter? Does this mean we get lactate cancer? lactic acid cancer.


Trevor Connor  31:54

Basically, the the short of it, what their research is showing is that cancer cells, or at least when you’re seeing the pathogenesis of cancer, there is an overproduction of lactate, because basically this huge ramping up of glycolysis, which we just talked about, and they’re trying to undo. So we’ve been trying to or I shouldn’t say we have nothing to do with this. But researchers for a long time have been trying to understand why this is. And Dr. Sam Milan and Dr. Brooks have come up with some really fascinating theories. And this is this is I’d like to believe and it’s a friend of mine. So I might have a slight bias but only slight. I’d like to believe this is really important research that they’re doing.



Good stuff. As important as cancer is. Cancer is the worst sucks. Well, that was a highly enjoyable and relevant rabbit hole. But let’s get back to lactate and exercise. We still haven’t really covered kind of my initial question. We’re getting to it. I can sense that we’re getting to it. But the initial question was, was was essentially the burn. That’s what I referenced in my fake little story earlier. Where’s the burn come from?


Trevor Connor  33:11

So this was the big thing that fooled so many researchers for so many years. Basically, yes, you do have a buildup of acid. Yes, your pH does drop. It happens at the exact same time that lactate rises. It is somewhat coincidental but not completely coincidental. And to understand why we have to take a little closer look at those MCT four transporters, the ones that transport the lactate out of the cells. So remember I said earlier, lactate is a great transporter, it goes across membranes really well. Our bodies are amazing at identifying opportunities and taking advantage of them. And they took advantage of lactate and said hey, it’s really easy to get lactate out of the cell into the blood, it’s actually pretty hard to take those hydrogen ions and get them out of the cell. So basically, these MCT fours are what are called co transporters. The hydrogen ion piggybacks with the lactate, whenever the lactate is transported out. So every time a lactate molecule is transported out, a hydrogen ions transported out. And hydrogen ions do build up when cells are going really hard and I won’t. Maybe that’s for another podcast, but there is a reason for that. And for the cells to keep functioning, you need to get those hydrogen ions out



with oxygen and water


Trevor Connor  34:38

a little bit there’s a bunch of effects we’d have to go into an ad and F ad and let’s not do that. Let’s just leave it alone.



We can leave it on for another day.


Trevor Connor  34:51

So but the key point here is as that acid builds up, your cells co transport hydrogen ion with the lactate,



lactate is pulling hydrogen out as well, pushing out pulling, pulling, pulling out of the cell removing from the cell, these high hydrogen ions, which could be damaging, right,


Trevor Connor  35:11

so you have at the same time that the pH is dropping, because all these hydrogen ions are going into your blood, you have a rise in lactate. And hence, that’s the reason they were fooled for so long into thinking it’s lactic acid. It’s it’s not. And there’s still some researchers to go look, lactate even though they’re not actually bonded, because you’re essentially coupling the the hydrogen with the, the lactate, you have for all intensive purposes, you’re talking about lactic acid. So there is some argument there. The reason I don’t go down that road is as soon as you’re talking about lactic acid, you are talking about a dead product that’s doing damage, where lactate is a fuel, it’s beneficial. And it’s so beneficial. It’s also being used to help clear keep maintain the pH of your cells that are working really hard.



So we like lactate, we like lactic we don’t like acid. We don’t like we don’t we don’t like lactate we don’t like those hydrogens necessarily,


Trevor Connor  36:08

right? Well, you don’t like a buildup of them, right? So we are always producing hydrogen ions we do need to make you you will actually die quicker of your base your blood becoming to base than your blood becoming too acidic. Interesting. So we don’t hate them. We just don’t like a lot of them. Right? Everything in our body, we like balance.



And that comes back to something that we’ve talked about a number of times before, which is the body’s love, of homeostasis.


Trevor Connor  36:36

And this is the reason why it is still beneficial. great segue on a Segway Pro. This is why it is still beneficial to do a lactate test and to monitor lactate. Because what we are trying to do is watch to see if the body is able to maintain homeostasis. So we used to call it and it’s still the common term anaerobic threshold. When you talk about what do I time trial that are we talking about FTP, everybody goes? Well, it’s the same thing as your anaerobic threshold, because that’s the point where you now rely on anaerobic metabolism, and you’re not going to last very long. That’s kind of an outdated way to think of it because you’re still doing a lot of oxidative work, you are not suddenly becoming totally anaerobic. So the term that I actually really liked for it that a lot of physiologist use is more what’s called maximal lactate steady state. It’s looking for What’s the hardest, you can go and keep your body in homeostasis. We just talked about production and clearance of lactate needs to be maintained at about an equal level. That happens when your lactate levels stay steady. They can rise but if they rise and and still stay pretty steady, you’re still in a steady state, you’re still in some form of homeostasis, what most people think of is your threshold is that point where your body can no longer maintain a steady state. And it happens that that’s the point where your body says production is exceeding clearance, I can no longer maintain a steady lactate level, I’m going to get into trouble here.



Because homeostasis is very, very simplified. It’s just balance.


Trevor Connor  38:21

Really it is it is the driving force of our bodies, our bodies like to maintain balance, we like to maintain a constant temperature, we like to maintain a constant pH we like to maintain everything. Yeah, and when we are exercising, think of fatigue as the point when your body can no longer maintain balance, no longer maintain homeostasis. There’s a lot of different ways to lose homeostasis, there’s a lot of different ways to fatigue, this is one of them. And that point when production is exceeding clearance and our bodies can’t keep up anymore, that means you aren’t going to last very long. That means you are now above what you think of as your FTP or there’s 50 different names for vt two MLS S anaerobic threshold, whatever you want to call it, but it’s that highest point that you can sustain. And actually, let’s bring in Dr. Sol Milan, again, he’s got a really good explanation of threshold


Dr. Iñigo San Millán  39:19

funding, because that term actually doesn’t really exist. As you know, everything is aerobic, right until very high when there’s no oxygen availability, right? Without a VPN, PC system, you know, keikain right. And everything until then, you know, it’s it’s Robbie glycolysis. Right. But that is a confusion, you know, people people assume the anaerobic threshold term is when you start becoming anaerobic, therefore, there’s no oxygen when they’re when the truth is that there’s plenty of oxygen availability, right? It’s more about you become more glycolytic you know, But, but yeah, it isn’t right, if you understand that with anaerobic threshold, the other thing, I believe is like, but what is lacking is a lactate threshold for 45 minutes and 44 opinionated 44 or 40 kilometer time trial, right? Or is like is wrestle for, you know, like 90 minutes less effort towards the finish, like, that’s the thing that they’re doing. In my opinion, they’re different type of friendships, which brings us probably, to the concept of the Marshall lackey dispatch. Right? Which is probably more accurate, in my opinion, you know, that the lactate threshold and martial act is much more steady state work. I mean, maximal lactate is 10 speed, it really talks more about what that metabolic status state that you can sustain before going on, for example, right. So I see that in my opinion, that’s a more accurate term to that’s where Yeah, we didn’t talk too much more. Lackey, stay stay for, like, a week you have an attempt to file or, or take a client, right? Or a five minute effort, right? So you know, if you want to do a very low nav for right, yeah, definitely the, the maximal lactate steady state for lactate is going to be much lower than for, let’s say, a five minute effort, right. So if for example, for a 40 kilometer time trial, your maximal lactate steady state could be somewhere between four to four to five minimal For example, when you want to go like for example, a that by kilometer time trial is going to be maybe orienta, six to eight minutes, right. So those are truly maximal lactate steady state, because if you go above, both concentrations are going to blow up. But they’re lacking concentration. Okay.


Trevor Connor  41:59

Now, when you have somebody into your lab, and you do a lactate test on them, I know that you have you put on their what their their threshold is, how do you measure that? What


Dr. Iñigo San Millán  42:10

are you looking for? Yeah, so this is this is a question. And that’s what I’ve tried to describe the whole maximal lactate steady state to what I call a maximal metabolic status, not just lactate, it’s a bunch of different metabolic events happening, right? So I say exercise intensity increases, right, you need to use more glucose to generate ATP. And therefore, you’re going to produce more lactic byproduct of glucose utilization is lactate, right? A lot of laughter has to be cleared out because a lot, not likely, per se, because lack is a great fuel, but to the muscles, as you know very well, but the hydrogen ions associate to lactate. Those are the ones that lead to fear that we should chose with that with muscle constructively, and it decreases both muscle law tractive force and muscle contract to velocity. So that can, you know, can it can decrease up to 50%. In the laboratory, what we measure is that whole metabolic response, and there are different metabolic effects, because we measure fine carbohydrate oxidation rates to the laboratory. And again, there’s that one area when when all sudden that that glucose utilization spike, that means you’re starting to activate a lot of flexibility, muscle fibers, right? Because the direct loading muscle fibers are the ones they use a lot of glucose. That’s how fast twitch muscle fibers. Yeah, that’s a matter of going to keep in right there. You know, and at the same time, we see that five utilization drops significantly for that metabolic event right there. And it goes to produce also of lactate. Right? Because a byproduct of glucose utilization, again, factor protection. And that’s where we could see that that that’s a lactic threshold for a given amount of time, what are the really key events that you look for? There’s a very high, like, they’re going to close to huge glycolytic flux, or glucose looks into the cell. Because of a very high demand for ATP production. We’re still talking about aerobic metabolism, right? because everything’s happening in the presence of oxygen, right? However, it is such a high glucose glucose into the cell that therefore there’s a lot of lucky production. And therefore, that’s key, you know, dot dot personal has a very good latitudes capacity to maintain or sustain that higher rate of glucose utilization, very high intensity right in there for the kids who stayed at f4 for a while, you know, it could be 10 minutes, 15 minutes, 20 minutes. It depends on what the capacity right as a percentage State. Now, that point two, we keep that fire utilization completely stops. There’s no funny lusatian. Right. So that’s another point that we see. Again, we see like, another second big spike of water. Right? Because there’s more electric production, we see that there’s a big spike in glucose utilization, and that’s where we can keep them. There is no fire station anymore. So the whole effort is hundred percent like medic, although still the plenty aerobic conditions, right. And that’s what some people might call does the anaerobic threshold to but actually it’s not an anaerobic threshold is that it’s a advantage where you have the body, it’s very metabolically stressed at that point. And they need a lot of glucose for fast ATP synthesis. So yeah, I mean, at that point, it’s that what we do in the laboratory, we observe all these, all these parameters to happen in pretty much at the same time, again, which is fine disappears completely. Glucose increased a lot dramatically. And then we’ve left it also increases at the second breakpoint of language that we see all seen coincide. And that’s where we translate that into either one, or heartlight. Or pace. Right. Right. And and that’s what we call that lactate threshold, or that you know, and the maximal.



Yeah, and so what what makes a really good cyclist basically, is the power you can produce while maintaining this homeostasis, correct.


Trevor Connor  46:45

Yeah, at least in this case, we’re talking about your lactate clearance production homeostasis, which is a really key one in endurance sports.



So let’s get into that. Let’s let’s get into how the listeners of this podcast are athletes. They’re mostly cyclists, maybe some triathletes and things like that. All of our listeners, we love you out there, you’re all trying to produce essentially more work, higher power, whatever it is, while maintaining homeostasis. So what what can people do to help stave off this particular imbalance, lactate, hydrogen, etc, in balance.


Trevor Connor  47:22

So even though lactate is a fuel, it’s not the lactate that’s fatiguing you. Keeping your lactate levels down, is going to help the body maintain homeostasis. So working on clearance, lactate clearance, or less,



or lactate buffering, or whatever, yeah,


Trevor Connor  47:41

is a really good thing to train a couple ways that I can recommend to do it. One. And this is what all our time crunched athletes are going to hate to hear me say. But you’ve already heard Dr. Sol Milan talk about this, you need to increase those MCT one transporters you need to read so you, you first need to get the lactate and the acid out of the cells, you need to raise your MCT force transporters. That’s pretty easy takes, they’re showing about six weeks, which you’ve heard me say many times, it takes about six weeks to build race form takes about six weeks to build those up. And they peak out pretty quickly. So just do some high intensity work, you’ll have all sorts of MCT fours, but if that’s all you work, you’re going to limit yourself because you’re going to raise your blood lactate levels and your city pretty quickly. So you need to also build your clearance. The high intensity will help the MCT ones, but they’re showing the to really build them takes much longer time. And guess what it takes long rides for talking six hour rides, or four plus hour rides, to really start building those because you have to fatigue or work those slow twitch muscle fibers and get them to want to take up more of the lactate for fuel. And what does that sound like? What do we recommend for bass takes much longer to build base, you need that long, slow distance. So here you’re hearing some of the physiology behind why you do a long slow base period. And then you do that high intensity work and it take and you’ll hear people say it takes about six weeks to build that top end. These MCT transporters appear to be part of that part of what you’re training. So to work on your clearance. Sorry, for those of you who want to hear I should only train an hour a ride. Those long slow rides are going to help you That being said yes, the intensity does help build MC T one as well. So do some sprint work.



I mean, how close can you get to sort of, you know, I want to say like maximal ability but what what percentages are we talking about here in terms of if you skip the base season if for example, you just have A job that you have to nine to six or nine to seven or something, you know, you just cannot get those long rides. And how much are you limiting yourself from from a lactate perspective?


Trevor Connor  50:12

From that pure clearance? MCT? One versus MCT for Not a clue. I actually wrote an article about this and that exact question that you just asked me. I tried to find research on that. And I could not, I found research that said, Yes. And I’ll post some of these studies. So I’m actually looking at one right now. That was 2013. In the Journal of Applied physiology. Again, we’ll put the references up on the website that really showed, yeah, you got to do that, that long, slow to build them up. But it doesn’t say anything about how long? How much does it build it up? How much better is it? I couldn’t find any research on that all that it said is, you hit a limit, you hit a peak if all you ever do is intensity, to maximally build up that that ability to clear takes the longer volume? What how much better? I can’t tell you I apologize.



Is there? I mean, the short efforts don’t teach your body to clear I mean, I would think saying they do the limited limited gotcha. I mean, yeah, cuz it would make sense to me that your body your body wants homeostasis, it would, it would learn to clear those things just like, right, you know, if you force it to, if you feel your body full of full of lactate all the time, you would think it would get better at removing it right.


Trevor Connor  51:30

And this, I think, is one of the reasons not all the reasons but one of the reasons when I look at the difference between a pro cyclist and a more amateur time crunch cyclist, that’s one of the big areas of difference. So for example, up in Toronto, we have this week day training race. And Michael Berry, who is a tour de france athlete has shown up to it. And we have this one minute Hillen, let me tell you, every time I do that hill, MC in red, and Michael berry shows up and Michael berry will kind of go up the hill with them. But then later on when they’re on the steady part, he rides away from them. And they all and they’ve all said to me, he’s just holding back from us on the climb. And I go now you guys, basically for that one minute effort, you guys are going as hard almost as hard as most pros can go. And that’s what you see people who are time crunched for 30 minutes for an hour. For those one minute Hill efforts, they can go super, super hard. And they have enough of those MCT fours to get that lactate out of the cells. What they lack is where you really see the difference. In top pros, we’re top pros can sit there and ride for four hours at 300 watts. And their lactate levels remain steady because they have not only the ability to get the lactate out of the cells, they have amazing clearance ability.



So what else can people do? You see long, slow distance LSD, we’ll do a little LSD throughout the wintertime. We’ve talked about the benefits of bass training over and over and over again on this podcast. What else can people do to train these particular systems.


Trevor Connor  53:09

So when I was talking about the long, slow, I was really talking about building those transporters. There’s obviously other benefits to long and slow but right now we’re just talking about lactate. There are other factors that play into clearance, including your body’s ability to deliver blood not just to the working muscles, but to tissues that will take up the lactate, because if it can’t deliver the blood to other parts of your body, that lactate is going to accumulate in the blood and have nowhere to go, which was what I was happening with that masters athlete, I coach she wasn’t producing that much he just couldn’t get the blood anywhere that that clear it. So all the different mechanisms that play into your ability to clear lactate, they’re showing those maximize actually just sub what we think of as FTP or anaerobic threshold or whatever term you want to use. And to make it simple for the rest of his podcasts. I’m gonna use the term I like which is mlss, maximal lactate steady state training just below that 90 95%. And I can hear Frank Overton smiling right now because now we’re talking about go do some sweetspot training. Yep, that’s going to maximize your clearance the problem with going harder. And this is I’ve seen athletes who get very frustrated is they want to improve their time trial and they want to improve their their ability to tolerate lactate. And they think, okay, I was given 15 minute intervals, I’m gonna go do 15 minute intervals as hard as I can. If they’re doing that, or especially shorter intervals, 510 minute intervals, you’ve actually gone over that bell shaped curve and you’re getting to a point where clearance isn’t as good. Because you’re, you’re you’re pumping so much blood to the working muscles and away from so much other tissue. You’re not clearing as well. So actually, if you want to be a good time trellis if you want to be that threshold monster, you need to do some good amount of time. Training just below that threshold, what do you think about, we go for a ride here in Boulder we go hit a climb, that’s exactly what we do, we don’t climb a 30 minute Flagstaff right at threshold except for periodically, and we just want to see who’s gonna fall over. Most of the time, we’re going close to threshold 90 95%, but not



added. And this comes back to actually a podcast that we did quite a while ago, six, seven months ago about doing your intervals in the right zones. So if you want more on this, I would suggest going back to that episode, actually, we talked quite a lot about making sure that you’re doing intervals in the right zones. And that doing intervals as hard as you can for whatever duration is not the right idea for this exact reason. Because yes, you could probably go hast go faster for five minutes or for 20 minutes. But just because you can doesn’t mean you should because the whole point is that you want to train the right systems.


Trevor Connor  55:50

So when I give my athletes threshold intervals, and one of my favorites is he’ll repeat till having 256 Hill repeats in about 10 minutes. And whenever I do that, I give them a maximum heart rate. So for example, when I time trial, if I go do a 20 minute time trial, I’m going to sit around a 175 176 heart rate. So when I do these Hill repeats, I set a limit for myself around 173 174, I cannot go over that heart rate. And that’s the keep me just sub threshold. I learned those years ago, and that turned me into a climber. That’s where I got to where I could start winning Hill Climb time trials, because what I was doing was, I didn’t know at the time I know now is really working that clearance system. And I could have done those Hill repeats harder. Had I done that I don’t think I would have seen the same gains.



All right. Well, Trevor, I think that’s I think that’s all the lactic acid talk that we can possibly stand today I’m gonna go, I’m gonna go ride my bike home, legs are gonna be really Bernie, like call you when I get there. See that ask you why the lactic acid is filling my legs.


Trevor Connor  57:04

I have no have no excuse to ever say that again. The thing



there is, as we said at the beginning of the episode, there is some inertia to this. And it is actually it’s kind of, it’s difficult for the lay person like myself not to use the term lactic acid. I will make an effort to do so. But I make no guarantees. I’m glad though, that I understand a little bit of the mechanics behind all this. And I’m mostly happy that I understand the mechanics because clearly from our last little section there there are some things that I could be doing on the bike to well, to make my lactic lactic acid filled legs burn a little bit less. Right. Exactly. That was another episode of fast dog, Trevor’s glaring at me from across the table. As always, we’d love your feedback. Email us at Webb letters at competitor Subscribe to Fast Talk on iTunes, Stitcher, SoundCloud and Google Play. Be sure to leave us a rating and a comment. And while you’re there, check out our sister podcast, the velonews podcast. We cover news about the weekend cycling with a slightly humorous bent, you can become a fan of Fast Talk on slash velonews. Magazine and on slash velonews. You can also find Trevor on twitter at let’s see if I can remember this.



A T.



underscore coach Connor. What is it?



I don’t actually


Trevor Connor  58:32

hold on. We’re gonna I’m gonna look up what my Twitter handle is.



That’s embarrassing. Ah,



I found it. You can also find Trevor on Twitter. Trevor, you have 190 followers now do I? Yeah, you’re listed by five people and you’ve tweeted at one times.


Trevor Connor  58:51

Thank you. I’m very glad you’re following me. I’m not too exciting to follow. Well, everyone



should follow Trevor on Twitter at coach underscore, t Connor, that co n n o r you can follow me on twitter at Kaylee frets. You can follow us on Twitter. Facebook is co produced by Connor coaching and velonews. The thoughts and opinions expressed on Fast Talker are those of the individual for Trevor Connor and Indigo sound Milan. Hi, I’m Kaylee frets. Thanks for listening

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