Time for the next course. In this second in a three-part series, Wahoo sports scientists Neal Henderson and Mac Cassin serve up knowledge on fueling strategies for during your workout to help you stay strong through the last interval.
Time for the next course. In this second in a three-part series, Wahoo sports scientists Neal Henderson and Mac Cassin serve up knowledge on fueling strategies for during your workout to help you stay strong through the last interval. Hope you're hungry for some top training tips.
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Neal Henderson 0:00
Hello, and welcome back to another episode of the knowledge podcast brought to you by the Wahoo sports science team in Boulder, Colorado. I'm Neil Henderson, head of Wahoo sports science.
Mac Cassin 0:09
And I'm at Casson senior sports scientist with Wahoo. Today we're going to be following up on our first episode on fueling where we talked about pre-training nutrition strategies. Right now we're going to be talking about fueling during training.
Neal Henderson 0:19
As we've previously mentioned, we are not dietitians. And if you have specific needs or medical concerns, you should always seek the advice of a registered dietician to help you meet your goals.
Mac Cassin 0:30
So Neil, how do you define fueling when you're training?
Neal Henderson 0:34
Well, basically, I think the combination of anything you're eating and drinking while you're working out or training is pretty much covering that during exercise during training, fueling.
Mac Cassin 0:45
And so if we talk about that, we probably can break it up into a few different components, like the composition of the food, you should be eating, the factors that go into planning that fueling, and then just general timing, when and how much you should be eating.
Neal Henderson 0:57
Definitely, those are pretty much the three biggies there. Let's start with the top of the list here, we often think about fluids, you know, we've got lots of evidence out there that hydration is important. And that's one of the better ways that we can get some of the fuels and other things that we need into our bodies like electrolytes, what do you tell me about fluids here?
Mac Cassin 1:17
Well, isn't that what Gatorade is for? Isn't Gatorade, the best thing ever for that?
Neal Henderson 1:21
Well, you know, it is something that's very well marketed. And there are a lot of other options out there. So you know, water is the base fluid, right? And then we can add things to it. So the primary things that we would add to water to make it more useful while we're training would be carbohydrates, because carbohydrate energy is what we use, especially with higher intensity exercise. And it's the only kind of fuel that our body really has a big or significant limitation in being able to store. And then we also have some need for electrolytes, because that actually has an impact on how our body is able to take in that fluid with sodium being probably one of the biggest players there. There may be some need for other electrolytes, but I would stick to sodium probably being the key one there.
Mac Cassin 2:15
Yeah, definitely sodium is going to help with moving fluid into your intestines, it also actually is responsible for one of the transporters in your gut to help bring glucose into your bloodstream. So you actually need sodium for some of those pumps to work efficiently. So even if you just have got nothing but sugar in your drink, you're not going to be absorbing it as well as if you had a bit of sodium in there.
Neal Henderson 2:35
Yep, and a combination of all the particles that are in a fluid is what we call osmolarity. And so it's the combination of that glucose, and sodium and any of the other potential electrolytes in there, those total particles per liter of fluid is what impacts osmolarity, which you can use a couple of different ways to describe whether a fluid that you have is either equal in the concentration of those particles to what we have in our normal cells in our body, like our blood cells. And that's isotonic, where it's equal, you can have a hypertonic solution where then there are more particles in the amount of fluid relative to what your body has. And then there's a hypotonic solution where there are fewer of those particles. Generally speaking, our body does a little bit better with an isotonic intake. And so if you pump up the number of carbohydrate particles that you have in the air, you might need to pull back a little bit on the sodium and vice versa. If you have a fairly high sodium concentration and of those particles, you may need to pull back a little bit on the amount of carbohydrate to keep it to being an isotonic solution.
Mac Cassin 3:44
Yeah, and that's a that's an important thing to think about when you're exercising in terms of what you're taking in. Because like you said, a hypertonic, it's when you have a higher concentration of particles in the fluid or even the food you take because once you eat it, it turns into fluid and in your stomach. But if you have a hypertonic mass of carbohydrates in your intestines, it's actually gonna draw water out of your intestines to make it balance what's in your cells. If you've ever been someone to have a gel, and all of a sudden your stomach just feels like you have a big old bomb dropped in there. It's probably because there was a hypertonic intake and now your intestines are pushed dumping water into even that house.
Neal Henderson 4:20
Yeah, so having an appropriate balance is important. Typically we see somewhere around a six or 8% carbohydrate solution as well as then somewhere between 408 100 milligrams of sodium ending up with an isotonic solution. There's a little bit of variability for sure in those values. And what we think about then is how much of each of those two things do we really need in terms of the amount of fluid that we lose? So when we exercise we sweat, we are losing some amount of fluid and it varies based on a few things what what are the key things Mac that you consider important for the hydration and understanding how much your body is losing in terms of fluids and sweat during exercise.
Mac Cassin 5:06
Yeah, so environments gonna play a big, big factor there, right? When it's really hot out, you're going to be sweating more. But even if it's it's cold out, and you're wearing a lot of layers, you can be sweating more than you think, especially if when it's colder, you tend to drink less. So you can actually get dehydrated in really cold weather, which can be counterintuitive to some people. But yeah, what you really need to consider is your own individual sweat rate. I think personally, my sweat rate is on the high excessive side of things. That so I know when I'm training, I need to drink a lot of fluid. I remember in 2012 nationals in Augusta, Georgia, it was like 1 pm in the afternoon was like 102 degrees, like 95% humidity, brutal, I drank 17 bottles and four hours in 10 minutes. Because it was I was just sweating, dripping sweat the whole time.
Neal Henderson 5:56
And I wouldn't even be shocked if you said you were actually dehydrated, after even drinking all of that in four hours, that that's actually probably not enough to keep up with your total loss. Yeah, I
Mac Cassin 6:06
was literally just limited by how frequently we were passing the to different feed zones and how many bottles I could grab each time.
Neal Henderson 6:12
Yeah, a good thing that you can do to just get an idea of your actual sweat loss for fluid is to measure you know, get your body weight before you go out and training, you know, this is ideally done, you know, without any clothes on because clothes can carry some of that water. So you want to do you know, a without clothes first before you ride, you know, don't do it anywhere where you're gonna get in trouble doing so, so better in your bathroom at home. But weigh yourself before no clothes, go out and do your training, write down how much you actually drink, and then weigh yourself when you come back inside. Again, nothing on and compare the total change in body weight plus the amount of fluid that you take in. And that's going to give you then that total change in fluid from start to finish and divide that say in liters. By the hours of your training session, you're going to have an idea of how many liters per hour you sweat.
Mac Cassin 7:07
And so Historically, it's been said that if you have a 2% drop in body weight, you're dehydrated, do you think that's accurate?
Neal Henderson 7:14
It's not necessarily true. One of the reasons is that when we're exercising, especially with higher intensity, we are utilizing carbohydrates. And when we think about tapping into our stored carbohydrate, which we recall is called glycogen, which carries with it nearly three grams of water, some would say three or 2.8. Some say 2.7, but nearly three grams of water. So if you actually deplete your entire carbohydrate reserves, which will be you know, depending on your size four to 500 grams of the stored carbohydrate, you're also then getting rid of or not, your body does not need those additional, we'll say 1200 to 1500 grams of water. So that total is between 1.8 and two kilograms,
Mac Cassin 8:03
Right. And if you weigh under 100 kilos, that's 2% 2% right
Neal Henderson 8:07
There. So keep in mind that that fluid loss is different than your actual sweat rate, even though you may have some of that fluid coming out. Net as sweat
Mac Cassin 8:19
It out. Yeah, it really acts as a good buffer, and that your sweat comes from the plasma in your blood. And as you release glycogen in the water there it circulates back into your blood. So for a while, you can get a pretty good balance there but then still there'll be your sweat rate is gonna vary based on those things. And a good thing remembers as well as exercising inside you can have higher sweat rates if you don't have adequate cooling. That's why fans are really important for working out on the trainer.
Neal Henderson 8:46
Go Matt go Oh, you mean air? Well, both they both help Yeah, it does help for sure. Keeps you cooler.
Mac Cassin 8:53
And so Okay, so we're talking about sweat that's water loss. But what else? I mean I think we all know that sweats are a bit salty. So what is
Neal Henderson 9:01
Yep, there are some individual things with how much sodium we lose there's an impact on your diet if you have a really high sodium diet generally, you will lose more sodium than somebody who has a lower sodium diet in their intake but you know that the range can be anywhere you know, around 400 milligrams of sweat per liter to somebody can be losing in excess of 2000 grams of sodium per liters, but that is very very salty. 2000 milligrams Oh, sorry. 2000 milligrams. Yeah. 2000 That would be bad. I don't think a human has 2000 grams of salt in us in every place but so 2000 milligrams or two grams. Sorry, great catch Mac. With that thought, the range is significant. And it is important to do a little bit of experimentation with yourself. There are some places where you can actually analyze the composition of your sweat and see how much how many milligrams are were per liter. It's you know, great to be able to get that identified, but do also know that it varies. So when you're less acclimatized to a given condition. So like if we think of, you know, our winter here in Boulder, it's a little bit cooler, you know, and maybe in March or April, more likely, we get a first warm day and you go out and your sweat in April looks most likely very different than what your sweat rate would have been at the end of the summer in August or September because you haven't been sweating at that higher rate. And so you'll have a little more concentration of sodium in that sweat when you're not acclimatized. As you become acclimated and trained in the heat, you'll see a little bit of a decrease and lose less sodium per liter of sweat. Yeah, if
Mac Cassin 10:41
you're someone who when you finish a hot ride, and you've got lots of white stains on your jersey from salt means you're probably a high salt sweater, I'm fortunate that even though I do sweat a lot, I have a very, very low amount of sodium in that sweat. So
Neal Henderson 10:54
yeah, I kind of get ghostie myself. So I have to do both a pretty high volume of fluid intake and relatively high sodium. So I usually think about 800 milligrams when I'm pretty well acclimatized to heat but in the early season that might be in excess of 1000 milligrams per liter to kind of keep up with what I'm losing and not get into trouble. Because there's a condition if you have too much of a loss of sodium, or you take in too much water without enough sodium, and that is called hyponatremia. And actually is a very dangerous medical condition. You can I mean, you can, you can lose consciousness and you can die actually if you sustain and get to an extreme level of hyponatremia. So low blood sodium.
Mac Cassin 11:37
Yeah, there have been lots of reported cases of people dying from drinking only water and drinking too much of it, which is counterintuitive a lot. But again, that just drives on the importance of those electrolytes that we were talking about.
Neal Henderson 11:47
Yep. And a good indication I find is if you're training and you're drinking a fair amount of fluid, and you feel like all of a sudden, you're kind of getting that sloshing in your stomach, you most likely don't have enough sodium to help move that fluid through your system. And so taking in some salty foods, whether that's you know, potato chips, or pretzels or beef jerky, or you know, course there's salt tablets and stuff like that, but getting some salty foods will help that fluid be able to move out and move out of your stomach and help you stay cooler. So you can continue to sweat and keep your blood sodium in that kind of narrowly regulated range. Yeah, so
Mac Cassin 12:24
on that note of you know, that liquid sloshing around in your stomach, we touched on this briefly in the first episode on this, but you know, when you start exercising your blood moves away from your intestines and moves towards your working muscles. So you're what's called gastric emptying is going to be slower. And so if you drink a lot of fluid in one go, that can be bad. Same thing with if you eat a lot at one time. So that's why we'd say in terms of timing, we'd say, you know, sip every five to 10 minutes and eat something like a little bit of something every 15 to 20 minutes, it's better to do that than to try and you know, have an entire bottle in one go or have an entire you know, Clif Bar in one go breaking it up. And on that note, it's the same like we were talking about in the first episode of the composition of the food you should be having here should primarily be carbohydrates. And you should really limit that fat and fiber content around it. Because that slows down your gastric emptying it you won't be able to digest stuff as quickly.
Neal Henderson 13:19
What about the aspects of the carbohydrate type? Number one, if we think about the glycemic index, is that a factor here?
Mac Cassin 13:29
Yes, it is. And again, we have a glycemic index, which is you know, how much does something spike your blood sugar and then the glycemic load, which is proportional to how much you take him. And really what you want when you're on the bike is just a super high ugly glycemic index with a super high glycemic load. It's the one time you can kind of go crazy with the sugar and not be detrimental to your health. Yep,
Neal Henderson 13:50
so like having some defused coke by writing might be a good fuel if you're definitely looking for a higher energy density.
Mac Cassin 13:59
For those who don't know that Neil has run out a Wednesday group ride with his athletes in town and everyone smiles, we do simulated racism. The winner of each one gets a nice cold Mexico, real sugar, Coca Cola. And those are some of the best cooks. I think I've had
Neal Henderson 14:14
definitely which means Mac has won some of those challenges to be able to earn the glass bottle coke man he is he can throw down and has many times burned in it. So what about then the different carbohydrate types? So if you kind of break it down, is there some value in varying that, or just is it better to have just straight up glucose?
Mac Cassin 14:37
Yeah, so what your glucose is the standard one, but actually, the different sugars use different transporters in your gut, and they're limited to how much they can move. Generally, the accepted stuff as you can. Most people on average can move 60 grams of glucose and galactose. They use the same transporter per hour. And then for fructose, you actually have different transporters that can do about 30 An hour So mixing that up means you can increase the total number but
Neal Henderson 15:03
twice the amount of glucose per amount of fructose. Yeah, a two-to-one ratio on that.
Mac Cassin 15:07
Yeah, exactly. And what's interesting is, it's that number of how much you can ingest has been steadily going up over the last couple decades a while ago, like 60 was the absolute max, you could take
Neal Henderson 15:18
Oh, yeah, when I was in school, you know, when I was in undergrad, it was 40 to 60 grams. That's the most that you think about recommending for anyone to intake, and I was doing some ultra-endurance stuff. I mean, I did my first Ironman when I was still an undergrad. And I guarantee I was taking in more than that because I know my expenditure was significantly above that. So why, how did that work?
Mac Cassin 15:38
So it turns out your gut, like most other parts of your body can actually train. If you constantly bombard your intestines with lots of sugar, when you're exercising, you're going to upregulate those transporters and you're going to be able to take in more carbohydrates, like when I was in undergrad, the recommendation was around 90, and now it's pushing up around 120 plus. And again, it depends part of that is obviously there's a caveat to your size if you're a 45-kilo Woman versus a 100-kilo man like there's a bit of difference in the service area of your intestine. So yep, the larger person is going to absorb more
Neal Henderson 16:11
Also, the energy expenditure that somebody who's 45 kilos is going to be sustaining, you know, if they're pushing, you know, both of those folks are pushing, let's just say three watts per kilo, that 45 watts 45-kilo person is pushing about 130 535 Watts versus that 100-kilo guy pushing 300 watts. And the absolute energy, then, is a very significant difference, that's more than a two-fold difference in that energy production. So the amount of intake should also be relative to your size and your output capacity. So we could have two people who weigh the same that is, you know, 75 kilos, but one has a sustainable power of closer to 300 Watts, and another one has closer to 200 Watts, the demand of intake for the person who can hold and push 300 watts for a long period of time, is going to definitely need more fuel than the person who's pushing just 200 watts.
Mac Cassin 17:03
Yeah, and even just the relative intensity, there is a factor as intensity increases, you use proportionately more carbohydrate. So if you're just doing, you might have one person doing a mellow ride at 200 watts. And then you might have the same person, same weight. But 200 Watts is their threshold, and they both ride for an hour, though their output is essential there's some difference preventing carbohydrate burn, but we won't get into that their output is essentially the same. But that rider who has a higher FTP was using maybe 50%. Fat during that, so they'd have less carbohydrate expenditure. So that is an important thing to think about when you're planning out your fueling for a given ride is what's your absolute intensity. And then what is that relative to your ability, if you have a hard high-intensity session, you're probably going to want to be pretty heavy on the carbohydrates.
Neal Henderson 17:48
Yep. And, and clearly, there's some individual variation in how people are metabolizing fuels at different intensities, but a pretty good ballpark for most folks is at a relatively low intensity, kind of like endurance pace, most folks are burning closer to a 5050 mix of carbohydrate and fat when we get into a kind of moderate-intensity into that tempo range, most are getting closer to around three-quarters carbohydrate, 25% fat, and when we get up to basically our FTP or threshold intensity, and above, it's almost exclusively carbohydrate 100% of all that energy that you burn, that is carbohydrate when you're at those intensities and above. So you have to think about the total amount of watts that you're pushing or calories per hour is a relation to that. And then the relative intensity that you're going is going to dictate. So if you're going on a low-intensity ride, your need for carbohydrates is going to be a little bit less than when it is when you're working on a higher intensity. Even if it's a short high-intensity session, you could potentially need a significantly greater amount of carbohydrate than you would in a really long ride if it's really low intensity.
Mac Cassin 18:57
And when we are talking about duration, it's also important to note that, you know, but the time between eating something and it actually hitting your bloodstream can be about 60 to 90 minutes. So there's the old adage of eating when you're hungry, that's not necessarily going to be good advice.
Neal Henderson 19:10
Yeah, have a plan and stay ahead of the curve. You don't want to be playing catch up and especially so that's what fueling you know, you get that feeling of low blood sugar. You know, interestingly, we now see some things on the market to actually be monitoring your blood glucose level continuously during exercise so that the CG eyes are out there. And I'd say they're getting you to know, to be seen a little bit more. It might be interesting for folks to see how their body responds to different fuels and different intensities and what happens there. We are all a little bit different and I'd say we're probably learning a little bit more about this fueling from some of that information that we're gathering right now. I'd say you know check back next year we'll know even more than we know right now. But there's also the aspect of your fluid too and if you get a little bit dehydrated actually will slow then your gastric emptying rate. So it's really hard to catch up on your blood glucose, you can rebound pretty quickly. If you do get low and you have an intake, you know, within, you know, 1015 minutes, you can feel a lot better. If you get dehydrated for a little bit, it might take a couple of hours to start to feel better. So it's better to always avoid getting into any level of true dehydration while you're out there training, especially when you're racing too if you're doing long stuff.
Mac Cassin 20:25
Yeah, and then just quick, rapid-fire here. The other thing you want to consider for your nutrition for a single day is okay, did you have a good pre-ride meal, if you don't know what that is, you can listen to the first episode in this series. And so if you had a good meal, you might not need to start feeling right away. If you didn't eat anything, you're just straight up out of bed, you might need to have something as soon as you get on the bike, the training the day before, which is impacted by your post-workout recovery, which we'll talk about next episode. But if you were not properly fueled after your previous day's workout, you might be low on glycogen. So you might need to add some more fueling in. And then another big one is What are you doing the day after? Are you doing another big ride hard ride tomorrow? Or is it a rest day? Because that can have some impact there. And I think, again, when you talk about that delay of 60 to 90 minutes, I've heard a lot of people when you see a rider in the tour and sprint stage, they'll take a gel with like 5k to go. And some people have been like, Well, why are they doing that it's not going to hit their system. And it's, it's not really for that sprint finish, it's to make sure that they've got food going into their system for the next stage.
Neal Henderson 21:25
Yeah, they're starting that recovery. Also, there is some interesting evidence about a little bit of carbohydrate in your mouth actually giving you a psychological capacity to do a little more work than if you didn't. So you know, just getting a little shot of a sports drink or a gel in your mouth may actually make you feel like you can do a little bit more and actually have a little bit more output. So you know, potentially a benefit there, and you may be starting your recovery. Second benefit. That's a two-for-one outtake.
Mac Cassin 21:49
And so I think nutrition is very individual, and what works for you isn't necessarily gonna work for someone else. So it's important to experiment with different strategies here. Now you don't want to do that on your event day, you don't want to spend six months prepping for something and then try something brand new day of the event you want to
Neal Henderson 22:05
Definitely definitely definitely nothing new on race day,
Mac Cassin 22:08
You want to take some lower intensity low priority training sessions and try some different fueling stuff and see what works for you.
Neal Henderson 22:14
Yep, and maybe start off at you know, with some lower intensity sessions first and then slowly try to add, you know, some higher intensity and see how you tolerate that because you may find certain things work when you're just doing you know, endurance-type work or a little bit of tempo. But when you're doing high-intensity intervals, that same type of fueling strategy or actual food or drink just doesn't work for you. So make sure you know how your body's gonna respond that those variations and intensity too.
Mac Cassin 22:39
So hopefully this is some good fuel for your brain. Definitely.
Neal Henderson 22:43
I feel like my brain knows more and now I can feed my stomach the right things based on what I know. All right, well, that's another episode of the knowledge again, this is part two of our fueling talk in in episode one we talked about your pre-training fueling needs and how to go about making sure that you're starting sessions well-fueled this one we tapped into the what do you need to do about food and fuel during exercise and next up, we will be talking about after your training, how to optimize your recovery with your nutrition strategies.