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Sorry about that, right. So I will make a start now then. So thank you for joining me for the second part of the teaching series. Today, we'll be looking a bit more closely at carbohydrate nutrition and um it's used for training adaptation and also for performance. So today, I will start this by saying, it's gonna be slightly more on the scientific side looking a bit more at different studies to understand why we've come to the conclusions we've come to. But again, following a similar format as last week. So first, I'll just be quickly discovering uh discovering, describing what the principles of training low are and the concept of carbohydrate periodisation. Then we'll be looking at training induced muscle adaptations and whether training low can amplify these signals. And this will be in terms of the gene transcription, muscle adaptations, endurance performance, and it will also include a critical analysis and then we'll quickly cover the negative effects of low carb diets followed by whether athletes should actually be competing low and this should be a relatively short um session. So feel free to go around at the end for questions, of course. So training low is the concept of training with low carbohydrate availability in the body. Now, it's important to distinguish training low from training with a low carbohydrate diet. Whilst a low carbohydrate diet is one of the ways of training low. There are many other ways to do so which is um training over after an overnight fast. There is um not consuming any carbohydrates during the recovery period, sleeping low. So a low carbohydrate or no carbs for dinner, long training periods without carbohydrate intake and training twice a day where the first training period is um to deplete the Glyco source. And then the second training period will be used as a training low period. Now, this is a sample of a paradise Glycogen depleted training. And as I said, the training twice a day is an example of Glycogen depleted training periodisation because you have the first session where you have carbohydrates in your system, you have glycogen stores and then the second session, you don't have Glycogen stores. And this is just another example of that where you have in the light blue some sessions where you're training with moderate amounts of glycogen. You have a train high session where you consume carbs right before the training to ensure you've got like source filled. And also you actually have glucose in your system as you're performing the exercise and then you have a train low sessions where um you have the glycogen depleted stores. Now, training induced muscle adaptations are generated by the cumulative effects of increased transitional activity during the training recovery. So kind of like what we covered last week in the muscle hypertrophy discussion, muscle adaptations are induced in part by mechanical stimuli. So when you're performing the exercise, you have signals such as the actual stretch of the muscle, but also metabolites that activate the transcription machinery and the nucleus that leads to protein um formation. And these proteins can be anything from myofibrillar proteins to mitochondrial proteins to enzymes needed for certain metabolic genes um for metabolic functions. And this is what Eligard et al looked into in 2000. So they showed that endurance exercise induced transcriptional activation of genes including mitochondrial biogenesis. So here we're looking at um P DK four, P DK four is a gene involved in um is a enzyme involved in fatty acid oxidation. And we just take this grab step by step. So, on the left hand side, we're looking at the transcription of P DK four. And what we can see is the first column. So the C is the control leg, the leg that's not being exercised at baseline. And then ce is the exercise leg at baseline. And you can see that they have kind of similar Acti activity of P DK four. Then right after the 60 to 90 minute exercise bout P DK four activity was measured again. And you can see that the transcription of P DK four in the exercise leg. So the posttraining um data are only from the exercise leg. Um You can see that right after the exercise P DK four, transcription is significantly increased and it remains relatively elevated for the following two hours after which it tapers off. And now looking on the right hand side, the MRNA of P DK four, which follows from transcription is also increased with a peak at four hours, which makes sense because it can only be high once transcription has reached a peak. And it follows that trend essentially. So what they showed is that P DK four seems to be transcribed more with endurance training stimulus. So now the question is, can training low amplify these signals. Well, the same study group performed a follow up study two years later where they looked at subjects training low versus training high. And they showed that training low caused a greater increase in P DK four transcriptional activation as well as UCP three, which is involved in energy and lipid homeostasis, lipoprotein lipase involved in um fat oxidation and hexokinase involving glycolysis. All of these four were all had a higher transcriptional activation after training low compared to training high. And Hansen et al did a similar study, but they showed that this actually is not just on the transcriptional level, it's actually seen in the muscle itself as well. So they showed that training low caused greater post training. Um so greater resting muscle glycogen after the exercise training regime in the trained low group compared to the trained high group. And on the right hand graph, they also showed that the resting enzyme activity of citrate synthase which is involved in the TCA cycle and H AD which is involved in beta oxidation. So, again, fat oxidation um were both increased more in the train low group than in the train high group. And perhaps as a result of this, they found found that the time to exhaustion at 90% work, um maximal work capacity was increased more after the training in the trained low group than in the train high group. So inter performance seems to be in house as a result of this. So does training low really lead to severe adaptations. Well, the studies we just looked at and some other studies suggest that training low increases the ability to break down intramuscular triglycerides in type one, muscle fibers, it seems to enhance muscle glycogen synthesis, post exercise. And it also seems to help maintain blood glucose in the PSA state and lead to greater adaptations in citrate synthase and HIV. So it was reasonable to conclude that the training in the fasta state resulted in severe adaptations. But studies performed where they allow carbohydrate feeding before the exercise have shown that time trial performance in um cycling improved by 12.5% with preexercise carbohydrate ingestion. And this was linked to a total increase in carbohydrate oxidation compared to placebo. And another study found that a time trial on a 30 kilometer run was improved with a high carbohydrate diet. So clearly, there are kind of two fields of evidence here. And before we dive into what exactly why we're seeing these differences between the two studies, I wanna just take a little look at the actual methods of the studies we've just considered. So sorry, I'm just gonna monitor the chat for a second. Um Sorry. So there's a common saying train low referring to low intensity. So no training low. Yes, thanks. Natasha training low means low carbohydrate and specifically, and this is the distinction to be made. Is that training low is your training in a state of low glycogen stores? You don't have much glycogen in the body nor circulating glucose. And that is a distinction to be made between the low carb diet because whilst following a low carb diet does allow you to train low because you have low glycogen stores. You don't need to follow a low carb diet to train low because as I mentioned earlier, um in the presentation training, low can be done by depleting the glycogen stores with the first exercise bout and then doing a second exercise bout a few hours later with no glycogen left in the body. Um It can be done by doing an overnight fast where you didn't consume carbs before dinner. So there are many ways to train low without actually following a low carbohydrate diet. Um I hope that's clear. Um So yes, looking at the methodologies of the studies we were looking at. Um so I've classified them as the pro low carbohydrate studies and then the pro high carbohydrate studies just to have a distinction. But so for the pro low carbohydrate studies, we were looking at um the pu it all study that looked at the transcriptional activation of metabolic genes, use 12 healthy, physically active men and they have them follow a diet of a minimum of 500 g of carbohydrates per day for the two days prior to the study. Um to allow them to maximally fill the glycogen stores. They then on the day before the exercise, uh before the trial, they asked them to perform one-legged exercise to lower the glycogen store only on that one leg. And then they followed that up with a two arm cycling essentially just like that to lower the liver glycogen. Um And with that protocol, the idea was that the glycogen stores in the muscle of the light that was trained and of the liver are depleted. And so, because the study was done the next day, they asked the participants to follow a high fat, low carb diet meal for the dinner and the breakfast um following the depletion training to avoid refilling those glycogen stores. And so the next day, they were asked to perform two legged cycling for 2.5 hours at 45% via two max. Um I will describe, I will explain why I've highlighted um it in red and green for a second but vo two max, um just to be clear, is a measure of endurance capacity in, in a way and the intensity as which your, what's rather a measure of the intensity at which you're performing the exercise um in terms of your respiratory um capacity and Hansen et al. Um the study, looking at the muscle adaptations and endurance performance use seven healthy untrained men where um they were asked to perform leg extensor exercise at 75% of their maximal work capacity for one hour. They were followed a controlled diet um of 70% carbohydrates for the duration of the study, which was 10 weeks. And the protocol was that on day one, they trained both legs. So they did um both legs of leg extensor for an hour at 75% work max. They then had a two hour break and then they trained one of the two legs again for a second time. And that leg was the trained low leg the next day, they would then come in and only train the train high day. So the train load day had uh morning glycogen depletion training followed by a glycogen depleted training two hours later, while the train hind leg had 24 hours to recover from the first session. And more importantly to refill the Glycogen stores for the second bout of exercise the next day and this alternation was followed for the entire 10 week duration. Now, the reason I've highlighted these um variables is because in red, we have the duration. So the duration was capped, it was specifically 2.5 hours or one hour of exercise. No more, no less. And the effort was also c it was 45% vo two max or 70% work ma 75% work max no more, no or less. So both of these studies were controlled for workload and training amount. Now, if we look at the pro high carbohydrate studies, this term at our study is active college students and they had their exercise and diet controlled for the two days before the test. Um And what they did is one hour before the exercise was done. They were given either placebo 1.1 or 2.2 g of carbohydrates per kilowatt of body weight solution. And this was blinded. So they didn't know what they were consuming. They were then asked to perform continued cycling for 70% V two max for 90 minutes. And then this is the part that was actually being studied was the cycling time trial where they were asked to compete uh complete the number of revolutions on the cycle equivalent to another 45 minutes at 70% view to max as quickly as possible. So revolutions um with revolutions we mean on cycling, one revolution is essentially like one turn of the pedal. And so they were asked to complete the equivalent of 45 minutes at 75% vo two max peddling as quickly as possible. Now, the Carlson and Sultan study, this was a crossover study and they used 10 moderately moderate to highly trained cross country runners and they were asked to run 30 kilometers as fast as possible. So it's a time trial two times with a 30 a three week interval between the two sessions. And so about half of them performed race one following a high carbohydrate diet and the other four followed a normal diet and then they switched for the second race three weeks later. Now, sorry, just going back for a second. I've highlighted this in red because as you can see here compared to the other studies, this is a time trial. We're asking the patients, the participants to complete a given amount as fast as possible, its performance, its power. So there is no C they have a set amount of work to do and they wanna do it as fast as possible. So we're looking at different variables and that goes into the reasons for discrepancy. So one is a training protocol. As we just saw the pro low carbohydrate studies controlled the participants work for work load and training amount. Whereas the pro high carbohydrate groups looked at maximum effort. These are two different measurements we're looking at essentially and equally, the primary outcome was slightly different in the pro low carbohydrate groups. They were measuring training out of patients. So they're looking at metabolic changes like transcription and enzyme activity and time to exhaustion, which is looking at the endurance capacity of the muscle. Because here we're looking at kind of in line with the metabolic changes is the body able to use other fuel sources other than carbohydrates to fuel them to be able to maintain the duration and the workload time to exhaustion. Whereas the pro high carbohydrate groups did a time trial and this is a measure of the capacity to sustain high power outputs. And with high power outputs, we're looking at the volition, the ab ability to mentally recruit the muscle fibers to mentally push yourself to keep going. Um So again, these are different outcomes of interest and this is where the importance of carbohydrate and exercise becomes underlined. Um because carbohydrate is the fastest source of fuel for muscle because it's both an anaerobic source of energy through g glycolysis, which becomes particularly relevant for power output, especially strength training, sprinting, things like that. And it's also an aerobic source of energy and this becomes more relevant for endurance exercise. Now, the important and the interesting thing here to understand is that carbohydrates and glycogen stores don't necessarily directly affect speed. They don't necessarily allow you to run faster, but they likely enhance the running economy. So as I said, they don't make you run faster, but they allow you to maintain your quick pace for longer. And perhaps a part of that is that carbohydrates are also the primary source of fuel for the brain. And as we saw last week, the brain activates the muscles, your, your, you tell your muscles to activate essentially. And so if you have carbohydrates in the system, it can also reduce your perceived exertion because it's easier to activate the muscles because you've got the energy to do so. And as I said, it enhances um central nervous system activation, especially doing these sustained or repeated maximal contractions where you have to tell your muscles again and again and again to maximally activate, that is exhausting. And if you have the fuel in your brain to send that signal, to send that message that may be able to enhance your performance as well. And this is shown in several studies which show that low carb diets both reduce running economies. So you're just not running as efficiently as you could be, you're wasting energy and it increases perceived exertion. And so you can't push yourself as hard because the same level of intensity feels a lot more difficult with a low carb diet than on a high carb diet or when you have filled like it stores. And just another point is that the same is seen in intensified training. So the D score is a measure of stress symptoms where the higher you're on the store on the score, the more stress symptoms you exhibit. And this study compared um a high carbo hearted diet versus a controlled diet. And they showed that with intensified training, the high carbohydrate diet, participants had reduced stress symptoms compared to the control group. So should athletes compete low? We've seen that training low can enhance muscle adaptations. It doesn't necessarily enhance time trials and performance. So should athletes compete low? Well, in line with what we just covered, numerous studies have shown that higher dietary glycogen increases endurance capacity. So on the lefthand side, we can see that in dark blue, the high carbohydrate diet on the top, right, they had the highest endurance performance, which was greater than a mixed diet and definitely much greater than a low carbohydrate diet. On the right hand side, the same thing was shown where high carbohydrate diet had a greater time to exhaustion than a low carbohydrate diet. And a similar pattern is seen in the power output where um Hilson et al showed in 2010 that high carbohydrate diet increase the power output consistently compared to low carbohydrate diets. And similarly, carbohydrates seem to improve speed both in eight and 16 kloer runs. So if competing low isn't really optimal, when is training low, really beneficial. Well, we touched on this at the start where periodise training can give rise to other other patients. We did see that training low can increase the transcriptional activation and enzymatic activity of um certain metabolic genes, especially those involved in um lipid oxidation oxidation. So, doing period training allows you to expose your body to v stimuli to from high carbohydrate to normal to low carbohydrate. But another interesting point and this is more relevant to competitions is to sensitize glyco in stores. And this becomes very interesting leading up to endurance competitions where around 2 to 3 weeks out of the competitions, athletes sometimes reduce their carbohydrate intake over one week step by step until they reach low to practically no carbohydrates. And they maintain that for about 3 to 4 days. This low to no carbohydrate period. With the glycogen sources are depleted. They're still doing some training. The glycogen stores become ex extremely sensitized to glycogen. They want to take it out. It's like a dry sponge. And that's why when they then start increasing the carbohydrate intake in the week leading up to the competition, the Glycogen stores avidly take up all that glucose because it's been dried out and they are extremely sensitized to it now where it becomes interesting is that athletes can increase their carb intake to higher than their previous baseline levels. And the glycogen stores will fill up more so they can fill up their glycogen stores more due to the sensitization than they would previously have been able to. And this is a concept also known as carb loading. So they're going into the competition with extra filled glycogen stores which will help them with their endurance performance. So what does all this really mean? Well, some studies do show that training low enhances metabolic adaptations. There are some potential disadvantages of training low, especially in terms of health and performance, which is why athletes should not compete low because acute performance is very strongly and positively influenced by carbohydrates. But there are two key beneficial uses of training load, which is pise training to expose the body to range of stimuli as well as precompetition to sensitize the glycogen stores before carb loading. And that is the end of this presentation. So thank you for listening. If you have any questions, I will um be happy to sit around to answer these. Now, um I do wanna say again, if you fill out the feedback survey, you will get access to these slidess and it also helps me a lot to get feedback on these talks. So yeah, I appreciate it and do stick around the next few weeks for many more talks to come. OK. So you've got a question asking, do you know if the same applies in sports that are not as endurance based? Most of the studies are of course done on endurance performance because it is a very, very carbohydrate dependent um activity. But it is pretty safe to say that all sports will benefit or at least most sports, all these maybe you out there will benefit from um having carbohydrate as a fuel because again, going back to the previous size carbohydrates are, I was looking back here. Um So what was it? Yeah, carbohydrates are the fastest and main fuel source for anything that's exertion. And that means that if we're looking at, for example, strength training, strength training or short bouts, it's definitely not endurance training, you're not trying to train your cardio respiratory system, but in these acute bouts of high power output, the main fuel is gonna be anaerobic glycolysis. And so that's where again, glucose in the blood is gonna be your friend, glycogen, then the muscles is going to be your friend. And again, with the the brain activation as well. If, if having, if consuming carbohydrates prior to your exercise or your performance allows you to push yourself harder because essentially by reducing perceived exertion, it means that for the same amount of pain and suffering, you're under essentially from the intense exercise, you're actually pushing yourself harder with the carbohydrates because it feels easier. And that also allows for greater adaptations in a certain extent, but it's it out, it allows you to have a greater power output. And the same goes for the central nervous system activation, this your brain activates your muscle fibers. So whatever the movement it is, you do whatever the sport it is you do. If the brain needs carbohydrates, sugar as fuel and the brain activates the muscles surely having sugar in the blood to feed the brain will allow the brain to more easily activate the muscle fibers. So I do think that it does extend um in terms of performance to other um sports, in terms of the muscle adaptations, it's maybe not as easy to extrapolate because endurance performance is also very much dependent on being able to use fat as fuel. That is why endurance athletes who are trained have this ability to preferentially use fat as fuel. And so in other sports like sprints or weightlifting where you have acute bouts of power, I'm not sure how relevant those metabolic adaptations can be. Um So that I'm not sure about, I'm not sure how much literature there's on there. Um But yeah, so that I'm I'm not quite sure how applicable it will be to that as well. Um We have another question. Do these effects change for trained and untrained individuals? Yes. So I did um just touch on that slightly but a lot of the studies we just looked at or at least some of the studies we just looked at and other studies like them are done on trained athletes. Um So I think that the in terms of training low for muscle adaptations, the effects, the effects would be the same in terms of the stimulus you give to the body to adapt preferentially to fat oxidation. Um because that's all it has to rely on. Um in terms of performance, I think it's difficult to say. Um, at least based on my knowledge based on, I know I'm not quite sure how to, what I think I can answer that. Um, the fundamental ideas stay true. Whether you're trained or untrained, which is that carbohydrates, fuel performance and training low lead to more training adaptations. Perhaps the extent of the training adaptations differ, perhaps the extent of the benefit on performance changes. Because if you are an untrained endurance athlete and you've therefore already trained your body to metabolize fats preferentially for endurance capacity, maybe you less relying on carbohydrates altogether. But this is kind of speculation on my end. It's not. Um I would have to read more to the literature to see how much there is out there on actual in athletes as well. Um So yeah, and then we have another question is carb loading effective for non intern sports. I don't think it's that beneficial in nonendurance sports. Um It depends on the sports. I, I'm not, I'm right now thinking primarily of things like sprints and weightlifting where they are acute bouts of explosive power where you don't, you don't need fully filled glycogen stores, you just need enough to fuel these few seconds, minutes of exercise. Um But I think the context varies very much. Um If you're thinking of things like dancing, although arguably that could be considered an endurance sport, but I think there, there are sports that fall kind of in between the categories where it may become relevant. But carb loading is really mostly followed by endurance athletes because that's where it becomes the most relevant. Um Yeah, I hope that answers your question. It's, it's really thinking about when, when is the glycogen needed? When would you benefit from having extra full glycogen source? Because Glycogen stores in average glycogen stores in the body, including liver and muscle are usually enough to fuel around 1.5 hours of exercise. Be it running or weight like in two hours at the gym or be it whatever you want to do. So it's really when you enter beyond that 1.5 hour mark. So marathons, triathlons, Iron Mans, that's where having these extra loaded Lycogen stores really become of come of interest. And I don't know how many other sports in which you have to continually see, perform that exercise for so long. And also perhaps without the opportunity to refill the Glyco, like to consume some, some sort of glucose or sugar or Glycogen within the run as well. Um So yeah, that's really just what you wanna think about. When would it benefit you to really have Glycogen stores for beyond 1.5 hours. Um Another question, slightly unrelated, but where can I find the slides for the teaching sessions? Thanks for today. Um So yes, when you complete the feedback surveys for each of these tutorials, um you should be able to access these slides on the, on the med all page. There is normally a slides tab where I then upload them after the sessions. Um I'll just pop my email in the chat if you want. So you can send me an email if there's any issues. Um, but you should be able to access them. I'll just write it now. Yes, but do try it via the Med All page and if there's any issues, um feel free to reach out also, if you have any other questions, obviously you can just email me. Um and then I see one final question. Is there an increased risk of injury with training with low glycogen stores? Um I mean, yeah, that's an, that's an interesting point to con to consider because especially when we're looking at the running economy side of things, um you're not running as efficiently as you could be on a low carbohydrate diet on many instances. And so that means that, well, firstly, maybe you consuming more energy than you need to for a given movement, but you also might not be limbing it safely. And that's not just for running, it's for cycling, it's for weightlifting. And um because carbohydrates are the primary, the quickest fuel source, it also means that in most activities we do most sports we do, there are many muscles that stabilize our movements and those also need to be activated, those also need energy. And so there is perhaps an argument to be made for the fact that, well, if you don't have that quickly accessible, so maybe some of the other muscles and maybe this goes back to, um, running economy or exercise economy, you're not stabilizing the joints as optimally as you could have. Or it's almost like maybe you're performing a more lazy version of the movement because, well, you don't have the energy for that. You don't have the direct fuel source for that. Um So an argument can be made for that. Um And it also comes to the stress symptoms with training with endurance, carbohydrates help manage the stress, the acute stress of the performance, the training, the exercise, but also the long term stress of the training. And so by reducing the stress through the carbohydrate in take through in the trainings, then you are also reducing your risk of injury because stress does increase the risk of injury. Um So I don't know to what extent it's directly correlated where you have the low glycogen means you have um greater risk of injury. But an argument can definitely be made for that. Um And it's something to keep in mind as well and to know your own limits. Definitely, I hope that answers your question. All right. Um If we have no more questions, then we'll finish here. Thank you again all for, for joining today. And I hope to see you again in the next couple of weeks.