It's chow time. In this episode, Wahoo sports scientists Neal Henderson and Mac Cassin tuck into pre-workout fueling strategies to help you get the most out of your training.
It's chow time. In this episode, Wahoo sports scientists Neal Henderson and Mac Cassin tuck into pre-workout fueling strategies. They break down how your body breaks down what you put into it, what to eat and the best time to fuel before your workout to ensure that you get the most out of your training.
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Neal Henderson 0:02
Hello! I'm Neil Henderson, head of Wahoo sports science.
Mac Cassin 0:09
And I'm Matt Casson, the senior sport scientist. Today we're going to discuss fueling your training is the topic we're actually going to break into a couple of parts. This episode specifically is going to focus on fueling before your workout.
Neal Henderson 0:19
Alright, Mack, well, we're gonna start off with some basic stuff, in the beginning, moving your body, which is really what training is, in some way, mental training, maybe not moving your body, but actually using your brain does require some fuel. So this is actually still gonna be useful there that moving your body requires energy. And your body can only use a couple of types of energy predominantly to contract muscles. The two main things that we use as fuels are carbohydrates, and fat. When we combine those with oxygen, we have oxidative metabolism, we get energy out of those, we can also break down carbohydrates without using oxygen to get some energy. It just can't be sustained for super long. Now their topic another time, right?
Mac Cassin 1:00
Yes. And during that topic, we'll discuss Neil's deep hatred for the term anaerobic.
Neal Henderson 1:05
Yes. And, yeah, absolute truth to that back. And hate is a strong word I know. So you might remember in school being taught about, you know, maybe Maslow's hierarchy. And some of these things, as humans, we have, you know, primary needs to stay alive water, food shelter. Interestingly, oxygen didn't make that list, which is actually probably the top of the list without oxygen, we definitely don't exist for very long at all, like even shorter than if we don't have water, or food, or shelter. But that means said water is one of the most important things that we do need to be taking in with some frequency to keep us alive. And when we exercise, we have some impacts on our bodies need for water combine through these different things including metabolism, digestion, and especially when it's hot, or humid, or warm thermoregulation because when it's hot, we sweat, water, and fluid to cool us down through the evaporation of that. That makes sense so far,
Mac Cassin 2:08
you lost me about a minute ago, but we'll keep it rolling. So yes, oxygen, big, the big important thing here for fuel for how your body efficiently produces energy. When we're again, like you're saying you're talking about carbohydrates, and fats as fuel sources, we'll probably have a whole other episode about ketones and ketone bodies and all that stuff another time. But we're not going to get into that, as you said, the brain uses energy, it can only use carbohydrates or ketones. But your brain can only use carbohydrates, your muscles can use carbohydrates or fat. And the forms that those take for carbohydrates are going to be your blood glucose, sugar in your blood, or glycogen, which is stored in the muscle themselves or in your liver. And as you're talking about with water, there's an interesting thing with glycogen where it's actually stored in your body in association with some water. And again, this is with something that you and I don't necessarily agree on the exact value. But I will say it's three grams of water per gram of glycogen, or 2.8.
Neal Henderson 3:05
But you know, we can round it to your three that's close enough for all intents and purposes. And keep in mind that glycogen is just basically chains of glucose together for a storage form.
Mac Cassin 3:18
So it's interesting glycogen, once it's in your muscles, it actually can't leave the muscles that have to be used there, your liver can store glycogen converted to glucose, which turns into goes into your bloodstream. So it comes, you know, blood sugar. So if you've got, you know, lots of glycogen stored up in your biceps, when you're riding a bike, it's not really going to help you out,
Neal Henderson 3:36
it's not gonna go elsewhere. It's gonna stay there locally. So if you get out of the saddle and start pulling the bike side to side, then you can liberate some of the glucose from those biceps, that would be fun. Yeah, but maybe not terribly efficient. So
Mac Cassin 3:47
again, coming back to Oxygen, that's how we're turning these fuel sources into energy. So you know, what's, what's the difference between carbohydrates and fat when we're talking about oxygen consumption,
Neal Henderson 3:59
oxygen consumption or vo two is one of the things at that as we exercise at higher and higher intensities, we are utilizing more oxygen to break down more of these fuels. And interestingly, we get about 10% More energy yield when we're oxidizing carbohydrates than we do with fat. And so when oxygen consumption is at its kind of higher highest level, which is the term we call vo to the max at that high intensity, we want to be utilizing predominantly carbohydrates to get them the most ATP, which is the energy form that the muscle uses to contract out of that fuel. And so we can look at this in a lab we can do what we call indirect calorimetry, where we're measuring oxygen and carbon dioxide that you're exhaling as you exercise and we see that at a low intensity there's generally a pretty even mix of carbohydrate and fat. Yes, some individuals use a little more fat at the same intensity, some people do use a little more carbohydrates at that same low intensity. And those shifts probably do a little bit both to training responses and the kind of training that folks are doing as well as their muscle fiber type individuals with more slow-twitch fiber will be using a little bit more fat at a given intensity than somebody who has a little bit more fast-twitch muscle fiber, somebody who's more of a sprinter type. But in either case, as we start to work harder, our total energy expenditure goes up, and we start to see a shift to greater and greater amounts of carbohydrates being utilized. And once we get to kind of around our FTP or threshold, we see almost exclusively all the energy being oxidized is coming from carbohydrate use. That's just human nature.
Mac Cassin 5:53
So it sounds like if you have a hard training session, you're going to be want to be topped up on your carbohydrate stores.
Neal Henderson 5:58
Absolutely. When you're pushing that those higher intensities are it is a carbohydrate that is the primary fuel you're using through that oxidative as well as again, the only fuel we can use in that nonoxidative or anaerobic pathway is carbohydrate. Interestingly, carbohydrates can only be then stored in the body in limited amounts both in your muscle, as well as again, in the liver in the blood glucose, you only have so much whereas fat to a degree, we have almost in a lot limited capacity, were having an extreme amount of extra fat carried on, you know, definitely doesn't help us go faster. But it is a fuel source that your body can store 10s and 10s of 1000s of calories potentially, whereas carbohydrate, generally speaking, maybe around 2000 calories or so for an average-sized person, we'll just say around 165 pounds or 75 kilos.
Mac Cassin 6:48
Yeah, and that that energy density becomes really interesting when you talk about the relative size of the fuel tank, because, you know, fat in itself has almost well a little more than double the amount of energy per gram. So carbohydrates about four fats nine. But if you remember, we were talking about the glycogen being stored, it needs water in addition to it. So you're talking about four grams really, or 3.8, as you might prefer to say 2.8. But with that one gram of with that one, total a total system mass, he can call it three AK almost four of four grams, or so if you do some quick math and divide four by four, you get one. So carbohydrate, you get one calorie per gram of storage capacity. And for fat, you get nine. So in terms of energy density, not only is you have a lot more of it stored, but it's nine times as energy-dense.
Neal Henderson 7:39
Absolutely. So again, carbohydrate has limits on how much we can store. And then with exercise, as we work harder, we're using more and more of it. So fueling, when we get ready to think about our training and preparing for training, we want to think about how we feel, and when right there are a couple of key things to think about.
Mac Cassin 7:59
So when we look at this fueling window, and the general rule of thumb that you're here is about three hours out, you want to have a substantial meal, before we get too deep into, you know what that meal should be made up of or the timing, it's really worth noting that the meal you have should be proportional not only to the training you have to do afterward but also your relative fitness in terms of, you know, World Tour riders, like someone like Rohan Dennis who could deal about he can sit along all day at 250 Watts, just crank along and all night. So you give him night rides his application.
Neal Henderson 8:31
He doesn't do that he's not ultra stuff, He just tries to go fast.
Mac Cassin 8:35
You know, 250 for him is not super intense. But it's a lot of energy output. Some of you might only be able to ride 250 watts for an hour, even just 20 minutes. And like we're saying that's going to be 100% carbohydrate for you. But so you want to look at, you know, if you're riding all day at 100 Watts versus 250 Watts, the energy band is quite different. So the feeling requirements are going to be different,
Neal Henderson 8:58
definitely for a short low-intensity session that you might be doing your need isn't for a lot of energy just for maybe more hydration, just enough to kind of get you through that. And so the timing and the amount that you take in are also part of them that that kind of calculus if you're going out for a high-intensity session that's going to be sustained fairly long, you need the most amount of kind of pre-workout fueling when would be the ideal time that you might want to take in and what are the key things you want to take in there? Are there any things I want to think about in that meal? Getting ready for say a pretty long and pretty hard again, it's all relative how much I can produce and what's really long, maybe three hours is very long for me for someone else, it might be two hours, someone else it might be eight hours, but in that context Mac, what would you say?
Mac Cassin 9:52
The considerations you want to take there are partially again, like we were saying three hours is generally a pretty good window to start fueling beforehand. It gets tricky as you go either earlier like four hours or you go closer like two hours, you want to change the composition of what you're eating. So one thing to know is that fiber content, like higher fiber content, will slow down the rate of digestion. So that's where you get really when you get complex cards, and people come slow-burning carbs, it's because it takes longer for them to be processed to be converted into glucose to go into your blood, fat will also slow down that digestive process. So when you're further out, it's okay to have a meal with greater fat content, higher fiber content as that window closes, and you go to like the two-hour mark, lower fiber content, and probably a little lower fat. Now, what happens near when you go beyond that, or get closer than that two-hour window,
Neal Henderson 10:41
in that case, you want to definitely simplify even more and really purposefully be reducing any kind of fat intake as well as even protein. So if you think of it like, carbohydrate is probably the fastest thing that your body can digest protein is kind of in the middle, and then fat is at the lower end of things. And then carbohydrate, you have that little bit of a difference between more of a simple or complex. And then a high fiber is kind of that continuum with the high fiber taking the longest time and complex carbohydrate taking a little bit less, and then a simple type sugar. So like juice would be in that simple, quick fast digesting. So that, again, as you get into that quicker time between eating and training, you really want to stick to the simpler and definitely stay far away from the fat and proteins then
Mac Cassin 11:35
Yeah, and so to be more scientific about this, what we're talking about here for these different rates of you know, spiking your blood sugar, that's, you know, there's something called the glycemic index. So it's really a rating for how quickly a given food will increase your blood sugar. And so when we talk about these quick-acting carbohydrates, they're a really high glycemic index, they'll spike your blood sugar quickly, and then that'll drop down quickly as well, the lower glycemic index won't be as high won't peak as fast, but it will keep your blood sugar peaked for longer.
Neal Henderson 12:05
Yep, and there's one other element there the total glycemic load, which is the glycemic index, multiplied by the amount of that. So even if I have a relatively low glycemic index food, but I eat a lot of it, there's still a fairly high glycemic load because we're going to have an elevated response to that insulin specifically. And that's going to be sustained longer because it's more of it to process. Whereas if I have a high glycemic index food, but I just have a little bit of it, it is a slightly more rapid response, but it's not going to be sustained as long. So it's not going to have this significantly catastrophic kind of long elevated, we'll say, insulin. And you know, what, what the problem with that is, is there's a little bit of a rebound. And what we want to think about then is the timing of what happens.
Mac Cassin 12:54
Yeah, so for that rebound, it's exactly when you get into that window of say, like an hour out. You don't want to be eating, you know, there's more complex carbohydrates with a lower glycemic index, because when you start exercising, your body moves blood away from your digestive tract to your working muscles. So if there's food, a big lump of porridge, and fruit and nuts in your stomach, when you start exercising, it's gonna sit there for most of the training session. So you don't really want to unless your GI tract is, you know, a steel trap and can put anything down there, then that's a different situation. But for most people, that's going to cause a lot of discomforts. GI issues are never fun when you're not training. And they're even worse when we are training
Neal Henderson 13:33
for sure. And then the intensity has a major factor there. So the higher the intensity, the more we get that shunting away from your stomach. So if you're just going out, like at an easy, slow intensity, you know, if you're just noodling along, well, actually, in most cases, you might not see as much problem with that gi discomfort. But on the other hand, if you are going out and doing a race, then you're definitely going to be at risk. Yeah, so
Mac Cassin 13:59
that's, that's why when you get to that short hour, you don't want to be eating a really big hefty meal. But you might think, Okay, well, I have a short amount of time, so I should just take high glycemic index, high glycemic load some really simple sugars, like 60 minutes before workout. Why is that? Not a good idea?
Neal Henderson 14:16
Yep, you're gonna get that significant increase in insulin, which what insulin does is it's pulling the glucose out of your bloodstream and take it out into the muscles to be stored as glycogen as well as into your liver. So what's gonna happen is your blood glucose level will plummet and it can plummet pretty quickly and leave you hypoglycemic, which is that bad feeling like a lot of times I get kind of that shaky feeling. If I've had a lot of high glycemic load and I'm just sitting there at rest, I get that big drop in blood glucose, I get a little bit shaky. Sometimes you get that little bit of sweat and things like that. And that is definitely not a good place to be as you start to exercise. Yeah,
Mac Cassin 14:57
you get a sugar crash y'all seen kids run around get some sort of. Yeah, exactly.
Neal Henderson 15:03
Yep. So typically takes about 30 or so minutes from the time that you eat a higher glycemic index meal to getting that glucose. And that's at rest. Keep in mind that when we start exercising, once we start a training session, everything's a little bit different, you don't get that same insulin response. So this is really the before you start training things that are very much important to think about your timing. So I would say the worst time to be taking in a high glycemic load or high glycemic index food before training is around 30 minutes. But 20 to 4045 minutes is probably that danger zone, where you really want to avoid a high intake, you could dive a little bit of water at that point, and then wait until you either start your training session or just like five minutes before a sports drink or a jail, you're not going to have that big insulin response. Because your body you're going to start exercising.
Mac Cassin 16:00
Yeah, exactly. You're when you start exercising your muscles react in a way they kind of open up to allow sugar from your blood to move into them. So you don't get that same sort of peak insulin response when you start exercising when you've just consumed something that also that'll come up later, when we talk about fuel, after a ride that sort of receptive nature of muscles after exercise. But again, for this beforehand, we're talking about, you know, four to three hours out, you can do a big, more complex meal, high glycemic load, preferably with lower glycemic index foods, as that window closes, you want to shift away from higher fiber content away from fat until you get to that that one hour that like you're saying that 2045 minute window, you really need to be careful about what you consume at that time.
Neal Henderson 16:47
Exactly. So how long and hard you go, impacts how much and what the composition should be, what you're taking in, there needs to be relative to the timing before you start your session, primary thoughts, and considerations.
Mac Cassin 17:02
And this is something that you definitely want to if you're training for a big event or something these are, these are strategies to practice beforehand. One thing we'll say without fail is never try something new on your event day. So if you're not used to available of origin fruit, then don't try that on your big event just because it's a big ride. And you're you have been told that's what to do.
Neal Henderson 17:21
Exactly. And I would say the other important thing here is we didn't really talk about a lot of very specific foods that you need to have this or that there are a lot of different options and opportunities that can work within these contexts to give you what you're looking for. And so there is no perfect food. And so that's something really important and again, everyone does have some different nutritional needs. So make sure if you have any special considerations that you do work with a registered dietician to make sure that you're feeling based on what your true needs are. And with that, I think we're going to let this one rest but we will be coming back to talk more about then your fueling needs during your training, as well as then what kind of refueling you need when you finish training to optimize your recovery and be ready for your next session. That's it for another episode of the knowledge podcast. We'll see you next time.