Allen Lim dehydration podcast

Dr. Allen Lim: Effects Of Dehydration On Your Athletic Performance

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About this episode:

In this week’s episode, Hillary Allen interviews exercise physiologist Dr. Allen Lim. They discuss the inner workings of how you lose sodium during exercise, why dehydration is so different for every athlete, and how it affects your performance.

Episode Highlights:

  • Sodium loss is partially genetic
  • Sodium intake should drive thirst
  • Where water is stored in your body and why it’s so important 
  • How to troubleshoot sodium loss problems

Guest Bio – Dr. Allen Lim:
Dr. Allen Lim received his doctorate from the Applied Exercise Science Laboratory in the Department of Integrative Physiology at the University of Colorado. Allen worked on the Pro Cycling Tour as a sport scientist and coach for the Phonak, TIAA-CREF, Slipstream, Garmin, and Radio Shack professional cycling teams. More recently, Allen founded Skratch Labs, a boot-strapped sports nutrition company, that was ranked in 2014 as the 3rd fastest growing food and beverage company in the USA by Inc., 5000.

Allen has co-written three cookbooks with Chef Biju Thomas – the Feed Zone Cookbook, the Feed Zone Portables, and the Feed Zone Table – all of which help to give people the basic skills and knowledge to prepare real food from scratch as part of a physically active lifestyle.

Allen has served as a consultant for the Chinese Olympic Team at the 1996 Olympic Games in Atlanta, for the US Olympic Cycling Team at the 2012 and 2016 Olympic Games in London and Rio, and for organizations and individuals ranging from the Joe Gibbs Racing Team, Kansas City Royals, and President George W. Bush.

A sought-after speaker, Allen has given two TEDx talks, guest lectures regularly at the University of Colorado at Boulder and has been a key note speaker for organizations like the American College of Sports Medicine, Training Peaks, Map My Fitness, Strava, The North Face, The Colorado Outdoor Industry Leadership Summit, Under Armour, and the Gold Lab Symposium.

Read More About Dr. Allen Lim:

https://www.skratchlabs.com/pages/about-us

https://www.instagram.com/allenskratch/

Listen to the episode on Apple PodcastsSpotifyStitcherGoogle Podcasts, or on your favorite podcast platform


Episode Transcription:

Please note that this is an automated transcription and may contain errors. Please refer to the episode audio for clarification.

Hillary Allen (00:00):

Hello, and welcome to the CTS train right podcast. Today we have Dr. Allen Lim.

Dr. Allen Lim (00:07):

What’s up Hillary Allen. Isn’t that great. That your last name is Allen. My first name is Allen. We’re like Alan and Allen,

Hillary Allen (00:15):

And it’s actually spelled the same way, which is free. He actually did not know that.

Dr. Allen Lim (00:20):

What are we going to talk about today? Let’s talk about training. Let’s talk about life. Let’s talk about whatever you want. Let’s talk about performance, about why people are. Could you talk about people being on their high horse and telling you what to do all the time?

Hillary Allen (00:31):

Yeah, let’s, let’s do that. And hopefully I won’t be on a high horse since I’m a coach and telling people what to do and giving them the wrong advice. Um, so today, uh, the topic we kind of brainstormed, um, we’re going to talk about dehydration and performance. Um, but before we get into that, can you let you introduce yourself? Who are you, Ellen limp?

Dr. Allen Lim (00:50):

Um, yeah, I am a complicated person with very simple needs. Um, that’s basically the gist of it. I’m also a trained exercise physiologist. Uh, I, my PhD from university of Colorado under the direction of Dr. William Burns and the applied exercise science laboratory. That’s where I cut my teeth. And that’s where I learned that I really don’t know anything. Um, or that we make a lot of assumptions about what we do now. Uh, worked on the pro cycling tour for quite a bit of time. And now I work at Skratch labs where, um, I am the quote unquote founder, but primarily I work on product development and future.

Hillary Allen (01:27):

Nice. Yeah. And that’s actually, um, that’s how I met you. And we, uh, started our awesome relationship between, you know, you keeping me hydrated and satiated during my runs. And, but also we know we can have plenty of nerdy conversations. Yeah,

Dr. Allen Lim (01:41):

Really Hillary the, I don’t know if I want to tell you this, but I’ve really just been applying one strategy when it comes to our relationship, which is something I call halt every time, you know, things might not be going wrong or right. I will tell you to just stop halt. And then I don’t know if you know this, but I go through this, this whole paradigm of, are you hungry? Are you angry? Are you lonely? Or are you tired

Hillary Allen (02:08):

Lately? It’s been a combination of all of

Dr. Allen Lim (02:10):

That. You’re hungry feed yourself, right. If you’re angry, hopefully, you know, you can talk it out if you’re lonely. Uh, I think we’re going to start this little, you know, retail site where we have a bunch of puppies and you can just get an, a cuddle puddle, a bunch of puppies. Yeah. Um, it’s like a nap room, but something different and the entire, you know, go to bed.

Hillary Allen (02:32):

Yeah. Yeah. Well, okay. I mean, that works for something, but, um, actually a lot of things, but, uh, so, but now I want to, okay. We’re, we’re, you’re going to ask me this question and I’m actually going into this blind, so hopefully we both end up learning a lot. So talking about hydration and performance. Yeah.

Dr. Allen Lim (02:47):

Let me, let me set the stage a little bit. Um, I think that there is kind of a big debate about whether or not athletes, um, perform better or worse if they did great. So like for, you know, there is this whole school of thought that if you lose between two to 3% of your body weight during exercise, that, that hampers your performance, that you may not be able to run as fast, go as fast work as hard. Right. Um, there’s another school of thought that says, Hey, you know, look that dehydration doesn’t really affect performance, that you can see these incredible performances that are done with a significant level of T hydration so that, you know, people have won the York city marathon at a five or 10% dehydration. So you look at those winners and you say, well, you know, it’s the question?

Dr. Allen Lim (03:39):

Could they have performed better? Or is the question that the only way they could’ve got that performance was to run so fast that they couldn’t properly hydrate? Or is there another idea that, Hey, look, maybe their power to weight ratio improved because they were offloading extra water. What is it? Right. Um, so a very controversial, I mean, there is, um, you know, even a great paper by, um, you know, Soka versus Noax where they debate this idea of whether or not, uh, dehydration affects performance. Um, you know, clearly there’s a lot of military, uh, you know, studies that have shown in soldiers that they, if they dehydrate a, their performance is greatly hampered. Um, and I think everyone has a different opinion of this. And I think that, you know, we throw around this idea of two to 3% dehydration equals poor performance. So I wanted to ask you a question, Hillary, let’s say that, you know, we weigh exactly the same, probably close.

Dr. Allen Lim (04:42):

Right. Um, you know, um, uh, you know yeah. And let’s say we’re doing the exact same event. Okay. Okay. And let’s say that we both lose exactly the same amount of water weight. So we G hydrate to exactly the same level. Let’s also say that we both been drinking ad libitum so that we’re both drinking according to our own sensation of thirst and that neither of us are more or less thirsty. Both of us have lost the same amount of total water, but let’s say you kick my. And up until that point, we were exactly equivalent. Or you could even say, you know, yeah. All things being equal. Like we were on track, we were on the same performance time. Now we have the same foot work, you know, same knowledge of the course, all that sort of stuff. And you kick my and yet, you know, our hydration levels are the same

Hillary Allen (05:39):

And our dehydration levels are the same. So can I ask, like with that same percent loss of, of water, the same salt?

Dr. Allen Lim (05:46):

Yes. So I will say this, and ultimately our aim here is to try to dissect what is happening in our systems that might prove that you are still capable of performing better than I am, despite the same amount of water less. And I will say this, you perform better and you lose less sodium in your sweat. So what gives,

Hillary Allen (06:08):

Well, at least from my knowledge of endurance sports, and I’m assuming we’re participating in an endurance sports.

Dr. Allen Lim (06:19):

Okay. Sure.

Hillary Allen (06:19):

Okay. So, but still, um, a certain length of time, I would say that the, uh, correlation of performance generally favors though, with those, with, uh, with less loss of sweat of salt. Why? Um, because I would think about it from like, I’ve experienced dehydration before, and it’s like this like wall that hits you. And, um, it’s, it’s something very hard to, to kind of come back from, cause I mean, to me like salt, it’s allowing your neurons to fire appropriately your muscles to contract appropriately, um, your whole nervous system to kind of function. And so if you,

Dr. Allen Lim (06:54):

So let’s say this, you know, we talked about thirst earlier. We talked about the fact that we were both drinking at Lubriderm and that we are both equally, you know, satiated in terms of our thirst. Um, one, you know, there are two mechanisms that control, first one is a loss of blood volume, right. So if I shoot you and you start bleeding out, you’ll get really thirsty, I’m bleeding. And I’m like, I’m so thirsty. Have you ever watched the movies? Uh, you know, the free state of Jones, there’s the opening scene in the civil war scene where this kid gets shot and he’s carrying around trying to get help from, and he’s like, I’m so thirsty. I’m so thirsty. Why am I so thirsty? And I’m like,

Hillary Allen (07:35):

Well, that’s why your blood volume is all over the place.

Dr. Allen Lim (07:37):

Yeah. So blood volume is one thing that controls thirst. So if you drop your water volume and your blood, then boom, you get thirsty. The other thing that controls it is your sodium concentration in your blood. So if you lose water and that sodium concentration increases, you also get thirsty during exercise because our heart rates are high and our cardiac output is high. We tend to have a high blood pressure. And so that sensation of, uh, volume loss, um, is not as apparent because we have that high blood pressure. Yeah. And so, uh, the sodium concentration becomes more important during exercise as a first mechanism. So let’s assume in this scenario that our blood sodium is fine. And so these ideas of, you know, nervous function and contractile function that you mentioned with respect to sodium’s role in our own physiology are the same. Okay.

Hillary Allen (08:29):

Well, uh, then I would, honestly I would go to, um, toleration of discomfort or, or pain or, you know, familiarity

Dr. Allen Lim (08:38):

Is better at being dehydrated.

Hillary Allen (08:39):

Yeah. And during an uncomfortable situation,

Dr. Allen Lim (08:44):

People talk about this, right. They’re just like, you just need to train without water so that you like learn your body learns how to GI Dre. And there could be some specificity to that. Maybe that’s, I don’t know. I’m just

Hillary Allen (08:56):

Saying I’m tougher than you Allen. Sure.

Dr. Allen Lim (08:58):

Yeah. I mean, ultimately that, that, that might be the safe, but let’s, let’s take our mental fortitude out of this because clearly you are, you know, mentally stronger than I am. We all know that. I mean, you, you exercise most days of the week. I kind of, I’ve been, you know, figuring rate time watching the Queen’s gambit.

Hillary Allen (09:22):

That’s about cheese. It’s about chess. Oh my God. Okay. Oh, okay. Well that, I was hurting something about cheese earlier, chess. Oh, the Queen’s gambit. Okay. Well,

Dr. Allen Lim (09:33):

Pills, um, let’s take mental, mental strength out of this, but that could be it. What else is going on here that is really profoundly affecting my performance. And I mentioned it a little earlier, so I gave you a clue. We, in this competition when we were making casual, no casually talking to you right now, I gave you a big, big, big, I give the audience a big, big clear.

Hillary Allen (09:58):

Oh no. Hm. Um, I don’t know. I’m trying to rack my brain about different.

Dr. Allen Lim (10:08):

We know that you lose less salt than I do, but we also know that the water loss is the same in this scenario,

Hillary Allen (10:14):

Right? Yeah. What gives, Hmm.

Dr. Allen Lim (10:19):

Come on Hills. Come on. Think about water. Think about the body. Think about where that water is stored.

Hillary Allen (10:27):

Oh, fat versus muscle.

Dr. Allen Lim (10:30):

Not necessarily, but yes. You know, so go with that. Go with, huh. So for example, when water is 40 muscle, where is it stored in the muscle?

Hillary Allen (10:43):

Um, I’m trying to think of like

Dr. Allen Lim (10:46):

In the muscle, well, in the muscle inside the cell, like mitochondria, right? So you have an intracellular volume of water, but you have an extra salary or volume of water. So let’s say that we are 70% water. Right. And let’s say we weigh a hundred kilos. That’s 70 liters of water. How many liters of that water is inside of the cell versus outside of the cell?

Hillary Allen (11:10):

Ooh, Ooh.

Dr. Allen Lim (11:12):

And people don’t think about this. Right. They think that all the water in our body is just in our body,

Hillary Allen (11:17):

But 50 50. I mean, I don’t know, like it should depend, it should depend on each cell, but you have like a, where it is in your body. Like, cause the difference,

Dr. Allen Lim (11:24):

So let’s, let’s, let’s create two compartments right now. Okay. Let’s say one compartment where water can be stored is inside of a cell, whether that’s a fat cell or a muscle cell or any kind of cell. Right. So there’s an intracellular volume of water. Let’s also say that there is an extracellular volume of water, a volume of water outside of the cell. What is the distribution of water inside of ourselves and the volume of water outside of ourselves? Do you know

Hillary Allen (11:55):

The district mean? I mean, it should be, I mean, this is at equilibrium, like it’s, it should flow three leaf freely between the cell wall dependent on if there’s an area of concentration of salt greater or less than inside versus outside.

Dr. Allen Lim (12:11):

So let’s just say, yeah, there’s equilibrium of water. So water is not moving inside or outside of the cell, but we’ll keep that in mind for later, how much water is stored inside of ourselves in our body versus stored outside of ourselves.

Hillary Allen (12:26):

50 50. Okay.

Dr. Allen Lim (12:28):

No, we have a lot of cells, right? We’re mostly cells, right? So more like 70, 30, right. And so here are the body compartments. Most of our water is stored inside of our body cells. Right. Um, but our cells also bathe in water, right? So the space in between cells that’s called the interstitial space. And so there’s a significant amount of water, maybe, um, you know, 20% of our water in the interstitial space, let’s say, you know, it’s, uh, 70% of the water in the inside of the cell or the intracellular space. And then the rest of that body water is what’s called our blood volume plasma volume or vascular space. Right? So we have a vascular space, we have an interstitial space and we have the intracellular space, the interstitial and the vascular space are what are known as the extracellular space. And so the electrolyte concentration of that extra cellular space, um, is the same, right? The intracellular volume also has an equivalent electrolyte concentration. And that’s why water is not necessarily shifting between one space to another, but what’s the electrolyte content of those two spaces. Are they the same meaning in terms of substance potassium, sodium, et cetera. Right.

Hillary Allen (13:57):

All salts. I would S I would say, no, it depends on each cell. I mean, I was, I remember this in my PhD, uh, like we were like each cell has a different kind of, um, voltage, right. Intracellular versus extracellular, which can basically that equilibrium can be perturbed to elicit a response, like, especially in a neuron

Dr. Allen Lim (14:18):

Potential. Exactly. So what maintains that, uh, what, what maintains that potential?

Hillary Allen (14:25):

Um, so, I mean, we’re talking about the beginning of this, like, um, you’re basically, uh, like your salt concentration, your osmotic, um, kind of pressure sensors. Like those can be activated open versus closed. Um, well

Dr. Allen Lim (14:40):

Ultimately this all starts with something called a sodium potassium.

Hillary Allen (14:43):

Well, Holly, of course, that this is the leaky pump that you’re constantly doing this, that the sodium potassium pump doesn’t necessarily have a, a mechanism to open and close it, but it’s kind of, it’s there based on concentration differences.

Dr. Allen Lim (14:56):

What does a sodium potassium pump do? It pumps potassium into a cell and sodium out of the,

Hillary Allen (15:01):

So, but tell me, what’s the difference between to potassium and sodium? They have the same chart.

Dr. Allen Lim (15:06):

Yeah. There’s, there’s, there’s, there’s no real difference. I mean, functionally in our bodies, everything could be flipped and it, the system would probably work the same. Um, it’s just that they’re different. So, you know, our proteins can identify and pull these two molecules apart from one another,

Hillary Allen (15:22):

From a chemistry set point of view, there are differences in sizes.

Dr. Allen Lim (15:25):

Yeah. Different differences, molecular mass, et cetera, but net, net from a number of things or from an automatic perspective, right? Same one potassium molecule is equivalent osmotically to one sodium molecule. But my point is, this is that if you looked at the electrolyte concentration inside of the cell, you would see primarily potassium. And if you looked at the X electrolyte concentration, the extracellular volume, you would see primarily. So right. Those molecules might be balanced. There’s no net movement, but ultimately what happens when we sweat is we primarily lose sodium, not potassium. Right. Um, you know, it’s a leaky system, so we do lose some potassium, but very little cause there’s very little potassium in our bloodstream. Right. So let me ask you this question again, you lose less salt than I do when you sweat, when you lose a certain amount of water. So what happens to the concentration of your blood sodium versus the concentration of my blood sodium?

Hillary Allen (16:36):

Well, if you’re losing, if you’re losing more than yours is perturbed more at a greater degree. So you have less extracellular sodium.

Dr. Allen Lim (16:45):

So here’s the deal. Yeah. You actually kind of got that a little backwards because if so, if I were to lose pure sailing, right. If I were to lose all of the sodium in my blood, my sweat question were about the potassium that you’re leaving. No, not yet. We’re not there yet. So what’s happening is this is if I were to lose more salt, right? The concentration of my blood sodium would not go up as high. Right. Uh, if you lost pure water, very little salt, right?

Hillary Allen (17:20):

My sodium would go up. Of course, of course. Yeah.

Dr. Allen Lim (17:25):

Use less salt. The concentration of my sodium does not go up as high. Now, all of a sudden between the intracellular space and the extracellular space, you have a higher sodium concentration. And so what happens now automatically between those two spaces,

Hillary Allen (17:42):

Well then more water would want to go outside to the extra, extra cellular space. Exactly. And so what happens

Dr. Allen Lim (17:47):

Is this is that you have a higher amount of sodium increase or concentration in your blood. There’s a greater osmotic gradient to shift water from inside of the cell, into your extracellular space or into your plasma. Right? And ultimately here’s the deal we could end up dehydrating exactly the same in terms of total body water loss, but your plasma volume could be preserved because of that shift and my plasma volume could decrease. And so all of a sudden you maintain your cardiac output. You maintain the delivery of blood oxygen, the removal of CO2, the removal of,

Hillary Allen (18:29):

And I’m impaired because

Dr. Allen Lim (18:31):

Even though we’ve lost the same amount of total water, you’ve been able to shift more of your stored water in cells into your blood volume. Whereas my blood volume is lower because I’m not getting that osmotic shift.

Hillary Allen (18:45):

So my question is, so can this be, can this be trained? Is this just, this is just a consequence

Dr. Allen Lim (18:51):

Of a difference in sodium loss,

Hillary Allen (18:54):

But this is genetic. Like this is, this is something

Dr. Allen Lim (18:57):

By a cluster called CF one, um, which is named after the disease, cystic fibrosis

Hillary Allen (19:05):

And insisting

Dr. Allen Lim (19:06):

Fibrosis. You lose all of the sodium that is in your blood. You don’t have the ability to re sequester sodium as that sweat or plasma goes through the sweat gland. And so what happens in a cystic fibrosis patient, and this is where this comes from. This comes from a study, comparing the, uh, difference in plasma volume between very salty sweaters,

Hillary Allen (19:33):

Cystic fibrosis patients,

Dr. Allen Lim (19:35):

Um, people who lose very little sodium in their sweat. Right. And what happens in the situation of cystic fibrosis is because they’re losing fluid. That is the same concentration as their blood. Nothing really happens to the concentration of sodium in their blood. And thus nothing really happens to disturb the concentration between the inside of the cell versus the outside of the cell. And thus water does not shift as they sweat their blood volume is what primarily decreases in a normal individual who loses, say, moderate Montessori, uh, assault. You’ll lose water, both in your, from your blood volume, but you’ll shift water from inside of yourself back into that blood volume. So you’re losing water primarily from both inside and outside of yourself. Now, if you’ve got a situation where somebody loses, you know, almost no salt, right? They get a very good, you know, shift, uh, of water from inside the cell, into their blood volume.

Dr. Allen Lim (20:45):

They’re able to maintain volume. Of course, losing interest. Water is going to have detrimental effects as well. But you know, likely the loss in blood volume is more important for performance, right? Cause the cardiovascular implications are so huge. The other thing is, is that the person who’s losing very little salt can just drink plain water and more easily replace all the water that they lose. Right? Cause they’re, you know, thirst mechanism keeps them in check and that thirst mechanism better matches both water, total water loss. Whereas if you’re losing a lot of salt, your thirst mechanism is going to keep you from drinking all the water you lose to prevent you from becoming hyponatremic or prevent the sodium concentration from going too low.

Hillary Allen (21:34):

So my coach always tells me to drink to thirst. Yeah. However I wonder. Hm. Like in an ultra event, um, there’s a certain point where I start to crave salty foods and not so, so much sweet. So I would, yeah,

Dr. Allen Lim (21:48):

That doesn’t take away your desire to drink the first, what it does is eating that salt enhances your thirst drive first driving.

Hillary Allen (21:58):

So is that something that you’re also able to listen to is like that, that your ability to crave solve is also on par with your thirst?

Dr. Allen Lim (22:06):

I, I, I’ve seen less, uh, work on that kind of, um, that’s, that’s sodium drives. Sodium drive is definitely there and it’s definitely connected. Um, but you know, my quick answer would be yes, because you would rather have intake of sodium drive first and drive your drinking behavior than w O and overconsumption of water to drive sodium consumption. You want sodium delete that water consumption, not water consumption to lead to you, having to like, you know, crave all that salt. Because by that point you’re probably screwed. It’s too late. That’s right. That’s right.

Hillary Allen (22:47):

So another question then, is this something that you can, I mean, I’ve heard a variety of theories on this. Like, is this something that you can train yourself out of as far as going back to this whole idea of dehydration?

Dr. Allen Lim (22:57):

I don’t, I don’t think so. I think that every, uh, physiological variable has some realm of training adaptation, let’s say 10 or 15%, whether that’s VO two max or lactate threshold or economy, or even say the fact that it is known that as we train more and become more heat adapted, our sodium sweat becomes more dilute. That’s clear, right? But if you have a genetic propensity to lose an average, 2000 milligrams of sodium per liter, versus somebody who has a genetic propensity to only lose 500 milligrams of sodium per liter, once again, the adage of you can’t turn a donkey into a race horse, you know, comes to light. Certainly that person, both people will have a certain level of adaptation, but not a level of adaptation that puts into a new genetic category. For sure.

Hillary Allen (23:48):

Hmm. So, I mean, this is the propensity for someone to kind of be quote unquote designed for or made for certain types of,

Dr. Allen Lim (23:56):

Well, this is also, I think why maybe there is a self-selection when it comes to endurance sports, and that has tended in the past to self-select individuals who didn’t lose a lot of salt in their sweat, but now it’s probably leaning towards a more diverse group of people because the availability of, uh, and wisdom that people have around consuming salt can overcome that. Right. And you certainly see that in society. And, you know, some people might even say that the reason why there’s such a big genetic variation and our sodium sweat loss is because civilization was built around the salt trade and that, you know, we have manipulated society in a way to give us some advantage there, with respect to our need for sodium. Um, yeah, but my whole point is this is that this dehydration controversy is a controversy that has never looked at how much sodium we lose in our sweat. And that loss of sodium in our sweat could create a hypothetical situation where two people lose the exact same water weight, but one person maintains their blood volume and another person does not. And in principle or hypothetically person who maintains their blood volume, we clearly have a performance advantage over the person who does not maintain their, their blood volume because of the necessity of cardiac output in any robotic activity. Right.

Hillary Allen (25:24):

Okay. I mean, I’ve had my, I’ve had my great, this is amazing. I mean, I’ve had my salt tested with, uh, like it was one of the, I came and had the little section cup put on my

Dr. Allen Lim (25:34):

Yeah. But yeah, I mean, the lesson is ultimately replaced. The sodium that you lose in your sweat, the lesson is, is that if you are a person who is dehydrating, no, you’re losing a certain amount of weight. And you know, that your performance is being hampered. Try experimenting by consuming more sodium in either your sports drink or in the food you consume when you work out or even try sodium loading ahead of the event. If there’s someone who, you know, dehydrates and has no performance issue, maybe you’re just one of these lucky ones who’ve done it where it doesn’t matter because you’re not losing a lot of salt. The idea is that everyone is different. And if somebody has an experience where they know that they can dehydrate and still maintain their performance, there’s probably a reason for it. But it doesn’t mean that dehydration doesn’t hamper performance, because you can also find someone who dehydrates the same and their performance and their thermoregulation falls apart.

Dr. Allen Lim (26:28):

Right. And so I think what ends up happening, and this is the distinction between science and practice is as practitioners. We have you come to the table with our own set of experiences. And if we come to the table with a set of experience that says that dehydration doesn’t affect my performance, and we start telling everybody to behave that way, we could be screwing some people and vice versa. You know, if I come to the table and I know that dehydration really hampers performance and I come to the table and I try to make everyone over hydrate, there could be also issues. Right. Um, but what the science tells us or explains is why both scenarios might be true.

Hillary Allen (27:07):

And that human experience is actually really important in determining this solution,

Dr. Allen Lim (27:12):

Your own individual experience. But that doesn’t mean that you can get on your high horse and tell me what to do.

Hillary Allen (27:18):

Yeah. I mean, it’s good to be able to ask questions and figure out what different athletes are experiencing and then, you know, troubleshoot. It’s like, I feel like everyone’s an N of one that’s right.

Dr. Allen Lim (27:28):

That’s right. And, and as an of one, I think that you have to make sure that, you know, that it’s you and, you know, not necessarily trying to prophesize that everyone has to live that way. Right. Yeah. And, you know, I think it also means that you can heat people’s advice, including my own about topics like this. Right. But I think that, that, yeah, the missing component in the G hydration debate is what about salt? Yeah.

Hillary Allen (27:56):

Always. And that’s, I feel like that’s the most important thing. Um,

Dr. Allen Lim (27:59):

But now you also know that water is in chest in your body. It’s distributed between effectively two compartments. And those two departments can even be broken down into three compartments, plasma or blood vascular interstitial between cells and intercellular. We also know that the intracellular content of electrolyte is primarily potassium. The extracellular content is primarily sodium and generally an osmotic balance. Meaning the number of sodium molecules matches the number of potassium molecules, but then when we lose water changes and that can automatically shift water from inside of the cell, into the vascular space. Right. And that can have performance implications that can also drive thirst. So the next component is, well, what are, y’all also putting in your mouth through your gut? So it’s multifactorial and complex.

Hillary Allen (28:49):

Yeah. Oh man. But that’s like, it’s, I love it. Cause it’s, it’s the Mo one of the most basic things I have to listen to you every day. That’s right.

Dr. Allen Lim (28:57):

So we’ve talked about sodium potassium pumps. We’ve talked about osmosis. We talked about sodium, uh, sweat, sweat glands, adaptations, genetics.

Hillary Allen (29:08):

So, okay. This leads me to, well, we’ll, we’ll wrap up this, but, um, your best piece of advice for athletes who are experiencing or suffering from dehydration and how they can kind of

Dr. Allen Lim (29:21):

Troubleshoot. Yeah. I think the first piece of advice is, um, you know, get a scale, uh, try to quantify what that dehydration is, um, and try to understand how different environments in different circumstances may cause more or less loss and try to put together associate for yourself, whether or not that impacts, uh, your performance, whether that’s, you know, actual speed or that’s, you know, a variable like, you know, how much strain you’re experiencing in terms of perceived exertion or say cardiac drift, heart rate increase, you know, for given pace. Um, you know, with that in mind, I would say this, that if you are experiencing a performance detriment, or if you’re experiencing guilt, eat illness, things of this nature to potential solutions, the first solution is that maybe you just have your logistics wrong. Maybe you’re just not, uh, you know, able to get enough water to appropriately drink ad-lib or appropriately, appropriately, uh, quench your thirst.

Dr. Allen Lim (30:22):

And so we’ve had to do things with training rights here at Boulder, in the summertime, for example, where we might pick a route and just park a car at one location that is loaded with a cooler of, you know, ice cold bottles, water, everything that you might need, and, you know, end up on a big long seven hour training day, doing multiple laps of a course, just so that we can always get back to a water source. And, you know, when you think about your racing, you’ve got to just figure out the logistics, because much of the time, this is not a physiological problem. This is a logistical problem. And you know, this is why Napoleon won Wars because he figured out the frequent logistics, right? He can, he can food and his soldiers didn’t go hungry. Right. Great. Um, if it’s not logistics, then the next big piece of advice is start experimenting with increasing your sodium intake during these long bouts of exercise, and then use that increase in sodium to drive your thirst, drink, to thirst, and then see at that changes what the scale tells you.

Dr. Allen Lim (31:26):

Right. And see if that changes how you perform, because even with the scale, you don’t know if that water loss is distributed more, uh, to blood volume loss or intracellular loss. Right. Um, and then, you know, last piece of advice beyond keeping your sodium game in check is to continue listening to yourself. Um, not necessarily how about this taking everybody’s advice with a grain of salt and not being one of these, uh, you know, Nimrods who then having figured it out, tries to go and tell everybody what to do based upon your experience. Cause that may not actually apply to anyone.

Hillary Allen (32:15):

I love it. This is perfect and great pun at the end there. I got to love a science fun, but, well, this is super informative. Thanks again. It’s always a pleasure talking with you and we’ll draw pictures next time. Oh yeah. Okay. We can, we can post it, but all right. Thanks so much for taking the time today. And um, I hope everyone learned something about dehydration and, and performance. I definitely, I definitely did.

Dr. Allen Lim (32:43):

Yeah. It’s always going to be controversial, but there’s a reason why. Yep.


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