The Time-Crunched Cyclist Podcast by CTS

Episode 208: How Carbohydrate Fueling Affects Durability in Long Workouts and Races, with Dr. Gabriele Gallo, PhD

August 07, 2024 • CTS • Season 4 • Episode 208

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IN THIS EPISODE

  • Carbohydrates and durability
  • What are Critical Power and W Prime
  • Research review: Critical Power at rested vs. fatigued state with CHO
  • Fueling for increased durability
  • Fueling by percentage of hourly expenditure
  • Nutrition timing and periodization

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GUEST
Gabriele Gallo earned his PhD in sports science and also recognized that scientific literature - including his own research - is complicated for non-scientists to read and comprehend. As a result, he created the Knowledge Is Watt Substack and Instagram account. He has dedicated himself to translating scientific papers into more easily digestible content to be read, understood and easily applied by all athletes and coaches.

HOST
Adam Pulford has been a CTS Coach for nearly two decades and holds a B.S. in Exercise Physiology. He's participated in and coached hundreds of athletes for endurance events all around the world.

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Speaker 1:

from the team at cts. This is the time crunch cyclist podcast, our show dedicated to answering your training questions and providing actionable advice to help you improve your performance, even if you're strapped for time. I'm your host, coach adam pol, and I'm one of the over 50 professional coaches who make up the team at CTS. In each episode, I draw on our team's collective knowledge, other coaches and experts in the field to provide you with the practical ways to get the most out of your training and ultimately become the best cyclist that you can be. Now on to our show. Now on to our show. Welcome back, Time Crunch fans. I'm your host, Coach Adam Pulford, In the past episodes with Dr Gabrielle Aguilillo.

Speaker 1:

From Knowledge is what we learned that training at Fat Max can help improve glycogen sparing for longer events, making you more durable to intensity when you hit it hard late in the race. We also learn that those overly focused on increasing FTP or VO2 max may not necessarily have high durability, but that's okay if that's in line with the performance determinants of your races. Now let's bring some of this all home by talking about how carbohydrate influences performance when fresh and when performance while fatigued. So, Dr Gallo, welcome back to the show.

Speaker 2:

Hi, adam, and thank you again for inviting me and also hello to all your listeners.

Speaker 1:

Yeah, yeah, no exactly. And you know I think our listeners they're going to learn a ton from you in all three of these episodes here. But I'll put this out there as kind of the not so shameless plug, because I think a lot of our listeners should probably subscribe to a little bit more of your research, especially in Substack. So could you take a minute and just describe what you're producing on Substack and if people like what they're hearing here, how they can access that?

Speaker 2:

Okay, so thanks. So basically, at the beginning I was just trying to put material on the social media accounts, so Instagram x or twitter or whatever, and so infographics, so just a graph with a one line or two line explanation of results. But then I I saw that people were commenting or writing in the indirect something like okay, but what about this, what about this? And so I I felt that a good way to extend the contribution to the community was just to try to make to write something about the infographics and each study that was explained in infographics in a short, in a short note. So basically, on substack, I'm just trying to explain the infographics results from scientific studies in a three minutes, four minutes reading, because, yeah, as as your podcast, because there is, there are time crunch cyclists and also time crunch readers. So this is the goal.

Speaker 1:

Yeah, that's it and it's you know. It's funny too, because I remember seeing your stuff on Twitter a while back and it was when, like um, oscar's, you can Roop, and there there was a few others. Like when infographics in exercise physiology were becoming a thing, I was, I was really into him, right. But then I saw your and then I, a lot of people were doing them and I was like, oh, just another infographic kind of got out of that for a while. But then I picked your stuff back up really in substack Cause I was like, oh, wow, this is, like you know, brilliant. It's on point, like it's clean, um, it is shortened to the point three to five minutes.

Speaker 1:

So I think taking complex information and making it simple is probably one of the hardest things to do in any science. And, uh, your evolution from kind of infographic to um and you still have that like uh as part of uh, some of the stuff I see on um, instagram and and I'm not really on X anymore, but um, that's really good, just for the like the quick visual. And then the sub stack just has has that like um, uh, just a little explainer, that goes on with it. So thanks again for producing that content. I think it's really relevant, uh for anybody who's been in this sport you know is as long as I have uh coaching for a long time or even somebody who's really curious, maybe just picked up the um, you know the bike and started training a year or two ago. Your stuff is really digestible. To make this complex stuff easy to understand, yeah, yeah, thanks, thanks, adam.

Speaker 2:

This was, this was and this is the goal. So just try to make learning as easy as possible, without over-complicating things, but explaining in a fast, easy way, but just but keeping the concept easy and understandable for everyone, so from the coach to the exercise physiologist, to the self-coach cyclist.

Speaker 1:

this is the goal. Love it, love it. Well, we're going to talk about another trendy topic today, since everybody is today, since everybody is guzzling and gobbling carbohydrates like it's crazy. I want to talk about carbohydrate and how it relates to performance, but, in particular, how does carbohydrate intake influence durability?

Speaker 2:

influence durability. Yeah, yeah, I think this is one of the hottest topic in the in the last year, in the last years, especially in a, in a in road cycling, because of is the one of the competition, one of the competition with the longest duration and basically, as as we said in the last episodes, we know that durability so the ability to decrease performance as much as possible during prolonged exercise or competitions is linked to being able to preserve muscle glycogens, so carbs inside the muscle. So basically, you have two ways to preserve this muscle glycogen. You have two ways to preserve this muscle glycogen. One is to use more fats and less carbs to produce energy. This is one way, and the other way is the types of carbs that you use to produce energy. So if you are using more exogenous carbs instead of endogenous, where endogenous is muscle glycogen, it can be, of course, better for performance because you are sparing that muscle glycogen.

Speaker 1:

And exogenous is stuff we're taking and we're eating and drinking.

Speaker 2:

Yeah, yeah. Exogenous is stuff that you are eating. You can eat it before and especially during effort.

Speaker 1:

Yeah. So really that glycogen sparing effect still playing a role we learned about that in part one and having enough carbohydrate or glycogen on board in order to produce the energy when it matters in the race. Really referring to that durability, um is what we're talking about here. So whether we uh load it and have it on board or we spare for it because we're so fat, adapted or whatever term you want to use, um, this is where it hits home. One one research that you wrote about that I want to talk about has some terms that I think we need to first um define, because the terms in your paper they're they're similar terms than what I talk about. Or or um, the terminology I use on this podcast but um, we're going to, we're going to see how it influences. So let's first talk about um. What critical power is and what W prime is. Can you describe to our listeners what those are and then I can fill in some gaps.

Speaker 2:

Yeah. So basically using critical power and W prime is just another way to describe human metabolism during exercise and there are two parameters that describe two different, two different parts of performance. We can say critical power has more aerobic qualities of performance and basically it is just a benchmark in power output that divides nonlinear response in fatigue. So above the critical power you are fatiguing very fast from a metabolic point of view. You're accumulating a lot of hydrogen ions and other molecules that inside the muscle are linked to fatigue, while below critical power these metabolites like hydrogen ions and K plus and other, but their accumulation is much slower, so you are fatiguing less below critical power.

Speaker 2:

So if your critical power is higher, you are more, let's say, aerobic qualities and you can have a better performance over 20 minutes, 30 minutes, 40 minutes, one hour and something like this, while W-prime defines the anaerobic reserve. So basically it's the work that you can perform above the critical power. So let's say that two athletes have the same critical power and one has a higher anaerobic reserve or W prime compared to the other one. The first can perform better in efforts like 30 seconds, one minute, two minutes that are using more anaerobic pathways. So these are the general uh.

Speaker 1:

General physiological description of the two parameters yeah, yeah, exactly, and I'd say to make things like as simple as possible and kind of link it to the terminology I use on the podcast is critical power correlates to FTP or LT2, or yeah, you know threshold, what threshold.

Speaker 2:

Yeah, it's very near. Yeah, yeah.

Speaker 1:

Yep W prime correlates to something that I refer to as functional reserve capacity or FRC. That marker is that's measured in kilojoules and it's an anaerobic marker measuring the highest amount of work, like I said, in kilojoules that you can produce over FTP for one time effort before you fatigue and have to pace down. So it's I would say it's similar to because even with that term I still call it the anaerobic battery, right and it's. It's more or less the same and it's important for listeners to understand critical power, roughly ftp w prime. If you're ever like reading or or listening to something where they're talking about W prime, it's very similar to that FRC component.

Speaker 2:

Yeah, yeah, I think are similar and different point of view, but the concept is exactly this one yeah.

Speaker 1:

Yeah, no, that's it. So, dr Gal, walk us through this, your research, when you're looking at critical power and arrested state versus a fatigued state, and then you throw in some carbohydrate as well as with W prime.

Speaker 2:

I Published a resume of this interesting research some weeks ago on on on sub stack and it was a paper from From a British research team that the leader is Professor Andrew Jones, that is very popular around the sports science is one of the most important exercise physiologists and basically they wanted to see if ingesting carbs during exercise is linked to better durability, so basically if the strategy that everyone is employing on the field is real, better for durability. And also they wanted to verify directly if preserving muscle glycogen is linked to a better durability. So these two were the main goals. So they basically just recruited cyclists they were not professional cyclists but they were just amateur recreational cyclists and they brought them to their lab and basically they performed three trials in the lab in three different days to evaluate the two parameters that we described before, so critical power and W prime, in three different conditions. The first one was a trusted state, so they just visited the lab and a trusted state.

Speaker 2:

After a short warm-up they performed a test to evaluate these two parameters. A second day they repeated the same test, but after it was two hours of exercise before the test without ingesting carbs. And on the third day they did the same of the second day, but ingesting carbs during the two hours it was 60 grams per hour. That is inside the general recommendation of carb ingestion during exercise to maximize performance. So this was the protocol.

Speaker 2:

And they also measure muscle glycogen depletion after the two hours to see if there was a correlation between this parameter and the durability. So durability was defined as the decrease in performance. Performance that were measured as CP and W prime. So these two parameters between resting state and after two hours of exercise, and I think the results are interesting and also sometimes difficult to completely understand at all. But what they saw was that generally performance was better maintained when they ingested carbs compared to when they did not ingest carbs, especially for critical power, while for W prime, even ingesting carbohydrates during the two hours, the parameters decreased. So ingesting carbs preserve critical power but not W prime. So this was the main outcome power, but not w prime.

Speaker 1:

So this was the the main outcome, yeah, so so essentially like ingesting carbs is going to help you when you do a bunch of work, you go 20 minutes really hard, um plus or minus a few minutes, right. So that's the hard, long, grindy thing. That's the fatigue resistance or the durability test kind of that we're talking about in previous episodes. So carbohydrates really helps with that, but it doesn't help if you've got a 30 second or a 60 second max effort at the end of getting fatigued. Why is that?

Speaker 2:

Yeah, this is an interesting question and I don't have the definitive answer to this interesting question and I don't have the definitive answer to this and I don't know. Maybe carbs availability and mass for glycogen is more linked to preserving the anaerobic pathways, so the pathways that are more linked to W prime and less to CP. But this was not measured in the study. So we we cannot uh answer at all and uh, yeah, that's it. So this is uh, let's say uh forced stone to understand that with other studies, other things that uh, so we can answer in a in a better way to this, this question. So we can just say that, uh, carbs preserve, uh, uh, uh, in some extent performance, but not all your performance level.

Speaker 1:

So this is the general outcome yeah, that's it, and I think what's what's a very okay answer is we don't know and, yeah, further research needed, right um? But it's okay to say we don't know.

Speaker 2:

But here's a here's an observation right, yeah, yeah, one. One time I, at a congress, I heard this, this phrase, that I think it's very funny that there is a something that we know we know, something that we know we don't know, and something that we don't know we don't know that's it.

Speaker 1:

That's it. Yeah, the older I get, there's a lot of this stuff that I know I need to know more. Yeah, yeah, but so I'd say so for those who you know, maybe the anaerobic animals out there that say, well, how do I improve you know, my, my W Prime or my FRC late in the game my advice, my personal advice and I'll be curious, what Dr Gallo says is make it higher in a fresh, in a fresh state, in a rested state. So if you can improve the absolute and that goes back to, like part two, what we were talking about improve your absolutes when you're rested. It's probably always going to decrease in a fatigue state, but it's going to be less than if you didn't train it to be high in the first place. Does that make sense? Yeah, yeah yeah, that's.

Speaker 2:

I think that's always reasonable. So, of course, uh, uh, if you, if you, if you can, if you are able to improve your parameters at resting state, then if then your decrease after three hours is the same, you are still better after three hours because you improved your parameters at resting state. So, as we said in the last episode, it's the last part of the cake durability. So to improve performance in general, just at the beginning, focus on improving your parameters at rest state, that W prime, cp or whatever, and then durability follow after all these kinds of things. So the outlet is FTP V2max, threshold W prime and then, if you want to optimize for long duration competitions, you can also threshold W prime, and then if you want to optimize for long duration competitions, you can also focus on durability. Just not start with durability, yeah exactly.

Speaker 1:

Yeah, that's a good summary, you know. Another thing, though, pops out to me when I read, when I read that review of the research, and it is that if somebody does their training properly and they identify themselves as having a high durability, but if they get their fueling wrong on race day, it doesn't matter, their durability is going to decrease. Yeah, yeah, yeah, yeah, yeah, talk about some ranges. Go with it wherever you want?

Speaker 2:

yeah, yeah, I think it's one. This is one of the hottest topic uh right now in sports science is the how much carbs ingesting during exercise. So this is the the hottest topic and I think that. So, just to understand the, the framework, as we said before, uh, ingesting carbs during exercise can make you able to use these carbs instead of muscle glycogen to produce energy and so, preserving muscle glycogen, your durability is likely to improve. So, how much carbs ingesting during exercise? I think that we can have two different point of views. I think that we can have two different points of view Research that have been already published and the latest approaches on the field, especially in professional road cycling.

Speaker 2:

So, from just a research point of view, the best range is something like between, let's say, 30 and 90 grams per hour. Let's say 30 and 90 grams per hour. So you have the best effect on performance at the end of fatiguing exercise using these amounts. So some studies show something like a reverse U relationship between performance optimization and carbs ingestion. So below 30 grams per hour is uh, is very low carbs ingestion and performance can be uh can be not optimized and the same as above 90 grams per hour. But so why professional cyclists are eating something like 120, 140 grams per hour in the longest and hardest races in World Tour.

Speaker 2:

One thing is that in the research, participants were, let's say, trained cyclists, so, but the FTP was lower compared to the professional cyclists.

Speaker 2:

So it is very likely, it is not likely, it is sure that their carbs consumption was lower compared to world tour cyclists. So this is one thing. The other thing is that maybe the main factor that limits carbs consumption exogenous, so ingested carbs consumption during exercise is absorption, so the absorption of carbs, and there is something like I think everyone knows gut training. Usually, in a research setting, people that are participants are not doing something like gut training before the protocol, before the test, while professional cyclists are more familiar with ingesting high amounts, for maybe they are doing it for years, at least for months. So a theory is that if you are trained to ingest more than 100 grams per hour of carbs during exercise, then you are able to absorb and utilize it. But from just data and research point of view, the maximum amount of carbs that can be used, so exogenous carbs, is something like 90, 100 grams per hour, not more. So there is a mismatch between practice and research in this topic.

Speaker 1:

Yeah, exactly, and this is evolving as well and I've covered multiple podcasts on this and this is an evolving topic of sorts and I have explained my rationale on the podcast and working even with some training piece stuff where, as opposed to just working with that 30 to 90 grams of carbohydrate with my athletes, I use percentages of uh burn rates from the kilojoule expenditure on their power meters. So when I'm having a performance race day or performance workout, I want the athlete to consume 40 to 50% of their output from their power meter using kilojoules and that usually ends up being around that it correlates to, say, the upper end of that 30 to 60 or, sorry, 30 to 90 gram range. And if you do the math for my like world tour athletes, they have higher FTPs, therefore higher burn rates, and they're going to be at the upper end slash over that. But there are some nuances that from other researches. It's gut training, it's the microbiome, it's the individuality of elite athletes that allow that carbohydrate utilization, absorption and substrate utilization at those high intensities.

Speaker 1:

I think that there's more there that research will deduce from Meanwhile, you know. The other thing is we've also been able to push upper limits. You know it used to be like 30 to 60 grams of carbohydrate per hour was the recommendation. But now you know, with kind of that, a better ratio of glucose, or sorry, multidextrin and glucose and fructose of that one to 0.8 ratio. That's also allowing for better absorption rates for for all athletes, especially elite athletes yeah, yeah.

Speaker 2:

This is one thing that all the all, the all the carbs that are on the market use. This, this ratio between maltodextrin and, or glucose and fructose, because of these two different types of carbs, uses two different transporters to be absorbed and to go in the blood, and so it's just like you have two doors to enter instead of only one if you use two different types of carbs. So maltodextrin and glucose, or glucose and fructose, or glucose and fructose. So this is why research shows that we can pass from 30 or 60 to 90 grams per hour combining fructose with glucose or maltodextrin.

Speaker 1:

Yeah, exactly so. I mean, carbohydrates are king when it comes to performance, and that performance is high intensity. Whether you do it in a fatigued state or in a rested state, carbs will always help increase performance. Now to that point, though, because, looking back on our little mini series here in the podcast, we started with peak fat oxidation and fat max training, then we talked about optimizing FTP, vo two. We're weaving in fatigue resistance and durability. Here, at the end of the day, like more training prevails, with training your body to be a high performance machine. So there there's, there's a lot to be said with training not only of the day, but training of the week, training of the year and training of the years Just having a lot of training impulses for, you know, over 10 years, okay, and we talked about how you as a time crunched athlete, you need to get creative on how you get those total hours done and when you have time, go longer for the distance and decrease some of that intensity.

Speaker 1:

But I think like, as I think about all these things, that we're talking about the preservation of muscle glycogen and utilizing fat as a fuel source. We have to also understand there's just a ton of fat on our bodies, even for, like lean people. So to me it seems like, in theory, if you can kind of optimize all of this, like get your peak fat oxidation rates up there, do your intensity training like you, you'll be able to just train more is. Is that a thing? If we just we optimize this, I mean you essentially can just do more on the day, recover faster and become a better athlete. Is that true?

Speaker 2:

yeah, yeah, yeah, it is one one interesting thing that uh, I, I also, uh, I also listen this from uh, my colleagues from university.

Speaker 2:

Uh, oakland university of technology that I cited in the last episode is where I spent my last year of PhD in New Zealand, and there, especially Dr Edmonder said to me that one thing about being able to oxidize more fats, yes, could be good for performance, for durability, because you can spare glycogen during the race, but also, if you Use more fats during your training sessions, maybe you can also be able to train more, but during the same, the same training session, because because maybe you can go longer at the same intensity because you oxidize more fats and use less muscle glycogen. And maybe maybe this was something that I was thinking about and that you that you just said that you can also be able to recover better between different training sessions. So, consecutive training sessions, maybe during the same day, maybe if you do twice a day, or maybe between consecutive days, because you start with higher glycogen the following day, or the second session during the same day. So, yeah, absolutely. This is not supported by a scientific study, but it makes complete sense to me.

Speaker 1:

Yeah, yeah, yeah, and I just want to mention that I mean, cause I threw a lot at you there and it's good to hear that they're, you know, thinking the same way with that kind of like total training approach. But I think, like the practical takeaways here are you know, from this, carbohydrate fueling, or carbohydrate is king is like first of all, use the right carbohydrate combinations, so that combination of maltodextrin, glucose, fructose 1 to 0.8 ratio, that's best you want to improve your ability to burn fat as fuel, like we talked about in episode one. And then you know. Last thing is, if you're going to have a high intensity session, make sure that you're topped off going into that and we spoke a little bit about this too. Where you can, you can do some macronutrient cycling or you know, kind of like live low in carbohydrate land and then kind of come back up when your intensity is high. But if you have high intensity periods, make sure that you eat pasta, you eat rice, like you have muscle glycogen on board before you go and smash the animals, yeah yeah yeah, I think it's

Speaker 2:

uh, it completely makes sense, uh, to adapt nutrition to periodization, but for the macro cycle. So, uh, for example, if you are going easier during the base period, maybe you, just, you can just stay a little bit lower with carbs and then, during the more specific period, with high training load, with high intensity workouts, just, uh, uh, you can, uh, you can eat more carbs, and but also at the, at the micro cycle level. So, uh, for example, uh, just before a lowensity session, it is not necessary to eat a lot of carbs pre and during, because then you can focus on improving or at least spending time at your peak fat oxidation or at high level of fat oxidation, while for uh shorter or medium uh duration and high intensity workouts, ingesting carbs could be very important to be able to perform at your maximum quality, the, the workout yeah, so I mean essentially what you're saying.

Speaker 1:

There is, if you take carbohydrate, if you take a gel, um, before your 90 minute endurance session, if you take it like 10 minutes before, you're essentially going to tell your body to start burning carbohydrate as a fuel source versus yeah, exactly yeah fats yeah, there is an inhibition of lipolysis if you eat carbs just before or during your workout.

Speaker 2:

Eat carbs just before or during your workout in the polices is inhibited. So of course there is lipolysis. There is not inhibition, complete inhibition, but your fat oxidation rates are lowered, is you? If you ingest carbs before or during exercise?

Speaker 1:

yes, yeah, but if you're at the start line of a cross-country mountain bike race, having a gel 10-15 minutes before, that's probably pretty ideal, right yeah, yeah, absolutely, absolutely, because here the goal is performance optimization and not physiological stimulation of fat oxidation. So two different scenario, two different goals, two different nutrition strategies gosh well, dr gall, I feel like I could probably do podcasts with you, like every day, all year.

Speaker 1:

So but yeah, I, I do need to get back to some coaching and you need to get back to pumping out more great content on Substack. So, yeah, I mean I just want to thank you again for taking all the time to talk to us and sharing your knowledge with our listeners. We talked about you know where to find you on the socials and again on Substack. Is there anything else that you want to tell our listeners in the way of finding more information from you?

Speaker 2:

Yeah, just stick with social media and Substack and Substack you can find everything there. On social media, I'm putting something like free content almost every day about cycling science to performance optimization, while on Substack, there is a small fee, something like five euros per month, and you can have a deeper look at scientific studies and understand more. So, social media and Substack, you can find everything that you want that I'm producing at the moment.

Speaker 1:

Perfect, Perfect. Well, I've already got some ideas for future episodes. So, Dr Gello, I'll probably be in touch soon, but for now I'll let you go and to our listeners. Thank you so much for listening to the Time Crunch Cyclist. I hope all of this information really adds value to your training.

Speaker 2:

Yeah, Thanks Adam.

Speaker 1:

Thanks, Bye. Thanks for joining us on the Time Crunch Cyclist podcast. We hope you enjoyed the show. If you want even more actionable training advice, head over to train rightcom backslash newsletter and subscribe to our free weekly publication. Each week you'll get in depth training content that goes beyond what we cover here on the podcast. That'll help you take your training to the next level. That's all for now. Until next time, train hard, train smart, train right.

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