Welcome to the Empirical Cycling Podcast. I'm your host, Kolie Moore. Thank you, everybody, for listening, as always. And if you're new here, please consider subscribing to the podcast if you like what you hear. And if you are a returning listener, thank you so much for coming back. We really appreciate your support. And if you would like to support the podcast, you can always let people know what you like. Sharing the podcast goes a long way. Thanks so much for all of that. Five-star rating wherever you listen to podcasts. And a nice review goes a long way. Thank you all for all of those. And also a donation. at empiricalcycling.com slash donate because we are completely ad-free so we can say whatever we want. We don't have any sponsors. We don't have commercial interruptions. We don't make a penny on the podcast except for obviously we are a coaching company and if you would like to work with us, we are always taking on clients of all levels. Students and professional athletes are negotiable of course because we know you all don't make a ton of money so we are happy to work with you anyway. If you would like to get in touch with us about coaching, please send me an email, empiricalcycling at gmail.com. And if you are interested in a consultation, we can do that too. We can review your files. We can plan for next year. We can discuss anything you would like. So please reach out to me again, empiricalcycling at gmail.com. And if you'd like to ask a question for the podcast, you can follow me on Instagram at empiricalcycling, and I've got some AMAs. up in the Instagram stories on the weekends. That's the weekend training Q&A. If you'd like to participate in that or just want to follow along, please join me over there. And joining to pinch hit today for Kyle is Rory Porteus again, and he was not on the last Wattstock. We tried to get him. He was a little bit busy, but he had time for this one, and I was really happy to have him. So I hope everybody enjoys what we're going to be talking about today. So today, this podcast is going to be interesting. and I'm a little apprehensive about recording it and I went back and forth on recording it for a while and the reason for this is because we're going to talk about glycogen depleted training and I don't want anybody to go out and go oh Kolie endorses this wait until the end of the podcast which I'm sure is going to be about two hours from now given how me and Rory usually go with this stuff so let's get some stuff out of the way first so Let's talk about some background with glycogen depleted training and like the train low model as in train with low glycogen, more fat oxidation, et cetera, et cetera. So Rory, what do we hear commonly on the forums? Cause you're about as active, you're more active on forums and talking to folks than I am. So where, where do you think people are at with this in a general sense? I'm a lot less active than I used to be. I think the common misconception is that if I go out and don't eat anything while I'm riding or go out fasted in the worst case scenario, spoilers, I will be much better at burning fats and thus I will be much better at endurance on the bike. I will be much more efficient in terms of how I am riding on the bike. Yeah. And this is something that we have looked at before on the podcast. in-depth on the racewalking studies that Louise Burke did, which were really excellently done. They had a performance component to them, which is rare for a lot of studies. And this isn't going to be exactly a podcast about what it's like when you burn more fat, because we've kind of, at least if you are a regular Empirical Cycling Podcast listener, at this point, you're well aware of how I feel about it, which is that burning fat does not make you better at endurance. Like just bar none. Like Wattstock 40 kind of goes into the really nitty-gritty mechanisms of why that is. And I spent a long time setting that episode up. And I hope people who were listening and paying attention and who are getting it, which is most of you, thanks for all that, by the way, really understand that at this point. So one of the things that we're going to do now is we're going to look at Glycogen Depletion, which is supposed to be another potent stimulator of aerobic adaptation. Supposed to be. So we're going to look at the evidence for this, for and against. So we're mostly going to be talking about the P38 MAPK pathway. And we're just mostly going to call it P38. And what is it? Why do we care? So there's been a lot of research into the P38 pathway in muscle because it's shown to be activated in response to Exercise. And P3A is a protein that detects cellular stress, including that brought about by exercise. So everything makes sense so far? Yep. Good. Because we need to think about what's a MAPK. And this is, and if you are not wanting to hear this, just fast forward the podcast about a minute and it'll all be over. A MAPK is a mitogen-activated protein kinase. And what is a mitogen? Mito, sounds... Mitosis. Mitosis, exactly. So generally speaking, mitogens are things that induce mitosis. And the reason for this is because in a lot of different tissues, P38, MAPK, and there's also, there's different MAPKs and stuff like that. They all have different jobs. And so in... Skeletal Muscle. That's where we're going to be focused today. And the initial review of the literature, especially in terms of the popular papers that have a lot of references, it seems to be activated by low glycogen levels. Seems to be. And we're going to look at a lot of the evidence for that in this podcast. So it's also activated by things like regular endurance exercise. Glycogen depletion is supposed to potentiate it. So there's another aspect of this whole thing. And low glycogen, sure, stressful on a cell, right? But another role that P38 has, and this is where more of the research in the literature has been, it's in cancer and in cell differentiation. Because in cancer, P38, MAPK, is downstream of the RAS protein. And if you just look up RAS oncogene, you are going to see a ton of papers on this protein, and P38 is downstream of that in the signal pathway. So, in muscles, in satellite cells, what, Rory, what do you think P38 MAPK is responsible for, knowing that it's responsible for? Mitosis? Yeah. So in a satellite cell, a muscle cell, like if we think about what happens in mitosis, you basically tie a string or a noose around the cell and you squeeze it so the cell splits in half like a piece of bread dough. And it's something like that. But if you imagine doing that to a muscle cell, which is extremely long and extremely dense, full of proteins, what are you going to do? Like cut all of your sarcomeres in half? That does not seem like a good way to do it. So the way that muscle cells grow is satellite cells, which are basically stem cells, differentiate. And P38MAPK is a signal pathway that's very involved in that. So a lot of the other literature that's not on cancer is focused on this, is P38MAPK in satellite cells and cell differentiation. So that's a big part of the literature. But I think given all that you could see how a mutation like upstream of P38 or in P38 itself could easily lead to cancer. Because it's governing the rate at which things are just going to proliferate. And if it's just activated nonstop, such as often the case in cancers, you're just going to result in a lot of cells, which you don't want and you're not prepared for. Exactly. And you just pray that you get to a Hayflick limit before it really gets to anything metastasizing. Who's the... Oh, Quadzilla, the German cyclist. Oh, Robert Forstemen. Is this something that he's got? Because isn't his thing that... That's a rumor. So there's a protein called... Oh, God, what is it? It's myostatin, which actually puts a brake on muscle cell growth. The rumor is that he's got a mutation in his myostatin gene where it's basically ineffective. That is not substantiated as far as I could ever tell because I've Googled it many times because I want to know too. But if you look at myostatin cow or myostatin dog or something like that, you're going to see Ronnie Coleman cows. They are weirdly jacked. And I don't know if that meat is delicious or not. I couldn't tell you. Anyway, so let's get into our first paper today because I want to look at all the evidence that I could find on MAPK-P38, low glycogen writing, and whether or not this is actually beneficial in terms of exercise and exercise protocols. So the first paper, again, these headlines always give it all away. Exercise stimulates PGC1-alpha transcription in skeletal muscle through activation of the P38 MAPK pathway. There you go. Okay, so let's get into the detail because the... I don't know, the devil's in the details or some shit like that. So at the time of writing, which was in like 2000, I don't know, five, something like that. So this paper is by Akimoto and I'm going to refer to it as the Akimoto paper. And it is highly, highly referenced because it's super, super well done. And at the time of writing, the authors note that there was yet no direct evidence that the P38 MAPK pathway had any effect on PGC1 alpha. It had been speculated. So they did an experiment. They actually did a lot of experiments in this paper. I think these days, this paper would have turned into like 10 papers. But at the time, it was just one. And they took a lot of different angles at the pathway. And they did some really, really excellent work. So they took mice and had them do either a single bout of exercise or yada, yada, yada. They had a whole protocol. It's not worth getting into. So they sampled muscles at different time points before and after this final run, and they found a transient increase in the expression of PGC1-alpha mRNA. So as we discussed in previous podcasts, PGC1-alpha not only is a gene, it's also a protein that's already existing obligately in your cells. And when you do any kind of exercise that stimulates this, You may not see an increase in mRNA for the PGC1-alpha gene because the existing PGC1-alpha is already active and doing its thing and helping transcribe genes and whatnot. So they also looked for phosphorylated P38, which is the active version, and saw a similar activation over the same time frame. So now we've got correlation between these two things. And I see Rory nodding his head. He's like, correlation, but he's waiting for causation. All right, so I'm going to give it to you, Rory. Let's look for causation. They took cultured myoblasts, which are stem cells, basically, or muscle precursors. And they added PGC1-alpha with a luciferase reporter gene. So, Rory, tell me about luciferase and why glow-in-the-dark protein is so cool. Yeah, so luciferase is, I think it's kind of evolved over time since they've started using it. But effectively, it's... And my own understanding of this is hazy, but they're taking the proteins responsible for the creation of photons that you commonly find in things like fireflies and using them as a way of trying to show whether or not the genes you're attaching that reporter gene to are active. If the gene's active, then the reporter will be active. And if the reporter's active, in this case, it's going to glow in the dark. And over time, this has been a technique that's kind of been augmented more and more and more. So in the early days, it would have to be fairly surface level for you to be able to detect it. And usually, you're going to be using a camera to detect it. And more modern luciferase. There's a trade name for it that I can't remember off the top of my head, but effectively they cultured it sufficiently to make it more and more potent such that it's giving off more and more photons. And now for something like these mice, for example, you could stick them underneath an infrared camera and you could see things being reported from inside the brain or inside their lungs. So it's a pretty neat tool for being able to... track whether or not a gene is being activated. Yeah, it's really, really cool. It's sort of like the same way as if it's like when Mark Cavendish went to a new team, he always brought Mark Renshaw. If you saw Mark Renshaw, you knew you had Mark Cavendish. You could say Mark Renshaw was a reporter gene. Or like Yuri Sagan, like Peter Sagan's brother. If Yuri Sagan was at a team, you knew Peter was there. That's a way to think about a reporter gene. Akimoto and his team took cultured myoblasts. They added PGC-1-alpha with a luciferase reporter gene. So if luciferase, like if you're getting this glow-in-the-dark thing, you know you've got PGC-1-alpha gene being expressed. And so they also added a constitutively active protein that stimulates the P38 pathway. And they saw a huge increase in luciferase reporting, which means PGC-1-alpha activity and transcription. But to close the loop here, they also added their P38 activators plus P38 inhibitors and even a dominant negative P38 gene, which basically means P38 is inactive. And they saw little to no PGC1-alpha luciferase activity. So now they've got pretty definitive proof that the P38-MAPK pathway is activating. PGC-1 Alpha, and PGC-1 Alpha Transcription. So we've got pretty good proof. I like this experiment. They did one more myoblast experiment. It's cool. We're not going to get into technical details because what we're going to learn out of it is very little. Spoilers. Yeah. But they made also transgenic mice. And speaking of luciferase, you can Google glow-in-the-dark mouse and you're going to see mice that have luciferase in every single cell in their body, and they glow in the dark. It's really cool. But they made mice that had a fast-twitch-specific expression of a constitutively active P38-stimulating protein. And they found in those muscles, there was a huge increase in PGC1-alpha protein expression, plus cytochrome oxidase, which is a mitochondrial protein part of the electron transport chain. So they had a muscle tissue-specific Confirmation of Expression. Like, okay, we can make this happen, then we are going to get more mitochondrial proteins. Like, done. We've got it. So, does all that make sense so far? So far, yes. Good. Because, like in our previous couple episodes for calcium and for AMPK, I thought it was important to show the molecular links. between all of these signals and improvement in the muscle markers associated with better endurance performance. And we can only at this moment say associated. Why? Because we need to show it with actual exercise performance. So this is kind of that you can see that the body's burning a lot of fat thing, but is it actually resulting in an improvement in performance? You're getting ahead of us. Oh my God. Spoilers, dude. Play some suspense. Suspense is for a hang glider. Oh, that's a good one. Fine. All right. We're in the sciences. I know. I know. I know. We could always say, oh, here, blah, blah, blah, and then everybody else in the sciences goes, all right, well, I'm interested. Prove it. That's the interesting part. Prove it. All right. So this next paper title. actually does leave some suspense. So we've got a hang glider title here. Acute signaling responses to intense endurance training commenced with low or normal muscle glycogen. We don't know what the responses are. We just know that we're looking at the acute responses. So now we need to think about our low glycogen twist because that's what this paper is designed to investigate. So as mentioned before, or maybe we forgot, P38 is a fairly general stress sensor in muscle cells. And so exactly what kind of stress it senses is actually not too well determined when it comes to exercise. So that's one of the things that this paper was trying to figure out. So if exercising with low glycogen is going to trigger better performance and better signaling, we're going to see it in this paper. We have two groups of six matched for training history and fitness levels. So VO2 max for both groups average about 61. Group one did a 100 minute ride at 70% of VO2 peak on alternating days. And the other day was eight by five minute max efforts with one minute rests. Fun. Sounds fairly stressful, but they were supposed to be evenly paced. We can assume around or just a bit above FTP depending on how well trained folks were at that point. I've got a bunch of people doing VO2 max intervals right now who will attest that a one minute recovery period is not going to be great. Especially not from an actual max effort. Yeah. It's going to be less than great. Let's say, yeah, just less than great. Significantly less than great. So now group one is alternating. 100 minutes at 70% VO2 peak. So this for most folks is probably going to be like mid sweet spot range on average. And the other day is eight by five minute, one minute max rest. So that's the high intensity day. Group two, they are exercising on alternate days. This is a three-week protocol, by the way. So they're exercising on alternate days, but so they got rest day, exercise, rest, exercise. On their exercise days, they do both sessions together. with a one-hour recovery in between. So they do the 100-minute set 70% first, they take an hour rest, and then they do the 8x5. And so one of the things that they were trying to do, well, they took biopsies done before and after every single 8x5 session for both groups. So that's where the data that we're looking at is reported. The double days... So not only are you doing 40 minutes worth of... Pretty miserable intervals, but then they're going to stick a needle in you. Before and after. And you do this three times a week for three weeks. I'm surprised they had much muscle left. I know the needles, it looks big, but relevant to everybody's muscles except like Chris Froome and Vingago. It's like, yeah. You got plenty to go around. The double days actually did achieve their goal. They started their 8x5 session with muscle glycogen down about one-third, an average of about one-third lower than the folks who were doing alternating days. So that's pretty reasonable, okay? Now we've got low muscle glycogen or lower muscle glycogen. It's not like tanked, but it's low enough. And then we look at the molecular stuff. So what do we see? We see AMPK activation. It's 40% higher in the double sessions, folks. 40%. That's pretty good. We also see other mixed but non-significant results. HDF5, CREB ATF2, these things are, well, we don't have to go into it, but no difference. or not significant results, not significant difference. This is, it's starting to look not great because if you've got like one out of four things, eh, okay, it's okay, but whatever. So where's our money shot? What about P38? No difference. Dun, dun, dun. All right. Is that like looking at the actual graph? Quite funny to imagine these poor bastards that had to do double day sessions for three weeks and get stabbed a few times and then at the end of the whole procedure the scientists turn around and tell them yeah you could have just had that 24 hour rest. But the AMPK activation, bro, I guess. Well, I think we should actually look at their previous paper because they did the exact same protocol in their previous paper and they actually had a performance test part of this paper. So we're going to look at this too because they also, like in that first paper or that paper that we just looked at where we saw no PTC1 alpha, sorry, where we saw no P38 activation difference, you know their justification for looking at these were were they had done another study with the same protocol and they thought they had some really interesting results that they wanted to look at the molecular pathways more because they were seeing things like higher fat oxidation etc etc so we're going to look at that in a minute well we're going to look at their details and justifications in a second but so in the previous paper with the same protocol they saw higher markers Of the Krebs cycle, so citrate synthase and HAD, so basically citrate synthase being the entry point for the Krebs cycle, and HAD being a protein that breaks down fatty acids for beta-oxidation. And that's in the group that did the double days for the higher markers. They also saw markers of the electron transport chain, so complex 4, were also similarly improved. But they had a performance measurement in the study. And I thought that was, this is honestly the only paper I could find that had a human performance element in conjunction with measuring P38-MAPK pathway activity. The only one. There might be more. I think there were a couple in mice. I read those. I was not too impressed with them. Didn't think they'd make good Wattstock content. I went with this one. Not pressing the mice or the studies? You know, the mice, they're always just going to do what they do. I admire the mice. They, you know, they give a lot for science and I'm all about it. So in the study, both groups over the HIT sessions improved their power output similarly, about 10% for both groups. But, and this is over the course of the three weeks, so the power output they were doing on their 8x5 was improved by about 10% steadily throughout. The low glycogen group did less power across the board over the three weeks of training. Which is potentially unsurprising if you think about the fact that they're effectively in a depleted state. when they're actually doing these intervals. Yeah, like imagine going out and doing a set of just 5x5 with 10-minute rests, doing that the day after the hardest race of the year. You're not going to have very good power output, are you? And if you do, well, congratulations, you are in the 1% of the 1% for people who can recover. Yeah, you're like Filippo Ganna doing the road race and then turning up for the individual pursuit. Oh, for real. And winning it. So their big performance test with these two groups in this paper was a 60-minute time trial. And in that 60-minute time trial, they found that both groups similarly improved also about 10%. So that's pretty good. So we don't actually see a performance decrease between the two, but we also don't see any better performance. in the group that was glycogen depleted. Yeah, so you've got this situation where if anyone was to actually look at the charts here, it's a 10% difference and a 12% difference, but the margin of error in each of these is wide. And it seems like at least one person in the high group responds extremely well whilst two don't. Part of what you're maybe seeing there is that 10% improvement is probably a large part of they all did the exact same protocol effectively. Obviously, difference in terms of when the sort of tempo, 100-minute effort was done either on the day or just before. The actual workload they're putting into their training is basically identical. And so if you were expecting there to be some sort of Efficacy difference in terms of how the training would turn out here. There isn't one. And, you know, it's just like the study before. These poor bastards have done so much work in one day. And, yeah, the sacrifices of performance sciences. Thanks. Won't do that again. Well, here's the thing is the author saw that the group The low group, the low glycogen group, had about 10% more fat oxidation. I'm sorry, not 10%. They had about 30% more fat oxidation in their 60-minute time trial than the high group. And these were the findings that were the pretext for the previous paper looking more at the molecular signals because they went, oh, okay, well, we've got these kind of mitochondrial markers that are a little improved. We see a lot more fat oxidation. What's going on here? So what's really going on here, this is not in the notes, but I will explain it real quick, which is that despite the fact that you are burning more fats, it does not mean that you are going to improve your endurance, and it does not mean, it doesn't mean anything really, other than your body has become accustomed to burning more fatty acids because when you're training in a glycogen depleted state, that's It's more of what's around. And so this is the metabolic logic is you have only a certain amount of oxygen delivery capability. You've only got a certain amount of endurance capacity in your muscles. And what your body adapts to in terms of substrate use is what's available, which means that if we think about this in terms of evolutionary context, You could be in a high-protein, high-fat environment, dietary environment, let's say, and improve similarly as somebody who's got in a low-protein, high-carbohydrate environment. And I think that's a brilliant way for evolution to approach it. The other part of this study is showing in terms of the actual peak power output of the efforts being conducted is lower in the low glycogen group. But what you can see within their figure is that it's also increasing because obviously at the end peak power output has gone up for both groups. The result of that has been the result of them just adapting to not having as much sugar available to them as they would otherwise like to be able to use. Yeah. So one of the things that I want to run by you, Rory, is in the paper that we looked at first for this group with the same protocol, they start the abstract with this, quote, increased the maximal activities of several oxidative enzymes that promote endurance adaptations to a greater extent. than subjects who began all training sessions with normal glycogen levels, unquote. Does that sound accurate to the data that we just looked at? So we saw more citrate synthase activity. We saw more HAD activity. We saw more fat oxidation activity. We saw similar performance benefits. Does that sound like increasing the... Activity of Oxidative Enzymes that Promote Endurance Adaptations. First of all, do oxidative enzymes promote endurance adaptations? Not necessarily. The answer is actually flat no. They don't. No. There we go. So if you're close, you were hedging. You were hedging, yeah. So that, I mean, and in the era where these studies were conducted, I'm not... Judging the Authors for Writing That. I give them a pass because unless you have – because especially if you're in exercise physiology, a lot of the time you're not entirely sure where the actual biochem and metabolism stuff lies. Like you're more focused on what you can measure rather than, you know, like digging into super nerdy mitochondria physiology like I do. on a regular basis. You're limited by the tools and knowledge of the day, which is why, you know, hundreds of years ago, they thought there were canals on Mars, and there weren't. It's just that they didn't have good telescopes back then to actually detect this sort of thing. What? The Romans didn't make aqueducts on Mars? I thought they made them everywhere. Oh, they made roads everywhere. They made the roads on Mars, but the aqueducts aren't. They don't exist. Okay, cool. King's Road on Mars. Got it. So, I think this is actually something that's unfortunate about over-focusing on substrate use. Because we've discussed this in a lot of Wattstock episodes previously, where the change in substrate use is not equivalent to the change in performance. So, I think that's also something where, I think the first place I ever ran into that was actually an Oscar Yukindrup paper. It was the Fatmax paper, the original Yukindrup Fatmax paper, where he was like, burning more fat might make you better at burning more fat and endurance performance, huh? And I think, what year was that paper, like 2001 or something like that? Like that's, you know, granted he hedged his bet properly, he was speculating, but I think a lot of people thought about that same thing, like, oh, you burn more fat, you're going to have better endurance. And in reality, that is absolutely not something that we ever see. Yeah, it's an availability thing. Like 10 years ago, maybe, I remember one of the things that seemed to come off quite a lot is whenever you do a respiratory test, when you do any sort of like cardiopulmonary exercise testing. Yeah, you're hooked up to a metabolic cart, gas exchange. Make you do a ramp test. One of the things that would usually come out of one of those tests is what is the body burning in terms of energy primarily and they're able to do that just by a ratio in terms of the gases you're exhaling and get pretty good measurement of what you're doing and the thinking 10 years ago was oh if you're really carb intensive then you're really carb reliant and you're never going to be as good an endurance athlete as you might otherwise like to be and we kind of know that's a bit bunk at this point because You need those carbs. Your body's reliant on sugar as a means of facilitating that sort of exercise. And that's kind of where that thinking has come to where we're talking about here today is we have a study here which is showing two people doing effectively the same. Training Protocol, just the difference being that one of them does it all in one day and one of them does it over two such that one of them is glycogen depleted and one of them is not. Which, side note, if you look at the glycogen depletion of the high group, it's a fantastic example of how 24 hours is enough to just refuel for most people. Maybe not fully if you're doing something pretty miserable, but you'll get it all back within a day. Don't stress too much about pounding everything in sight after a ride. But what we're actually seeing in this study is, you know, if they had hooked them up to that metabolic car, probably what you would have seen is a flip in that ratio. One of them would be very clearly be very carb-dominant, judging by their breathing, and the other would be very fat-dominant, or more fat-dominant, judging by theirs. And that's all a study is effectively coming out with at the end, is the body adapts to what is available to use. Point that I've been trying to make on the podcast for probably years now. So now I actually want to look at the research recommendations, research and recommendations from a big figure in exercise physiology who I actually respect quite a bit. He does great research and he wrote a paper big braining this type of research. And I'm not going to link in the show notes because I'm honestly like... I read this paper at first like a long time ago, pretty much like right when it came out and I went, oh wow, yeah, he's, man, he's on it. And since then, having chased down all the references, I have actually been quite disappointed in his interpretation of the references because some of the stuff that we just looked at are some of his references. So also, I think in context, he was probably writing that paper less in terms of targeting it at endurance athletes like cyclists, marathon runners and such, but it was probably more aimed at team athletes, weightlifters who need to do a little bit of cardio or some stuff like that. By the way, if your endurance exercise, if you call it cardio, you are not an endurance athlete. We're just going to gatekeep a little bit. Because everything you do on the bike, pretty much, unless you're a track spurner, is cardio to some degree. And we all know that there's a lot of nuance to the word cardio now. So this author suggests that in muscle cells, P38 is activated by endurance exercise. He references the Akimoto paper. True. He says that it's potentiated by glycogen empletion, which is the Yo paper. That was the first exercise paper that we looked at. And this is not true. It's flat not true. We saw no difference in P38 activation. We did not see potentiation at all. We saw increased AMPK activity, but we did not see improvement in P38 MapK activation. So I don't think that these references support his conclusion here. Do you, Rory? Well, funnily enough, as you were saying all that, I got an email saying from one of my clients talking about how much food they ate. during their workout yesterday. And you might have seen me quickly hitting the keyboard doing some maths. And suddenly I know why his workout didn't go so well for what I estimate was 20 grams of carbs an hour. It's funny, somebody exercises for five hours and they give you what looks like a lot of carbohydrates. They're like, oh, I ate all this. And you go, you know, at first glance it sounds pretty good. Yeah, then you do maths. I don't know why you... Folks in Europe always say the plural of maths. Math is just one thing. It's all related. But yeah, and then you find out that somebody was having 20 to 30 grams of carbs per hour on a long, hard ride with intervals or something, and then it's a sinking feeling, but you go, oh, I know the problem now. We have something to fix. No, this guy, bless him, has inflated the numbers even more by listing them as calories and not grams of carbs. So all the numbers are four times larger than they actually should be. I ate 1,200 calories. His workout went well, so I'm happy in that respect. But he was probably very hungry and tired when he got home. Almost started. Anyway, so let's continue with this paper and the training advice based on... based on what turns out to be what I think is a misinterpretation of the available literature. His advice to enhance molecular signaling was training in the morning before breakfast in a calorie and glycogen depleted state. This obviously would increase the stress and should increase P38 signaling, but that's not actually what we see. He suggests, you know, caffeine, carbohydrate mouth rinses because This is pretty well known at this point that rinsing your mouth with carbohydrates can help you improve exercise performance without actually consuming it. Yeah, if you pretend you're going into diabetic shock and need to quickly spike your blood sugar, this is what you need to do. And he also suggested training at a low intensity for a long duration to minimize mechanical strain and maximize other signaling like calcium, calcium signals. stuff in this paper, by the way, a lot of his summary of other mechanisms acting on PGC-1 alpha and it's basically exercise activators was really excellent. I have followed many of those references for years now and thought, okay, this is good stuff, this is good stuff, this is good stuff. Then I got to this one and I was sadly disappointed. The great news about my field of science when I was actually still interested in doing science is that you never have any of this sort of level of disappointment. It's usually because someone's gazumped you to an idea that you have rather than, oh, this is not usable data at all. Do I need to, is gazump a dirty word? Do I need to bleep that? What is that? No, gazump, that's pretty PG. Okay. Unless it's one of these words that accidentally has hidden racist connotations, but I'm pretty sure it doesn't. Oh, I feel like most words at this point do. So we'll bleep the whole podcast. Sorry, everybody. Oh, gazump, definition, informal British. Ah, okay. There we go. It's like tying your ones and twos. It's like rhyme slang, right? Nobody actually understands where it's from? Yeah, I haven't a clue what you just said. Cool, me neither. Okay, so back in the day when I first saw this paper and I thought that it was pretty cool, At the time, I also knew that just burning fat didn't make you better at endurance performance. Like I already knew that part. So I was like, all right, I can change this protocol a little bit. So I did similar protocols with clients with low glycogen endurance riding, not fasted, absolutely not fast. I knew that wasn't a good thing. And so one of the things that we did was we would like deplete muscle glycogen with a hard workout, similarly. and then do long endurance, low intensity stuff. And in terms of the performance adaptations, I saw, when we saw improvements in folks, a lot of the time we didn't. But when I did see them, they were no different in terms of adaptation and performance. than doing any kind of increasing TTE work, like sweet spot, FTP work, and increasing the length of time you can do that kind of stuff. The adaptations were basically identical, and the downsides were myriad, because you've got to keep your muscle glycogen low, which sucks, because you get home from a ride and you're like, oh, I can only do this many grams of carbohydrates, and then I've got to QS with meat and vegetables and fats. and like that sucks to like want to eat a bowl of cereal and be like I think I need to have a steak instead. It's not the worst thing. It's not the worst. But after that steak you're still sitting there like oh god I'm hungry and everybody was everybody was grumpy doing it. Even the folks where it worked the best they didn't like it and they never wanted to go back because they would rather just do regular harder training and get the same benefits and just eat whatever they want. Go fucking figure. One of my clients, his common ride food seems to be gummy bears, and I can't imagine ever taking that away from him. And I wouldn't want to based on how strong he is. Yeah, no, you wouldn't. Yeah. And see, here's the other thing, is that with this protocol, I knew that low glycogen was the stimulus, or would be the stimulus if this really worked. And that meant that eating on the bike, is not bad if you are doing this kind of protocol. I don't think anybody should, but if you are doing it, you want to, for whatever reason, I don't know why you would at this point if you trust what we're saying and our coaching experience, but eating on the bike would not hurt. So you can get on the bike and just eat normally. You know, 50 grams an hour, 80 grams, 100 grams, whatever you do. Like, that's fine because you still have to ride. You still have to do the riding. And if your ride is cut short to like two hours when it should have been six because you are bonking and feel like death, that is not a good stimulus. Just blanket, not a good stimulus no matter what your dietary protocol is. Yeah, I remember in one of those Peter Attia podcasts, it was probably the ones with San Milan, talking about staying in keto and also eating shitloads of sugar while riding the bike. entirely because he was able to do that within the period of being on the bike and then stop when he gets home and he was still in ketosis. Well, ketosis is a weird thing because it's measured by a certain amount of ketone bodies in the blood. And ketone bodies in the blood are made by basically having excess acetyl-CoA. And so acetyl-CoA, so basically acetate and beta-hydroxybutyric acid, Beta-hydroxybutyrate. These things are ketone bodies and they go out into the blood and when they're in a certain amount, okay, great, you're in ketosis. Who cares? Honestly, who cares? Well, from my perspective, who cares? If you care, great, cool. I don't want to wreck your vibe with this stuff, but I feel like we are anyway. Sorry, folks. Anyway, in the big scheme of things, it's... In my coaching experience and terms of the available stuff in the literature, I think it's better to fuel normally with carbohydrates and sufficient proteins and fats, of course, for your regular diet and do the normal harder efforts that your body is actually capable of because all the available evidence suggests there's no difference or in my experience, It's actually superior to train as hard as you can possibly train rather than pull engine timing and reduce your horsepower because you're on 70 octane or some shit like that. Yeah, and the athlete's going to feel a lot better doing it as well. Yeah. Obviously, one of the end results of training better and getting stronger is, guess what? Your body's going to burn more fats, but not because it's doing it in a different ratio of what it was doing before, simply just because you're getting stronger and your energy demands are going up. Yeah, and I think one of the things that's actually not discussed anywhere, and I didn't even think to add it into our show notes, but I'll mention it here, is that carbohydrates are a huge source of energy for adaptation. They're easy to use, they're easy to access, they don't take a lot of processing to make into useful energy. And so your muscles having topped up glycogen stores is super, super, super beneficial to you recovering faster. Just blanket bar none, like eat, fuel yourself well, and you are going to recover faster. And that doesn't mean you can't recover on more like proteins and fats and low glycogen stuff because people certainly can recover. It's harder. and it seems to take longer in my experience coaching this kind of stuff and having done a couple of these protocols myself it fucking sucks which is one of the reasons I never had anybody do more than like two days of this kind of stuff ever like we would do like a day a week or maybe two and that would be it yeah I just had someone come back from like I think it was an endurance a long endurance ride saying oh I'm feeling a lot better like day after day on my rides. I was like, yeah, it's because I told you to eat more. And it was like, oh yeah. Yeah. Yeah. And so if you're not putting yourself into a huge energy deficit during your rides, you get back, you're not quite as hungry, your body is like already able to start repairing itself. Yeah, when you have that ravenous feeling at the end of a ride, if you know you've not eaten enough or if you've gone too hard. That's the result of not feeling well. And it's also why downstream of that you could get ill. Your body's preparing to try and unfuck the damage you've done to your muscles. And the result of that is it doesn't have the energy to supply things like your immune system health lead. Yes. Yeah, actually, that reminds me of something that's later in our podcast notes, because unbelievably, we are not done yet with this. So I'm going to move us on, because in the Akimoto paper, the first one with the mice, I thought the intro of it was fantastic. And all these papers, by the way, pretty much are available full text. So if anybody wants to go check them out, please do. So I'm going to quote the Akimoto paper. Quote, adult skeletal muscle is remarkably plastic. Increased contractile activity, such as endurance exercise, elicits multiple signals to activate a large set of genes, leading to phenotypic changes in skeletal muscle, including type IIb to IIa fiber type switching, enhanced mitochondrial biogenesis, and angiogenesis to match physiologic capability to functional demand, unquote. I love this quote. I love this. Akimoto wrote a fantastic paper. It's probably one of my more favorite papers I've read so far. And that's saying a lot because I've read a ton. This is like Wattstock 1 through 10 in paragraph form. Yeah, it kind of is actually. Actually, how do you remember what was in Wattstock 1 through 10? I don't know. I was there and I barely remember. I've got to go back and figure out. Ah, man. Anyway, so. One of the things I appreciate about this is that in 2005, he recognized the plasticity of skeletal muscle, which I think up until the last couple of years was still contentious, really contentious. He recognized the multiplicity of signals that go through just a handful of points like calcium energy stay, glycogen levels, regular energy, cellular stress, et cetera, et cetera. and they turn on a large number of genes to generate aerobic adaptations. Like he recognized this whole thing that there's a lot of stimuli and there's a handful of points where that really just generate like a set of whatever. And, you know, we've got AMPK, we've got calcium, we've got P38, we've got stuff that we're going to get into in subsequent episodes, like oxidative phosphorylation demand, stuff like that. There's a lot of stuff. that acts as a signal, but it really all goes down to improving just a couple things, like a large set of a couple things, a large set of genes, but it's like an hourglass. You got a big signal, you funnel it through a small point, and then you get a big response. It's also, if you think about what we've just talked about in terms of looking at one pathway, and last week you looked at a different one. it's why there's kind of a it's a mistake to only think I'm going to target this thing that's the purpose of what my training is because you don't want to advantage one pathway potentially and what we've basically talked about today is that you didn't actually manage to do that because there's all these other things that are also contributing and if you're trying to maximize you know that Response to Training. You need to hit as many of these things at once in reality, which is why good, healthy, well-fed training is an important part of training. Yeah, totally. And that's why just thinking about regular performance is really all you need to do. And I've said this before on the podcast many times, understanding what's going on on a more molecular level oftentimes is not advantageous. It doesn't help you train better, really. In some ways, it can help you understand what overachieving on certain types of rides is. But generally speaking, it seems to be more beneficial to understand the kind of training that is not working, the kind of training that's not going to benefit you. And so I think the other thing that that's what Akimoto also recognized with this intro paragraph is that He recognized the general function of stressing the body with exercise, which is the functional demand part, leads to more general adaptations in several systems like cardiovascular, muscular, to meet the demands imposed. And we're getting dangerously close to Rory's favorite thing in the world, which is progressive overload, which is match physiologic capability to functional demand. Means, you know, once you're able to meet demands, you might have to do more of that thing in some way. Shout out to everyone on my roster doing sweet spot right now. All of which who have the exact same comment afterwards saying, yeah, it felt great. And then that last 10 minutes was a bit of a fight. I was like, good, going well. Nailing it. Keep it up. And so. And they wouldn't get, the point is they wouldn't be able to do that if they were, you know, feeling good, well-rested, well-fed, able to go out and do the work. Because, you know, much like what we said earlier around. If you're glycogen-pleated in a triangle, hit some five-minute intervals, they're not going to feel great. You're going to feel like trash. You might have one good one, but then the next one, it's going to go completely downhill. Yeah. And so you're not going to be able to accomplish the work. And that is true even at a lower intensity where you might be able to sit at the intensity for a bit where you're not going to be able to do as much of it as you could have. Yeah. And especially for what we saw in the AMPK episode is that the absolute intensity Absolutely Matters. Working to your capability matters a good deal. That's just not AMPK signaling. That's just what we see in coaching, generally speaking. If you're going to do, let's say, anaerobic capacity efforts, if you're going to go do a set of five minutes of 30-30s, if you are dead on that day and you can barely push the pedals, if you're pushing rope when you're trying to do these efforts, That's a different phrase. Oh, why? How do people usually use that phrase? Don't answer that. Then the adaptations you get out of that ride are not going to be very good. You have to do that ride to your, like, pretty much within your entire capacity to do those kinds of intervals. So, and you're not going to do any better riding with low glycogen. that it really cuts performance a lot. And by all accounts, that's fine for low-intensity riding. Like if you do a long, easy ride the day after a hard interval set or a race, that's totally fine. That's good training. Low-intensity, fuel it, of course. You've got to recover. But I read a lot more papers on this signaling pathway than appear in this episode. And the evidence as a whole for low glycogen... Riding being Beneficial is entirely equivocal. Similar to does vitamin C help cure the common cold? It's equivocal basically means there's no effect. But there were a couple patterns I could see based on the few papers that really looked at the exercise performance of all this stuff. Is that there tends to be more P38 activation with more well-trained athletes than sedentary. Or did I say that in the reverse? I think, no, it's the reverse. There's more P38 activation with sedentary athletes versus the more well-trained ones. And I think this makes sense because, well, and many other studies show no difference, by the way, but I think this makes sense because one of the things that we're trying to do in exercise Like I've harped on this for many podcasts now. What is exercise doing? It is disturbing your, you okay, Rory? Are the cookies done? No, it's my laundry's done. Oh, okay. Good timing. Yeah, sorry about that. So the, what we're doing is we're disturbing cellular homeostasis. And P38MAPK being an energy or being a cellular stress sensor. If you are not good at maintaining homeostasis, you are having more cellular stress. And the better trained you are, the less cellular stress you have, meaning you are going to activate P38MAPK less. Because your body's just too good at coping with it. Just too good, and you might have to progressively overload in order to get some adaptations. Say it ain't so. Yeah, it is so, I say. Anyway, like I mentioned before, the more general literature is focused on pathology, therapeutic targets, and skeletal muscle is more focused on differentiation and myogenesis. And typically, in a more general sense, activating stimuli for P38 kind of depends on the tissue, and metabolic oxidative stress is usually put out there as a general signal, which seems to be the case. Is it probably reactive oxygen species in terms of oxidative stress? The answer is probably not, but we don't really have any evidence to say yes or no, really. And if we never have any evidence to say yes, then the answer is probably no. But we're going to have to wait maybe 10 years and revisit this at some point and see what we got wrong. So the best evidence I ever saw that low glycogen riding is effective comes from people who actually are not well trained. But in things like this, one of the things that we also see is greater interleukin-6. And I don't want to spend a ton of time because interleukins are an absolute mind field to get into, but it's one of many things that muscles produce in response to stress, along with like P38 activation and all that kind of stuff. So it's generally speaking a signal for inflammation and tissue repair, meaning that like, you know, this kind of goes back to my hypothesis that If you're less well-trained, you're going to get more activation because you are disturbing your cellular homeostasis more. And that means that you need more signals for tissue repair. So even in a paper where the title says, low glycogen increases PGC1-alpha expression in trained men. Sure, we can see increased PGC1-alpha mRNA expression. We see activity of like AMPK, ACC, which is related to AMPK, and P38 are honestly oftentimes worse in the low glycogen group, although not statistically significant, so we can even say no difference. And oftentimes there's no performance testing available. So this is my general review of the literature, which I've not really done in a Wostok episode before, but I thought it was worth doing because our evidence so far has been so inconclusive. The more well-trained you are, the more you need to progress the overload to elicit a response is just what it all kind of comes down to at this point. You need to disturb your cellular homeostasis more to elicit adaptations. And you can do that by riding longer. You can do that by riding harder, kind of doing middle in between, not well-fueled. It's probably not going to get you much. That kind of overlaps with the, there's no such thing as a non-responder. where it's just about at a certain point you have to do more than you did previously to elicit a response. Yeah, and that's a tough thing because doing more than previously, especially for folks who are time crunched, leads to problems. Like if you're like, okay, I'm doing well on two hard days a week. I'm doing like, let's say two sweet spot days, but I'm not quite getting the response I want. I'll do a third and then you get the response. Okay, cool. Then that stops working after a bit. You rest, you do everything you can, and you're still doing three hard days a week, and nothing's working. What do you do? You do a fourth? Maybe. I've done that. And it, well, first of all, it sucked. I think if someone's got seven hours a week, then there's probably other problems. Yeah. And I remember I was doing four or five hard days a week on the bike. Not like hard, hard, but like I would say four truly hard days in one medium day. Medium Long Day. I was training 17 to 20 hours a week. So that's the kind of thing where I'm a reluctant responder to this kind of training, and that's the kind of stuff I need to do once I'm fairly well trained to elicit any response. But the cost is fatigue. And I could not imagine doing any of that without pounding homemade waffles every single day. That's the worst ways to fuel your training. That's true. many worse ways, like not eating waffles or carbs at all. So regretfully, we don't have much actionable advice here besides our normal progressive overload suggestions, but we didn't go through all of that just for a nothing burger because I really wanted to demonstrate that even when you're looking at substrate oxidation, Enzyme Activity Markers. You still cannot forget about actual performance. Because remember, even if you're looking at mRNA for PGC-1-alpha, if you make more PGC-1-alpha, that does not necessarily mean you get a stronger signal the next time you exercise. Because you have to do exercise that overloads it in such a way, yada, yada, yada. So even that is... Not always a slam dunk in terms of, wow, this is really going to help. Yeah, this kind of overlaps with if people are really overthinking their training and they're trying to think of every little thing that influenced a workout, they're probably looking way too deep in it and not just at that sort of macro scale view of what have you done over the past month, what have you done over the past year where you're actually able to see. the influence of training because I think it's often very much a mistake to look at an individual workout as just here's how I responded to last time. That works sometimes but it's going to be much less interesting than how did it go this week compared to last week because you're seeing the wider view of all of it and how it sits which is why something like WKO is extremely useful. It's an extremely powerful program in terms of what it allows us to do. But this week, well, last month, during all the troubles with trading peaks and my inability to get anything to upload to WKO, I realized I don't look at WKO nearly as much as I used to because I'm just looking at what's happening at that large-scale view in terms of workouts. like people shouldn't get caught up on things like particular genes being activated, particular markers, signs they think result in actual training because the thing that matters is actual training. Yeah, actual performance data. And also a lesson to folks, especially mice, this is me talking to myself mostly, even when you see that the experts Decide that there's enough evidence for something, always check their references. Always. Because when I did check these references, and I, to my shock, and it didn't really support what I thought were the same conclusions, my interpretation of literature being different from this other much more well-known and smarter author. And people get it wrong, too. I've gotten stuff wrong, too. I'm not saying that he's a bad guy or he's dumb or anything like that, because he's certainly a lot smarter, better rather than stuff than I am. But I thought that his interpretation of literature was different than mine. And it really made me kind of remember to second guess everything and everyone, especially including myself. This is something I think is particularly a problem in a field like exercise science where In other fields of science you can control variables much more easily and in exercise science it's really difficult because you have to deal with population spread and the population spread within the groups that sign up for your study and then you also have to deal with the intricacies of how are you designing a study in which you're going to get a bunch of people to probably do a bunch of exercise and that's hopefully going to be showing the same effect within each group via a control group or one or many experimental groups. Yeah. And the context matters too. There's too much there. And it's like, what training have you done previously? Like, if you've got well-trained athletes who take a month off the bike and then do a month of easy riding and then do VO2max intervals, like, you are setting people up to have a good VO2max response, which oftentimes, where we're going to talk about this in a future episode, is really just like short-term noob gains. It's been like two months since you did any hard riding. You're probably fairly detrained in a lot of ways. And so that's the kind of thing where, oh, these are well-trained athletes. This raised their VO2 max more. I think I don't buy it a lot of the time because I want to see when somebody is well-trained, they've done everything. Now what improves their VO2 max? Like the context matters a lot. And I also think in terms of practical, you know, all the pros are doing X kind of training now kind of stuff. I always think what Are they not only like what is the new training doing, but potentially what is it replacing and what did they stop doing? That always fascinates me as much as what's going on. So the context of everything is so hugely important. And that's why having not only the being able to look at your workouts and seeing your adaptations week to week matters, but also taking that 10,000 foot view in WKO5 like we like to do. That's why that is such a powerful tool as well. And you can't really do one without the other. Yeah, it's like what I think I said in the last podcast. Of course, we've recorded two, so now I can't remember which ones got published. But the differences between a scientific study and actual application of coaching are much larger than you would think from looking at the papers because like some of the papers we've looked at today have been one or two days of a moderate tempo workout and then some above threshold intervals and on the face of it that could look like something that was actually applicable to what people are doing in real life but also it could completely not be if you think about Oh, there was a study, I can't remember who wrote it, comparing 16-minute intervals, 4-minute intervals, and 8-minute intervals as a way of determining. Oh, I think that's that famous silent paper, isn't it? Yeah. Was he on it, or was he just referencing it? I don't remember. I don't remember. I think he might have been on it. But that study shows 16-minute intervals weren't the best at putting up VO2 max, which I'm not that surprised about. And no, it's 4 reps of each duration. Whereas eight minute intervals are significantly better at raising VL to max than four minute intervals. But the difference there is that they're doing four intervals of each duration every time. So it's no surprise that the one that does double the workload gets a greater training response. And that's the sort of thing that you have to remember when you read these papers is pick out, and this is somewhere where like... I used to teach a biology course, and one of my lectures was on how to read a scientific paper. Is that the one where you had the Olympian in your class? Yes. Big smile from me. There's two ways to read scientific papers, I find, and I always taught them the basic way, which is you've no scientific background and no topic background, and that is Read the abstract if you understand it. Read the start of the introduction and the end of the introduction. Basically pick out the bits where you are able to read it because that's just here's the current understanding of what we're about to talk about and then here's what we're going to do. And then you skip to either the discussion or the conclusion and just read up on what they did there. Look at the nice graphs. But if you're experienced in something... you're going to not do any of that you're probably going to read the abstract then read the methods because the methods you have the knowledge to understand what they're actually doing and what you find is when you read a lot of exercise physiology stuff is you read the methods and you realize like okay this is an interesting study design but if you're trying to compare two methodologies here You have to decide whether or not it actually resembles something you do in training. And I don't know about you, but I give people more than four four-minute intervals. Yes. So that's the sort of skepticism you sometimes need to carry whenever you look at some of these papers. What's the limitation of the study? Study might be high quality in terms of what it's trying to show, but it might not actually be applicable to implementing directly into training. Those are two different fields. Yeah. So I think we should think about what do we have for actionable advice today? Because honestly, I don't feel like we have much, but we do have inactionable advice. So this is stuff not to do. So we have do not do fasted rides. This is like... I can't believe we said that. This is the worst version of this type of protocol. because you are setting yourself up for, well, energy depletion doesn't help with your adaptation on the other side. It also sets you up for riding at lower power outputs than you're capable of, especially if you are doing any kind of efforts at all, especially if you suck at pacing easy endurance rides. Like if you are still trying to hammer 70% FTP for your easy endurance rides and it doesn't feel easy and you can really only do two hours and it's down to like an hour 30 when you're fasted. You're not helping yourself. Don't do that. I'm specifically going to declare half my clients being called out right now. Yeah, the number of messages I get after a statement like that is much greater than zero. Also, do not do rides just to oxidize more fats by manipulating your diet or glycogen stores or anything like that. That's my recommendation. My conclusion here is that there's only equivocal evidence at best That low glycogen or highly energetically stressful rides like you would get with low glycogen are any more effective than doing normal ass training. And you absolutely cannot do this with high intensity. Don't even try. Good luck. Yeah. Let us know when the funeral is. So if you want to do this kind of training, eat on your ride because the stimulus is not burning more fat. The stimulus would be low glycogen. So if you want to do this, that's how to do it. I don't recommend you do it, but if you want to, that's how to do it. And again, in my experience trying these protocols with folks, there's not much upside and there's a lot of downside. And granted, the time that we were trying these protocols were like 2020 when there's not much going on. Everybody's in lockdown, everybody's all alone, yada, yada. Dism in 2019 too. And that's pretty much where it ended also. So, you know, we tried it, didn't really work. We're done. That's it. 2020 was a good time to just try some shit. It really was. I learned a lot in 2020 in terms of what's effective and not effective, et cetera, et cetera. And I'll also kind of conclude, before we get to our listener questions, here's a listener observation. When I put up the Q&As in the Instagram for this episode, somebody asked a question and we chatted a little bit and he said, Every intervention has a cost to implement. Even things that we know are very effective, like FTP efforts, sweet spot efforts, VO2 max efforts, race efforts. We know that there's a cost to everything, but we know that the benefits are there despite the cost of fatigue. Maybe if you do a super, super, super hard ride, you can't really ride hard again for like a week. If you know the benefits are there, it's worth it. If you don't know the benefits are there and you're trying to figure it out, Try it, but you've got to make sure that you watch your refractory time after all the hard stuff. So everything has a cost to implement. I thought that was a great... That puts a nice ball on it. Yeah. I told him I was going to steal that for the podcast. So shout out to that guy who does maths. You know, he's from the UK. So do we have any final thoughts? We kind of actually, we kind of touched on a lot of final thoughts during the podcast, but do we have anything before we get into listener questions here? No, I appreciate some of my athletes getting passively called out for their high zone two riding. I've got at least one zone three enthusiast who is extremely strong. And so whilst I tell them ride easy sometimes, I'm also just like, it's working for now. But yeah, I think we did quite well. Don't fix when it broke. Okay, so. I asked up on the Empirical Cycling Instagram up in the stories for listener questions for this podcast and most podcasts we do. So let's start with my favorite question from somebody who is obviously a fellow nerd who didn't know exactly what we were going to get into in the podcast. And so I wanted to put this right up front. Has the increase in PGC-1 alpha and P53 activation been quantified due to low muscle glycogen? Rory. What do you think, where do you think we're at here in terms of the literature review today? The word increase is doing an awful lot of heavy lifting in this question. We've shown that it will go up, but it's not because of that. The mRNA transcription seems to go up. Yes. But once it becomes a protein, so we didn't see any increased protein levels, and then we need to see increased activity levels, then we would need to see Increased Performance, along with mitochondrial markers of yada yada. And looking at one mitochondrial marker is usually not sufficient. We're looking at, you know, cytochrome oxidase, so complex four, not an okay marker, but not amazing, still need better performance testing. So I would say it's equivocal at best. I'm still going to give it a 10% maybe, but 90% no. That's fair. Yeah. So, any benefits to fasted rides? There's benefits to fast rides, but not so much for fasted rides. Well said. Can this shortcut base training? I always get sad when people talk about shortcutting base training, because one, the answer's no. But also, there's two parts here. Do you not enjoy riding your bike? And two, I'm sorry you don't have enough time to ride your bike. I think it's more the latter is the issue with folks. It's not like a lot of people don't want to. The latter, as I find in Scotland, the weather. Although I'm about to find out in Majorca the weather because I'm about to get thunderstorms for pretty much the entire duration in which I go. Unbelievably common in Majorca from my folks who have been there. I would actually say, because I have actually tried the low glycogen endurance and even up to tempo sweet spot type riding with folks who are short on time. And the answer is no. We did not see any benefits to it in my coaching experience with these protocols versus regular ass training. And I actually think that in a lot of ways, regular training would have been better than trying these protocols. Like regular, harder training, more towards what people are physiologically capable of would have been a lot better. And then the folks who we did not do these protocols with, we were up against the usual stuff, but it wasn't like, they were also not miserable doing these protocols. Yeah, I would say absolutely not. You'd also just generally feel better and have a good time. Yeah, who wants to be miserable while training, like especially off the bike? That sucks. Don't do that. How can you tell if your glycogen stores are sufficiently low? Well, the reality is you can't actually really tell without a biopsy. Just not going to happen. The general way to tell if your glycogen is low is if you do hard training and then you don't eat enough carbs afterwards and you are miserable going upstairs. Also being sleepy seems to be a thing. Sluggish legs. Sluggish legs. Sluggish brain is a big one. I get sluggish brain really bad. Are there any differences between chronically and intermittently low? Yes, because one of them is low all the time and the other one is low. after you've done some treatment. Would you rather be miserable intermittently or chronically? Well, you're Scottish. Some would say if you're intermittently miserable, then you're chronically miserable. I figure the weather in Scotland, everybody's intermittently miserable. It has been pretty shit this year, it has to be said. But I don't exactly envy everyone around the rest of the world boiling their arses off. Or inhaling smoke constantly. Yeah, but here it's been an impressively shit summer. Well, chaotic system, some places are going to have energetic highs, and you're getting the energetic low, so sorry for you. And that's why I'm going to meet you. Yes. Let's see, what's next? Why does sleep suffer with the low protocol? Because your brain also requires a lot of glycogen, and it takes a long time for the brain to get used to working with ketone bodies. The brain prefers glucose and lactate by and large. There was a study. I do not remember the name of it. It got linked about two years ago by Johnny Whale of formerly HubWatBike, and he was on the Escape Collective podcast recently. But he was talking about how you can look at lactate levels rising within the body just in response to doing something hard-thinking-y, like an exam, because your brain loves that shit. Yeah, consuming a lot of glucose when it's available, for sure. Yeah, so sleep also suffers because your body is in an energetic deficit a lot of the time. And one of the things that I tried to do with these protocols is make sure that people were not in an energetic deficit that they were eating sufficiently. But it's fucking hard because when you're eating a lot of proteins, fats, and vegetables to fill yourself up, you actually get a lot more satiety. Seishity? Satiety? How do you say it? Whatever. You feel a lot more full. Seish. Yeah, you're a lot more seish when you are eating more proteins and fats, and so it's actually really difficult to bring your body up to energetic balance. You're in a deficit a lot of the time, and that's very, very stressful on the body as a whole, and not just the muscles when they're exercising. So that's one of the reasons that sleep sucks with this kind of stuff, and I personally find when I was trying these kinds of things, I gravitated, and this happens anytime I'm dieting actually, I really gravitate towards caffeine. And that absolutely fucks my sleep. Fucks you. So bad. I mean, the other general part here is even if you're not trying to do some purposeful low glycogen training, if you do your training in the evening and thus give yourself no time to actually recover between the end of it and sleep, like that's always... a key to having a really restless night and probably a couple of bad days after as a result because one of the things I sometimes have to pick up with my athletes is when are they doing their training and usually that's going to change according to what day it is and so I have to kind of plan in advance you know what days are we expecting that you're going to have to do your intervals because I don't want people to do them after you know six o'clock at night if at all possible. Sometimes that's unavoidable. Yeah. Like if you go to bed at midnight like I usually do, then it's, you know, 6 o'clock is not that late. It's like when people say like, oh, you shouldn't eat past like 7 or 8 p.m. It's like, well, I go to bed at midnight. Like I'm going to eat at 10 o'clock if I want to. Sorry. Yeah. So, oh, next question. Do any of these protocols translate to performance improvements? and yeah yes but not because of the reasons and they were trying to look at it yeah no better from the papers that we looked at no better than anything else that we that we than anything else but in my experience also with these protocols no better than anything else the thing that I have not seen is in the durability realm so in terms of like Durability being what power outputs can you produce after so many kilojoules relative to body weight? Like kilojoules per kilogram have you done? Like so 10, 20, 30, 40, 50, 60. I think that people usually don't look at much more than 50 usually. So that's one of the things that I would want to see in terms of seeing these rides and testing this. But I would also want to see it in terms of individual. variation instead of a population average of like eight riders versus eight riders. I would want to see how does each individual rider respond to this. So I love it when papers report the individual like ups and downs with their averages like a couple of these papers that we did that we looked at actually reported and you saw those. So let's see. Can you tell if you're depleting liver versus muscle glycogen? You kind of can, but you kind of can't. It's kind of irrelevant. Yeah. You can avoid all fructose. That's going to deplete your liver glycogen while you're exercising. Don't do that. Yeah, that's like a whole body bonk. And like the muscle glycogen depletion is more like your legs kind of give out. In general, that's not a great way to measure it either. So yeah, realistically, you cannot tell. Also, the stimulus is in the muscles, not the liver. So you want to maintain liver glycogen because that helps maintain your blood glucose and that helps maintain general homeostasis. So yeah, don't deplete your liver glycogen. I imagine diabetics are able to tell when that happens and that's about it. I have never asked. That would be interesting to know. Next question, if you are doing this protocol, is it okay to lower power to maintain the same RPE? That is exactly what I had folks doing. And that's effectively what happens in this study as well, only the protocol is asking them to do a quote-unquote max effort matching through the duration, but what's actually happening is they can't produce as much power, and so it's just coming down naturally anyway. Yeah, for endurance riding, I usually suggest doing this anyway, so that way if you're fatigued after a hard workout, even if you are eating everything appropriately, a lot of the time people will ride a couple watts easier when they're fatigued, and I don't see that this makes any difference whatsoever. So if you're going to do this protocol, yes, lower the power to maintain the same RPE. Is there any use at all for ultra athletes? 

I mean, I can't think of a discipline more demanding for you to eat as much as possible. But on the other hand, I can't think of a discipline where your chances of being glycogen depleted are much higher than, you know, normal, for normal training. Like, that is an interesting question. I ultimately think the answer is probably not. But, yeah. See, that's interesting because this is the one use case where I think it's okay, but we have to asterisk this with a couple things. So the big one being, we've kind of seen in a bunch of papers at this point that, and we've kind of, we discussed this in Wostok 40 also, that eating carbs does not actually spare muscle glycogen. It spares liver glycogen, but not muscle glycogen. So regardless of what you're eating as an ultra athlete, you've got to pace it right and you've still got to eat. It's like blanket statement. I would say for ultra folks being more fat adapted and having to eat fewer carbs to maintain the same power output, it's not going to spare muscle glycogen, but it can reduce the amount of food that you have to bring because you're burning more endogenous fats a bit more. And so in terms of logistics, it's like the one use case where I'm like, maybe it's worth a shot. I consulted with an ultra guy recently and he actually was doing this type of stuff. and he was dreading talking nutrition with me and I was like you know what I'm I don't hate it it's not it's not my favorite I'm kind of I'm kind of like if it works it works camp the good news for a lot of ultra distance races unless you're thinking something like manic like unbound is that you can probably predict quite well when your neck's going to be able to stop and refill plan for that for sure And so you're planning for your nutrition in a way. And if you're doing something like Odd Axe, you know, those are events where you have to do things in a set time, but not necessarily the fastest you can. Yeah, Paris, Paris, Paris. Yeah, your actual rate of doing things is controlled in such a way where you can work out, here's how much I can eat in a day. and here's how often I'm going to be able to get it. And we've coached a bunch of ultra athletes who do odd axes and that kind of stuff. Odd Axe? Odd Axe? Is the singular also the plural? Who knows? I don't. By your look, neither do you. Actually, on our roster, we've only had a handful of people who have ever done the fat adapted ultra type riding and it's not gone terribly. It's not been great. It's not been any better or worse. We still are up against the same kind of training stuff and the same kind of performance limiters on the day. So we haven't seen it be amazing. We also haven't seen it be absolutely awful unless somebody does a protocol totally wrong. Also, these are athletes that are devoted to doing the easiest pace they can manage. for the duration they're going to do it. Well, not all of our clients have been. Well, not all of them, but in most cases, if they're riding sensibly, they know what they're in for. If you've got 48 hours ahead of you and you're going to get a seven-hour nap scattered throughout the event in half an hour chunks, you're probably going to be pretty good at not going much past. LT1. One would hope for sure. Yeah. Yeah. All right. Next question is, does training status affect the efficacy of train low? Seems like maybe, but if you are new to training, newer to training, if you're more untrained, I guess we could say, it seems that, well, it seems that in a little bit of in one sense yes but in a more general practical sense you are ripe for adaptations for pretty much anything you do so it doesn't even matter so I would say don't bother yeah I don't really get why training status would maybe affect us this much like you certainly shouldn't be doing this if you're brand new yeah Yeah, there's absolutely no, you're in the wonderful nookane space, savor it. If you're coming in from an off-season break, that's like, that would be the one case where it's like, oh, baby, I want to try this. Like, if you want to try it, like, go ahead, but just don't, make sure that your training is normal. Like, do your normal training if you're going to try this stuff, and I bet most people are going to figure it's not, the juice is not worth the squeeze. Yeah, do your light. Two or three weeks of just noodling at zone two. Yeah. Well, and that's kind of what I saw, generally speaking, in the literature, is that the people who were less well-trained got a bigger P38 activation from being glycogen depleted because they're less good at maintaining cellular homeostasis. But in reality... In my experience with these protocols, again, it's sort of like people who are lower on training time. There's really not a huge amount of difference. So I would say it affects the efficacy of train low in that if you're really well-trained, you're probably not going to get much out of it. And if you're not that well-trained, you're probably going to get a lot out of anything. So again, it's not probably not what we're doing. So next question, is this good for weight loss? No. Back when I was young and stupid, I thought it was. And it's actually not. You're absolutely right. Like your weight loss problem is ultimately just what are you putting in versus what's going out. Yeah. And that's kind of the only safe way to do that and to ideally not do it aggressively. Yeah. Burning more fats does not necessarily mean you are better at burning fats because a lot of the time. A lot of the fats that you're burning are exogenous. And if you are burning fats endogenously, it comes down to the energy deficit you are sustaining. The one good example I have of that is, I think it was like, I didn't watch it, so I'm going entirely on secondhand knowledge here, but there was a season of, I think, Australian Survivor, where someone turned up purposefully overweight. and then basically did absolutely fuck all to help catch food or go fishing and he relied entirely on the fact that he was just digesting himself for the most part, having a bit of water, occasionally getting some protein but managed to survive the best because he just had his own stock but the reason he lost weight during it is because he wasn't putting anything into the system. He's doing pretty much nothing but burn fat. But that's not the reason he lost weight. He lost weight because he didn't eat. Australian survivor, otherwise known as Australia. Australia, yeah. So many poisonous animals there. I visited there once, and I was terrified of every insect I saw. I'm extremely arachnophobic, so I'm never going. That is reasonable. If you've got to check under your toilet seats before you take a shit, so you don't die from a spider bite. That's a terrifying country to live in. I'll do the old Alpine squad. Next question. Are there any gender differences with this kind of thing? The answer, as far as anybody can tell, is based on the literature available, probably not. But we have no, as far as I can tell, we have no direct evidence on this kind of stuff in adult human women. There's probably female rats that were involved, and rats and mice, but that's as far as the literature goes at this point, as far as I can tell. Yeah, it's kind of the age-old problem with any sort of human population-based study is... Not enough women. There are a lot of differences between men and women in terms of what homeostasis looks like, but the studies are just really shit at actually making sure we capture that. Yeah, if there are any differences, they are likely small. So, let's see. What's the minimum time per session for this to be worth it? The answer is... Zero. I'll come at this from another point. I will presuppose that this is effective. Presupposing this is effective, you still have to do the exact same amount of writing that you were doing previously. You cannot shortcut this. The writing is still the writing. 

That's a fair way of putting it. Should this protocol be done sparingly, if at all? Yes, it should be done sparingly, if done at all. Are there better adaptations than high-carb training and more volume? Fairly conclusively, no. Yeah, I'm going to go with no there. Can you combine this with high-intensity training? I mean, in theory. Well, you can steer a car with your feet if you want to, but it's not the best idea. So in theory, yes, but in practice. Yeah. If you think through what high-intensity training involves, it's usually going to require a lot of energy. Yeah. And the worst thing you can do is come into it with not much energy. Yeah. And especially because high-intensity training. And you'll know it when you do. Glycolysis because the oxidative phosphorylation isn't sufficient. You are necessarily depleting glycogen at a much more rapid rate just because you need the ATP immediately. You can't make it with sustainable oxidative phosphorylation. In order to make two ATP, you need to pluck one glucose off of your glycogen stores. Then it becomes lactate and then the lactate does not go through Krebs cycle and electron transport chain and all that. So it doesn't mean – some people have interpreted this previously in the incorrect way. Maybe I misspoke or something like that, which is likely, so sorry if I did. But it does not mean that there is a greater energetic expenditure with high-intensity training. It means the rate of glycogen depletion is higher. The energy kilojoule output is still the kilojoule output. The stress of high-intensity training can make you a lot more hungry, and so it can make you go, oh, I need to eat more because the adaptations are you need more energy for the adaptations, yada, yada, yada. But reality is there's not a lot of, you know, yeah, you need that glycogen to do high-intensity training. Absolutely do. And that's one of the big reasons why. Can you consume carbs during the train-low sessions? Can and should if you're going to do it. Yep, for sure. If it's an effective stimulus, the stimulus is low glycogen. And while you're exercising, you are most likely not building glycogen stores. So, yeah. Yeah. Well done, whoever asked that question for preempting everything we talked about. Yeah. I mean, and I didn't really ask. I kind of, for the prompt for this, I was talking about the train low. and that kind of stuff. But I wasn't really, I didn't really give anybody else much context, so they didn't know where we would go in the podcast before we got to this section. So I noticed you didn't even announce that it was me coming on. Oh, well, I didn't want to get a thousand coaching inquiries in addition to the podcast work that I was already doing. So the last question. Difference in Stimulus for Mitochondria if the ATP production is more via beta-oxidation versus oxidative phosphorylation. I see you squinting at this one. All right, this is my camp. This is my expertise. So the answer is, I think that this question is confusing a couple things, and metabolism is confusing. Anybody who's confused about it, I totally understand. I used to be confused about it too. And then I thought about it every waking hour of my life for 10 years. And now here we are. So the answer is you don't get much ATP via beta-oxidation. You get one NADH and one FADH2. And that goes to the electronic transport chain. When you are sending acetyl-CoA to the Krebs cycle, you get a lot more out of that. So beta-oxidation is a step before oxidative phosphorylation. So beta-oxidation produces a little bit of NADH, a little bit of electron reducing equivalence, but then the rest get made in the Krebs cycle. And that all goes to the electron transport chain. So I think this person might be saying like, I'm not sure what this person is saying because it's kind of confusing. So let's look at this question another way. Is there any stimulus depending on getting – is there any difference in stimulus between creating ATP in different ways? I mean, beta-oxidation is – resulting from fats, isn't it? Yeah. Yeah. So, like, surely all this is is what we talked about at the very start of this, which is what is fueling things? And the answer is it's just you do the same work, but the actual fueling source of the energy is identical. Yeah. And one of the things that I've been trying to get across in the podcasts is that the substrate use is irrelevant. It is the disturbance of homeostasis. Like, that's why Of the three pathways we've looked at so far, we have calcium, which signals muscle contraction. We have AMPK, which signals muscle energy state. And we have P38MAPK, which senses, in a general sense, just cellular stress. And none of this has anything to do with we're burning more carbohydrates, we're burning more fats, nor ever will it. It's just not gonna happen. It's just not gonna come up in this podcast series because there's zero evidence to say that burning more carbohydrates means that you're going to be worse at oxidative phosphorylation. It's not gonna happen because it's not a thing. So that's where we're at. That is the end of our listener questions. Do we have anything else to add to any of this today? Yeah, when your coach writes, have a big tub of ice cream on your rest day, that's a hearty encouragement promise. Yeah, I mean, and whenever I've been stuck on a plateau with somebody, honestly, usually adding more training is not the answer most of the time. Adding more rest. Looking at nutrition, looking at off-bike stuff, that's where we usually find the biggest benefits. A lot of folks, I don't know how this happens, but a lot of our clients don't eat enough carbs or enough in the day in general. Which is especially a problem for people who are maybe getting up and having to start their workout at 6 a.m. Or they've got stressful family life, stressful work life, stressful school life. Or they're just not a person who gets hungry that much. Or their natural food choices are more like fats and proteins and stuff like that rather than carb-hungry people like myself where I've got to make myself eat protein and fats even. A lot of people are accidentally training a lot with low glycogen. That's kind of where I was going with that. and quite honestly their training is like not good after like just a couple weeks because I think when you are training yourself and not eating sufficiently not replenishing your glycogen stores or anything like that on a regular basis you before you start working with a coach like us you are auto-regulating you're not working that hard and when you are you feel good and when you're not which is a lot of the time you're not working to a high degree of you know a high degree of let's say RPE in your session or there's a higher RPE but it's not nearly what you're capable of you know there's a mismatch between RPE and yeah and so that's one of the things that that I harp on in consultations with folks I always try to tell them these are signs of fatigue these are signs of progression and if you're not seeing yada yada if you're seeing xyz together like these are signs you need rest these are signs you can push That kind of stuff. And that's what we're looking for as coaches all the time. Is this person able to progress or are we stuck somewhere and why are we stuck? And low glycogen training is by all accounts not any more effective than actually doing regular training. And so the answer is like, did I see an effect with this stuff? Yeah, I saw some of the longest TTEs at threshold I've ever seen, but nobody's threshold went up. And that's one of the reasons, like if I knew that that was going to be the output, would I have spent that like, you know, month or two or whatever, however long we did this protocol, would I have spent that having somebody do just more threshold efforts? Would we have seen the same benefits? Absolutely. We absolutely have. And I've seen people eating a ton of carbs. and Fueling Right and doing a lot of threshold efforts. I've seen people do 80 minutes of threshold test eating all the carbs in the world. It's all risk and very little reward. That's a good way to put it, for sure. Alright, so thanks Rory for coming in to Pinch Hit for Kyle and thank you all for listening and if you are interested in coaching with us please reach out to me empiricalcycling at gmail.com if you think that we know what we're talking about or at least have enough self-doubt to know when we are wrong about something because we are always trying to individualize what is best for everybody that is our main overriding coaching philosophy so if you are into that please reach out to empiricalcycling at gmail.com and if you are not interested in a coach are interested in self-coaching or you're a coach yourself or you just want to have a consult If you want to have a second set of eyeballs on whatever you're doing, if you hire me for a consultation, empiricalcycling at gmail.com. And if you have any questions or comments on anything, also let me know, donations at empiricalcycling.com slash donate, Instagram at empiricalcycling for questions and the weekend Q&A. And besides that, I think that's going to be about it for today. So we will see you all for the next episode. Bye.