I'm Patrick Wilson and this is the run to the top podcast. Hello fellow runners, I am your host, Finn Melanson and this is the run to the top podcast podcast dedicated to making you a better runner. With each and every episode, we are created and produced by the expert team of coaches at runners connect dot net where you can find the best running information on the internet as well as training plans to fit every runner in every budget. How many times have you been in a training run or race environment where issues like nausea, bloating or cramping, have interrupted performance or how often have you tried to experiment with the latest drink mixes, gels and bars? Only to find yourself back at square one wondering what will keep you properly fueled and focused on the task at hand during prolonged exercise personally, I've lost count of how many times gut distress and nutrition choices were the limiting factors on my performance in these scenarios. And that is why I'm excited to have robert Wilson, a professor of exercise science and a registered dietician on the podcast.
Today, robert wrote a book a few years ago called the athletes gut the science of digestion, nutrition and stomach distress. And we use his work in this area to talk about the sources and remedies for common gut distress issues that runners face, as well as overall strategies that runners can implement to make sure that they are in good positions from a nutritional standpoint to execute their most important, most challenging runs in training and on race day. If you're looking for a way to naturally boost energy, enhance athletic recovery and get the most from your training, then you should take a look at adding essential amino acids, also known as E A s, to your pre or post run drink. I'll go over the benefits later in this episode. But if you want to see some of the research yourself, head over to get Keyon dot com backslash, run to the top. Before we get to our conversation, I wanted to talk about the importance of electrolytes, especially in the winter, maintaining healthy electrolyte levels is not only important for your run but your recovery and overall health as well.
That's why we recommend all runners Check out element this winter. It's loaded with everything you need to replenish your electrolyte balance with 1000 mg of sodium, 200 mg of potassium in 60 mg of magnesium and doesn't include anything you don't need like extra sugar or anything artificial. Stay tuned for how you can get a free sample pack at element dot com. That's L M N T dot com forward slash runners connect. All right, Patrick Wilson, welcome to the run to the top podcast. Thanks for having me on. I appreciate the invite. So, I'm excited to chat with you here for many reasons today. Uh First off, we're gonna be going quite in depth on your book the athletes, gut and uh you know, in my free time, I am an amateur ultra runner and I've lost count of how many times nutrition choices and gut distress was the limiting factor in my performance. So just having read your book, it was invaluable in uncovering areas where I could do better in troubleshooting.
Uh yeah, just excited to cover parts of in the conversation today. So thank you for your work in uh in this area. Well, I appreciate that. And I, the positive feedback is always nice. You hear a lot from runners, especially ultra runners, I mean, that's I think the community that deals with it the most in terms of impacting their performance and even their training. Um you know, you see some studies where it's 40% of competitors in a race say that it impacts their performance. So, yeah, obviously, I think almost every, especially ultra runners had some of their own experience, where it's been a problem enough that it's impacted them negatively. So yeah, you hear that a lot and that was, you know, part of the impetus for writing the book. There's a couple of questions I want to ask you to set the table for a couple of the topics, we'll go in depth on the first uh, what were your own professional and lifestyle experiences that motivated you to put all this work together into a book?
Yeah, that's a good question. I think it was a combination of my research agenda over a period of a few years, just started gravitating more and more towards got issues with athletes, you know, I had done some studies um as a PhD student that looked at feeding with distance running and how that may impact physiology and performance. But one of the measures that I took was, you know, kind of gut symptoms or gastrointestinal perceptions. So the major study that I was doing in the lab was basically a protocol where people came in and they did Two runs on the treadmill. Each of them was two hours at a set pace roughly. I think it was 60 something percent of their view to max and then they did a four mile performance test at the end one condition they were ingesting a beverage that had all glucose and then the other condition, it was a mixture of glucose and fructose. And one of the measures that we were taking was got symptoms and uh just my experience from that and seeing the impact of just carbohydrate source and how that can impact how people feel and how they perform, how they got functions uh was kind of the initial study that I did that looked at that and then I just became more and more interested in over interested in it over time as a athlete myself.
I've personally never had major issues like regularly that some athletes experience, but I'm not an ultra runner, you know, I've played basketball, did distance running, but the farthest I've really done for races as half marathons. Um, so it was more coming from my own research experiences and just kind of seeing that in certain areas of the research, there just wasn't much there. So it kind of was an opportunity for me to explore some things that hadn't really been looked at as much. Um so kind of a combination of things, but it was just a natural progression over time over my research was very cool. Well, there were, there's one other question I wanted to ask. I think this will be important just to sort of define terms and set up the rest of the conversation. You spend the first few chapters of the book providing an overview of gut anatomy and physiology and for non scientific folks like myself, I appreciated the analogies to like the automobile assembly line and the interstate highway and the gut acting as a quote unquote second brain. Are there anything I know that, given that this is a large topic to dive into?
Are there any summary key points you could provide about uh these two areas of science that would be helpful for the rest of the conversation, especially as they're relevant to runners. Yeah, I think in terms of just got anatomy and function. I think an easy way just to remember what your gut is doing is breaking down the stuff that you eat into small components that can actually be absorbed because when molecules are too large or substances are too large, it's you know, the body doesn't want those circulating around um and you're not able to absorb these larger molecules, you know, complex carbohydrates or even carbohydrates um or peptides which are amino acids that are you know multiple um chains in length. So like you know, a molecule that's got four or five glucose units, your body's not gonna absorb that. You need to really break it down into individual sugars. So that's obviously a major goal of of the gut is to break down and then absorb the stuff they're eating for the purpose of supplying your body with energy beyond the energy function or the needs of the body would be you know, micronutrients, vitamins and minerals that play a role in metabolism and growth and all sorts of things.
So that's a priority. And the easiest way thing for people to conceptualize this is it becomes more chemical the farther you get down into the gut. So it starts out very mechanical in terms of how you break things down with chewing movement of muscles and the tongue in the mouth. And then as you go farther and farther along as you get into the small intestine the stomach, it becomes more chemical in nature. The stomach is kind of a good mixture of mechanical and chemical where there's a lot of churning a lot of squeezing going on to kind of mix things up and continue to break them down physically. But there's also enzymes that are breaking down the nutrients that you're consuming and then as you get into the small test and of course it's a tube that is kind of contracting and propelling things. There's not as much mixing so it becomes a lot more chemical, It's the enzymes that are splitting apart those larger molecules into smaller things that you can actually absorb. So as you get farther and farther down that tube, it essentially becomes more and more reliant on chemical digestion.
Uh So I think that's just something kind of to keep in mind in terms of the function of the gut and how that may impact people. Like what would be the practical application of knowing that is, you know, if you don't split apart these larger molecules, they can't be absorbed, you might say, okay, so what they gotta go somewhere um they're gonna end up going out the other end of you. If they don't get absorbed, they're gonna end up causing havoc in the intestines. And especially the colon, if you're not absorbing sugars for example, the bacteria are gonna all feed on them and eat them and that produces gas as a byproduct. You also get water pulled into the tube because water is attracted to molecules like sugar. So that's a practical um consequence of not being able to absorb what you're actually eating is gut effects, including cramping loose stools bloating gas that's pretty specific to carbohydrate malabsorption, but if you don't absorb the nutrients that you're ingesting it's gonna be a problem in terms of the way you feel eventually.
So yeah, that's kind of an overview of just how I like to think about it as it goes from very physical, mechanical to more chemical in nature. Uh The goal being to absorb what you're reading is efficiently as possible and you don't want a lot of stuff left over. Especially like a lot of carbohydrates for example, can cause a bunch of symptoms that are pleasant or are not conducive to performance. This is a question I've always wondered about and I think you're the perfect person to ask it. If you think about the physical performance realm or the mental performance realm, we talk about people that just have like genetic or biological advantages in those areas of athletics. Is it the case that there are people out there with quote unquote elite gut performance, like they can just digest food without needing to train it to the same level that the common person like myself might need to or is the gut system trainable to the same extent? Or are we born with the same processes across the human race? You know?
Finn, That's a good question. And I honestly it's something I've thought about a fair amount. Um I do think that they're probably like any characteristic or any body system or any feature of physiology that there are some people who have um anatomy or physiology that predisposes them to having either more or less gut issues especially with exercise. And that could for example, it could be the size or location of some of the blood vessels that feed um the intestines. You know if someone has smaller blood vessels or something like that or arteries um you know with heavy exercise, they may have more limited blood flow for example, as compared to somebody who has you know different anatomy and and the reason why that could impact you is if you've got less blood flow to the gut, it tends to cause some dysfunction. You know, you don't have oxygen and nutrients flowing as much as you want. So it's an example of how like anatomy in theory, you know could have some impacts or someone has like advanced heart disease or arterial disease and they've got blockages that prevent blood flow to the gut that could be problematic.
Now in terms of genetics, I honestly my guess is that there are certain things in terms of genes that would predict people having more or less issues for example, with exercise in terms of their gut function. No studies to my knowledge have looked at that. I thought about trying to design the study to look into that. Um I don't do gene sequencing. So that isn't my area of research that could be twin studies we could do where we identify um you know identical twins that exercise and run and see how much they're reporting in terms of their gut issues with exercise and compare that to non related people or non identical siblings with the idea that if there's some sort of genetic component here, you you think that there's going to be, you know, probably more similarity among people who are genetically identical, you know, they're identical twins. But long story short, there's not any research that I'm aware of specific to exercise, um, and gut issues and function that has looked at, you know, genetics, for example, what role that plays.
But I don't think anybody should ever be surprised by a study that says genetics impacts this. Of course it does. Like we're that's what we are. We're basically, you know, these bodies walking around that are largely controlled by our genes and the interaction between our genes and the environment. So I think, yeah, some people have an iron gut. Um, some of that my guess is is probably their anatomy and their genetics plays a role in that. How exactly does that, you know, very, very much unknown at this stage, fascinating. Um and I know we're gonna get into this a lot in the second half of the conversation, but you mentioned in the book in numerous chapters about strategies that runners can deploy to train their gut to get used to the foods that they're gonna consume on race day and just to avoid problems in later stages of the race. But you also mentioned that there is evidence out there indicating that if you sort of just wait out this this process and you stay in the running game longer, that you Just as a function of being in the sport for like 10, 15, 20 years.
A lot of these gut issues may subside. And um I guess the question I have here is uh like how long like a did I under did I describe that correctly and be um like how long do you have to be in the sport until you enjoy the benefits of just like a gut that's accustomed to the demands of running? It's a it's a good question with, you know, a nuanced answer. I think in that we see that in surveys, more experienced athletes, runners tend to report fewer G. I. Symptoms with their training and with competition. Now, those are just observational studies and it's not, you know, conclusive that it's actually directly due to experience, It could be other things like, you know, more experienced athletes are also older. So is it a product of aging and not necessarily experience itself? That's an unresolved question. But there are studies that show over a period of months, more experimental studies or studies that look at the physiology of what's happening, is that as people train and become fitter, the reductions and blood flowed to the gut with exercise at a given workload become attenuated or lower.
So you seem to be able to adapt better and handle a given training load without having as much of a reduction in blood flow to the gut. You know in terms of symptoms, I think it's complicated because I've heard you know, lots of runners and athletes who get better over time. I think that's the average experiences that you probably be experienced fewer problems from most people. It's probably a combination of giving fitter. There's some physiology behind that. You're also just getting more experienced with how much can I eat beforehand, how much can I eat during? You know, there's things you might kind of figure out over time that come with experience. But for some athletes like I get sometimes emails from people saying you know, I used to be able to do you know, an ultra race or an iron man. But the last three years I've suddenly developed nausea and I throw up at every race and they're very experienced athletes and it's hard to figure out what is that. Um I think on average though most endurance athletes tend to get a little bit better with um experiencing G.
I. Issues symptoms, they have less of that overall. But it's not I wouldn't say that it's a massive effect. You know, it's not like you go from someone who starts out, they've got a ton of issues and then you can just expect all those to go away. You know with a year of training, it's more of a modest association in these studies. So combining all the evidence together, uh it's one thing that does play a role, but um I think it's one among many and you shouldn't necessarily expect as a novice or a new runner if you're having a lot of issues, them just to go away on their own after a couple of years, there's probably other things going on with it that's contributing to those problems, whether it be poor nutritional choices or um, you know, anxiety or stress or medication use or something else that's underlying those problems. Most of the time it's multifactorial. It's not, you know, a single, you know, single one thing occasionally it's like someone just did something real dumb or a poor choice, you know, with their pre pre race plan or during training.
And it's like, yeah, if you just don't do that, you're not gonna have a problem. But in a lot of cases it's a mixture of things. I wrote down three common gut symptoms here that runners often experience and that play a significant role in curtailing performance. Um and I figured we could kind of go through each of them one at a time and talk about maybe the common ways you found work to resolve them, the first being nausea. So when you think about nausea and runners, uh in what circumstances does this typically occur in the context of running and what do you see as the best ways to combat it? It's one of those where it kind of, it hits the extreme, so it's short high intensity stuff and then super long stuff that's prolonged like ultra races where you see the highest prevalence is. So you know if someone's doing a hard interval workout or something like that, they can experience some decent amount of nausea, you know if you're doing a middle distance race, something like that. Obviously it can also happen.
And then as you get into the ultra territory, I mean surveys from like the Western States endurance run, I think I remember correctly. I mean it's in the ballpark of 60% that have some nausea and most people sound extreme but that's a very high percentage of of runners in a race reporting nausea. You don't typically see that with shorter races like a half marathon or a marathon. So the causes in both of those situations may be different though, right? So with high intensity exercise, short duration, it's probably the stress response, the increase in um adrenaline and cata cola mean hormones that might trigger what's called the basically the vomiting center in the brain uh to increase these feelings of you know, like having having to throw up. So there's other studies from different realms that suggest that those stress hormones do play a role in nausea. So people are fasted which increases stress hormones.
Um You're more likely to be nauseated with exercise if you ingest caffeine a lot of it before exercise you're more likely to report nausea and caffeine also increases stress hormone secretion. Um So that's one example I tell people is like if you're doing a workout in the morning, you don't eat much, you drink a bunch of coffee with a lot of caffeine and then you do hard workout and you feel nauseated. That's probably a potential reason why. Um Now in longer duration stuff like ultras. That's a tougher question that I don't think there's a clear answer to. I think part of that is because it's very difficult to do experimental studies with ultra runners. Because if you're gonna bring people into a lab and try and isolate things that cause nausea, you'd have to ask people to exercise on a treadmill for like 10 hours. And those are just you know difficult studies to do. So most of what we know about ultra running and the physiology and nutrition and that stuff comes from just surveys and observations that happened at races which is fine.
Um But it does make it tough to kind of tease out exactly what is going on. Um My guess is this combination of stress hormones um are the hormones that might trigger nausea. Uh Arginine, vasopressin is a hormone that's secreted with exercise. That also in some studies has been linked to nausea. Heat load, heat stress will definitely do it. So if someone is competing in a hot environment that is going to likely exacerbate it Um there's other like muscle breakdown products that build up in the blood with ultra races that theoretically might contribute. So there's just like a stew of stuff. If you exercise for 15 hours that starts to accumulate in the bloodstream, that might be triggering Nausea is my guess, but that's hard to hard to isolate and prove that it's exactly that it's still, you know, kind of an unanswered question with ultra races, how do you really get a handle on it? What are exactly the mechanisms involved?
Um And it's, you know, it's kind of ubiquitous for ultra runners to experience it at some point or another and they're honestly at this stage is a, I think some ultra runners you just have to expect that you're gonna have some nausea, you know, with that extreme you have to you might have to adjust your feeling, you might have to maybe look at trying some sort of medication and seeing if that helps. Um I think the reality is it's somewhat inevitable for some runners with that that level of effort. So, you know, I know runners don't like to hear that, but if someone had an easy fix to it, you know, i it would be in widespread use and you'd see, you know, runners having some success with it, but it's a tough nut to crack for long distance stuff. Another reason I would assume for mental skills to be so important on race day and in problem solving troubleshooting, um what what what if any, like, solid recourses, do runners have to combat this issue in your opinion? Like if you were experiencing nausea, what would be your checklist of fighting it?
Yeah, I would look at, you know, potential triggers which can include, um, you know, things like consuming too much caffeine, caffeine is a performance enhancer, but if you've got a lot of it in your system, especially um, you're someone who's sensitive to it, that might be something to look at. Certainly if you are under feeling or over feeling, it could contribute, especially with an ultra race. If your blood glucose levels are trending downwards, you haven't been able to eat all that much or you've been behind on eating theoretically, that could play a role, but if you're overeating, I think that's probably the more probable cause. And, you know, the gut is struggling, I think, to digest stuff the farther you get into an ultra race because it's just a stress on the, on the gut. And if you're throwing a lot of stuff down the hatch and it's starting to slow down and build up in the stomach that can be a problem. So, training, yes, training the gut during your uh, you know, weeks and months leading up to a race. If you're not habituated to eating during those longer runs, you should really be trying to practice that and getting accustomed to it if that's what you expect you're gonna do on race day.
So I think that can help attenuate some of the symptoms that arise from eating. Um You know, there's some other things, like, interestingly, I've got a masters student who's going to be doing a thesis here in the next few months, we're looking at the extent of chewing and how that impacts um digestion metabolism and perceptions with endurance running, because in non athlete studies the amount that people chew foods and this is solid foods um seems to impact how fast it might empty from the stomach, how quickly it's integrated into the bloodstream. And just the perceptions that they might feel. So. Some studies that have looked at feeding people bars with exercise have shown that they do elicit more G. I. Symptoms including nausea and bloating. So if you add that up over like an ultra 15 hours, if people are eating more solid foods, but they're not chewing them thoroughly. In theory, that could kind of lead to stuff sitting in the stomach.
Now, that's theoretical, we'll see if that actually plays out in the study that we're doing in the next several months. Um But for those athletes who are primarily choosing solid foods or a good amount of solid foods, that's something I would actually think about is that do more work here in your mouth and make your stomach do less work because it's already under enough stress, right? Like you don't wanna just gobble down a slice of pizza or something like that without really chewing it because you're you know extremely hungry at an aid station, it sounds good to you. Um And I know not every ultra runner is using solid foods like that, but if you are that is something to ponder over. Um And then yeah, I mean you gotta kind of trial and practice out the different foods and products you think you're going to use on race day and and hopefully dial in as best as you can. Um And then the last thing I guess would be you know, trying some anti nausea medications or supplements that at this point don't have much direct evidence that they actually work in ultra races but um you know, if you've got nothing else, I I guess it's like it's potentially we're trying I think, you know, as long as you think about it and make sure you're not um overdosing with any of these things or especially with any prescription medications you're talking to a sportsmen talk about it or someone who is going to be prescribing those medications and getting an idea about whether or not that's something worth trying.
If we move onto bloating, what uh what are the most common causes in running events and again here, what's your checklist for remedying the issue. I think that one is actually a little bit easier to isolate nausea. I think out of all of them is the hardest to kind of get a handle on because there's just so many different potential causes bloating. I mean you think gas build up, right? That's kind of what bloating is, is build up of gas and it's not necessarily just the build up of gas. It's also people just perceptions of how they feel, you can feel bloated um without necessarily having eaten something that produces a lot of gas. So it's a combination of things producing gas and then also how you perceive that um in terms of how people will report their level of bloating. So usually though with bloating it's something's being fermented um in the guts there's gas being produced and that kind of is filling up the intestines and kind of putting pressure on the wall, which you're gonna feel as as bloating, right, is the most basic thing you can kind of think about.
So when I think about sources of gas being produced, it's usually carbohydrate being fermented um and that produces things like hydrogen and carbon dioxide and methane, um gasses that um you know, well in large amounts or in greater amounts of lead to some feelings of bloating. So I look at what are you eating beforehand, how much fiber um how much of what we call fod maps, Those are formidable, ala, ala, sack rides um polly is kind of short chain carbohydrates that some people don't absorb super effectively. So you can look at your intake of those if you've got a high intake that might be something to target and yeah, and then also what you're consuming during the event. If it's if you're overloading the guts with too much carbohydrates, you can get some inefficient absorption and that can also cause bloating. So those would be the kind of the main things I would look at. You might taper fiber intake before competition, you might taper fod map intake.
You know, you might also again make sure you're paying attention closely to how much carbohydrate you're consuming during and making sure that if you're gonna consume a lot that you definitely train your gut to do that every runner wants more energy, more stamina and less soreness. Right on our recent episode, everything you need to know about amino acids for running performance and recovery. We went into how amino acids are the key to unlocking these three benefits. So if you haven't listened to that episode, definitely check it out. But here's the gist of why amino acids are so important for runners and for fitness in general, in a nutshell they are as essential for life as water. In fact, amino acids are the most abundant substance in your body after water. A whopping 50% of your solid muscle mass is amino acids. And this is why supplementing with essential amino acids also known as E.
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So I think that'd be a good thing to talk about here before we go to cramping. Yeah, first, I guess fluid, there's studies that, you know, that have looked at feeding people different amounts of fluid and different beverages with exercise and once you get above one liter per hour, that gets to a territory where some people are gonna have maybe difficulty kind of getting all that out of their stomach because there is a, you know, there's an upper limit to hunt how quickly you can empty fluids. Now, most runners don't approach that anyways, most runners are not consuming over a liter per hour of fluid, but you might see that actually happens sometimes with cyclists, so that might be something that they should be cognizant of us, just, you know, there is for most people, you know, you're not gonna go above 1 to 1.5 liters an hour and it's just too much now in terms of carbohydrate. Um it's not necessarily as much about gastric emptying as it is probably about how much that is absorbed in the small intestine and you know, glucose and fructose are the two main sugars that are included in most sports nutrition products.
Um Sucrose is as well, but sucrose is a mix of glucose and fructose. Um and for each of those sugars it seems like there's maybe an upper limit of you know, somewhere between 45 and 60 g an hour that you can actually reasonably absorb if you go above that for either sugar, it's more and more likely that some of that is not gonna be absorbed and when it's not absorbed right, it kind of hangs out in the gut. Um It attracts water so water gets pulled into the gut, you know, you can get loose stools gets fermented causes gas. So the general rule of thumb is that if it's just one source of sugar that you're using, um max amount for most people is probably gonna be around 50 to 60 g an hour. If you combine glucose and fructose, it ends up being higher than that, probably 90 to 120 g per hour. We've seen in some studies but that is not for the faint of heart. So um even if theoretically that is the max rate if you haven't practiced that and you haven't had haven't given your gut time to kind of up regulate some of those transporters or doors that allow those sugars to be absorbed into the cells and blood, then you're probably gonna have some issues.
So that's kind of, the overall is once you get above 60 g an hour, you're getting into a territory where you definitely want to train that. Um I guess some people have an iron stomach that can handle it, no problem. But most people, especially with running where there's a lot of jostling up and down, you kind of need to get accustomed that if you're gonna try that. So, I know, like in the marathon's reportedly, you know, uh you know, maybe around 9220 g an hour from what I've seen from different sources. Uh but not every, not every athlete needs to go that high. I mean, it is also for higher level runners that are burning a lot of carbohydrate, right? If you're a slow runner and you're not number one. Expending that much, as much energy anyways, and it's a smaller proportion as carbohydrate? There's no real reason why you would need to go that high, because you're not even burning probably that much carbohydrate per hour. So, those targets are for the higher targets are for more developed, elite, highly competitive runners going beyond, you know, you know, an hour and a half to two hours is when you would start to even think about consuming that amount of carbohydrate.
If it's a shorter race, there's no reason to consume that much, the last symptom I wanna talk about, if we move on to uh some of the nutrition stuff is cramping. So in what circumstances does this often arise? What are the remedies in your opinion? And then could you also talk about how sodium supplementation might not necessarily be the answer in some of these cases as well? Yeah. So abdominal cramping, we can kind of think of cramping as right, abdominal intestine cramping. We can also think of the cramping as muscle cramping and the legs and things like that. So it's important to distinguish between those two in terms of gut symptoms, intestinal cramping. A lot of times. It's similar things in terms of if you're not absorbing things, there's fluid going being pulled into the gut from the bloodstream, there's some muscle contracting in the walls of the gut that kind of causes may be a feeling of the cramping sensation. So it certainly can be the same things that cause bloating and that you would expect to see un absorbed carbohydrates will cause a sensation of cramping. But it could be other things.
It could be, certain medications can do it sometimes if you take a lot of uh non steroidal anti inflammatory drugs like Nsaids that can do it if you've got a G. I illness, you know, some sort of foodborne illness. Obviously I think most of us have had an experience where you kind of have some of those perceptions as well. So that could do it. Um People who have a lot of anxiety at least perceive maybe cramping to be more common. Exactly, are the is the physiology actually different underneath in terms of their actually experiencing more muscle contraction in the walls of the intestines? Hard to say, but they may perceive that symptom is being more severe under a given set of circumstances. So there's just some examples of things that, you know, you can take a look at um as being potential causes, because usually that's what I recommend is you try and find the causes as opposed to putting on like some sort of band aid, um whether it be through medication or something else um like a short term medication, trying to uh identify what might actually be contributing in your individual situation.
So, those are some things people could look at, potentially. Let's talk about feeling strategy and I think this is, it can be a large debate in our community, um we're looking at carbs versus fat in what scenarios is it prudent to fuel with one over the other? Is it situational? Or is it always the case that there's a clear fuel source winner in your opinion? And is this are we thinking during the event or is this globally in general? Let's let's let's go, let's do during event. Okay, so during event it's primarily gonna be carbohydrate? And the rationale for that is, you know, for the most part, even a super lean runner has enough fat stores to, you know, uh supply what they need during the event itself. Um Usually the limiting factor for most athletes. Again, those who are working at a higher intensity, this is more true for is, you know, your storage limit of carbohydrate. For most people, it's gonna be, you know, something on the law along the lines of a couple of 1000 calories worth of carbohydrates storage more than that.
If you're loading and you're eating a lot of carbohydrate, you know, you can definitely increase that baseline amount, but as you're burning through that um and your stores start to get low in those muscles that are repetitive li being used. You know, there's gonna be changes in the ability of your muscles to contract at a given rate. Once you start to rely more on fat for fuel, it's, it is a less efficient feel um when you, compared to carbohydrate, in the respect of um for basically a given workload or intensity, If people are burning fat versus carb, their oxygen use is actually higher when they're burning fat at a given workload and that's because it's a fuel that requires more oxygen to basically break down. Now, it's not a massive difference, but it is a less economical fuel. Um So for like a marathon or like a standard marathon or whose, you know, elite and exercising at 9 90% or more of their view to max for the marathon, they're burning almost entirely carbohydrates.
Now, there's some fat, but it's at the elite level, it is almost all carbohydrates and they're going through those glycogen stores, there's carb stores very quickly. And the only feasible way that they can maintain the intensity that they're aiming for is to actually consume some carbohydrate during the race itself. Because once you start relying under that, in most cases, you're gonna slow down a bit now for an ultra runner, it's a different story. I mean, if the race is done over 12 to 24 hours and the average youtube max intensity is 50% you know, you're less reliant on carbohydrate in the first place. So, you know, I think it becomes a lot more difficult to exactly say what is the right approach um, for ultra runners, they think during the event though, still probably the priorities. Carbohydrate mainly. Um, pre event though, chronic diet, that's more debatable. Exactly. You know, which of those is more advantageous or they basically, you know, equivalent, um, my guess is it probably depends on the athlete, to some extent, there may be some advantages to a high fat diet for some athletes, like, let's say, they do have a lot of feeding intolerance with carbohydrates and they don't want to have to rely as much on carbohydrate during the event, maybe going on a high fat diet, consuming a smaller amount of carbohydrate during the event is gonna be helpful for them.
But if you've got an athlete that's got an iron stomach and they can ingest 60 90 g an hour, no problem for 12 hours. You know, they're probably gonna be the type where eating a high carb diet in general is better for them. Because if you try and need 60 to 90 g of carbohydrate after eating a high fat diet, your gut is not really accustomed to that, that carbohydrate load. If you're traditionally eating a high fat diet before the race, I think it's the pre event diet where it gets more difficult to say, you know, what's a rule of thumb for ultra runners in ultra endurance athletes for standard marathon and shorter and an elite level. I don't really think there's a whole lot of debate among most um nutritionists and physiologists that do research in that area, that higher carbohydrate is generally going to be better than low carbohydrate in those events. I'm starting to see a fair number of products brought to market that include a few grams of protein in the gel, for example. And I'm curious is there any method to that madness?
Does protein have a role to play in supplementation during or feeding during a race environment. My sense is that it's mostly uh if there's a benefit would be on recovery in terms of going towards the next exercise session about whatever that is, if you've got a relatively short turnaround time and you're looking to Um, you know, maybe enhance your recovery over the next 12 hours? I think ingesting some protein with carbohydrate during the exercise itself may be helpful in some cases. In terms of just sheer performance. No, I don't really think that most of those products, there's much science behind you know, any real advantage to having protein in there. Um Yeah, I think the studies that show that you know, either they uh they didn't have an equivalent amount of energy provided. So like they added some protein to a beverage, but they didn't add some extra carbohydrate to make those two beverages equivalent in terms of energy. So that's one example of some of the mythological things with some of the research in that area that make it challenging to kind of just say, is it the extra energy and the protein that you're getting or is it just, you know, something unique about the protein itself?
I think mostly though it's it's going to be if you're gonna exercise again soon and you're thinking about speeding recovery, that would be where I would probably think there's a benefit. Um direct performance benefits itself. I don't really see much research, they're suggesting that that's really a big benefit to please fact check me here because I was I was taking notes from the book and I may have misrepresented some of the findings, but my understanding is that if you're running an event that is at or less than two hours? The research suggests that you should just drink to thirst, is that correct? And if so, could you talk about why that's the current, uh, conclusion in the scientific community? Yeah, that is probably one of the most debated things with during event nutrition is how much you should drink. I think over time, kind of the extremes of the different camps, there's kind of been a drink to thirst always as best. There's been a approach where it's like, you know, you need to know your sweat rate and measure that and, you know, replace a certain percentage of your, your losses.
And I think over time, those extremes have kind of moved a little bit closer together. I think, um, there's pretty good agreement among people that I've talked to with shorter events less than two hours, assuming you start off well hydrated, that's the, that's the assumption is that you're starting off well hydrated, um, that you probably can just use thirst and there's not really a reason necessarily to have to know what your sweat rate is and get real complicated with the replacement rate because it's just not enough time for most people to accumulate a big fluid deficit, you know, two hours. Yes, maybe if you've got an elite runner, um who's exercising in a very high intensity in a hot environment, that might be different. You know, you do have very large sweat rates there, you can lose, you know, five or six liters of sweat in two hours. So I think maybe even in that two hour range there might be some cases we're having a more structured approach could be helpful, but most runners, most cases less than two hours, I don't think you really need to probably overthink it a whole lot because there is a risk of over doing it.
You know, if you if you, let's say you can calculate your sweat rate to be 1.5 liters an hour and you say, I want to replace, you know, two thirds of that because that's what this paper or book says that's a leader per hour. I mean that's a lot of fluid for people to handle and if you have not practiced that, it is not going to feel comfortable for most runners. So just blindly looking at a recommendation from a textbook or an online article or even a journal article where they say, you know, replace as much of your sweat rate as possible, That's not gonna be reasonable in every case, especially from people who have higher sweat rates. It's just think through logically it isn't gonna work practically for most runners. So I think shorter races. Yeah, most of the time you can just use thirst as a guide as best you can longer races, That's a different story, There's a lot more debate there. Some people still say that thirst is just the easiest approach. Um I think others would argue that for some athletes that works fine, but others, for whatever reason, they just kind of under drink and they do accumulate kind of a food deficit that is harmful to performance.
So I think there's more ambiguity there. Um I think you've got to kind of experiment yourself and see what kind of seems to work out. One thing you could do is, you know, if you've got a training run that's two or three hours or even a race, um look at your, your weight change before afterwards um and see where you're at um with, you know, drinking the third strategy and if you're still in a seemingly a big deficit, that might be a sign that, hey, I might need to take a little bit more of a structured approach here than just kind of saying, okay, I'm gonna drink when I'm thirsty. So in events like the half marathon or the marathon or ultras where you're going over two hours and you use the term like fluid hydration plan in those scenarios, are you recommending drinking at regular intervals? Yeah, one way you could do it is if you are concerned about under hydration or even even over hydration. Sometimes if you've got a slow runner, you know, they stop at every aid station and they just drink, you know, they drink to thirst and they end up gaining weight over a race because they're drinking so much.
So I think there's there's a risk of both under hydration and over hydration sometimes with, with the thirst approach. So how you can handle that is you could go and do a one or two are run at the pace that you think you're going to run that race at measure your weight before and afterwards. Um It's easiest if it's easiest if you don't drink anything during that hour, um and you measure your weight difference And that's basically your sweat rate. Because anything you're losing in one hour of exercise, the vast majority that is fluid, it's not gonna be a lot of carbohydrate or fat that you're burning. I mean, there's some mass, you're actually breathing out carbon molecules, you're breathing out, um that are coming from the fat and carbohydrate that you're burning, but it's a small amount. So the weight change in an hour over exercise is almost 100% fluid loss. So if you know what your flu losses in an hour at that pace you're intending to run at during the race, you basically figured out your sweat rate.
So if you lost one kg in one hour, that's basically one liter per hour of fluid losses. Now, what do you do with that information? You Say? Okay, I guess I want to maybe target, let's say two thirds of that. I want to try and replace two thirds that because if my race is 10 hours. If I'm only replacing half of that, that's gonna add up to a massive deficit by the end? For example. Um so that's an example of how you could use a more structured approach, but obviously requires more effort in time. You need to know what your sweat rate is under a variety of conditions and paces because that's those are the main things that impact sweat rates, pace and environmental conditions. I want to talk about supplementation before we close up and I've really enjoyed this conversation by the way, I really appreciate it. Um for context on this next question, about two weeks ago, I was down in the phoenix Arizona area, crewing a friend at a race called the have Elina 100 and one of the cool things about this race is it's a loop race. So there's this whole tent city that forms around the major aid station there and I'm super curious.
So I'm walking around and I'm seeing the runners seeing their crews and one of the most common supplements that I saw at the race was these bottles of exogenous ketones and I talked to a lot of the cruise, I talked to some of the runners post race and like why these ketones and their theory was that as the race duration increased supplementing with these ketones, it was sending energy to the brain and improved cognition. They were not forgetting to eat. They were making better steps on the trail and they were just more like mentally in it to persevere through pain. And I guess my question is is there any sense to what they're saying? There is any of what they're saying backed by the research or is this still early days? And um none of those claims have any basis in the research. I mean I think it's definitely still early days with the ketone research. I mean there are some suggestive studies that um that show that it might influence metabolism or the fuels that you're burning during exercise.
Um There are some studies not as much with exercise but there are some that it may impact cognition. Um And you know those types of things decision making. Uh this study's overall with exercise actually most of them have been shorter duration. So I think it's it's hard to extrapolate what exactly that's doing it our you know 10 of of ultra in the heat or something like that. My I guess thought on that is if they're using it and it doesn't cause them problems because one side effect of ketones and high dosages is is got distress. So there's some studies that have shown reduced performance because they had ketones administered before exercise during exercise and relatively large amounts. And yeah, they can cause gut issues. So that would be my my kind of recommendation to somebody is um you know if you're gonna use it, make sure to try it out and make sure it doesn't cause you any of those issues otherwise if it seems to be helpful for you uh there's not a lot of research to say definitively that it's it's helpful or harmful or neutral.
Um You know feel free to give it a go. I don't think there's a whole lot of harm to it, assuming it's not causing any gut issues. I think most athletes in terms of ad versions to it would be um the taste I've bought um some of it and pride, some of the most common product on the market. Uh Common brand. And I mean it kind of tastes like flavored rubbing alcohol. Um And the cost is actually fairly high as well as you're gonna like supplement it throughout you know a race. I mean I think most people who are willing to do that are willing to spend some money on it. But the main product on the market that I'm aware of is quite expensive because of the R. And D. That went into developing it and making a pure product. So yeah it's one of those where it's yeah definitely popular and a lot of endurance sports. I mean the Tour de France I know a number of teams were using have been using ketone supplements and becoming more popular ultras. I'm sure we'll have more research coming out on it.
Um So it's an interesting it's an interesting phenomenon and and the use of it. I don't really have any good solid scientific answers for you in terms of whether it's really worth your time or effort. Like a lot of those supplements if it's not doing any harm and you want to spend the money on it. I don't necessarily see there's a problem um, with it, assuming you're getting it from a company that is legitimate is actually making ketones and it's not just a bottle of nothing because you know, supplement regulation is is a pretty loose in most countries, including the United States and some supplements don't have in them what they say they have in them. So that's the only caveat. I guess one of the take away and you just mentioned it. One of the takeaways I got from your section on supplementation is that there should be a lot of skepticism about what's out there on the market. Um This is not necessarily a question about supplements but the energy gels commonly used among runners like made by GU and spring and morton.
I almost without fail. Like it's it's an exception to the rule that runners that are incorporating them into their nutrition strategies. They especially in ultra so maybe not in the road scene, but they lose their tolerance for that source relatively early in the race. And so I guess my question here and it's a loaded question, but how far off the mark in your opinion are these companies from creating something that can be sustainably consumed all event long. And should that even be the mission of what they're creating? I mean, the flavor fatigue thing is definitely real. I mean, athletes kind of just getting sick of consuming the same thing, whether it be the flavor, the consistency or whatever else. You know, I think a lot of these products were kind of developed originally with the idea that they're going to be used during half marathons, marathons, those types of events, maybe an ironman in certain parts of the race where you're gonna be using them. Um but not necessarily, you know, most athletes just eating gels for 15 hours straight. Um so I'm not that they don't market those products that way, but I think originally a lot of these sports nutrition products were meant largely for stuff that was intended to be shorter because that's where most endurance athletes were, were, you know, when a lot of these products started hitting the market was that um, I mean, of course Iron Man had been around a long time, but ultra running is kind of exploded more recently.
And yeah, I don't necessarily think just relying on gels is a good idea for an ultra race for any number of reasons. It can be the flavor fatigue issue. Um you know, can also be later on the race for some athletes, it's, you know, it's a big kind of dose of carbohydrate at once and that can be, you know, something that sits in the stomach a bit like a brick, if you're not really used to it. Um I think that if, if an athlete has no problems with them, it's a easily digested consumed source of carbohydrate from that perspective, I think they're great. Um But when the, as the race gets longer and longer and longer and the intensity gets lower and lower and lower your ability to probably handle some more solid foods um You know, might, might go up. So I think if you are the type of person that has trouble with flavor fatigue or just getting these gels down without feeling like you're gonna throw them up um Yeah, all mixing it up and using other things, whether that be pretzel, pretzels or gummy bears or raisins or whatever you want to use.
I mean, I think the key is just, you've had some experience with it, you practice with it um When it comes down to it, most of these products are just sugar and most of them, it's not like the science behind them is magical. It's uh the only real science, I think that is backed up pretty strongly that if you're going to ingest a lot of carbohydrate, you want a mixture of glucose and fructose and most products have a mixture of that, some in different ratios than others, but there's nothing magical about most gels, it's just, you know, it's a process. Carbohydrate that's fairly easy to digest and fairly easy to consume quickly and when you're exercising at a high intensity. Most people prefer something that's easy to get down, um, you don't see marathon runners stopping, you know, to chew and and and throw down a bar because it's counterproductive to their performance in an ultra race where you've got more kind of ability to vary what you eat to some extent. I think it's, yeah, more common place where you're not going to be relying just on gels and goose and things like that.
Couple more questions for you. Before we close up the first, I'll ask this question with the assumption that listeners have the time and the resources to invest in this area. But are there any tests or lab protocols that you recommend runners go through, like sweat tests or other nutrition tests to get to know their gut better, their biology better so that when they're creating a nutrition strategy for a race, um they have as many of the facts as possible. Yeah, I mean, that's an interesting question. I mean, I know there's, you know, there's a possibility of trying to standardized, like bringing athlete in, have them exercise for an hour or two. Um, you could, in theory feed them a set amount of carbohydrates and look at their responses both perceptually and physiologically. For example, One thing you can look at is um, markers of carbohydrate malabsorption where you have people breathe out into a specialized device that measures the amount of hydrogen and methane that they're expelling because when you have a lot of carbohydrate that's not being absorbed, that's the production, what is being produced as those gasses.
And some of those gasses actually get absorbed in your bloodstream and then you breathe them out. So if you see someone with spikes and the amount of methane and um hydrogen that they're breathing out, it's suggested that they're not absorbing carbohydrate as efficiently as they might want. So some studies that have done good training protocols have used that as a marker of carbohydrate malabsorption. Now, if you could work with the lab or something like that, they could theoretically do that sort of testing. Um, you could kind of do before and after gut training to see whether you're improving, but there are no like there's no like standard, just run of the mill tests. You can just go to any exercise physiology lab or, or clinic and just get ordered and say, hey, you know, I want to know how my guts gonna handle this. It's, and largely because there are so many potential causes of gut issues that it's, you know, it's frustrating for athletes. I think when I ask about like, how do I fix this problem and it's oftentimes difficult to identify what are the causes.
And then oftentimes it's more than one cause, um, that's involved. So it's a challenge, I think to get it fixed and to get it improved, but standardized tests, I mean there's not really anything I would recommend across the board. Um, sweat tests. You could make it simple and do what I just described and, and do an hour or two of exercise at your race pace and measure your weight before and afterwards. Um, and assuming you didn't drink anything during that hour or two, you can know what your sweat rate is. That's a pretty easy thing you can do on your own sodium sweat testing. I know some companies do that and um, is there value in that? Maybe I think if you are a heavier sweater with sodium concentration, you might get some value out of that. So I think, I think those are a couple of things, you know, athletes could do in terms of testing beyond that, it would be like, you know, if you've got a lot of good issues getting worked up for I B. S, celiac, um, other issues that would be causing those. I think that's probably a more productive use of time to at least make sure and rule out it's not any of those things before, you know, investing in other things.
That might not actually be the underlying issue. Last question I have for you, um, for runners that are interested in what you do, what is either the frontier or the most exciting realm of digestion science right now. Like what gets you up in the morning, you're like, this is exciting. I am stoked for what's on the horizon here in terms of breakthroughs. Yeah, that's a good question. Um Me personally, a lot of my research in the last few years is more geared towards the interaction between psychology and nutrition and gut tolerance. So I mean I've done a number of studies now just observational that show people who have more anxiety are more likely to report got issues with exercise. Now those are just correlations. So I would not get carried away with those. Um So we are in the in the midst of doing some studies and designing some studies where we're trying to more experimentally show that mood state um is an important potential player and how they got response with fueling and response to feeding.
So I guess, you know, in the next couple of years hopefully we'll have some some papers and studies that come out looking at that more experimentally. I think beyond my own research though, I think it is the gut microbiome and how that impacts performance. There's a lot of interest in that. I think for good reasons. I mean the microbiome or kind of this collection of microorganisms and everything that they produce is known to impact physiology, mood, all sorts of stuff. Um And you know whether there's a actual ability for us to manipulate that as the as a way to enhance performance or improve gut function with exercise. I think that's definitely something people will be looking more into. Um So I would expect that in the next 10 years, that's gonna be an area where there's a lot of, a lot of research that comes out. Not something that I specially specialize in personally in terms of my own research work, but I know that is one where people are very, very interested in it, working on it awesome.
Well Patrick, we really appreciate your time here. I enjoyed the book the athletes gut, we'll make sure to link to it in the show notes of this episode as well as any other relevant links. Hope you enjoyed that conversation with robert. I took away a lot of great information, including how to address symptoms of nausea bloating and cramping and running situations. The differences in fluid hydration protocols for events under and over two hours. The roles that carbs, fat and protein play and race day nutrition strategies, whether supplementation with stuff like exogenous ketones make sense and tests that runners might consider taking to understand their body better and better inform their nutrition strategy. What were some of your takeaways? Please let us know in the comments section of this post on social media. Thank you so much for listening to the run of the top podcast. I'm your host, Finma Lance and as always, our mission here is to help you become a better runner with every episode. Please consider connecting with me on instagram at Wasatch Fin and the rest of our team at runners connect also consider supporting our show for free with a rating on the Spotify and Apple podcast players.
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