Hydration for Ultramarathons with Stavros Kavouras PhD aka Dr. Hydration | KoopCast Episode 31

what's going on trail runners welcome to another episode of the KoopCast as always i am your host Jason Koop and the summer is here it is heating up trails everywhere people are getting out the sun is a shining and every single year i see athletes make the same mistake again and again once the temperatures start to rise and that is they fail to hydrate properly they either go out on their standard run with the same amount of fluid that they were used to during the winter times they run out of fluid in the middle of run they come back parched or they don't even start the run with any fluid at all thinking they can kind of get away with it and normally that mistake happens one two three maybe four times before the athlete finally learns and thinks okay i've got to take more fluid on the run with me but that doesn't necessarily need to happen we can be smarter than that and so on the podcast today i brought on another none other than stavros kovaras who is a researcher at arizona state university he is otherwise known as dr hydration and as that moniker would indicate his expertise is in hydration and fluid balance where he has been the author of more than 130 peer-reviewed articles many of which have to do with performance hydration and fluid balance and we've all

heard conflicting advice on this in the past personally i remember standing at the start of the wasatch 100 one year and having the medical director the race director tell the entire group there that you cannot drink enough hydrate hydrate hydrate you cannot you cannot drink too much do whatever you can do to hydrate the very next year i remember standing at the pre-race briefing for the leadville trail 100 and having their and having their medical director tell me to drink to thirst and these two pieces of advice we have all heard as trail runners and they can and they can come into conflict with each other and so i used a little bit of that dialogue alongside of some of the recent american college of sports medicine position papers to kind of paint this picture of hydration and why it is so confounding from a performance standpoint to ultra runners this episode is chock full of a lot of practical information that you can take out on the trails with you tomorrow and i hope it does clear up some of the confusion around how much to hydrate when to hydrate different variables that affect hydration and how you can dial in how much fluid you need to take in during your next ultra marathon i really appreciate appreciate stavros coming on the podcast today as you can tell he is an

he is an endurance aficionado we talk a lot a lot about uh some of his early days being a professor and going out to the spartathlon and uh watching the event from an aid station there and what about what you know what a better place to study heat and hydration than that particular ultra marathon it is a really hot and a really hard uh really hard race we had a lot of fun with this one you guys are going to be a little bit of a little bit of a little bit of a little bit of a little bit of information out of this that they can take out on all of your summer adventures so you stay healthy stay happy and you just have fun on the trails people so here we go without any further ado here's my conversation with stavros cavaros all about hydration thank you for all the other papers interestingly enough the proton pump and uh inhibitor one that you sent me over i've used that protocol myself and with my athletes before a lot yeah and for what for what it's worth i noticed it makes a difference the first author actually uh marcus talman is a great ultra guy and he he won the spartathlon one year uh he's about i don't know if you're familiar with spartathlon yeah oh yeah 24 hour runner yeah uh i worked for spartathlon for 10 years i was a volunteer in one of the biggest checkpoints in ancien coriant and i loved it i haven't i mean i haven't been doing

that since 2012 that i moved back in the u.s so but it's like it has a very dear place in my heart and our entire family used to go there and volunteer used to bring like a whole bunch of students from my lab it was like friends and and it became like a friends and family our checkpoint we were like 30 people we had we were the only checkpoint that we had ice oh my gosh and they will stop by they will see ice so they will be like they will get on my they will get on my legs they'll be like i love you i love you i love you i love you so it'll be like 95 degrees they'll be running for like i don't know 50 miles already and they will stop by and they will find ice and they will take it and rub their back of their head rub their knees and they'll be like oh my god it's great well i'm sure first off spartathlon is brutal i mean that race is is like the quintessential brutal of the brutal ultra marathons in a lot of ways it's more brutal than bad water because the um the environment with all like the slow moving traffic around there just it just makes it feel hotter and you're sucking in all those noxious noxious fumes and whatnot the beginning the first part of the probably the one third of the race it goes through the city yeah and it goes through a not very pretty very industrial area actually which is not the good part of athens to be you know uh but there is no other way to leave

from the city going towards corinth and then down to peloponnes to go to sparta that's that's the way yeah and it's all asphalt during the day so you get all the heat wave of day one and then you go through the mountains at night where the temperature occasionally might be as low as close to freezing maybe not freezing but like mid 40s maybe and then next morning for the people that they don't finish within 26 hours they get the second day heat so it's like it's so brutal as a hydration researcher when you went out to those things and you were you know manning an aid station with your family were you like did you have like your research hat and your aid station hat on at the same time and just like look at this are you like a kid in the candy store at those things it was it was a little bit like this especially with you know it's you teach all that stuff in the classroom you talk about it you experiment things but when you see things anyway i can share some of my experience from spartathlon through the podcast i can give you some examples like you see things i remember one day actually this is a great story i'm sitting in um we used to do almost every year the the major checkpoint which is in ancient corinth right across the street from the archaeological site um so there is this japanese lady she must she was probably mid 60s maybe she comes over and she has all the classic symptoms of a

heat stroke so i am there with my students and i'm teaching pretty much i'm like so she got this that we talked in the classroom she got this she got this so there is no way she's gonna go on she's gonna drop either here now or in the next checkpoint she's either has she will either quit or kind of collapse yeah yeah long story short that person rested ate drink you know a little bit and then next thing you know she keeps running and she keeps running through the next checkpoint the next and the next and she ended up finishing in like top three top four woman probably wow that's really amazing you see people they come back from death like you see them and they're like they will either die or well crampings cramping that i've seen in spartathlon i have never seen in my entire life like whole body cramping from your cuffs to your stomach to your pecs to your hands like like a wave going up and down and you're like you're there is nothing you can do there is somebody on the ground laying and and screaming and there is nothing you can do you cannot touch them you touch them in one hand you know they get a cramp because you move their arm a certain way that's exactly correct oh my god oh my god but a lot a lot of those runners will finish like despite how terrible you see

them in that rate that aid station as you mentioned is early in the race like usually when when ultra marathon athletes have those types of problems that early you could very easily like diagnose that as all that person is for sure going to dnf but for whatever reason like if they if they get their act together and they're reasonably fit they're not pushing cutoffs or anything like that they can still go and finish the race so there's your other lesson to your students right it's not just the clinical presentation of of you know being overheated or hyponatremia hyponatremia or anything like that it's also hey the fact they can you know pick themselves up and finish but let's since we're on that we weren't planning on starting on on on spartathlon but since we're already talking about it we might as well one of the one of the reasons it's such an interesting playground is because you did some research out there that showed an incredibly in fact if if i'm not mistaken it's the highest rate of hyponatremia that's been demonstrated in the literature why don't you give like an overview of that of that research and what you guys found um yeah these are data actually that we collected over the course of two years so uh in the first year we wanted to examine primarily the frequency of uh hyponatremia in ultra running and something of that long which is like the main finishing time was around 30 hours so spartathlon is 246 kilometers like about 162 miles if i remember correct by heart

um so you're supposed to finish within 36 hours so the the zero volume and the length of that race and the duration of this race it's a good candidate to become hyponatremic so uh so the first year we we uh just assess hyponatremia we took blood samples before and blood samples after so looking at hyponatremia we were looking primarily what is the the percent of runners that they will have plasma sodium which is uh below what is a normal value 135 is the normal value and below 130 you typically call it uh severe hyponatremia or more serious hyponatremia where you typically start seeing symptoms associated with uh decrease in plasma sodium uh so the incidence that we found at the beginning it was crazy it was something like 50 something 60 or more of them they were like meeting more than the 30 the 135 limit and then the second year we came back and we took uh blood sample before and we managed to take some blood samples right um in in ancient current actually which is um it's approximately uh about 60 miles is the thing it's right before 90 kilometer checkpoint uh so they have run already two marathons in the heat um so there were two observations that they were very interesting

so number one um about 10 percent of the runners they show up in the in the starting line with plasma sodium below normal 10 percent they were starting their race hyponatremic and those people obviously was a very very mild degree of hyponatremia but there were people that they were not aware that they were in that situation obviously uh the second interesting part is that we had several people that they had already uh severe hyponatremia by the um ancient current checkpoint so by kilometer 90 they had already developed hyponatremia with plasma sodium levels below 130 and and some of those people were able to finish so all the data that we reported in the study those were data of finishers only so we did not include anybody that we took baseline blood samples and those people did not manage to finish the race and the reason we did that because uh logistically speaking this is a very complicated race uh it gets very long after a certain point there are people that they have proceeded through several checkpoints people are on the back and and it it's depends on where you don't when you quit the race you can get picked up and taken back to athens or if you are farther in the race they might pick you up and take you down to sparta so it's very difficult to identify

those people take blood samples right on the spot and literally with 70 something checkpoints and and a span of dozens of hours from the beginning to the end pretty much uh it would take like an army of scientists to be able to uh do this kind of control and potentially having i don't know motorcycles running next to them up to a point because you know when they go through uh one of the climbs you can you barely walk or crawl there to make it to the top um we published another study a few years ago actually back it must have been 2006 or 7 if i remember correct where we reported muscle damage and uh pretty much what we call um um exercise induced rhabdomyolysis so we were measuring one of the indices that we assess rhabdo and the values that we had the main value of the finishers was above the value that any medical doctor would have hospitalized anybody so just to give you an idea we had people in the hundreds 100 120 000 international units of cpk which is the creating phosphokinase enzyme that leaks from the muscle fibers in the circulation in the blood uh when the the normal value for a normal human being is below 200 uh the mean value was around 40 000 units so anybody with this kind of of evidence uh in a

in a biochemical analysis we have been taken to the hospital to be treated from rhabdomyolysis what is interesting is that you talk to these runners and they know about it so they are aware of this is what happens when you participate in a race like that and their answer is simple they say we know about it we rest the next few days there is not much you can do and we drink a lot of water to save our kidneys so we try to drink a lot and p dilute urine for the next few days and clear out those big proteins out of the kidney uh the the kidney stress must be absolutely crazy i remember the the first year we did the the very first data collection we took the blood samples in the lab and we tried to analyze them and uh we use one of this essay we call it color or metric so we measure color so it's supposed to turn into a little light purple color so we run the first samples the samples turn out black immediately i'm like what happened we're like how about if they were very concentrated in this molecule we're trying to measure and we kept doing serial dilutions over and over and over we end up diluting the sample how many times to be able to measure what we wanted to measure because it was you know those uh biomedical diagnostic kits are not developed for people that they have 100 000 units they're developed to measure from 200 to 800 yeah normally 100 000 units they're talking about

people going into the er for a heart attack or or a car accident or something like that and it's always been crazy to me when i see those studies and it's and we we see those studies a lot in ultra running where people do get 40 000 units 50 000 units 80 000 units 100 000 units i've always been i've always been kind of amazed at the variability and the fact that it doesn't seem to be linked to finishing time like you see people that finish really fast that have super high values and very low values and you see people that are that are chasing the cutoffs that also have super high values and very low values but it's i i agree with you ultra marathon running is a really good um case study for a lot of things because of the the physicality of the events right it's such a physical event and people are pushing themselves to the limit and i'm actually really appreciative of a lot of the research that's now been done in that space because when i first started working with ultra runners like in the early 2000s there was hardly any research on any of this at all and now to see all of this come out over like the last you know 15 or 20 years it it helped it just helps my my my coaching practice a lot but we could go that i i do want to come back to the hyponatremia thing because it's it's something that i think that we don't have a very good fix on in the running space and the coaching space and maybe even from the from the research space but i think even before that hydration which is your gig as a whole just for health

is something that we don't really have a good fix on either and the the the way that i the way that i really illustrate that is i was doing some research for this in advance and i just pulled up the usda guidelines on how much vitamin c do we need and how many apples a day do i need to eat and all that other stuff and the the usda guidelines that roll every five years it's like a 120 140 page document it doesn't mention a water recommendation ever in the whole thing the only recommendation or the only the only references to water are the water content in food and how to wash your hands or that you should wash your hands are we getting it wrong from the get-go at that like really basic level absolutely yes and and it's not anybody's uh bad intention so nobody's trying to uh work against the water or thinks that water is not important you know every single human being would agree that without water you cannot make it it's absolutely essential for survival yes we can produce a tiny tiny amount through metabolism but most of the water that we need we take it through drinking so uh

the strongest evidence is uh my plate the uh the the um diagram of of a plate with you know portions of what type of food you're supposed to have and what to pay attention when you eat uh does not include water i got excited when it came out a few years ago because i thought that circle on the top right it was water and it said it says dairy it's a blue circle actually that i don't know what is a blue dairy probably blueberry yogurt um but uh definitely it's not water there is a big move and i'm optimistic that in the next cycle of the dietary guidelines we will have a new version of my plate that uh there will be water there there are some pyramids around the world actually because i've been um traveling a lot not nowadays with the covet 19 but um and i give a lot of lectures around the world talking about hydration and dietary guidelines i was involved with the development of the chinese guidelines uh a few years ago they do have water um in france there is water in indonesia there is water so many countries around the world they do have water in the dietary guidelines some of them they still have the pyramid uh one interesting exercise that i actually when i speak about hydration i like to do this exercise in in in my slides um if you go to the dietary guidelines and uh i think it's called healthy eating

um no it's not healthy eating it's it's uh dietary 2020 2015 to 2020 dietary guidelines for americans um this document that you mentioned earlier it's available there online and you can go and search and you know what i did i went to the box and i put the word water enter and i got four things one of them is a definition of what is a calorie number two and number three is the importance of replacing sugary drinks with plain water to avoid obesity diabetes dental disease and on and on and on and the fourth one is as you mentioned wash your hands with soppy water so so these are the four mentions for water so the the long story short in this conversation is nobody has a malintention against water the truth is that we still lack of a lot of research and a lot of information to identify what is the impact of drinking adequate amount of water on health so there is a lot of data on hydration and exercise performance and myself um and and many other colleagues have done a lot of work in this area but there is relatively very little being done in hydration and health and and just to give you a strong example about it um many people have heard that the classic advice for uh people that they get urinary tract infection which is something more common in women they say one of the easy things you can do

drink more water and by flushing your kidney and urinating more often that decreases uh recurrence of uti so the first randomized control trial it was published last year wow there is no other evidence of that so that was a good advice nobody had a bad intention but this is the first time that something was scientifically proven and supported that it's good for you wow so to give so in the u.s one could assume that water is not important because it's not in the dietary guidelines obviously we know it is and maybe you'll get your shot next year because these guidelines run every five years and we're in the last year of that cycle being 2020 but why don't you give the lesson the listeners a little bit of perspective of what those hydration guidelines look like in other countries and then we're going to move into the sport and performance area which a lot of the listeners are going to be interested in uh kind of the most here um i i can spend probably two days talking about differences and why they're different between countries so like in in europe they are about 30 percent lower than they are in the u.s we do have actually dietary guidelines in the u.s uh the institute of medicine that publishes all the dietary references for all the nutrients in 2004 for first time they published the dietary guidelines for water those numbers are published in liters so for adult males it's 3.7 liters of water per day

for females is 2.7 liters per day so to make it more relevant especially for people that they are not good with volumes in liters and ml in ounces etc if we correct because this is the total amount of water that we also take by eating bread rice pasta fruits vegetables etc if we do the correction that at least the 20 percent of the water comes from solid food and we translate that volume into glasses of water and we take the a small glass of water eight ounces which is a standard maybe in the u.s is not the standard anymore but if we translate it into eight ounces glasses size for males this is equivalent for 12 glasses per day and for females is eight glasses per day so this is the practical advice this is what i can say today based on what we have in europe these numbers are slightly smaller there are about 2.5 liters for males and 2.2 liters for females why they're different we don't have good methodologies to assess water intake we don't have good biomarkers so there are a lot of reasons but just to close the the topic of uh why water hasn't been studied that effect that extensively like other nutrients um is um i think

number one it's a little bit forgotten uh forgotten because it doesn't come with calories it doesn't come with guilt even if you ask people how much water you had yesterday probably you have to think very carefully and go through the day trying to remember how much water you had because you don't think of it when you drink water versus if i ask you i don't know how many beers you had over the weekend you will probably remember you know so guilt association it's something that makes things you know easier or um or not so and and on the other side um it's it's something that um water comes from the top you know you turn on the top you have water that's it and in um most places uh in most countries and in most cities in the u.s the water is relatively safe and and good and you don't have to pay for it so the initiative of funding studies on plain water has been very very limited i almost think that now that la croix and all these seltzer waters are becoming the it drinks that those might actually be more likely to get funded than plain water like they're going to study seltzer water and maybe the the guidelines are based off of those studies versus with plain water because that's where the money is it's true and if you pay attention actually uh now the the beer companies are getting into that that's right uh-huh croix was one of the first ones that they start making bubbly water in the u.s

uh the bubbly water i think it's pepsi if i remember correct uh there are many companies that they do that pepsi bought recently the soda stream which is a machine that you can create your own sparkling water at home uh americans traditionally are not uh big consumers over sparkling water actually uh it used to be more of a european fashion and mainly central and northern europeans used to drink predominantly sparkling water but now it's catching up in the u.s and i think it's a good alternative for people that they're trying to get uh unhooked from soft drinks and they still like something different than water they like the carbonation this is a good way to do it yep i think it's a good substitute okay needless to say drink your water even if you can't find out exactly what the right amount is three four maybe five liters a day might be more for athletes and we're going to get into some of those specific recommendations so as confounding as just day-to-day hydration guidelines can be it's different for whatever reason all over the world in the us it can be hard to to come by in a sports performance setting it can be confounding as well and you've been in the research field for a while and i've been in the i've been in coaching for a while and we've both seen the recommendations change and we've also seen athletes attitudes uh change on this as well and this is really no better illustrated than the acsm's

guidelines so the acsm puts out guidelines for a lot of things every year and one of the things they put out is is how you should how you should hydrate and i had to pull this up beforehand and i'm going to kind of read it verbatim just to set the stage on this in 1996 their guideline was quote as as davros starts to pour his water into his cup over there right on cue during exercise athletes should start drinking early and at regular intervals and attempt to consume fluids at a rate sufficient to replace all of the water lost through sweating or this is my emphasis or consume the maximal amount that can be tolerated and the emphasis on the last part is kind of what i was trying to drive home go ahead can you continue the reading a little bit read the sentence right after that i didn't pull i didn't pull it i didn't pull it up what is it without drinking beyond your sweat losses there you go without drinking this is something that people um that are accusing this guidelines forget to read but it's but the reason it's confounding is because it's conflicting in those two sides of the statement right so so let me tell you my interpretation of the there is what is called the letter of the law and the spirit of the law and the spirit of the law so so let me give you a little bit of a background where this

statement comes from so it comes from a fact and the fact is that we are human beings programmed to drink less than what we lose via sweating during exercise so even myself that i am a hydration scientist this is what they do for living i think of it every single day uh i when i go out to exercise and even now you know that it's it's already hot here in phoenix arizona when i go out i i cycle usually early in the morning um i almost every time i do this exercise i get my nude body weight before i leave nude body weight as soon as i come back and i see even though i'm drinking how much i what kind of deficit i have i'm always on a deficit for going out for just one hour bike ride you know i don't have more time in the morning to exercise before work uh so i know what to do i have convinced myself that this is it's good for me to try to keep up with that so what i'm trying to say is this that the spirit of that as much as possible says it refers to the fact that even if you cannot keep up with your sweat rate try to drink as much as possible okay so let's say um like back in 1996 one of the interesting case study that was published that by one of the co-authors in that piper uh larry amstrong um he published a

uh a well-known article about alberto salazar when he was preparing from for the 1984 olympic games and alberto had the sweat rate for uh of approximately one gallon of sweat per hour yeah it's impossible to keep up with like how can you keep up with this so what would you say to this guy drink as much as you can yeah yeah this is the guideline nobody can drink a gallon per hour you know and nobody insane mind will recommend to any human being drinking a gallon per hour right so the the maximum ability of your gi system to absorb it's there are obviously differences it's like one and a half maybe max yeah maybe two absolutely max liters per hour so so this is where these guidelines are coming from nobody was saying drink beyond and above to what you need the guidelines are they didn't say it in the words but they meant if you cannot drink close to what you lose drink as much as you can yeah and first off before we go any further i always try to avoid using alberto salazar references in the current climate right now anyway i've heard i've heard that story as well but my point with going through this this these acs guidelines is really the chronology of things so if we really wanted to

stylize it in 1996 they're trying you're trying to hydrate per your fluid losses as much as you can tolerate it if you fast forward 10 or 11 years what starts to emerge is an individualization approach to it and the the guideline goes as follows in 2007 because there's considerable variability in sweating rates and sweat electrolyte content between individuals customized fluid replacement programs are recommended so there's this shift right from trying to replace sweat to to let's try to individualize it and then you fast forward it to 2013 which is the emergence of the drink to thirst guideline which had all of these other caveats to it which i always like to read the statement because of all the caveats because it's like this ping pong match in front of me that i can't really get a fix on where the ping pong ball is going and so the 2013 statement goes during exercise drink according to your thirst no more and no less and and and finally they end up with fluid replacement strategy should be individualized and taken to consider consideration environmental conditions exercise and intensity and duration pre-post body weight body size and other individual characteristics so once again the ping pong matches is drink to your thirst but individualize it maybe outside of that thirst and so that's why so i'm trying to paint the pictures that if you're trying to

get a fix on what the actual recommendation is it's actually hard to pull that apart just from this recommendation so my question to you is how do athletes do it like what's the best mechanism so um i think we're barking at the wrong tree to be honest um so one thing that i wanted to clarify uh since 2007 acsm the american college of sports medicine has not um renew their dietary guide their position statement for uh drinking during exercise so uh the 2013 was a consortium of scientists that they talk about hyponatremia and ultra exercise and they came up with a drink to thirst um and there was actually a very early version of that paper and it got immediately revised and they had the second version right after so so the story it is indeed very complicated and there are people with strong opinions both sides that they strongly believe that what drink to thirst is the best and there are people on the other side that they strongly believe that drinking to thirst is not good so the question that we have to ask first before we answer this question is what is your outcome what do you want to achieve do you want to complete a race or do you want to win a race or do you want to go out just for fun have a you know do a 10k race do a half marathon what are you

doing so if we take it completely out of context then the answer will it's not easy to give an answer or you can give an answer that it doesn't apply to all scenarios uh when i talk about anything actually when i give any lecture on any topic uh i always get the attention of the audience and they pull out their pen and they start taking notes as soon as i give numbers so if i say so the amount that you're supposed to drink every 10 minutes is like everybody pays attention and they want to write down that number what is that magic number it's like if you if i keep pushing you because you're a coach to tell me what is the best size shoe that i supposed to wear tell me is it nine is it eight is it ten is it eleven is it eleven and a half what is the best size of shoe that i supposed to wear because i want to run this i don't know this ultra race you cannot give me an answer you have you know you have to measure my foot foot you have to try different types of shoes and then in the race some people change shoes in training there were different size in the race that may have a little bit wider shoes i've seen people changing shoes during the race so you cannot give one by one advice to address every single situation so this is what the most recent advises are the answer is individualized hydration protocol

which is easily said easily estimated it doesn't it's not as easily applied though so let me back off a little bit to give you a little bit of a um of an idea of why it is difficult so you're supposed to drink to address the amount of water that you lose via sweating during exercise so if you and me do the same let's say that we have exactly the same running technique the exact same muscle mass and body mass and percentage of body fat and we do exactly the same exercise it doesn't mean we're going to sweat the same so one of us could sweat way more or way less for doing exactly the same thing exactly the same intensity so one of the issues is how much you sweat and things can get very complicated when you find people on the extreme cases especially when you have what we call the heavy sweaters people that they sweat profusively there are people i mean i mentioned earlier runners that they will sweat as much as close to a gallon of water per hour um and and i'm not taking the examples of a defensive lineman you know like a massive person 350 pounds i'm talking about that a legit runner somebody who's like 150 pounds sweating like three liters of sweat per hour and on the same side you can have somebody

similar fitness sweating half of it so when you extrapolate that to an event that lasts 15 hours then these small differences can be extremely complicated to give one advice that will fit both of those extreme cases 100 so to make things a little bit more complicated and tying into the the sodium balance the the hyponatremia case is sodium concentration in sweat it's also not the same among people so there are people that they have very very low sodium concentration down in the 20 30 40 milli equivalents per liter of sweat and we have people that they have very close to 100 why we don't know why this is how humans behave so all human beings have that they are not in the in the intensive care unit they have almost the same level of sodium in their blood but in the their sweat they're sweat the sodium concentration could vary in a factor of three or four so when you have somebody sweating 100 milliequivalent per liter and somebody who sweats 20 so the the first person sweats five times more sodium per hour if that person happens also to sweat a lot then you have massive sodium losses

so what advice again do you give are you the high sweater and salty sweater or are you the low sweater with relatively low content of sodium in your sweat so this is why things are very difficult and very complicated so let's start barking up the right tree then because i i'm on board with you that these need to be individualized as much as possible from both the fluid replacement perspective and also the ratio of sodium per unit of fluid that the athlete needs to be ingesting and there's not going to be a universal answer for everybody it's not like we can say okay everybody just take 20 ounces an hour and even if we could say okay we'll take 20 ounces an hour if it's 80 degrees and 30 ounces an hour if it's you know 90 degrees that still wouldn't be the case because then we'd have to invite individualize it per individual on how much they're sweating and then also on the sodium concentration as well can i make it a little bit more complicated go ahead you can cut you guys go down the rabbit hole plus your pace totally yeah totally the terrain is it flat or is it is it the climb are you climbing over a mountain yep and because you're climbing your intensity goes up even though you're running the same speed yep so you your your relative intensity goes up significantly and the number one determinant of how much you sweat is intensity how fast you exercise you know are you standing or are you running you

know yeah yeah and i mean we so one of the one of the exercises that we give our athletes a lot and we do this at our camps and we have them do do it at home as well it's just a sweat rate test and their strengths and limitations to that obviously but it serves as a little bit of an education point first and foremost and then also um like a trial to kind of keep to keep coming back to and so so to describe that a little bit as we just have an athlete go out weigh themselves before a run go do a run weigh themselves after the run and figure out how much body water they lost during that run whether it's an hour hour and a half we try to standardize it to an hour and then that gives us some sort of target to your point stavros in those temperature conditions and those terrain conditions and in those intensity conditions now ultra marathon just happens to be a kind of a unique not unique in this case but the intensity tends to be relatively monotonous for the most part you could say that the elites do they can do a higher intensity on the climbs and lower intensity and since but once you kind of wash it all out so that piece of it actually i don't think gets too complicated in a race situation it might be different in a training situation but so let's take this away from the recommendation pieces one there's not going to be a universal recommendation for everybody it's going to be individualized and it's complicated before we go down that rabbit hole too much let's talk about how important it actually

is for performance and that's the tree i want to bark bark up and in in context for the rest of this conversation is what are the right hydration work or what what are the hydration implications of ultra marathon performance so you have a runner that does the western states 100 in 28 hours and they want to improve their time to 26 hours how is hydration a you know component of that there's been this rule that's that's floated around that a lot of runners are going to be familiar with and this is the two percent dehydration rule and it has just like everything else we've been talking about kind of come under attack recently why don't you give the listeners covenant of of an overview of that and how important even mild dehydration can be on performance okay so uh the two pincer the two percent came in 2007 actually the american college of sports medicine when they recommended the individualized hydration protocol they shift the focus from uh drink as much as possible to avoid to replace as much as possible of what you lose to avoid dehydration greater than two percent so the two percent was taking based on studies that they were published up to 2007 and most of those studies they use dehydration of

three four or greater percent so there were most of the studies were using actually at least three percent so there was almost an assumption that up to two probably doesn't make a big difference so if you're up to two you're probably okay so it's a guideline to prevent people from over drinking and and let me spend just a couple minutes to to describe what is over drinking so humans are not programmed to over drink during exercise humans are programmed to under drink during exercise so we don't drink that much and we're okay with that because we don't get thirsty very quickly and if we drink a little bit we wet our mouth and we swallow that process kills thirst very quickly so if you keep drinking a little bit thirst goes away availability of water also you don't have when you run you don't have water constantly next to you you know nobody wants to carry you you know liters of water with them so so that leads to uh what it is described in the literature as an involuntary dehydration so um some people however they thought if drinking a little water is good drinking a lot of water is better drinking way more than a lot of water it's ten times better probably so who really gets um dehydration and uh who really gets i'm sorry over hydration and hyponatremia are usually people

that they go above and beyond what you could ever imagine so just to give you an idea that one of probably the best studies ever published in in marathon running and and hyponatremia was done in the boston marathon i think in 2004 by almond from harvard and it was published in the new england journal of medicine which is the the most prestigious medical journal they found that the people that they develop severe hyponatremia they gain in a marathon listen to this seven to twelve pounds so you finish a race you finish a marathon and you gain 10 pounds you know what is that i call it not a running race i call it the drinking race because you also sweat yeah you exercise and you sweat you spend more time drinking than running a thing this is like this is not normal and and i'll tell you one thing which is which is the main reason that i don't like the argument drinking to thirst if you ask some of those people that they develop hyponatremia you know what they say if you ask them why were you drinking i was very thirsty thirsty yep so you could be thirsty and develop hyponatremia the more you drink your mouth dries up faster and you start feeling that you need to drink more water so we have people that they develop hyponatremia and they say thirsty so why would i go out and say drink to thirst that

you could also develop hyponatremia which is hyponatremia it's a terrible thing to happen you know it doesn't happen very often to be quite honest to the extent that would be very dangerous and lethal there are not as many people dying from hyponatremia most people die from complications of heat stroke and dehydration right but but it is a very very dangerous situation and we don't definitely we don't want people to become hyponatremia so so this is where the two percent comes from the two percent in an effort to avoid all these people thinking of you know let's drink as much as i can let's go crazy with it and if one is good ten would be better and 100 would be 100 times more um so um two percent it's something that probably unless the intensity is very high and unless the heat is not the the heat is not very high you might have a a very small decrement in exercise performance i would be happy to go and and explain you some very interesting work that we have done over the years i don't know if you wanted to comment for whatever i said so no so i want to get back to first off this two percent rule it's not like a hard line i think that's one thing correct for for people to understand you're above the line and you're good you're below the line and you're not good the second thing is is that yes even small amounts of dehydration can impact your performance and i think

this is where you're going at with some of the studies that that you're referencing let's let's go through that and probably start with what are like the practical levels of this quote unquote mild dehydration that you put your that you put the subjects through and then what are the like the practical outcomes of those so so um we made up the definition of what is mild dehydration we said if you're supposed to avoid dehydration greater than two percent than anything below two percent i would call it mild dehydration so this is how we define mild dehydration so anything at least one percent but less than two percent so that threshold of very very small amount of water loss so um ourselves and several other people have done series of studies uh and we have found that even a small degree of dehydration like minus one percent of dehydration could have a detrimental effect on exercise performance most of those studies are done in cycling performance we have done studies in a laboratory and we have also done studies outdoors we did a study a few years ago actually where we took cyclists and i use cyclists specifically because cyclists are obsessed with power to weight ratio especially when you when you have climbers and they through the fronts and they climb mountains etc so the idea is if i start a little

bit dehydrated so if i lose one or two kilos before so i'm like one two percent maybe down then if i can produce the same amount of power which is a big big assumption then per kilogram of body weight going up hill in the mountain i should be able to produce more power per kilogram of body weight because i have less water in my engine yep this is the team sky chris frum nonsense that you're referring to so chris frum never i'll call it nonsense you can call it nonsense if you want to chris frum never said that there are a lot of uh things in the media about that like chris frum was doing low carb diet i don't know chris frum was eating carbs like crazy last year when he when he did this crazy um attack in in giro ditalia and he won with a solo attack of 80 kilometers before the end of the stage anyway but anyway what i'm trying to say so the first study was done by an australian group and and they create a water deficit and they they make cyclists run race on a treadmill on on a massive treadmill on a big grade and they found that yes you lose weight but you cannot produce the same amount of power output so not only you don't go faster you go slower so some scientists have

suggested that this thing is because you do studies indoors and when you do it outdoors it's different etc so we we did this study with with um highly competitive uh cyclists and we did that study actually in athens in greece and we went to a mountain which is right outside of athens and we took a specific route which is a race route so there is a classic climb time trial race in athens and every cyclist who lives around athens they do that for practice like very often so it's something that you know it's a challenge you want to do something tough go climb that mountain and see how fast you can do it so we did that under two occasions one when they were well hydrated what we call you hydrated condition and another time when we use a minus one percent dehydration and we found that even one percent of dehydration which is literally one and a half pound of body weight loss for those skinny cyclists uh it decreased their exit their performance they did the route was approximately six or seven kilometers they uh they completed the race by approximately close to one minute slower even though they were lighter and this is the interesting part even though they were going slower their body temperature was higher right so they were going slower and they were hotter and the water deficit was minimal so i know you asked me the question what would be the implication for

an ultra the honest answer that i should give is i do not know because i don't i'm not aware of anybody who has done any studies of of that nature during ultra marathon we do not know however i assume if i had to guess uh that you should have some sort of an effect in ultra things get very complicated and they're very difficult to really assess such small small differences yeah well if if we're theorizing a little bit on that from one standpoint you could say that the thermal stress on the ultra runner is higher because the speed is lower and they've been exercising for longer so therefore the dehydration would have a bigger impact but on the other hand because the intensity is lower maybe it's the actual opposite so i don't know and i i appreciate the answer i don't know and because it is a it's a hard condition to study this is the truth i mean uh the lower intensity might be a little bit forgiven right because your your your cardiovascular demand it is not as um excessive so your heart rate you are not i mean those cyclists that they were climbing the mountains their heart rate was like over 90 of their max so they were going heart rates like 180 something mean which is nothing that you would ever experience during an ultra yep but i also think we'd be remiss not

to mention though the the training analog between the cyclist time trial that you're that you're describing and the training analog as it pertains to ultra running is the same i mean a lot of times they're going to be training at that exact same intensity and if anything i honestly this is my observational input from coaching a lot of athletes is they put more athletes tend to put more of a focus on their nutrition and hydration and race conditions as compared to training conditions and i think that those two should be equal because what you're trying to do in training is you're trying to optimize the output you're trying to optimize the power output in cycling you're trying to optimize the pace output and in running in order to create a super compensation effect and if you can use proper hydration to do that you should absolutely use that tool when in a lot of cases you can get away with it in two hour run in 60 degree temperature a lot of runners will just go out without anything and that's not what they should be doing in order to optimize their training for that day absolutely you're right we tend to forget that then we remember everything right before the race you cannot you cannot imagine how many people send me emails hey i'm running this marathon tomorrow i get those i get those emails from a training perspective i'm doing this ultra marathon tomorrow what should i do i'm like just go have fun at this point yeah go run okay so needless to say there's a performance implication even with small

amounts of dehydration one to two percent and even greater than that is it linear is it exponential like what are the consequences of greater than two percent uh greater than two percent i think uh especially when you reach the level of three to four percent then the detrimental is really really obvious and you have implications to other things that you don't see in the mild percent of dehydration you have effects on strength you have effects on balance you have effects on cognition cognition actually it's something that uh and mood is something that changes even from mild percent of dehydration and for some reason the data so that women seems to be more sensitive on uh on mood effects so their mood changes a little bit faster with mild dehydration and women versus in men at least this is what the the data that we have right now in the literature um indicate uh what is what is really interesting with uh with dehydration because this is something that some people have been all the way to the other extreme and saying you know don't worry about dehydration your body will figure it out and even if you lose four five six percent you're okay as long as you're outdoors and drink whenever you feel like um and and and i think where where these people were coming from uh they were thinking that most of the studies that have been published in in scientific laboratories they're limited by nature by two things

number one it's very very difficult to mask drinking so if you come into my lab and you are one of my volunteers and you do a study it's very hard to fake whether you're drinking or not so you know you're drinking and you know when you're not drinking so when you know that today we're doing this experiment that you're not going to be drinking anything psychologically you might be predisposed of you know today it's gonna suck and i'm not gonna perform as well as i could just because i'm not drinking anything so what is called the the predisposition or the expectation of low performance because um i have a handicap today the second part is that when you exercise and you get thirsty because you're not drinking and you get mouth dryness you develop so many negative cues that it makes you feel bad and you underperform not because dehydration is bad for you because you have those negative cues per se so the thirst that goes away if you drink on your own and you have even a little bit of access to water so so this is a legitimate concern that we took a very serious and we did this study actually that we published in 2018 we took athletes and we put nasal gastric tubes so instead of them drinking in one of the experiments we will push fluids directly into their stomach and on the other condition we

would not push anything we will pretend that we were doing the same thing so we had connected the tubes behind them and and the tube was connected to a a pump one of those pumps that we have in hospitals for intravenous infusion of fluids so we will plan we will um uh infuse uh plain warm water actually we even infused the water in body temperature so they would not feel the temperature going in so we were super super careful so we were able to blind them we even measure stomach fullness whether that would get any cues from their stomach of being fuller or anything and they had no absolute no idea what experiment they were doing the second thing we did we make them drink just uh two-thirds of an ounce of water every five minutes so just enough which is like a big sip of water just enough to wet their mouth and swallow that act of rinsing your mouth and swallowing that activates some receptors in in the back of your mouth that kills thirst so so we induced the situation where people were blinded they didn't know whether they were drinking or not and they were not thirsty so we were able to induce dehydration during exercise in one case that they were not thirsty and they didn't know whether they were drinking or not and on the other side we were you hydrated by infusing a lot of water into their stomach

and also drinking that very small uh sip of water every five minutes just to kill thirst so even under this scenario we found that exercise performance uh decrement is present so even if you don't know about it even if you're not thirsty your body knows your body knows and you're dehydrated and because you're dehydrated your exercise performance declines and the explanation is simple when you get dehydrated even a small amount of dehydration unfortunately you lose significant amount of water from your blood so your blood gets thicker and as a response because you have less blood your heart has to work harder to maintain oxygen supply so that stress in the cardiovascular system seems to be one of the first and most important implication that leads to decrement in exercise performance and also all the signals also uh um um as a response they create a condition where it's more difficult to dissipate heat so one of the things that happen when you get dehydrated less blood goes to your skin so less heat gets transferred from the muscles to the skin to the environment so what we see over and over and over and every dehydration study two things one we see higher cardiovascular stress so your heart rate beats faster your

cardiovascular system gets stress and number two we see your body temperature being higher and what is funny we find higher body temperature but with lower sweat rate so you end up sweating less with higher body temperature so your thermoregulatory system gets compromised that study that you just went over i remember when it came out i i thought it was a just a really brilliant and elegant way to do it i would not have volunteered for that study by the way you got some hearty volunteers from the way that you described it i'm sure we did the data collection in arkansas we end up recruiting people all the way to missouri and cancels we were we went to every bike team every bike shop we begged people to the extent that the year after we were doing a different study and we had to advertise any other study that we don't use nasal gastric tubes because everybody was like are you gonna put tubes through my nose down to my stomach i'm like no no no no well like like everybody else when i read that i'm like oh this is a really cool way to do it and then i started reading through the methods i'm like oh i would never sign up for this jason we did we did a lot of cool stuff actually in this study other than the tube and all that stuff we end up we paid the subjects to participate and we also pay all the subjects based on their performance outcome every time they were doing the performance element of the of this study so at the

end of the protocol was a very high intensity um performance element and we create a ranking of 20 different levels from 300 all the way down to 20 so when you were doing the performance and you had the nose the heat sensors inside the skin sensors iv lines and on and on and on you were hooked up you know and you were dying because you were doing very hard exercise we said now you have to try as hard as you can and you have a chance to make another 150 dollars in the next 10 minutes or 200 so even if you knew that jason is also competing who is very better way better than me maybe i won't make the 300 dollars maybe i'll make the 250 or the 200 or the 150 or the 125 or the 100 or the 100 or the second so we really really tried to make it work we we really really tried to make it as to eliminate other factors that could influence exercise performance as much as possible and you have to do that because as you know being a researcher and there's always going to be holes in studies and whenever one gets put out somebody's going to say oh well listen this didn't happen or this condition wasn't you know standardized for or you didn't control for this variable and that's part of science is you gradually kind of move the needle and you control for different variables and things like this i think that that one in terms of controlling for the act of drinking right wetting your mouth down and

blinding the blinding the subjects to being able to drink was is there any other plausible way to do that besides the way that you guys set it up uh we've done other studies with intravenous infusion so we infuse water directly not water actually sailing you cannot infuse intravenous water i mean you will kill people yeah but uh so we've done studies with intravenous infusion um and we've done with mild dehydration and intravenous infusion um otherwise still you know whether you're drinking or not there are other studies that they have done drinking with diuretics but then when you pee every 10 minutes like you know like if you pee like you know non-stop you know that you took diuretic so it's it's i won't tell you but it's not hard to figure it out okay let's move on to the sodium equation or the sodium side of this equation because you really can't in a performance context you can't talk about taking in fluid without also taking in some sodium on board um and the recommendations here similar to the hydration recommendations kind of go all over the map there was a recent uh issn position paper on on ultramarathons which kind of which kind of pegged the sodium in this range of three i should have looked this up beforehand but 300 to 600 milligrams of sodium per liter of fluid and while

you're going over why that's relevant i'm going to get that number specifically but my point is is the range is usually the range whenever it's presented is usually double from the low end of the range to the high end of the range which starts to speak to your individualization nature of how much sodium is contained in sweat why is it important though why is it important to just to not just drink to also have sodium be contained in what an athlete is consuming while they're you know while they're trying to perform so um so sodium has uh gotten very bad uh reputation first of all so let's start by that because uh it is very clear in the literature that for uh at population level people that they consume high amount of sodium they tend to have higher blood pressure lower bone quality and and consuming a lot of sodium it's not a healthy behavior so if you ask any random human being and say if you had to improve your diet what would you do so they will come up with the simple things i don't know maybe lower sugar lower fat maybe probably the third thing they're gonna say it's gonna be eat less salt right so there is the overall perception that salt is bad the next one is um it the important thing of this recommendation is that this is designed for people that are not athletes and definitely it is not designed for ultra marathoners

so unfortunately that method hasn't been disseminated widely so people don't know that they uh they should drink way more than uh the recommendation for inactive people so just to give you one idea uh there was a study published uh looking at it back in 2010 by ron mon where he measured uh soccer players in europe uh and he was measuring sodium losses in a 90 minute soccer training so he found that the amount of sodium that they were losing it was between 600 milligrams to 3 100 milligrams so the range again is is massive range it could be like from half a gram to three grams so six folds difference from one side to the other uh but this is excessive amount of sodium loss so if you give to these people consistently what are the dietary guidelines which is like a lesson of what they lose during a soccer practice these people progressively they will end up going on the on a negative sodium balance so so definitely this is not something that you can do and and this is not healthy for them and i have seen it from practice over and over with with many different people that they have all sorts of symptoms and complaints etc

and and all those complaints can go away just by adding a little salt in their diet i mean i can tell you stories like one after the other we did another study with uh i don't know if we will qualify as ultra it was uh um um over a marathon it was that qualifies come on 50k is the ultra marathon we're not pretentious about that stuff all right okay so um 50k race in um in in a trail and it was actually the olympus marathon again in greece uh and and it's a very tough one because it starts from sea level and it goes all the way up to 10 000 feet altitude and then you finish back down to sea level so lots of climb and and difficult terrain and and you you run the entire olympus marathon actually from the base all the way to the top um and uh we were doing a study there actually that was published a few months ago and we were also looking for hyponatremia and i remember at the end of the race this guy comes to me because he knew that i was running that study and he was like can you help me i was like i am getting cramps i was getting in i get cramps all the time in this race i had to stop and rest and stretch and eat etc i was getting cramps everywhere so i'm talking to this guy and i'm looking at him and the salt deposition on his face he was like unsafe for a couple days probably it was like salt scales on his

face i end up asking him permission to take a picture i'm like can i take a picture of your face i have pictures of people with you know massive salt stains i use them for presentations i have published one of those pictures actually in a in a book chapter a few years ago but so i start asking the the classic questions and the classic questions are are those do you live alone or do you live with somebody who's hypertensive i'm like i live with my dad and my dad is hypertensive do you do low salt diet like absolutely we don't buy salt in the house at all wow and i started laughing and i'm like what do you laugh i'm like it's good for your dad probably yeah but for you you need salt like you're sweating you lose a lot of salt so what i'm trying to say the take home message is that salt has for a good reason has gotten very bad reputation there is uh sodium uh uh sensitivity and and hypertension associated to high sodium intake but for an ultra athlete high sodium diet is very good for you it's something that you need so it's i've seen things going from one side to the other i've been to races and and give talks before water races and talking about the importance of taking sodium and then i've seen halfway through the race i have seen people taking a glass with very little water pouring maybe an inch of salt on the

water stirring it with her finger and chugging it the whole thing i was like that's not what i meant well it there was there was one point where sodium was pushed copiously on ultra marathon athletes to where they would recommend you know over a gram or even two an hour and for the life of me i've never understood why why those recommendations had ever come out in terms of per unit time but to drive it back to the recommendation is just as a little bit of a clarification i did just look up the the issn statement it's 500 to 700 milligrams of sodium per liter of fluid and that's sodium coming from all sources so sodium in your drink sodium in your food sodium in your gels and things like that your story of the of the salty sweater is one that a lot of ultra runners are going to identify with is would that be a reasonable tool to dial in that record that individualized recommendation like if i go out on a run and i don't have the salty scales on my uh you know on my on my face everywhere i'm not going to be one of the people that you take a picture of i can be towards the lower end of that recommendation the your salty scaly friend might be on the higher or even over that recommendation is that a reasonable way to even think about it i think it makes sense um it's it's not scientific but you know how in

hydration you say take a look of how often you go to the bathroom and how dark is your urine that would be take a look at your clothes do you get massive salt stains when you exercise for relatively short period of time if yes this is a sign that you're losing way too much sodium so so this is a a ballpark estimation if you want to be scientific you know collect sweat measure the concentration and be very scientific um i've i've measured hundreds if not thousands of people over the years and and unfortunately the range it's absolutely crazy there was uh there are multiple studies there was a study published a few years ago from the gatorade sports science institute because they do a lot of sweat testing with athletes that they sponsor and they collect all this data and they had hundreds and hundreds of athletes and they had you know ranges uh there was another study that just published recently in people with muscle cramping history and looking at sodium losses from sweat it was just published a few days ago by kevin miller susan juergen and brendan mcdermott i believe um so there is again this large range and if you don't have access to a lab laboratory based assessment that's a an easy way to say the massive self stance is an indication that you're losing a lot but you do need so let's just like

get the obvious stuff out of the way okay in an ultra marathon situation you do need sodium that is coming from that can't or i get that can come from a multitude of sources in the sports drink from food from salt you know putting salt in water and stirring it from from from somewhere from somewhere because the losses are so long so big that it's it is really matter of time that you will develop hyponatremia it's math so if you keep drinking only water and you keep losing sodium and you don't replace that sodium loss it's matter of time when hyponatremia will develop and it's a factor of how much you sweat how concentrated is the sodium in your sweat and how long is the race so if you're a salty sweater with and high sweater and you exercise in a long race like spartathol is a good example for hyponatremia because it's like mean finishing time of our volunteers was 30 hours so you will develop it unless you take some some sodium intake through your diet whether it is a peel or whether it is a salty cracker whether there is something but you lose way more than you think you do and and um it's drinking salty drinks during exercise it's not very pleasant to be quite honest well and they've tried

to mask it recently right with just the flavor profiles i actually think that the the the higher quality commercial sports drinks so the scratch labs the fluids cliff has one that's quite uh that's quite good osmo has one that's quite good they generally do a pretty good job of balancing the flavor profile and the sodium content as well as the energy content because they know that it works yeah and and those are stuff that you should try and one thing which is very important in ultra probably the the single most important determinant of whether you're going to finish or not i think an ultra race is whether you can maintain good gut health during the race uh if something happened in your gi system and you have vomiting and diarrhea and you cannot eat food you cannot finish the race it's over if you cannot address if you cannot have a healthy gut during the race you're not finishing the race uh especially races that there are you know multiple hours uh yeah you need you cannot sustain energy supply with what you started with you have to take it absolutely 100 i mean that and that's and that's what uh uh that the author of the issn position paper that we were just referencing he was on an earlier podcast nick tiller that was one of the things that he kept emphasizing is that if you can't take in calories your day is going to go away that's the single most important thing to to to keep in mind with any of

this stuff so sodium intake for all the ultra i think in my opinion it is necessary uh if your exercise duration is up to three hours you can get around with just drinking um water you know you don't really need electrolytes when the duration is and and if you uh read more specifically the 2007 position statement from the american college of sports medicine it says this is for uh prolonged period of exercise this is when you really need the sodium and even carbohydrates if the exercise duration is up to one hour of high intensity or um even longer with lower intensity you could probably get around without even carbohydrates but for the long events uh taking electrolytes um and and obviously calories and carbs yeah it's it's necessary to be able to sustain energy production there there's been a movement in the ultra world over the last uh few years away in with regards to sodium moving away from the pills the s caps and things like that and towards sodium sources that are either contained within the drink or contained within food stuffs and a lot of that rationale is based around the dump of sodium that you're getting all at one time with those pills how like how valid is that or should that still be taking in those pills with that big sodium dump should that still be part part of the strategy so the

the concept is the the idea against it is if you put a massive amount of sodium at the same time in the stomach you put a massive osmotic load so you keep something which is very concentrated in in your stomach so when whatever you eat gets liquidified and it's very highly osmotic so very hypertonic it takes longer to be absorbed so you you give a little bit of a shock in your stomach and your gi system when you run this kind of races it's already sensitive so you're in the border trying to maintain gut health and finish the race we know that most of the ultra runners by the end of the race they develop some sort of um especially running they have most of them they have a micro gi bleeding um this is very evident the mechanical um torturing i would call it you know i mean running mechanical stress yeah the mechanical damage by itself from the vibrations of running um it's contributing to this kind of issue um we have done studies with um looking at gi distress and we were measuring specifically we were collecting stool samples after the race measuring hemoglobin concentration from uh runners versus cyclists for example so we will have cyclists in 40 degrees plus c like over 102 degrees celsius uh sorry far night and they will have not no hemoglobin whatsoever right you you look at runners that they do the equivalent

uh running and you have like incidents of like 80 percent so so gi system is very stressed overall so it's a good idea not to shock your gi system by giving a massive amount at the same time or if you take some pills just paste them don't take too many together so that's the concept trying to give something which is not too concentrated so your body can absorb easily fluids uh yeah everything else and that's why from a practical recommendation standpoint we tend to try to drive a lot of the sodium needs through the fluid because then they're getting it in that constant drip and it doesn't create that osmotic load in the stomach plus it probably tastes better yeah 100 percent palatability is very important uh when people drink um so so it's a palatability can drive fluid intake as well trying to maintain good hydration during the race yep okay so we talked about even very mild i'm going to expand upon your mild definition between two percent and zero percent to be very very mild one percent or even less that amount of dehydration is going to impact performance we know that sodium needs to be consumed in conjunction with water in order to maintain the right electrolyte balance but is weight loss weight loss inevitable as a result of dehydration or water loss is weight loss inevitable in an ultra

marathon situation given it's so long so many calories need to be processed you're mobilizing fat stores you're mobilizing carbohydrate stores how much can we extrapolate this one to two percent weight loss declining performance in any other situation how much can we extrapolate that into ultra or is some amount of weight loss tolerable this is a very good question and i wish i had a good answer um and i'll tell you where where i think the root of your question is that in laboratory settings we use change in body weight as the definition of dehydration so we bring somebody in the lab we take their body weight uh we measure that there are 150 pounds we put them on the treadmill they run for the for an hour they lose four pounds and you said you're minus four pounds dehydrated which is let's say two percent roughly two percent um dehydration so when you go in prolonged type of exercise that could be multiple hours you don't have only water loss you also have you know nutrients that you lose plus things that you eat and occasionally in some cases you might even have bowel movement during a race so all these things could play a role so the the calculation change and body weight equal change on hydration status it is not perfect uh when you're

looking into um endurance races and and it has to be i mean obviously it can be calculated but it becomes so complicated even for scientists that it's i would say impractical what they would recommend i would say overall um up to one percent of dehydration probably and again is it the six hours ultra is it the 26 hours ultra that could make a difference um that would be something that i would consider you are probably okay the one percent i think it's fine uh having a scale and i know uh athletes have support groups etc and measuring your body weight during the race the value of taking your body weight during a race is is tremendous i think it can give you a very good idea how you're doing um we have people i mean we have a lot of data from from this sportathlon race which is difficult to keep control of what you're doing in so many hours and people get exhausted they're they're hot they're hypoglycemic they're hyponatremic they're exhausted physically emotional uh they're athletes that they're like dilutional at the end of the race they don't know where they are i remember some years ago there was this japanese uh ultra guy who finished in sparta you know in the finishing line it's so emotional and everything and the guy had no idea what he was i bet anything he would not remember anything from from the at least from him finishing

the race i've been there this is such a shame you know you did it you you did the race he was out completely so how would you expect that person to have a good perception of how thirsty this person is or how well hydrated this person is so having a scale you can get a very good idea approximately where you are um ultra race fluid balance it's the most complicated case uh to to really monitor yeah and when you start seeing minus two minus three percent of your body weight then within the margin of error that you do have because it's not a perfect tool it gives you a very good advice whether you should pick up the game or if you start seeing that you're gaining weight you're doing something wrong you know slow down your drinking you don't have to do that much so some so some weight loss i i think we can kind of stylize this is some weight loss one to three percent or so in an ultra situation obviously depending upon the length of it would be would be tolerable and probably wouldn't result in any sort of performance decline but i also think the other thing that especially the medical professionals are really wary of is they don't want the athletes to gain weight because of the medical because of the medical risk associated with over being over hydrated and hyponatremic at the same time and that's where we come into the weight recommendations as well this is absolutely right so you should pay attention you by any means you should not be gaining weight during a race and and i think the

data from boston marathon i think are some of the best data that we have and they had hundreds of subjects that they were running the race if i remember correct they had about five six hundred runners and and they indicated they once that they were developing hyponatremia they were gaining um seven to twelve pounds in a marathon race which is mind-blowing over five kilos and that would be hard to do if you tried i remember seeing that and going like that's that's an event in itself i've done the math um and i was trying to figure out like how much does it take so um i mean i do it in my head it's a little bit over a pint every two miles so so you're supposed to drink uh to gain the the that limit in kilos is three to five kilos in a in a marathon race so in 26 miles right so you have to drink 700 to 1200 ml above what you lose by sweating or urinating right right every 10k right every 10k you need to have almost a liter one of the two miles above to what you naturally your body's gonna lose anyway i know so it's there

so is that reasonable no yeah you have to try to screw that up you have to you have that that's my argument so that's exactly my argument this is it becomes a drinking race i call it not a running race yeah don't do that don't you will for sure end up in stavros's medical tent very early in spartathlon if you undertake that strategy you will not be finishing spartathlon with that strategy no chance these people are very experienced we didn't have anybody i think that gained so much weight yeah yeah okay we're gonna let you go i really appreciate it i really appreciate your time and i appreciate the little bit of baiting that you uh that you had to put up with me with the acsm statements and whatnot but it makes it interesting right because it is as you mentioned it's confounding yeah um it is difficult and i think it's difficult i don't think anybody has an intention to hurt anyone uh nobody's gonna gain you know anything by drinking more water you know nobody sells water you know we don't have uh i don't have uh i don't have stock in uh in the local phoenix water company or anything you know you know um the i think the intention behind those guidelines when they came out in 90s drinks uh drink as much that got very very heavily scrutinized it was the intention addressing people that they could not

drink much at all and back in the 90s most people will not drink anything whatsoever they will just do the race and don't even bother at all like use the sponge and put some water in the head you know maybe a little bit on your lips and and and that's it and drink very low yeah so so the thing this is the mindset and um the the the more you drink the better it is it's something that some athletes you know the paradigm you know and it goes with everything with nutritional supplements somebody says you have to take i don't know creatinine i was in an acsm conference a few years ago and we had this uh uh professor from uh university of massachusetts her name was priscilla clarkson she passed away a few years ago one of of the most distinct professors in muscle physiology in america and she was presenting data from a bodybuilder who was taking for more than six months 80 grams of creatine as a supplement per day like the the dietary guide the the guidelines for creatinine as a supplement right now is around two to five grams per day some of the older protocols were 20 grams per day this guy was taking 80 grams for six months he developed this muscle issue they had to take him to the hospital but the only reason i'm bringing it up is if if five is good 25 is five as five times as good and 80 is

probably 20 times as good you know what i'm saying so it's that mentality sometimes that if one time is good multiple times is better and i think this is has this is what has driven the over drinking sometimes in some races and ultra runners are notorious for taking that advice to a tee if five miles is good 10 miles is twice as good 20 miles is twice as good as that and 40 miles is twice as good as that so i'm just gonna do the the the maximum tolerable dose right is is what gets put in the literature every once in a while so we would be good we as a community as a as an ultra running community would always be well served to to realize that there's some reasonableness that we need to apply with any sort of recommendations and more is not always better absolutely all right where can people learn more about you and the research that you do um i have a twitter account that i post things that we do in the lab and things around hydration and it's uh my twitter handle is dr hydration and dr hydration so one word and i also have a twitter lab uh page that we put stuff more related to hydration science per se which is uh hydration sci s-c-i awesome you have an awesome twitter handle by the way i'm envious of that you can't talk to

hydration i'm glad you nabbed that really early on thanks what you do we'll have uh links to all that stuff in the show notes for the people that are listening and keep what doing what you're doing in stavros it's awesome work there we go there you have it that was fun this whole thing with hydration has always been so confounding to me and i can remember at several points of my career as we went through uh during the podcast of where these different recommendations come out to drink as much as you can to offset uh any sort of body water loss drink to thirst and i really think that we found the right solution now where we're trying to as much as possible come to customized individual hydration plans for each and every single athlete but that takes a lot of work it's a lot more work to go out there and figure out what your sweat rate is in different conditions under different intensities as opposed to just saying that i'm just going to take in a liter an hour all the time i realize it's a lot of work but it's worth it in the long run and as we went through during the the podcast there are real absolute performance uh implications for this that can either happen during the race or during training and you want to perform at your best during training as well those the way that you perform in training absolutely has an impact on how much you can improve and then therefore will have an impact on whatever race or event you are training for hope everybody found

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