Nutritional Revolution Podcast

Carbs & Training Adaptations: What Athletes Need to Know with Dr. Mark Hearris

• Season 5 • Episode 161

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In episode #161 we spoke with researcher Dr. Mark Hearris about:

  • Carbohydrate metabolism and exercise performance
  • Co-ingesting protein with carbs for recovery
  • Dual-source carbohydrates and liver glycogen repletion
  • Periodizing nutrition and training goals

Dr. Mark Hearris is a Senior Lecturer in Exercise Metabolism and Nutrition at Manchester Met University. His research interests lie in the field of carbohydrate metabolism, where he has investigated the influence of carbohydrate availability in modulating exercise performance and training-induced adaptations. This research has informed modern carbohydrate feeding guidelines during exercise as well as current periodisation strategies for the endurance athlete. Mark’s current research focuses on the use of 13C magnetic resonance spectroscopy to non-invasively measure skeletal muscle and liver glycogen metabolism in response to exercise and carbohydrate feeding.

Mark is also a Registered Nutritionist with the Association for Nutrition. He has applied his expertise across team and endurance sports, including as a consultant performance nutritionist in pro football 2016-2021.

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Welcome back, everybody, to the Nutritional Revolution podcast. Today we have for you guys Dr. Mark Hearris and he's a senior lecturer in exercise metabolism and nutrition at the Manchester Met University. His research interests lie in the field of carbohydrate metabolism, where he has investigated the influence of carbohydrate availability in modulating exercise performance and training-induced adaptations. This research has informed modern carbohydrate feeding guidelines during exercise as well as current periodization strategies for the endurance athlete. Mark's current research focuses on the use of 13C magnetic resonance spectroscopy to non-invasively measure skeletal muscle and liver glycogen metabolism in response to exercise in carbohydrate feeding. As a practitioner, Mark is a registered nutritionist with the Association for Nutrition, AFN, and he has applied his expertise across both team and endurance sports, serving as a consultant performance nutritionist in professional football between 2016 and 2021, and currently provides consultancy support across team and endurance sports. Enjoy the episode. Hello everybody and welcome back to the Nutritional Revolution podcast. We have for you guys, Dr. Mark Hearris Thank you so much for joining us. Yeah, thanks very much for the invite this afternoon, Kyla. We're excited to have you. But before we dive in and get to learn all about your study and for our listeners, we're going to be diving into a study em listed out here. Co-ingesting whey protein with dual source carbohydrate enhances amino acid availability without compromising post exercise liver glycogen resynthesis. So excited to hear about that. But before we get to learn all about that, I'm going to let you break down your two truths and a lie for me. Okay, no problem. So first one is I once ate nothing but potato for two weeks as part of one of our research trials. Second one is the last time I visited the US, I actually ended up in a Las Vegas hospital. And the third one is that I've given a total of 12 muscle biopsies as part of various different research trials that I've been part of. feel like these are all very real things that could have happened. Potatoes for two weeks. Yeah, it sounds pretty rough. Las Vegas hospital. If that's true, I definitely want to hear what that story is at end of the episode. I feel like maybe you're doing a time trick on me. Like maybe you ate potatoes for one week instead of two or something. So I'm gonna guess that's the lie. And then, or it could be the biopsy thing, maybe you didn't do 12. But I'm gonna go with the potatoes and then we'll find out which one of those was the lie at the end of episode. Those will be fun ones. So this research article that we wanna dive into, it caught our eyes, certainly because there's an endurance athlete component to it for many years. And I think through my undergrad, there was the conversations around using protein as a recovery source. But I don't know that they necessarily were targeting endurance athletes. So I think this article is very interesting. So I'd love for you to kind of break down what drove you to dive into this em specific study. Why were you kind of questioning this? Yeah, great question to kick us off with. think what we try and do in all of our research studies is try and understand the scientific basis of what we actually see athletes are doing in practice. So really all of our research questions come from athlete behavior that we see in the field from working with these athletes or working with the coaches and the practitioners in the field. And actually it You know, we see a lot of endurance athletes consuming protein in the post exercise recovery period But what we really don't know is how that specifically affects the storage of carbohydrate and specifically relating to the liver whether it's a good thing or whether it's a bad thing and I Guess to give the listeners a little bit of context. There's two different things that might happen when you ingest protein. The first one is that you get a release of a hormone called insulin. And insulin is a key hormone that actually allows us to store the ingested carbohydrate within our tissues in that recovery period. But I guess on the flip side of that, we also get an increase in a hormone called glucagon. And glucagon essentially does the opposite of what insulin is trying to do by stimulating the breakdown of nutrients from the different tissues that you're trying to store that carbohydrate in. So really the interesting question was whether consuming protein in that recovery period changes the balance of these hormones and if it does, does it actually improve or does it impair the storage of carbohydrate as glycogen in that recovery period? Okay, now I'm hooked. walk us through what the application was in the study, what you had the athletes do, what were you tracking, how were you monitoring these things, like glycogen synthesis, that kind of stuff. Yeah, sure. essentially all of our participants who were good level cyclists, definitely not like top, top level athletes, but good local cyclists who were performing probably around about 15 hours of endurance exercise a week. So relatively well trained. And they came into the lab very early on in the morning in a fasted state and they did an exercise session that We essentially call it a glycogen depletion session where you're basically exercising to the point where you can't exercise anymore. And that's not very fun at 8 a.m. in the morning, but that's essentially the protocol that we use to deplete all of the glycogen within both the muscle and within the liver. Now, once they completed that exercise bout we then track them over a five hour period. where they consumed 60 grams of carbohydrate per hour for that five hour period. Now we had a number of different nutritional conditions as part of that. So that was essentially manipulating the type of carbohydrate that they were ingesting, which was either purely maltodextrin, purely fructose. 50-50 combination of maltodextrin and fructose. And then we had a final trial, which was again, a 50-50 combination of maltodextrin and fructose, but also with the addition of 30 grams of whey protein immediately post exercise, as well as after three hours of exercise. So they were our nutritional treatments. And what we're really fortunate at our institute is that we've got three Tesla MRI scanner m essentially down the corridor of our physiology labs and we were able to use this really unique and novel technology to actually measure glycogen within both the muscle and in the liver without actually having to do any invasive measures like take biopsies that you typically need to measure these types of things. so cool. I think I saw one of those devices for the first time at, I think was Boulder Springs Physio Lab. yeah, it was very, I think it was two or three years ago, but at the time it was very rare, And so when you're looking at glycogen, this is maybe a little off topic, but are you able to measure glycogen in the tissue? How do you know how much glycogen is in that device? Yeah, so it is complex. Luckily in our institute we've got clever physicists who are much smarter than I am. But essentially what you're looking at is that the carbon atoms that make up glycogen, they have a signal, so they give off like a small magnetic signal. And when placed in the magnetic field of the MRI scanner, these atoms essentially give off signals and what we're able to do is measure the strength of that signal and the stronger the signal the more glycogen we can interpret is actually within that tissue. that's so cool. So when you're measuring that glycogen, are you taking specific points across the body or is it one localized point that you're looking at? Yeah, so essentially the way that it works is we have something that we call a coil and the coil sits over the region that you're interested in measuring. So we know that the two primary sites that we store glycogen in the body are firstly the muscle, but secondly also in the liver. So what we can do is we can place our coil over the thigh muscle. And can do this across different muscles as well. You can do it across the calf muscle if that's something that you're interested in. And we place it across the liver and that allows us to measure the glycogen across that wide region that is being covered by the coil. That's so neat, tech-mology. Yeah, super cool. We're super fortunate to have it in our institute as well. So question on that fourth group you mentioned. So they were consuming, you said 30 grams of whey protein right away after the glycogen depleting exercise plus the 60 grams of carbs. And then again, they did the protein and carbs three hours later, but were they also doing just the carbs at the two hour mark and four and five? Yeah, that's a great point. So every hour they would consume the 60 grams of carbs in that 50-50 ratio with maltodexin and fructose. But in addition to that, immediately post exercise and three hours post exercise, they had the 30 grams of whey protein. And the reason for that is, again, we try to mimic the typical recovery feeding patterns of what we see athletes doing in practice. If you look at the traditional recommendations for protein intake, it's to consume that around about every three or four hours in recovery. So we try to mimic that as part of our research trial. Nice. Was there any crossover in this study? When you say crossover, you mean like the actual experimental design. did the participants cross over with the different trials? Like did some do, yeah. sorry, yeah exactly that. So every participant would have performed all four forms of that research trial and you know we do that in a kind of randomised and crossover manner to try and minimise any of them like external variables that might influence your outcome measures of interest. Very cool. And so what did you end up finding from your study? So as you probably guessed from the long-winded title that you read out at the start, I think the most interesting and probably most important finding for the athletes is actually if you co-ingest protein alongside your carbohydrate, it doesn't have any negative connotations in terms of the rate and the amount of glycogen that you can store. in either the muscle or the liver. So I think that's really important because you know replenishing that glycogen pool in both of them tissues is really critical. And we know it's probably one of the key determinants of subsequent performance having replenished our liver and our muscle glycogen. But actually we know that protein has also important effects on different recovery parameters. So the fact that, we can combine these two nutrients to hit different recovery goals without having any sort of negative permutations. I think that's really important for the athlete and especially considering that these are the typical things that athletes are doing post exercise. You know, they probably finish exercise and a lot of the time they will consume a commercialised recovery product and that recovery product typically will contain probably close to 60 grams of carbohydrate and probably close to 20 to 30 grams of protein. So it's nice that they can carry on doing them routine practices and knowing that they have the science there to underpin what they're actually doing as well. yeah. The protein thing is a fascinating thing because yeah, again, for the longest time it's been, I feel like, yeah, protein powders. It's like post-workout protein powders. And a lot of people were forgetting about the carb piece. And then I feel like literature came around and was like, well, protein timing post-workout maybe isn't the biggest thing. It's more carb. Where do you fall with that specific to endurance athletes? Yeah, that's a great point. And I think, to be honest, athletes across the board, a lot of the time there is a real big emphasis on protein. So you see when you talk to athletes and you read the literature in this space that they typically always consume enough protein in this post exercise period. But actually the thing that maybe falls down in some cases is actually the they don't place enough emphasis on the amount and maybe even the type of carbohydrate that they consume when actually that's maybe one of the bigger drivers, at least in the short term of how they recover from exercise and then how they are able to perform maybe the next day or the next couple of days, depending on the type of athlete. yeah. One question. Did your study have men and women? Unfortunately not, and this is probably one of the biggest criticisms of all sports science research, right? We do a lot of research in males and very, very little representation from females. I guess as a caveat about that, there is normally reasoning for that and the reasoning is normally that we don't know very much about how things such as hormonal contraceptives or how the menstrual cycle can influence some of these things. So how it can influence how we handle sugar or how we store sugar in the different tissues and whether that changes, for example, across the menstrual cycle or whether that changes depending on, the phase in which you're taking the hormonal pill or not. So. I guess what we really need is more high quality evidence in female athletes to try and understand these things. And actually, once we have that evidence, we can do a much, much better job of including female in sports science research. Yeah, yeah, certainly. We've got to find out what's going on at that level. yeah. eh So with the four different groups, just maltodextrin, just fructose, and then 50-50 and the 50-50 protein, was there a difference between any of those four groups in terms of the ability to replenish their muscle glycogen and liver? Yeah, that's a great question. when we looked at the muscle glycogen data, there was actually no difference in the repletion of muscle glycogen, depending on the type of sugar that you consume or depending on whether there was the additional protein as part of that. And actually that was quite an interesting finding in itself. But actually what was more interesting is that when we looked at liver glycogen data, we see that when you consume maltodextrin alone, the repletion of liver glycogen is actually much lower than when you consume the combination of different sugars. And actually, like this has already been reported in the scientific literature. So we confirmed findings from previous studies to show that these dual source blends that contain fructose are actually really important. for replenishing liver. I think where we probably advanced our understanding in this space is that we showed that the hormone glucagon, and I mentioned that before, the glucagon hormone, if that is increased, that infers potentially that you're breaking down some of that glycogen within your liver. And we actually seen that was the case in the maltodextrin-only trial. So the case might be twofold. It might be that the storage of the sugars that you're consuming isn't as high when it's just maltodextrin because it's not a very good substrate for the liver to store glycogen. But actually it might also be having some sort of hormonal influence where it's increasing the breakdown of glycogen that's already stored within the liver. So you've almost got like a two pronged influence where you're not storing as much of what you're ingesting, but you're also potentially breaking down what you already have stored in the liver to maintain your blood glucose levels. with the maltodextrin only group. Yes, So we do see an increase in that hormone but it's not as high as what we see with the maltodextrin only trial. Okay. So this is not on your study, but now that makes me think, what about all these maltodextrin during-sport fueling products? Yeah, that's a good point. I mean, the hormonal response during exercise and in the recovery period is very, different. what we actually know about fueling during exercise is that when we feed carbohydrate during exercise, especially at a high rate, we can actually prevent the breakdown of glycogen within our liver. So I think that, you probably can't translate that data from the recovery period into the during-exercise feeding period. But I actually think it's an interesting question and one that we'll probably look at studying over the next couple of years, actually trying to understand does the type of carbohydrate that we consume during... exercise how does that influence things like muscle and liver glycogen depletion during that specific exercise session? Yeah, that would be very fascinating. Now I'm curious. I thought there was something do do you follow Asker Jeukendrup's research? I thought I recall him presenting on something where they were looking at the different amounts of carbohydrate consumed per hour. And I thought it was in relation to glycogen breakdown within the tissue. And I thought they were seeing like the higher consumption of carbohydrates per hour actually was showing also a faster rate of breakdown from the tissue. Does this sound am I do you know what I'm talking about? I'm I totally off track. no, no, mean, like, yeah, Asker's probably got two decades worth of carbohydrate feeding research. All of it is excellent. And there is some suggestions in the literature that really high carbohydrate feedings can actually, like you mentioned, increase the rate at which we use our muscle glycogen, but it's not really that. clear and consistent. And actually what we're seeing in the literature now is some studies are really pushing the boundaries when it comes to fueling during exercise. A couple of years ago actually we performed one of the first studies where we fed 120 grams of carbohydrates per hour during a three hours worth of cycling. There were some interesting findings from that study actually and one of them was really that feeding at such high rates of carbohydrate ingestion allows us to maintain our rates of whole body carbohydrate oxidation during exercise, which typically at lower rates you would see decline over the course of two, three, four hours of cycling. So the more you seem to feed, the better that rate of carbohydrate oxidation is maintained. Wow. Okay. Now I have another question that's also not your literature related because we're talking about this. If someone is getting up to utilize like trains their body to tolerate that high level, say it's 120 grams of carbs per hour, and then they go on a training ride and they're consuming half of that, maybe 60. is their energy going to be affected differently because it's used to receiving more carbohydrates per hour and how they utilize their energy. No, not necessarily. think with the training piece in terms of training the body to utilise, that's really, I guess what we're talking about there is really the capacity or really like the ceiling which we're trying to push. So we're trying to give our athletes, I guess, a higher ceiling or a higher capacity to be able to use really high amounts of carbohydrates. when it's appropriate or necessary but of course like you mentioned there might be some rides where you go out and then high rates of ingestion really aren't that necessary so for example you know it's long slow duration or it's recovery there's not really a need or a demand from the exercising muscle for such high amounts of fuel but if you're consuming less than that it won't affect you know, ability to use them lower amounts that you're giving your body. awesome. So with the information you guys found in your study, what type of athlete scenario do you think this would be beneficial for following this application? Yeah, I think the main applications are really where you've got athletes that have got maybe back to back sessions or they are competing in things like Grand Tours or tournament type scenarios where your recovery window is really, really small. Right. So if you think about someone like a Grand Tour rider, they're expected to ride. day after day for multiple days before they get a rest day and the recovery window is probably somewhere in the region of 12 to 14 hours. So at that point refueling your glycogen stores becomes a real key priority because we know that the amount of glycogen that you have in them tissues is directly linked to the amount of work you can do. at a set intensity. So for them guys it's really, really critical. I think at the opposite end of the scale, if you've got people who are just training a couple of times a week, where they might have a bigger window or opportunity for recovery, then actually these real small, nuanced pieces of the recovery puzzle probably aren't as important. Okay. And for an athlete, for example, I've seen this where they'll have two kind of like key races a week apart. Following that first race, is that, is this fueling like recovery protocol? Would that be beneficial or having a week in between gives them plenty of time to fully replenish and be prepared for that next A race? Yeah, exactly that. we know that it probably takes, depending on the athlete and the type of exercise that they performed prior, it probably takes anywhere between 24 and 48 hours to fully replete glycogen stores, and that's both across the liver and the muscle. So for someone who's got such a big window in between, think, you know, them real specifics in terms of type and amount probably aren't as important. But that's not to say that they might not be training during that seven day window either, right? So even though they've only got races a week apart, they might have important training sessions during that period where, you know, they still need to be recovered. So actually, It really just depends on what's coming in the next couple of days and what the priorities of them sessions are as to how hard and how aggressive you recover during that period. OK, that's helpful. And then one last athlete kind of case study scenario. This five hour recovery, makes me think of athletes that have done multi-day stage races, but they're 80 to 100 miles every day and they get in at the end of the day and it's the end of the day. do you theorize or do you know if there's any difference if they were to take that five hours of six times 60 grams of carbs and eat it all right after they've crossed the finish line so they can go to bed or is there that benefit to continue like keep it spread out over five hours? Yeah, that's a great point actually. I think that the reason we typically advise to spread it out is because the rate at which the carbohydrate you ingest can be digested and absorbed through the gastrointestinal system, it has a limit, has a capacity for, you know, a specific amount of carbohydrate. And if you consume that all at once, then, you know, that process is going to be much more. slower it probably will happen eventually as your stomach empties and it passes through the gastrointestinal system. I don't think we really have any great evidence to show that splitting that up is really important. So I think you know if it's a choice between having it all at once or not having enough then probably you know having it all at once is the better idea but I think in an ideal scenario and it doesn't have to be hourly if you can just split it up a little bit better then that's probably beneficial to the athlete and that might even just be a subjective comfort thing if you're consuming a lot at once and then trying to sleep on that it might be quite difficult to do as well. yeah. That's a great point. OK, so then now that also makes me think carb loading. And you mentioned kind of the glucagon hormones activity. And then you also bring up the stomach's tolerance on an hour by hour basis. what would you suggest for carb loading or do you have a specific recommendation of how an athlete should approach that from a like a preparation to a race? Yeah sure so carb loading is probably one of the things that athletes don't do very well. I think they probably think they do it better than they maybe do. I think what they think they need is much less than they probably actually do need. But I guess from a scientific point of view we know that probably 24 Hours worth of carb loading if you do it correctly and if you combine that with a complete day of no training Then that is probably sufficient to maximize your your glycogen stores But of course before races athletes might do little top-up sessions or kind of little little spin sessions just to kind of You know keep them moving. So, you know, it might be that you extend that period out from 24 hours to 48 hours just to make sure that you're consuming enough carbohydrate over that period. But essentially the main driver of glycogen synthesis or the most important thing that our athletes should be thinking about is just the total amount of carbohydrate during that period and that the recommendations are typically in the region of 10 to 12 grams for every kilogram of their body mass. um And the way to do that is probably actually things that sound quite unhealthy. really high sugar, low fiber foods. I'll give you an example that'll probably make some of you laugh. When we do a lot of our research studies, we typically provide a standardized diet to all of our participants and that's typically to maximize their glycogen storage and standardize that before any of their experimental visits. And we feed things like large bowls of Coco Pops, Jaffa cakes, sugary fruit juices, or things like that. Purely just because it's really high sugar, it's low volume, low fiber, so it's quite easy to ingest. Mm-hmm. But I think sometimes where athletes go wrong is that they have a real high carbohydrate dinner like a big pasta or something like that and they think that that's it they're done when in reality they probably need to every meal like that the day before a race in order to reach them targets that I spoke about. Wow. Yeah. I think that's really helpful for listeners to hear. think you're spot on when we do first time carb loading with a lot of our athletes and we have them track it, almost always they come in under and they say it's really hard to hit. So I think in our natural state, like you said, we think we're getting close and we're choosing these things. Like maybe we wouldn't choose on a normal day to day, like the sugary stuff. And so it feels like a lot. but when you actually add it all up, you're no, they're nowhere near the 10 to 12 grams per kilo recommendation. So Yeah, it's quite hard, If you think if you take an 80 kilogram athlete and you're trying to consume over 800 grams of carbohydrate and if you're just trying to do that through traditionally healthy foods, starches of pasta, rice, they will be big, big, big bowls of pasta and rice and not very feasible. Whereas if you have half a carton of fruit juice, that's probably already 50, 60 grams of carbohydrate that you could have alongside that meal. Yeah, yeah, that's really smart. The juice, the liquids, that empty fast from the stomach. OK, so in this study, you mentioned how nutrition can shape muscle signaling and adaptation. Can you unpack that a little bit for our listeners? Yeah, sure. mean, it's a very broad topic, I would say. But I guess there's two things that What We Eat in that recovery period does. Firstly, they provide substrates. So for example, you know, if you consume carbohydrate in that recovery period, is a substrate that then gets stored within your muscles and that energy can be used, you know, on another day during another training session. But also actually, What We Eat in the recovery period can actually influence the signaling response of how our muscle adapts. So essentially the way our muscle adapts is that we turn on or off specific proteins that then send the signal to our genes, this switches specific genes on and off. And then genes, as people may know, are essentially what codes different structures within our body. So for example if we're wanting to turn on a specific gene that might have a specific function, what we eat can actually significantly influence that. That makes me think of one of my nutrition professors where there is the I think there was an analogy of something like if you are prone to a genetic condition of like everybody in your family has heart disease or has had heart attacks young that the genetics loads the gun and then then this action you take will pull the trigger or not So you choose to smoke and drink and et cetera. That kind of loads the gun for that condition that was maybe already teed up in your system to be turned on or off by that nutrition or dietary behaviors that you're. Yeah, that makes complete sense. actually, like our lab from one of my previous institutes actually did a lot of work in this space where we were really interested in how restricting carbohydrate intake around exercise actually does a better job at switching on some of these signals that drive the training adaptations that the endurance athlete is interested in. So actually a lot of my PhD research was looking at when we exercise in a low glycogen state. So if we purposefully restrict carbohydrate intake before we go and exercise, what we actually see is that some of them signaling proteins are activated to a much greater extent. activated genes, so, in fact, we, some of them are. how we adapt to endurance training are also switched on to a greater extent. And if you do that over a series of weeks and months, what you actually see is when you measure them adaptations within the muscle itself, you see that they're much, much greater than if you didn't restrict carbohydrate before exercise. Fascinating. so is this kind of essentially the train low concept? Yes, yeah exactly that. And so that's also for our listeners been primarily only researched in men, correct? Okay. Just for our listeners, for lady listeners out there. and so, but from a, performance lens, so they're driving adaptation, but are they competing in races at that time and still performing well, or is this a specific tool that we put in the base training phase before we're kind of more in like prep pre-race training phase? Yeah, you hit the nail on the head there. So again, it really comes down to how you plan and periodize that specific block of low glycogen training. And you're exactly right. You will put that in your general prep-based training phase. But there's actually a really nice case study by Trent Stellingwerff who works at the Canadian Institute of Sport. They showed how they implemented this strategy in a number of their Olympians. And again, like you said, they would have a couple of sessions a week of these low carbohydrate, faster training sessions in the general prep phase. And then as they transition more towards the competition prep phase, what you see is that the number of them sessions drastically reduces. So it's probably One if that of them sessions per week, whereas the majority of the sessions are then focused on quality, intensity, performance, and fueling and all those other things. Wow. And in the going in low carb, are they fueling during those sessions as well or going in low glycogen and not fueling during as well? Yes, and that's actually really important. I think there's only one study that I can think of off the top of my head, which was really interesting. And it showed that if you go into a session with low glycogen, but actually you feed sports drinks, essentially during that session, you completely offset any of the benefit that you get from starting that session, low glycogen. Interesting. OK, this is all good nuggets, all good nuggets of info coming in today. Yeah, I mean, it's fascinating the fact that you think of it by just changing what you eat before, during or after exercise, you can completely change how you respond to that exercise. And I think, you know, a lot of the time we focus so much on the specifics of, manipulating training, volume, intensity, duration, and maybe actually like forget a little bit about nutrition. But when you look at them studies and you see how much of a potent impact nutrition can have on how we respond, so not just how we feel and we perform during the session, but how our muscle responds, it really does show you how important and critical eating the right things at the right times can be. Yeah, yeah. So kind of another case study question here, if we have an athlete that is weight cutting, so trying to drop weight, they're in an energy deficit. If they don't want to sacrifice performance, they should still prioritize this glycogen replenishment strategy post, but remain in a deficit as best they can, like outside of that post recovery, kind of like refeeding window. Yeah, that's a great question. And I think again, it comes back to how you carefully plan and how you periodize your nutrition across your training week. So for example, if you've got a session where you know it's going to be intense and you want to get the best performance out of that session. then of course you will prioritize fueling before, during and after that session. But in contrast to that, if you've got a session which is low volume, low intensity or recovery, where, hitting really high power outputs or high speeds isn't really what you're interested in doing, then actually you should target them specific days as your weight loss days and by doing that you can actually over the course of that training week still be in a calorie deficit and support your weight loss goals but actually also support your performance goals on them key training sessions where that's really important. Yeah, that's a great idea and way to structure it. How do you see the research on recovery nutrition evolving in the next five to 10 years? I think from, I guess a personal view at least, a real focus on the liver. And the reason I say that is because we've probably got now over 50 years of research that is solely focused on recovery and muscle. But actually we've got very, very limited research data on how all of them things apply to liver glycogen. Primarily the reason for that is because it's previously been really methodologically challenging to measure what's going on in the liver and it would have required liver biopsy samples being taken which not really anyone wants to volunteer to do. But I think with the emergence of these new MRI techniques that we've got in our institute in Manchester and there's different institutes across the world. We're more and more interest in how these different nutritional strategies influence the repletion of glycogen specifically in the liver. Yeah, fascinating the technology like you're saying no one wants to get liver samples taken Okay, and if you could leave our listeners with an actionable tip that could upgrade their recovery nutrition starting this week, what would it be? I think I probably already mentioned this a couple of times, but a lot of the time it comes back to real clear understanding of what you're trying to target, what specific goal that you're trying to target, and then how you carefully plan and periodize your nutrition to specifically match that target. for example, relating to recovery, if your specific goal is to quickly replenish your muscle glycogen, then some of the strategies that we spoke about on this call today might be important. But actually, you know, if you've got a bigger window of recovery and that isn't the focus, then you can maybe potentially focus on other areas of recovery that you're interested in and make sure that the things that you're eating are specifically targeted at that adaptation that you're trying to achieve. Do you have an example of what that would be? for recovery? Yeah, for like an alternate, like you're saying. Yeah, so I'll give you an example of that and it comes back to some of the low-glycogen training that we spoke about before. So there's some evidence to show that if you limit your carbohydrate intake in the recovery period, you can facilitate some of them enhanced training adaptations that we spoke about. So if your goal is to enhance them adaptations, actually restricting carbohydrate intake in that recovery period would be your outcome. But if you have a small recovery window and you're training again the next day, that's probably the last thing that you want to do right. And your focus is on actually replenishing and recovering them glycogen stores. So I think a lot of the time I think athletes go through the motions and eat the same things day after day, whether it's because of routine or habitual things. and probably don't change what they do depending on the sessions that they've done and the adaptations that they're trying to achieve from that training. And I think, I guess just a little bit, being a little bit more mindful of what are you actually trying to achieve from your nutrition and your training and then changing what you eat in order to. be able to achieve them specific targets and goals. Yeah, I think that's really important because I think some people might hear this and hear, well, if I don't eat after I could just drive more adaptation. like you said, it's true. But then also if they have to do a hard training session or they have a race in a week or, yeah, kind of think think about it a little bit and decide how you want to apply that. exactly. you know, there's one thing driving a kind of adaptation from a molecular point of view but if you've got a session the next day and you feel completely terrible and you can't train, then, you know, that almost definitely defeats the point. So, you know, like you said, it's really about trying to understand what you're trying to achieve and how you do that through. what you eat in that period. Yeah, I think that's super helpful. Okay, I'm going to jump back to your two truths and a lie. So you said you once ate nothing but potatoes for two weeks for a research study. The last time you visited the US, you ended up in a Las Vegas hospital and that you've given 12 muscle biopsies. I thought the potatoes for two weeks was the lie. Which one was it? Yeah, so you're spot on. That was the lie. Alright! Did you have to eat them for any period of time or was it not true at all? Okay. interestingly we have similar studies to that but the potato content was a little bit less I think it's like 70 to 80 percent rather than nothing but potato. Okay. And, you've given 12 muscle biopsies to research. So kudos to you for that. do you want to share with us how you ended up in a Las Vegas hospital or is that not appropriate for podcasts? No it is, you know what, it's actually a much more boring story than it probably should be being in Las Vegas. To be honest, I don't actually fully know what was wrong with me in the end, but I took a bad turn when we were in Vegas a couple of years ago, ended up in the hospital for the day and then flew back home. Not probably as exciting as you'd imagine being in Vegas. So what is on the radar for research for you coming down the pipeline or any conferences you're speaking at or anything like that we should share with our audience? Yeah, so I'm actually speaking at the International Sport and Exercise Nutrition Conference that is based at Manchester Met University in the UK. We're hosting that in the middle of December this year. And then in terms of research, we've actually got quite a lot of interesting projects going on in the next 12 to 18 months. A lot of work on our MRI scanner all around. Yeah. feeding, muscle and liver glycogen. So hopefully over the next 12 to 18 months we'll have a few more publications coming out in that space and try and evolve our understanding of that a little bit more. Cool, amazing. And where can our listeners find you and follow you or your research? Yeah, so I'm not very good on social media to be honest with you. I do have a profile on Twitter or X. I also have a profile on LinkedIn that I probably post on a little bit more regularly. And then in terms of our research, you can find that either on my LinkedIn page or you can follow our Research Gate page, which will keep your listeners up to date with all the cool things that we've got going on. Perfect. Well, we will link all that in the show notes for our listeners. And this has been super fascinating and informative. for myself for sure. And I'm sure for our listeners. So thank you so much for joining us, Mark. This has been awesome. Yeah, thanks very much for having me. It's been a pleasure.

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Kyla Channell, MS

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