Hydration Consideration for Female Ultrarunners with Nidia Rodriguez-Sanchez, PhD #208

View all show notes and timestamps on the KoopCast website.

Episode overview:

Nidia Rodriguez-Sanchez, Ph.D., has spent her career in the field of sports nutrition and physiology. She earned her BSc in Dietetics / Clinical Nutrition and later pursued postgraduate studies in Anthropometry and Nutrition applied to Sports, which gave her a better understanding of the unique nutritional needs of athletes and physically active individuals.

Dr Rodriguez-Sanchez has worked as a sports dietitian for a Mexican professional football team and as a nutrition advisor for the Gatorade Sports Science Institute Mexico. She also holds an IOC Diploma in Sports Nutrition, and she is an ISAK Level 3 Instructor.

Dr Rodriguez-Sanchez holds a PhD in Hydration Physiology and has completed post-doctoral research in the field.

She is a Physiology and Nutrition Lecturer at the University of Stirling, where she also serves as the MSc Sport Nutrition Programme Director.

In addition, Nidia is a Fellow of the Higher Education Academy (FHEA), a Graduate member of the Sport and Exercise Nutrition Register (SENr), and a member of the Physiological Society (PhySoc).

Episode highlights:

(17:53) Theory on hormone cycles and hydration: estrogen and progesterone can impact nutrition needs, performance, brain function, investigating fluid and electrolyte balance

(25:27) Practical considerations for females: no meaningful differences in hydration for female athletes versus males or across different phases of their cycle, no performance differences, avoiding overhydration, cross-cycle variations in core temperature are insignificant

(36:23) Sweat testing: Precision Hydration sweat testing at CTS, sweat testing protocol, menstrual cycle phase does not impact results

Additional resources:

Fluid and electrolyte balance considerations for female athletes-https://pubmed.ncbi.nlm.nih.gov/34121620/

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Transcript

Speaker 1: 0:10

Trail and Ultra Runners. What is going on? What's happening? Welcome to another episode of the Coupecast. As always, I am your humble host, Coach Jason Koop.

Speaker 1: 0:21

In this episode of the podcast, it attempts to shed some light on the off-debated and misunderstood aspect of the hydration requirements specifically for female athletes. Let's face it, there's a dearth of research on female athletes, and when you combine that with the different practices and philosophies out there that at times prescribe different training programs and even different nutrition strategies for females, either as a byproduct of their sex or in conjunction with the fluctuations in their menstrual cycle, the landscape can get quite confusing. So to help us understand the hydration side of this a little bit better, welcome to the podcast Nydia Rodriguez Sanchez, phd, who is coming to us from Scotland via way of Mexico. Nydia just wrote a fantastic review paper titled Fluid and Electrolyte Balance Considerations for Female Athletes, and a link to that will be in the show notes. During the course of this podcast we go over it all. We go over why females might have different hydration requirements, what are the mechanisms that could cause their hydration requirements to be different, and ultimately try to answer the question that makes the most impact Do females have specific hydration requirements that we as practitioners need to take into account.

Speaker 1: 1:43

All right, with that out of the way. I am getting right out of the way. Here's my conversation with Nydia Rodriguez Sanchez all about the hydration requirements for female athletes. I appreciate you coming on the podcast today. I'm always really excited to bring up these topics about females, and particularly with female researchers, because I believe that's the right way to do it. Sometimes I feel like, with all due respect to the dudes that do this research, it just feels weird talking amongst a bunch of men about potential differences in female physiology. I always appreciate it when we can bring in our female researchers to talk about these subjects, but before we get into it too much, we were talking off air about some of your athletic endeavors. Why don't you just run the listeners through who you are as a person and then also some of the research that you're involved in?

Speaker 2: 2:39

Hi, jason. Well, thank you very much for inviting me. It's a pleasure to be today in the podcast. First of all, I'm originally from Mexico, where I was many years in Mexico City. That's where, from the professional point of view, I am a clinical dietitian. I studied nutrition for years and then was very into having practical practices in the hospital. Then I decided, well, this is not quite right for me. I kind of look into more the nutrition side applied for sports. I just love how having another weight nutrition strategy can help athletes and meaning athletes and not specifically elite athletes or professional athletes at any level. Well, having another weight nutrition, another weight dietary strategy, can really change the outcomes. Just the fact of enjoying the sport, enjoying the activity that we're practicing. I love that of sports nutrition.

Speaker 2: 3:43

Then I worked for a while for the Gatorade Sports Science Institute in Mexico. I had the opportunity to work with different athletes, with football players. I had the opportunity to work with the National Performance Center where we had hundreds of athletes from throwers, team sports, like a very wide range. Then I did the IOC Diploma in Sports Nutrition. That was an online program. I did in 2008-2009. I remember thinking it's an online program, it will be an easy one. I think I will manage. It was not.

Speaker 1: 4:17

No, it's not. I know a lot of my colleagues who went through that around the same time and they had the exact same thing. They all came. I remember them coming into the office every day with just wide eyes. I can't believe I'm trying to absorb all of this information.

Speaker 2: 4:29

Absolutely. The language, of course, was another challenge, shall we say, and having that with a full-time job working for different companies supplement companies. I work also for a football team in Mexico City. Then I just started trying to grow, or to develop further. I found out about the possibility of doing the master's conversion from the IOC Diploma. There was a possibility to come to the steering in Scotland to do a six-month master's conversion. Of course, those six months converted into 10 years that I have been in Scotland. Now I was just enjoying my time in Scotland.

Speaker 2: 5:11

I ended up doing a PhD that was on hydration, basically Hydration, and we're looking at the impact on body composition estimations. And also I've contributed to the development of the Beverage Hydration Index. That was a multi-center study that we worked with Love Photo University, van Gogh University and well, the steering with Professor Ron Mon as the lead of the project. And then I had also the opportunity to do a postdoc period and I was also working on hydration. And then I have been a lecturer for five years now on physiology and nutrition and well, parallel to this, I also love running, which is interesting enough.

Speaker 2: 5:53

All my life, since I was a teenager, I started practicing in a sport and I was a gym goer and I also was a spinning instructor when I was at uni.

Speaker 2: 6:04

I remember I would cover the six to eight am classes and then go to uni, quick shower and go to uni. I remember seeing the people that were running and I was like I don't understand why they run like that, like no one is chasing them, no, so I kind of didn't get it at the time. And then, well, just because of my job, I needed to go to cover a race and it was just basically to be there in a race and pick up a number and the numbers pick up of a 10K race in Mexico. And the organizer of the race he told me, like are you running the race? And I was internally like no, I don't really know I was. I had seen that it was sold out as a shame I could run it, but I am. I know there is no any number of I love alone. He was like well, if you want to run it, I'll get to one of the only.

Speaker 2: 6:48

And that's how I ended running my first 10K, that I was quite happy with it Because I did it well. I did 52K, 52 minutes in the 10K. Nice and I just I was, I think this is nice and I just love it, and that's yeah. When I got the running bug and then, well, my aim was to run a half marathon, then a full marathon, and well, I just got into it. And well, just last September I ran my 10th marathon. Wow, 10th marathon.

Speaker 1: 7:14

Congratulations, that's cool.

Speaker 2: 7:16

Thank you, thank you, thank you, and you know I also feel like for being able to work with athletes, and well, with runners particularly. I couldn't be recommending anything if I haven't experienced that myself. No, like I know how it feels, like, yeah, getting the horrible cramp and well, how, like, yeah, yeah, even being a dietitian, yeah, once I experienced, I think, what was close to be the wall and I was like, well, I really understand how I might feel and, of course, well, I need to work on that. No, so, yeah, definitely I, yeah, I think it's important to to experience that, to be part of that, to be able to understand the needs and, well, to, yeah, to feel what they are with my field.

Speaker 1: 7:52

No, I appreciate that background. You know you're it's not indifferent from a lot of the people that I interview where they have a personal interest in the sport that they're all also studying. I also appreciate people who come from a broad sports background and then eventually kind of tailor into their area of expertise. And for you it seems kind of and this is going to be the subject of what we talk about today it seems like a lot of those roads have started to narrow down into the lane of hydration and fluid balance, which is kind of the subject of the of the discussion. So this you kind of came on my radar with a recent paper, a recent review paper that you wrote, which is the title of which is fluid and electrolyte balance considerations for female athletes. I picked it up and you have to forgive me, I'm I'm forgetting temporarily if it's open access or not, but I was able to easily find a copy. Is it an open access paper?

Speaker 2: 8:40

Yes, okay, perfect.

Speaker 1: 8:42

So I'll leave a link in the show notes so that people can go and read this. It's a great read, it's well illustrated. I think people who even have just a cursory exposure to scientific literature will be able to kind of pick up on on some of the main points. But I want to kind of go through. I want to kind of peel back your thought process on writing this paper. Because whenever you do a review article it's a very deliberate decision, right? You don't. When you have like experimental data, you have to turn that experimental data into paper, into a paper. But when you do a review article and you're taking in kind of more of a consensus of the literature with you and your co-authors, there has to be some sort of like catalyst for that. And I'm I've always curious what is the, what was the catalyst for that and what, ultimately, were you trying to kind of like tease, tease out with this review article?

Speaker 2: 9:31

Yes, so I think the main reason for well for this article in particular and well for it's a collection of articles, so I think well, there is a are a number there that it probably just 30% of the sports and exercise science or sports nutrition related studies include females, which is shocking, I think. No, like well is how the, the women are generally underrepresented. No, and I think that was what triggered the, the preparation or the planning of this special number of the journal. So the European Journal of Sports Clients, they, they decided to create this issue. So it's a special issue where, well, where this review is is part of there are, there's a, it's a collection of papers, of reviews, so there is one on carbohydrate, there is another one on a protein and well, this special issue that is is is typically targeting nutrition for the female athlete, was well, the editors or a where, professor Kirstie Elliot sale, who is in Manchester Metropolitan University, dr Jose Areta, that he's in Liverpool, john Muir's.

Speaker 1: 10:36

So they weren't there in the Westworld.

Speaker 2: 10:38

Sorry.

Speaker 1: 10:39

Jose is a former podcast guest as well.

Speaker 2: 10:41

Oh, excellent. So, yeah, he's a good colleague. So, yeah, they actually were the ones with the original idea who decided to put this together. So I think they, yeah, they look into well who is doing research on these topics and well, they organized that special number. So this is issue number five, I think, and, well, it's all the topics around nutrition for female athletes, and I love that issue of, well, not because I'm part of the authors, but because I think it's very relevant to the part of the carbohydrate that they actually, yeah, they have been to well, do we need a special recommendations for the female athlete? And well, the same for protein. And it is a very nice collection of reviews.

Speaker 2: 11:24

And well, they got in touch with Professor Stuart Galloway, who is, well, my mentor and he was my PhD supervisor and well, because we will his expertise in hydration and also Paola that, well, he said the main author of the paper. Well, they did a study where they investigated the impact of the menstrual cycle phase in the on rehydration. So actually, in that study I contributed a bit and I was one of the participants as well, so I had, I experienced the trials for firsthand. And well, yeah, they had a fluid restriction protocol. And then, well, you would need to go on their exercise period and then they were measuring, yeah, the different responses on post-hydration, yeah, like impact, or how the menstrual cycle would impact the post-hydration responses. And well, that's how we started working on this review.

Speaker 1: 12:14

Well, and there's been definitely an uptick in interest over the past maybe seven or maybe even 10 years in how we need to look at females differently through the research lens, and it has a lot of different contexts to it, but I can kind of summarize it into basically like two buckets.

Speaker 1: 12:37

Part of this interest is some of the mechanistic plausibility of how females respond differently to interventions, to metabolism, how their hormone cycles are, how their hormone cycles affect different parts of that adaptive response. And then part of it is you alluded to earlier there's a really a dearth of research that's actually conducted on women. So it's kind of led to this really interesting milieu of practice which we see from coaches and nutritionists that is mainly based on the mechanistic side of things and this rapidly emerging science of how women actually respond differently to. We're going to talk about hydration today, but also the overarching umbrella within sports science. So whether it's a strength training intervention or even a training intervention and things like that, and before we dive too much into the hydration piece of it, I kind of want to just get your perspective of it, because you've seen that evolve over the course of your academic and practitioner practitioner career and I'm just interested to just hear that perspective of how you've seen that landscape potentially shift over that course of time.

Speaker 2: 13:47

Yeah, I think that's really interesting, that, well, how things have definitely changed. And well, if we think in the previous years, and well, I'm talking about probably some decades, you know, when even females, they weren't allowed to take part in a marathon because you know the fear that, well, they were too fragile or that something might happen. And yeah, I think there are some documentation that was some like, well, historically, yes, since I think, the Olympic Games in, I think, in 1928, when they, like the women, they were a band for their participation in distance events. So that's very scary. Well, there were some assumptions about the sex differences that, well, they might impact the, yeah, like their responses or their physiological capacity. And well, when we think about the Catherine, a sweet sir, well, of course, running in 1967, boston Marathon illegally, and well, you tell these pictures and all these videos of the other organizers chasing her because she wasn't allowed to do this. And well, it wasn't until the early 80s when there was a couple of stories when they demonstrated, well, actually, there is no difference between the thermal regulation between male and female. So it's not women are at that disadvantage, or that they might be at this risk or at the higher risk of heat illness. So I think that's when things started to change. Like, well, yeah, we are different physiologically, but not that different. Like, well, we need to take that into consideration, but there's no, that is I don't know. Like we are talking about completely different organisms. Yeah, like we need to consider some aspects, but probably we're like.

Speaker 2: 15:25

My opinion as a research researcher, as a practitioner, is, as with a man or with a male athlete, we go to talk about individualized strategies for the carbohydrate protein, or well, thinking about the pre-odization or depending on where they are at, their competitive vision, et cetera. Well, it's the same with females, in my opinion. Like well, we'll need to work on sweat rate, like the different requirements in that we'll talk about that later but, yeah, how much sodium they are losing through sweat. Like, well, thinking about the different environment conditions, like for a male or a female, it will be different if they are training in a 20 degrees environment or if they are competing at 40 degrees environment. So all of this will be different regardless if they are male or female. So I think, yeah, we need to focus on the personalization, but not just like the differences caused by the sex. Yeah, like the sex differences.

Speaker 1: 16:22

I think that last point is actually very poignant because I can remember long enough ago to where some of this initial practice that we need to design training and nutrition interventions markedly differently for females as opposed to males it was kind of the premise of that was kind of based on that two prong aspect that I mentioned earlier. First, there's a dearth of research around women, and so when you don't have that to draw from, of course you can draw different conclusions. But the second thing is the kind of the mechanistic plausibility around why we would actually want to design interventions differently around women versus men. And the combination of those two, the mechanistic plausibility with the dearth of research, led to a lot of this practice that, hey, our strength training interventions should be maybe our strength training I'm trying to be very careful, because this isn't something that I necessarily ascribe to and I want to kind of tread the waters kind of lightly Our strength training interventions might need to be different, or our hydration interventions might need to be different, or even the endurance prescription might need to be different.

Speaker 1: 17:33

And when you said we're all the same organism, I think that is the bigger category we need to think about.

Speaker 1: 17:38

Right, we're all humans first, and then we can have these individual differences of one of which and this is a powerful one, but with all you know, to be honest with you one of the one of those differences is sex. So with that as a little bit of a backdrop, we're going to, we're going to kind of drop into your review paper which specifically looks at the fluid and the electrolyte considerations for female athletes broadly, and then what we'll try to do is we'll try to tailor it into an endurance audience which we're going to be kind of the most, which this audience is going to be the most concerned with. So let's start out with a little bit of that dialogue that I mentioned earlier, kind of the mechanistic plausibility. You spend a lot of time in this paper talking about, theoretically, how hormone cycles can't I'm using the term theoretically intentionally theoretically how hormone cycles can actually impact the hydration status. Why don't you walk the listeners through that first, and then we'll get to some of the kind of the finer details of that.

Speaker 2: 18:34

Yeah, absolutely so. Well, the review, as you said well will be well presents the how hormonal changes during the menstrual cycle well can affect different aspects of the female athletes. And well, in terms of the hormones, well, the main hormones that we will be considering of course, there are many other hormones in a woman's body, but then those that have been observed that might cause some impact in terms of thermoregulation, in terms of thirst regulation as well, are the estrogen and the progesterone. Well, in general terms, well, they can impact the nutrition needs, the athletic performance. Well, some brain function.

Speaker 2: 19:15

Well, in the review, we've just focused basically on how the estrogen and the progesterone well can influence fluid and electrolyte balance during the menstrual cycle. And something that is important that we need to consider here as well is that, well, the facts, or what we discussed in the review, is thinking of normal or the normal or regularly ovulating women, which, if we think about that, that's another big challenge. That, well, we normally talk about the 28 days perfect menstrual cycle, which I don't know, you know, amongst my friends, amongst my relatives, I don't think any of them have that textbook 28 days.

Speaker 1: 19:58

And all the women listening to this are thinking the exact same thing. So don't worry, it's not just limited to your friends and family, for sure.

Speaker 2: 20:06

Which is, you know, it's one of the challenges, you know, in terms of research, like, I understand why just 30% of the studies have included females, because, yeah, of course, it's so difficult to control and if you wanted to be, like, really rigorous or very strict with your research methods, well, you would need to be testing the female participants exactly in the same moment, the same day of their menstrual cycle, which, if we think methodologically well, that would take four times or three depending on the intervention that you might have.

Speaker 2: 20:38

Nobody, I might take four times longer than testing a male. So I understand that's why. But well, again, there are some discussions about, well, like, how to write or how to describe this perfect menstrual cycle. Well, it's 28 days long as a normal length, but, again, in a human or a normal cycle, a woman, that might take between 21 and 35 days, so that's kind of still considered as normal. And well, in terms of the menstrual cycle, well, we know that there are, we can like, like to keep it simple. So there are two big parts of our faces of the cycle, so it's the follicular cycle and the luteal cycle, or the luteal phase. Sorry, it would be the follicular phase and the luteal phase, just to make it easier. So, whatever happens before the ovulation, that will be the follicular phase. Whatever happens after the ovulation, that will be the luteal phase. So and well, normally we would start the cycle, or when we start counting the days of the menstrual cycle is from the men's test or when the bleeding actually happens. So the start of the bleeding or the menstruation, that's day zero, and normally the ovulation, in this perfect 28 days cycle, that could be around day 14.

Speaker 2: 21:51

And well, in the you know about this, well, there is a. So there are the two hormones that will be contributing towards the fluid balance, the thermal regulation. And the third regulation will be estradiol or estradiol progesterone, and, in the like, when the woman is about to start the ovulation, there is an increase of estrogen or estrogen, and then it is kind of when we have like the biggest peak, and then the estrogen will also increase a little bit in the mid luteal phase. So those are the two, the two peaks that we might observe during the menstrual cycle. Then, in terms of the progesterone, will be like kind of a very low level. Then when the ovulation happens, that's what triggers the increase of progesterone and it will be at its highest level in the mid luteal phase again, so during the around, so day 22, day 24 of the menstrual cycle, that's when the there is an increase of estrogen and progesterone.

Speaker 2: 22:49

And that when it has been observed that there might be some changes in terms of the, for example, the body color temperature, there might be a slight increase in temperature, in the like, in that in the day 22, 24 of the menstrual cycle that's, and whether the mid luteal phase, so that's when possibly there is a well, there is a slight increase of the body color temperature and also temperature, there might be some increase on, well, the estrogen has also been observed that when the estrogen increases, that will reduce the osmotic threshold for thirst.

Speaker 2: 23:23

So what does that mean? That well, our the osmotic threshold is basically how Concentrated, just to keep it easy, like, well, how concentrated is our blood plasma or the plasma in our blood, and when the estrogen is increased, that will, that will mean that we will be Thirsty when there is like that, like the blood is less concentrated. So that has been an issue that has been discussed, that probably the fact of having greater levels of estrogen that might promote that females drink more. To work on that, something that we discussed in the paper that if females might be at a higher risk of hyper nitrime or this hyper hydration, when, well, if they drink too much water, that the, the, the sodium, in our blood gets too diluted and that might put us at risk of, yeah, having some Important negative effects in our health. I will also ask one of the aspects that has been discussed if the hormone changes in the Female physiology and then during the menstrual cycle, that might change. Well, that's something that might be different in women.

Speaker 1: 24:29

Okay, so you honed in on two of the aspects that probably get discussed the most within these hormone changes, and that's an increase in core body temperature and changes in the desire to drink. And A lot of women and men who work with female athletes, like myself, will recognize the first one through the lens of the wearables that are coming out that are trying to predict when the menstrual cycle or what phase of the menstrual cycle a woman is actually in, and a lot of that is just based off the Temperature that the device can measure not all of it, but a lot of it is actually based on that. So now we come into the, we come into like the meat and potatoes of this whole, like this whole discussion. Right, we recognize that these, that some of these hormone fluctuations do impact certain pieces of the physiology. Right, we can see rises in core temperature and we can predict things based off that corn terapature. We can see differences in the drive to drink and we can, you know, we can definitely observe and measure that and that's not really that disputed. What we can get into now is how does that actually impact people on the ground? Should we actually be prescribing things differently?

Speaker 1: 25:39

Compump, based on what part of the menstrual cycle female is in, or the fact that they are female in general and this is where we start to disentangle this do those physiological differences that we Can absolutely measure and recognize? How much weight do they have within the entire picture, especially when we're talking about athletes and there's a whole host of other things, whole host of other things going on, and that aspect of looking at the impact of the hormonal fluctuations to Reality, to performance, is not indifferent to to women. We can always look at mechanisms and how Exercise or interventions affect the mechanisms and then compare that to end performance or whatever end goal that you're actually kind of looking at. So I want to try to, like you know, go not to get too far ahead of ourselves here or to take any of the nuance out of your paper, but let's kind of go for the jugular and then we can back up and as to why. So when you can summarize all this paper Should women be?

Speaker 1: 26:44

Should women do they actually have different fluid and electrolyte needs During the course of their menstrual cycle? To the extent that we can prescribe, we should be prescribing things differently to them at any one of those points.

Speaker 2: 27:00

My opinion is that, well, we need to Keep well, like the recommendation is always. As for the males, I will like keep the hypo hydration or the dehydration levels to yeah, no, anything more than losing two percent of their body master sweating. So that would still apply for Females, regardless their menstrual cycle. So I think in this case, I don't think there is a. We don't need to prescribe something different based on their menstrual cycle phase. So, yeah, probably, yeah, it's important to understand Well what menstrual phase they are at, but it won't make any difference.

Speaker 2: 27:35

I'm just recently there was a review that was published by that Professor, stuart Phillips in Canada. He is one of the co-authors, is a he's a senior author in that paper where they demonstrated that, well, there is no any difference in terms of exercise performance, regardless there, the the menstrual cycle phase. So I think, for hydration recommendations, yeah, we need to stick a female athlete. They should be drinking enough fluid during the exercise to avoid any significant hypo hydration or dehydration. So that means they, the female athletes, they shouldn't lose any more than two percent of their body mass, and well, just to avoid any impact on their exercise performance. And Also the recommendation and this is linked to the hyponatremia Aspect that I had mentioned before, of course, preventing any body mass gain just to avoid the Overdrinking. I will probably that. I think that's another thing that happens with female athletes, that sometimes they are so concerned about getting dehydrated that it's easier to fall in the hyper hydration. So, like, well, answering to the question, I don't think there is a need to have recommendations Specific to the menstrual cycle.

Speaker 2: 28:47

So I think it's more about the conditions, about, yeah, the environmental aspects that, for, the Erroneer will be training, well, to know if they, if the humidity, to know, yeah, like, the temperature that they will be facing and, of course, well, this could be linked to the fueling, not to the adequate fuel strategies.

Speaker 2: 29:06

So, yeah, that's it, my recommendation, probably avoiding that. And yet, in terms of the, we were talking earlier about the differences in and the core temperature. So like, just to make that clear, yeah, the differences that have been observed in the mid-luteal phase, that the other is an increase in the core temperature, well, it is around point five degrees. So like, well, just to avoid thinking that we, and, well, that's a Celsius degree, so it's not going from 36.5 to 42 now, so it couldn't be something like that extreme. So it's a slight difference that yet has been documented, but, yeah, that wouldn't justify any change in the hydration strategy. So it could be more linked to, yeah, what they are actually doing, the requirements based on the Exercise, the intensity, the duration, rather than the the menstrual cycle phase.

Speaker 1: 29:57

Okay, let's let into the next question that I was gonna have with the very tail of that answer. So let's consider the situation of the individual all. Actually, to put your nutritionist hat on right, you're a practitioner, you work with individual people. You have one, you have a single person and everybody out there can kind of or all the women that are listening to this out there Can relate to this and they have a really dialed Hydration strategy. They know, and we do this with our athletes, we, they know, listen, I sweat out 500 milliliters per hour when I'm in, you know, 21 degrees Celsius, and then it's 600 milliliters per hour when the temperature goes up. They have it really dialed. What could that potentially change for that single individual Across the mental cycle, to the extent that you would change the prescription of how much they should be hydrating? You mentioned that this 2% rule, which is kind of an end rule. I get that, but on the prescription side of it, in order to prevent that, should that actually be changing on the individual level?

Speaker 2: 30:53

I would say no, I would say well, I think, like, and also this is a recommendation that when the athletes I've worked with this, well, when we can't have the same sweating rate for all the year round, so it depends on, yeah, like, for example, if it was a training or competing at 21 degrees and well, we know that's the sweating rate, that would be pretty much the same in, like, during the luteal phase or the follicular phase, so it wouldn't make any difference.

Speaker 1: 31:21

In the. I think what I think, one of the things that you also mentioned is the magnitude of the change of the core temperature. So, yes, we recognize the fact that core temperature changes throughout the menstrual cycle. But what we what? Sometimes what gets lost in that discussion is what is the magnitude of change? Just due to exercise and Typically in almost all of these hormonal discussions and core temperature discussions, and there's a whole host of other things Exercise to tends to be the bigger hammer in the room, the hammer that makes the, that causes the most damage, that has the biggest effect, and that's just because your metabolic output Kind of controls everything and in your metabolic output goes up 3x, 4x, sometimes 10x from from resting. That has a cascade of a whole host of effects that Drown out. The other thing, the other effects that we're looking at in rest, is this in your opinion Is this the same case, so that we see, when we're looking at these core temperature changes that we very do, we recognize very readily across the menstrual cycle? Yes, absolutely.

Speaker 2: 32:27

So, yeah, I definitely did exercise. Yeah, good, being like out greater way bigger like factor that will be changing the core temperature rather than the menstrual cycle phase. So, yeah, something that we need to consider. Yeah, like well, it's kind of observed. Yeah, it's just around 0.5, like well, the temperature 0.5 higher in the luteal phase compared with the early follicular phase. So well, it's just minimal. And when we think about that bigger scheme of things, yeah, absolutely yeah, it's nothing that we would need to be concerned about.

Speaker 1: 33:04

Okay, so we've teased apart some of the We've been using the term hydration and I don't want the listeners to kind of come away with it. That means just water, right? There's an electrolyte component of this as well that I think that we can look at separately and it's a component of the paper that you mentioned. So can you give a broad overview of how the electrolyte sodium, potassium, the whole magnesium, the whole host of electrolytes, how those requirements may change based on these hormonal fluctuations?

Speaker 2: 33:36

Yeah, absolutely In that regard. Well, always keep that in mind that when we talk about hydration, definitely we need to consider electrolytes, as you mentioned sodium, potassium, magnesium, calcium. They are key to, they are those components in our cell that will be helping to bring the water in the cell. And well, of course, the kipinos, well-hydrated, and of course they facilitate if we think about the carbohydrate intake. They will be also related to that. And in terms, there has been observed that, in terms of the differences in the sweat electrolyte concentrations, well, it has been observed that in general, well, like what is sodium and chloride concentrations, they tend to be slightly lower in women when they are compared to men in the general population. So, when we talk about the sodium concentration in males, like, well, it's around like 45 millimolar per liter and in terms of women, they are around 40. So it's slightly lower concentration and well, it also has been observed.

Speaker 2: 34:48

A big factor that has also modally a little bit the water regarding the research comparing sexes, is that many times these studies they are not matching the absolute exercise intensity or the body size.

Speaker 2: 35:02

That's another factor that is compared or that is considered a and well, like sometimes researchers, they just forget about that and they just compare, or they just put them to perform the same exercise, or well.

Speaker 2: 35:15

There's something that we need to consider, and when, in terms of the concentration of this electrolyte, well, we need to consider the exercise intensity and well, we go back again to well, the individual sweat testing should be conducted. Well, to estimate what's required, because we know that the salty sweaters like those athletes I tend to sweat quite a lot and well or those that tend to lose a lot of sodium, or those that we always mentioned that they have some residual in their forehead or in their clothes, and well, those are losing a lot of sodium. So we go back to their recommendation. Well, it has to be personalized. In general, yeah, females, we tend to lose a little bit less than sodium and chloride compared to males, but again, it's not that much. If we think about these numbers that I shared, like well, between 40 millimolar for females and 45 for males, again, it's not a massive difference. We are not talking 10 versus 100. 100. So that's the big difference.

Speaker 1: 36:23

So we just recently started offering sweat sodium testing in our lab here in Colorado Springs. It's a commercial product. Somebody can come in. We use the precision hydration system, but there are other ones out there. To describe it to the listeners a little bit, you basically sit there with these electrodes on your arm and there's a collector that passively collects sweat. That is induced electrically, essentially, and we measure that with a desktop system and it's a very good way, kind of an industry standard way, of collecting passive sodium sweat concentrations and you'll notice big individual differences.

Speaker 1: 37:08

So you take a huge population of people. You mentioned the millimolar concentrations earlier. I'll do it in milligrams per liter because most people will recognize that as it compares to their sports drink. Sometimes it'll be 200 milligrams of sodium per liter and sometimes it'll be 1500 or maybe even 2000 milligrams per liter when you look at it across individuals. But we're going to have a lot of female athletes out there now that we use this and this has been available for a long time, it's not like it's novel to us.

Speaker 1: 37:35

That will ask what phase of my cycle should I get this sweat testing done on? What's the most accurate representation of this? Because if I'm going to tailor electrolyte. If I'm going to tailor the concentration of electrolytes in my beverage to my sweat concentration, I want that sweat concentration to kind of be the most representative or like the most functional. Should that be a consideration? Should they go in one phase or another? Should they go in when they're in their follicular phase or when they're in their luteal phase, or is it kind of indifferent? Can they just get it and just apply it?

Speaker 2: 38:07

My opinion is yeah, just in any phase, because, also, I think there are many other factors that I think you had Alan McCovey before. He has done some very nice research about the impact of diet on the electrolyte concentration. I have done a couple of pilot studies on that as well. It seems that, for example, what we have in the night before or day before that impacts the amount of sodium that will be reported in a sweat test. In that regard, there are other factors that might have a major contribution towards the results that we are having, rather than the menstrual cycle phase. So, yeah, it wouldn't have a big impact there, like so it would be indifferent. Probably it would be if we wanted to replicate the study or we're to rep.

Speaker 2: 38:58

I don't know many athletes that they like to be tested, probably at the start or at the end of their competitive season, or probably once in the summer, once in the winter, or yeah, if it's like that type of comparison, well, probably it would be recommended just to record, just to have that factor as a standardized condition, just to do it in the same phase. But it couldn't make any difference. It couldn't be something like oh well, when we were, when the female athlete was tested in their follicular phase was like 200 milligrams, and then in the luteal phase was 2000,. Wouldn't be that difference.

Speaker 2: 39:35

And there are many other factors that will be related or might be affecting the results.

Speaker 1: 39:40

I think what you're saying is, while there might be a change in that sweat sodium concentration, it's not large enough to constitute a difference in the actual advice. Because even with our male athletes, when they come back with 673 milligrams of sodium per you know, per liter of sweat, we're not saying that you have to take exactly 673 milligrams of sodium for every liter of fluid that you're taking in. We're putting them into a product that's in the same ballpark, right, and we kind of use a t-shirt analogy small, medium, large type of things. There's all these different things. But I guess my point is is the precision is not? It's not very precise in terms of what we're actually doing with that information. And so if the range actually changes by maybe even 10%, it's kind of the same, it's almost the same deal, it's almost the same outcome in terms of what you are actually functionally prescribing the athlete to do at the end of the day.

Speaker 2: 40:37

Yeah, absolutely, and also thinking about that when we are designing a strategy to replace electrolyte, that we're lost. Well, it's not that we're going to. Yeah, like, as you said, we won't have even. It might even be difficult. Imagine like well, you need to drink 613.5 mils of I don't know of the sports ring to cover that. And well, as you said, it will never be exactly much. We're trying to approximate it as much as we can. But yeah, with that room of yeah, like of variation.

Speaker 1: 41:05

Okay, so we're going to move on to the final piece of it. I feel like we're getting a bunch of nothing, burgers, so I've got a challenge question for you at the very end of this podcast, once we cover this last topic here. So the last piece I wanted to cover is post-exercise rehydration, and once again there's been a lot of focus on this right. Women respond. Women need different, need a different rehydration prescription depending upon their menstrual cycle, especially as compared to men, and a lot of this can be driven back to their drive to drink, which is recognizably different across the across the spectrum. Let's go back and refresh the listeners a little bit about why, mechanistically, that might be the case. Why might women need different hydration requirements across different phases of their menstrual cycle, and then we can back into the prescription from that kind of from that mechanistic side of things.

Speaker 2: 41:57

Yeah, so it's just well remembering how well estrogen can change the third step perception. So that, well, it has been observed that, yeah, like there is the increase, or when estrogen peaks, that's well remembering just before the ablation, so around the 10 or 12 of the classic menstrual cycle, of the 28 days menstrual cycle, and then also when we have the like in the middle of the luteal phase, in the mid luteal, around the 22, 24. So in this case, well, it has been observed that estrogen might well reduce the osmolarly stress. So this, well, also male, has an impact on the third perception. And the vasopressin that, well, vasopressin is one of the hormones that is also related with how we are drinking and we're drinking behavior. And also it has been observed that well, progesterone also may increase a aldosterone production.

Speaker 2: 42:55

So these are well some of the hormones that, yeah, they are different and they are affecting the well, all the kidney, well, affecting slightly the kidney function and the absorption of the fluid at the plomerular level.

Speaker 2: 43:08

So we think about the our kidneys and well, but the most important aspect here is that, well, the menstrual cycle phase, well, it seems that it doesn't have an impact on the at levitation dehydration. So we allow our female athlete to drink and well, it's actually related to the fact of that decrease of the osmotic threshold or that decrease of the like. Well, the osmotic threshold is like an indicator of when we need to drink or when we don't need to drink. So basically the estrogen decreases that level and well, it says like, oh, we need to drink now. And well, if we compare when the estrogen levels are higher, and well, I'm having that impact on the search regulation, it has been observed that actually it doesn't impact the rehydration and well, it doesn't have an impact on the overall fluid balance or the fluid retention and interestingly, this has been observed at rest and also during exercise and, of course, after exercise.

Speaker 1: 44:04

So once again it kind of comes back to not a big difference. Does that play when you get down to the actual functional prescription of how women should rehydrate?

Speaker 2: 44:16

Yes, yes. So basically, yeah, it doesn't matter what phase of the menstrual cycle probably will need. Yes, for the investigation, but with the evidence that is available at the moment, it hasn't supported. Yeah, like enough, well, that we need to have a different rehydration plan.

Speaker 1: 44:34

Okay. So let's back up here. We're going to try to, we're going to encapsulate all of the take home messages with this specific paper at the very end. But before we want to get to this, I kind of want to ask you this question, just as somebody in the field, because you've seen the progression of this kind of from start to where we are at in the cycle 50% done or 100% done or whatever. I kind of want to get your perspective on it, because there was a call several years ago for more studies to be done on, specifically on, females.

Speaker 1: 45:10

And then there's a subsection of that trying to trying to tease out any sort of physiological differences within the menstrual cycle. And way more often than not please correct me if I am not encapsulating this correctly way more often than not those differences don't tease out to be very much, if any at all. We can tease out some of the very specific, some of the very, very specific things, but then, when it gets down to a functional, what are we actually prescribing to females? It tends to be to colloquialize it a little bit it tends to be a little bit of a nothing burger. And so I'm always caught I'm always caught between this yin and yang of.

Speaker 1: 45:48

I want to see more research come out in this area, but every time more research does come out in this area, it tends to not really tease out anything different than what we knew beforehand. So, in your estimation, like, where do we need to, where does the research need to go from here? Right, do we need to continue to try to hammer out some of these physiological differences to have meaningful impact on the prescription, or do we have a robust enough basis, even though there still is a dearth of research? I'm going to say that before I get a lot of hate mail. Do we need to continue to hammer out some of that research in order to find where some of these differences can actually be? And you can take this within hydration or kind of extrapolate it into nutrition in general, since that's your wheelhouse, obviously.

Speaker 2: 46:32

Yeah, absolutely, jason. So I think that the, I think, well, yeah, I just said it was a challenging question, but, yeah, definitely, I think we need to keep investigating and just to make sure that, well, all of these, that we are observing that, yeah, there might be an impact, but actually, for the practical recommendation, well, it doesn't affect. Well, like the hydration strategies, it won't make a great deal in terms of, well, how it looks when we are working with athletes. However, for example, I think an area that needs a lot of research is, well, those that are using oral contraception or those using other contraceptive methods, because, well, for example, in terms of oral contraception, well, around 25% of the female population uses, uses them. So, yeah, we need to look into that and, well, to investigate further. And well, also, I know that this is opening up kind of worms Because, of course, well, if we think about the older methods, well, if we think about the, the coil, or the patches, or the, the transterminal, a dispositive, all of these will have to be studied. So I believe there is a need to keep studying this, studying all the oral contraceptives in all the other hormonal contraception methods, and well, before we are able to say, well, males and females? Well, the same in terms of thermoregulation, in terms of hydration responses, and well, just thinking about how many athletes and how many women in general know are using them.

Speaker 2: 48:03

Also, another aspect that I think has to be investigated further is working with a menoreic athlete. Unfortunately, there are many athletes. Well, yeah, they have amenorrhea, so that means that they don't have a normal menstrual cycle, or that they have missed more than three menstrual cycles. Or, well, the oligomenorex, those that are having like a bit intermittent menstrual cycles, but they don't need to be investigated. And, unfortunately, well, many of the athletes, even if they are having some energy like relative energy deficiency or something like that that might have been impacting their menstrual cycle. So I think that's something that has to be investigated and I think, yeah, definitely, even if we are finding like very little impact or very little effect, it's important to make sure that we know that's the way it is. So I think it's important to keep the research around those areas and those topics.

Speaker 1: 49:00

Now I really appreciate that perspective because it's not. You know, once again, I'm trying to avoid as much hate mail as possible on this one. I don't want to present the fact that I don't want to see this research because I do want to see it. I do want to see it, but really over the course of the past several years, every time I see it, I can keep coming back to the same conclusion where there's very little that would actually impact what I do on a day-to-day be or I'm kind of speaking for nutritionists as well, like yourself, would impact what we do on a day-to-day basis. Yes, there are some things, but it's not so overwhelming that we're treating them as different organisms, to use your analogy. Okay, so let's go through one final exercise here.

Speaker 1: 49:38

I want to really take this from a practical perspective and use your expertise specifically with it within hydration, because this is a great point of consternation amongst the ultramarathon crowd. Our events are. They're just complicated, they're long, they go through big temperature ranges. There's the opportunity to screw it up. You know, I can bring up all the statistics on how many people show up hyponatremic. At the end of the Western States 100. That's very well. That's very well studied and because of all of those factors, hydration and electrolyte balance becomes a big performance determinant that you can absolutely screw up. So let's kind of go from tip to tail. So we've got an ultramarathon athlete.

Speaker 1: 50:22

Everybody's listening to this. It's the winter here. We don't want to, you know, we don't want to neglect hydration in the, at least in the US. It's the winter. If athletes are out there that are thinking, how can I get a fix on this and you can bifurcate this however you want to female athletes, male athletes, whatever how do I get a fix on my fluid and electrolyte needs that I'm going to actually deploy during an ultramarathon race? How would you go about assessing that athlete and then coming up with whatever the prescription is going to be? Are there some general steps that you would take people through it?

Speaker 2: 50:56

So I would definitely go into, well, yeah, considering the big diversity in sweating rates and, of course, yes, sodium losses and electrolytes in general, I, yeah, I would always start with the personal light sweat testing and well, this is it would be yeah, there's the estimation of the sweat rate, at least to get an idea of how much sweat has been lost. Yeah, and again, perfect SNIO would be in a similar environment of where the competition will be and the race will be, and Well, based on that, start working with the athlete and well, designing and strategies. No, because, also, I work with runners when they are like well, I don't want to, for example, with the carbohydrate, no, I don't like jails, I hate jails. Okay, so we need to work around and we'll see what you like, what you will be actually able to do. Know that, yeah, of course we can recommend. Yeah, you need to drink. Yeah, 1.2 liter per hour. Is that realistic?

Speaker 2: 51:52

So it's not no so, so we need to. I think something that I believe is that, yeah, it's something that has to be, yeah, working together with the athlete and see, and, of course, training, training the body. I was so training. We always talk about training the gut, not training for the amount of carbohydrate and, of course, for the sodium capsules, and yet, to Let the body that, physiologically to be able to tolerate different amounts of sodium, or well, they even drinking, like well, I like myself as a marathon drinker, like well, as a more than running, a marathon drinker, well, the fact of being running and griffin cup, that's complicated. No, it's just, yeah, how do you do you? Do I stop and I run? I Stop, drink and then run, or what do I do? No, so it's always that, that question. And, for example, myself, I'm always panicky about stopping and not being able to start again. That's, I always try to grab the drink and run while I'm drinking, but again, probably I have to low a little bit then the the speed. So I think it's something that we need to work with the athlete. I will of care. This is the recommendation based on your sweating rate. Yeah, you need. Well, if it was one, one liter of sweat that was lost per hour. We'll try to work with, with him, or with her, like I, or with them, like well, to work what's the, the best, the best scenario. Well, if you, the best scenario would be that you are not losing anybody, master sweating and well, what's the kind of almost like creating a strategy like, well, the what's the? The least amount of fluid, the least amount of sodium that they'll need to be ingesting to avoiding any negative impact on their race, and and, based on that, will work like well, and and again, it's almost like well, it's really like practicing that during training sessions that I understand.

Speaker 2: 53:37

Also, like Distance runners that, yeah, like they tend to to train quite a quiet lot and will have long trainings, of course, probably not as long as their races or well, close enough, but, yeah, probably practicing that and well, based on their requirements that they might have.

Speaker 2: 53:53

Well, trying to get as close as possible and, of course, to get them trained and I even think, yeah, to train their mind, to get them used to do well, to drink While running. If they are using any, any sodium capsule, that well, those might cause also some GI Stress. So, also, well, you need to work with that and well, to practice that and well, hopefully, for the race day to be as ready as possible. No, and it's something like the one of the gold rules that I will never, never Start using or doing something on the race day not always practice beforehand. And you, just as you are training your body for that big race also, yet, like training the training for the distance also, well, trained your stomach, well, of course, your GI system and, of course, train your mind for that as well.

Speaker 1: 54:37

You know it's funny. You mentioned this don't ever try anything new on race day. I don't think a lot of people appreciate the detail of that statement because they Simplify it to I don't want to try a new pair of shoes on race day, or a new pair of socks, or maybe even a new nutrition product. But what it also expands to is the rate of the rate and the amount of things that you are taking in during race day. So you mentioned that you can do these personalized Sweat sodium concentrations and also personalized sweat rates that you can figure out across a host or at least the sweat rates you're figuring out across a host of Different temperatures, and figure out how much fluid I need to replace based off of that. Well, you can deploy that during the race 1.2 liters per hour, as you mentioned, or whatever. But if you're not deploying it during training, I'm gonna consume 1.0 liters of fluid per hour during the race.

Speaker 1: 55:34

If you're not doing that during training, technically you're doing something different. During the race, you're consuming 500 milliliters per hour during training and you're over doubling that During the race. When you present it in that context and people do this with carbohydrate intake all the time I'm gonna take in 40 grams of carbohydrate during a three-hour run, right, so whatever math that works out to 12 and a half grams per hour. But then during the race, I'm gonna take in 50 or 60 grams per hour, right, you're like three or four X's in it or whatever.

Speaker 1: 56:07

That difference in rate, the ingestion rate, is something new on race day, make no mistake, that is something new on race day and the same rules should apply to that. So I appreciate your final Appreciate, your final sentiments. I've don't do anything new on race day and within the context of hydration, part of that is, yes, products and the amount of sodium that's in them and the amount of carbohydrate that's in them, things like that. But also is the rate of ingestion that you're taking in. That should be. That should not be novel. That should not be new. On race day as well. That should be exactly as you had Practiced it per the conditions that you should be competing in yes, and I know so well.

Speaker 2: 56:47

I think this is kind of perfect world, like ideal scenario, because how many times like, yeah, like we plan for something. And environment, yeah, absolutely. I remember my first marathon was Chicago marathon. Yeah, in 2013. I remember I basically got lost and then I didn't start with the block I had I was meant to start, so that meant that I started like half an hour later and, of course, I had drunk everything yeah, like, yeah, according to starting 30 minutes earlier. So I had to stop. And at the first game to the toilet now I was like, yeah, I did so and yeah, that wasn't in the plan and, of course, well, it was just because, yeah, I got lost. So, yeah, I had my perfect hydration strategy. That, of course, didn't work and, well, I, yeah, it's when you see in the, yeah, like the running a start, yeah, stop, is I I probably say why I didn't stop.

Speaker 1: 57:37

Everybody's got a plan until they get punched in the face and Running a punch in the face a lot. Okay, I'm gonna leave a link in the show notes to the paper. Brilliant job with it. Like I said, I learned a lot from it and even if it's comes back to I I keep presenting as a nothing burger. I'm saying that not to like trivialize what you have done, but if, even if we come back to these things aren't as impactful as the exercise or as we actually think we're, I think that's useful information. So I appreciate the work that you've done with this. Aside from the article and some of the links that I'll leave in the show notes to where you work out in your university, where else can people find more about you and the work that you do?

Speaker 2: 58:16

Well, you can find at the University of a sterling website. So, yeah, and yeah, you can find the my list of publications there. And yeah, like all the many of them are open access, most of them on hydration. I also have some work on visual supplementation, so yes, later there. And body composition that's another area of my research.

Speaker 1: 58:38

So excellent, nydia, I appreciate you coming on the podcast and we'll have to bring you back on and talk about Fish oil or something like that at some future point in time.

Speaker 2: 58:46

Yeah, absolutely. I love that.

Speaker 1: 58:51

All right, folks, there you have it. There you go. Much thanks to Nydia for coming on the podcast today and shedding some light on this Incredibly interesting topic. And whenever I discuss this with researchers in the field and also practitioners, I always kind of come back to some of the same Philosophy or some of the same sentiment, and that is, we can recognize that Female athletes are different than male athletes and we can also recognize that there's a big impact of the menstrual cycle on their training and hydration and nutrition. However, those impacts kind of pale in Comparison to the individualization that you should already be using with any of those types of prescription, whether it be strength training or endurance training or nutrition prescription. So for those of you out there that that ascribe to Some of the philosophies that might change some of these requirements or some of these practices Across exercise and nutrition a little bit more dramatically, either due to the fact that your client or you yourself, or a female, or you're in different parts of your menstrual cycle, I encourage you to look at the research a little bit more in-depth because, as we see it right now, there's really no compelling high quality evidence to To fluctuate any of these components any more so than you would do on a Normal basis when taking into consideration the normal individual variances with any one particular athlete.

Speaker 1: 1:00:22

But if you happen to disagree with me, my DMs are always open. You guys know that I'm always open to discussion on these things. I'm happy to engage in any sort of dialogue possible, so you can hit me up on any of the social media channels if you want to partake in that particular debate. Much thanks to all the listeners out there. I appreciate the heck out of each and every one of you. If you like this podcast, please share it with your friends and your training partners. That means a lot to me. I always like it when I go out in the community and I hear people talking about this podcast, or they just thank me for putting the content out there. That is it for today, folks, and as always, we will see you out on the trails.