Episode 53 - Why aiming for 120g of carbs per hour is a mistake

Why aiming for 120g of carbs per hour is a mistake

❗️ Let’s get controversial! ❗️

For many years carbohydrate fueling targets during exercise have been set at around 90g per hour for endurance exercise. But recently, a paper was published in elite mountain marathon runners who pushed the limits and hit more aggressive targets of 120g of carbohydrate per hour, while running hard! 

I’ve seen many age-group athletes boast about how they’ve hit this target or are trying to achieve this in their own training. But because I want you to have all the facts, I’ve dedicated this episode to explaining why this might not be the best idea for YOU.

In this episode, I explain the research paper, the methodology, athlete characteristics, and the findings with my Advanced Sports Dietitian critical thinking cap on. 

I also take things one step further by explaining the practicalities of how this research could be applied to you, and why this is probably a mistake for many age-group triathletes.


Link to original paper for some light reading 😆 : https://www.mdpi.com/2072-6643/12/5/1367

Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. Nutrients 12(5), 1367, 2020. doi: 10.3390/nu12051367.

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Episode Transcription

Episode 53: Why aiming for 120g of carbs per hour is a mistake

Taryn Richardson  00:00

Welcome to the Triathlon Nutrition Academy podcast. The show designed to serve you up evidence based sports nutrition advice from the experts. Hi, I'm your host Taryn, accredited practicing dietitian, advanced sports dietitian and founder of Dietitian Approved. Listen as I break down the latest evidence to give you practical, easy to digest strategies to train hard, recover faster and perform at your best. You have so much potential, and I want to help you unlock that with the power of nutrition. Let's get into it.

Taryn Richardson  00:45

Welcome to Episode 53 of the Triathlon Nutrition Academy podcast. If you haven't listened to it yet, we recently hit a massive milestone of 52 episodes, or one year of podcasting, which is pretty exciting. If you're not a podcaster, then you'll have no idea how much work a podcast is.

Taryn Richardson  01:09

It's not as simple as just recording an audio and then off it goes. There is so much behind-the-scenes action that happens in to dropping a weekly episode. So if you haven't listened to it yet, go back and listen to episode 52 where Stef, turned the mic around on me. And I take you behind the scenes of the podcast, where we've been over the last 12 months and where we're heading.

Taryn Richardson  01:32

Now, today's episode, I'm going to get a little controversial. And hopefully the title of this podcast has sparked your attention. But I want to talk to you about why blanketly aiming for 120 grams of carbohydrate per hour is probably a mistake for you. And it's not something that people talk about. But my job is to get you to understand the research. My superpower is translating deep science into something that's practical, and achievable for you as the everyday age group athlete - that you can walk away with knowing what to do.

Taryn Richardson  02:10

And I want to talk you through a paper that is new-ish. It was published in 2020. And it's where people are getting this new target of, "Oh, I need to be having 120 grams of carbs an hour when I'm training or racing". So I want to walk you through the study, the design, what they did, what they found and then some practical tips for you so that you can understand where you should be aiming for with your fueling. And that 120 grams an hour is, potentially, not right for you. So I'm going to get a little bit controversial, but you know, whatever, I don't care. Someone's got to do it.

Taryn Richardson  02:50

When it comes to sports nutrition, there is research happening all the time. It is one of the most rapidly evolving spaces as we learn more. And previously, our recommendations were for no more than 60 grams of carbohydrate an hour. And that was because we kind of tapped out there. And we know that the intestinal transporters of glucose, do max out at one gram per minute or 60 grams of carbohydrate per hour. Then we realised that there was another transporter that could run simultaneously and increase our fueling from 60 to 90 grams of carbs an hour, which is pretty cool. And so now we're starting to see the beginning of research exploring higher intakes than that - upwards of 120 grams of carbohydrate per hour.

Taryn Richardson  03:41

And the paper I'm talking about is the 2020 paper that came out of Spain, from Aitor Viribay and his colleagues. And they studied elite ultra distance runners. This is the paper that people are referring to when they're talking about that fueling target. So I will link it in the show notes if you do want to dive into it. But I'll talk you through it and translate the research jargon into something that you can understand.

Taryn Richardson  04:08

So let me walk you through the paper. So it was 26 male (and that's important because there was no females) elite, ultra distance runners. Now these guys were elite - like we're talking about top level, best in the world type athletes. And that's also really important because that may not translate to you. And what they did was they randomly allocated them to three fuelling groups for a mountain marathon. So there was a group that did 60 grams of carbohydrate per hour. There was a group that did 90 grams of carbohydrate per hour, and another group that did 120 grams of carbohydrate per hour. And they did nutritional training for about three weeks heading into that to make sure that they could deal with that load of carbohydrate. They also carb loaded them for forty eight hours before the race, and then they did a race in a research setting. So it wasn't a real race for money or prizes. But it was set up as a race and they were quite competitive.

Taryn Richardson  04:08

And they did a mountain marathon. So they ran 42.2 kilometers, with just under 4000 meters of elevation difference, which is nuts. So really hardcore trail running, right? It was in 10 degree Celsius, which is also really important because your gut doesn't work as well in the heat and we don't seem to be able to tolerate as much nutrition when it's hot. So it's quite cool conditions, only 60% humidity. And they ran from between four and a half hours to four hours and 45 minutes-ish. And for their fueling during that event, they used purpose made gels to reach their targets.

Taryn Richardson  05:53

So they randomly allocated into a group. The 60 grams in our group started with eight athletes. And they lost two due to injury throughout the race. The 90 gram an hour, they started with nine, and they lost two throughout that race as well, one to injury and one with gut issues. And the 120 grams of carbohydrate per hour group, they started with nine athletes and finished with seven because they lost two through that race with gut issues.

Taryn Richardson  06:22

So they use these purpose made gels to hit their targets each hour, and they drank water ad libitum. So there was no plan for how much water they drank, they could drink it as and when they needed. And what they did was they measured a few things before and during and after the race. So they measured their RPE or they rate of perceived exertion to see how hard they felt they were working. They also measured some markers of muscle damage before the race and 24 hours after the race. So creatine kinase (CK), lactase dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), urea and creatinine. And then the athletes recovered. They had certain recovery meal targets that they had to hit. And it was a really high carbohydrate diet. So it's basically to try and refill their muscle glycogen fuel tank again, after they've done a glycogen-depleting race.

Taryn Richardson  07:19

And a quick summary of the results is that they found that the athletes that fueled at a 120 grams of carbohydrate an hour, reported lower RPE. So they didn't feel like they were working as hard. And they had significantly lower markers of that muscle damage after the race. In particular, the creatine kinase, the LDH, lactate dehydrogenase and the GOT (glutamic oxaloacetic transaminase), which is pretty exciting to see, right? So they didn't feel like they were working as hard when they fueled more aggressively, and they recovered better and faster. Now, some did report fullness and flavor fatigue, because it's a lot of sweet for a long period of time and trying to hit those targets. And also remember that there was two in that group that DNF because of gut issues.

Taryn Richardson  08:12

So this paper is where a lot of people are starting to think that they should hit that target themselves. So now that you kind of understand a little bit about the paper and the research that that's come from, I just want to break that down and you know, put my critical thinking, sports dietitian hat on and walk you through that. So that you're not blindly following what everyone else seems to be wanting to do at the moment.

Taryn Richardson  08:40

All right, so the first, most important, thing about this paper is that these were very well trained athletes - like these guys are the elite. There was two world champions in the group and one international stage winner. So you need to think, “Is that you"? Can you put yourself in that group? These athletes are well-oiled machines. They have their day-to-day nutrition sorted and they have probably a relatively high amount of carbohydrate in their day-to-day diet, probably in the realms of carb loading on a day-to-day basis. When I work with Triathlon Australia and those elite athletes doing Olympic distance races, their day-to-day carbohydrate intake is in carb loading realms. So for them to carb load, all they have to do is eat the same and taper training. But a lot of the triathletes that I work with are a little bit carb phobic, and don't have enough carbohydrate in their day-to-day diet, let alone have enough to be in the realms of carb loading to support high level training.

Taryn Richardson  09:49

If you have very good carbohydrate periodisation, then your body is well adapted to deal with that carbohydrate in training. You have more carbohydrate digestion enzymes, the pumps and channels that we use to absorb carbohydrate and oxidise it for energy - that whole system is really well sorted. So to hit those targets of fueling per hour, is not too much of a stretch from what they're doing generally, anyway. And we see this in other sports as well. You think about professional cyclists who are winning major races, like think about the Tour de France or the Giro. Those guys would be churning through carbohydrate in the actual event, as well as what they need to do to recover, to back up and go again the next day. We also see these targets in a sprinkling of pro Ironman athletes who were doing things like Kona.

Taryn Richardson  10:48

So these Spanish trail runners were elite, they're world class. Are you that person? If you're not, then this research is not particularly well translated to you, unfortunately. The other thing that's really important to hit these targets is we need to do some serious gut training to get there. You can't just go out and go, "Alright, I'm gonna get to 120 grams of carbs now in my sessions". You have to slowly train your gut to deal with that and absorb it and oxidise it for energy. You can eat it, but I mean, it's just going to sit there. It's not going to do anything. It's just going to slowly fill up your gut if you're not good at emptying your stomach. Or it's going to back up in the upper intestines because you don't have the ability to transport that across from the intestinal wall into your bloodstream. And that's when we need it.

Taryn Richardson  11:33

We don't want it sitting in our gut, it's useless there. We need it into our blood streams, so we can transport it to the working muscles. So importantly, these guys are well adapted to high daily carbohydrate diets, so that that whole process works more effectively than somebody who's a little bit afraid of carbs, as well as they're used to having high amounts of fueling during their training. So the step up to a 120, is not that great. Do you have any idea how much carbohydrate you have per hour? That could be a good point of homework for you is to actually go and think about that? Are you anywhere in that realm?

Taryn Richardson  12:23

If you are, then how do you go tolerating it? It's not until we're out there for a little while, that things kind of rear their ugly heads. Like I said, you can consume it - like you can chuck 200 grams of carbs an hour into your stomach. But it's what your body then does with that is important. We have to train our gut to empty it from our stomach, which can be done. And then we also have to train our gastrointestinal tract to absorb that into the bloodstream. That's really important. And we don't actually know how long that takes to happen. There's no clear cut guidelines around gut training and timing yet. But to be honest, it's probably highly individual anyway. It would purely depend on your day to day diet, and what you're doing. You need to train your gut if you want to do this sort of fueling, just like you train your muscles and your body to get fitter and faster. You have to train your gut to deal with this extra carbohydrate as well. So it really depends on what your baseline is.

Taryn Richardson  13:24

So a couple of key things in there to think about if you're looking at doing this, or if you already are. Are you at that elite-elite level where your races are really high intensity for a long period of time? Like you can maintain really high percent VO2 max and extended periods of time? Or not? Are you walking through aid stations or not? And what sort of gut training have you done? That's super important. I'm not going to talk about it here. Because it's highly individual. It's something we do dive into inside the Triathlon Nutrition Academy. We have a whole week on gut training and a whole week on multiple transportable carbohydrates. Because if you want to step your fueling up above 60 grams of carbs an hour, you have to rely on multiple transportable carbohydrates. It's so important. You can't just eat whatever the heck you want and expect your gut to deal with it. Because we know that our glucose channel maxes out at 60 grams an hour. So we need to rely on other types of carbs and sugars to increase our fueling beyond that.

Taryn Richardson  14:30

The other thing I wanted to say was - is your recovery as important as these types of athletes? Elite athletes have a very busy race calendar. And so their recovery becomes really important. Like think about the Tour de France. They have less than 24 hours to recover before they have to go again. So that type of strategy for this level of athlete is really, really important. But for you, as an age grouper, who might do maybe one Ironman a year, maybe two, you're not usually doing multiple endurance events back to back - unless you're Jason Currie who's a little bit crazy, but he's one of my athletes inside of the Triathlon Nutrition Academy. So this sort of thing could be useful for him. He's essentially doing an Ironman a month, or an ultra marathon a month or something like that. But for you, does recovery need to be this dialed in? Probably not. You've got the time to recover before you have to go and run a marathon again or ride a 200k stage race.

Taryn Richardson  15:40

So I just want you to be mindful of those things. If you're hearing that chatter on the band waves and seeing people boasting about hitting those targets, we really need to take a step back and understand the research for where that's come from. And if that's translatable to you. Now, I think it is awesome research. It is the start of what we're going to see an explosion of research in this space. And what often happens with sports nutrition is there's anecdotal evidence and people are trying stuff and having cool little results before it becomes well studied. So I think we're kind of in that space at the moment. So I'm not saying don't try it. But for the majority of you, it is a mistake, because you're not going to be able to tolerate that level of fueling. You have to train your gut to absorb that, because your intestine is the rate limiter of that. You can eat it, you can consume it, you can chuck it down your stomach. But whether or not you're absorbing it is another thing. The longer you're out there for, the more things will kind of backup in your guts in a way.

Taryn Richardson  16:50

So you can throw 200 grams of carbs an hour in, but it's not going to go anywhere. So over a number of hours, it'll sort of slowly build and build and build until it leads to gut upset. Whether it's nausea, fullness, slushiness, vomiting, diarrhea, whatever it is. The only way is out, in a way. And typically that happens after a number of hours. So three, four or five hours at the back end of the bike. Or it's when you go to run off the bike that we kind of get into strife. So if you put yourself in that elite category, like you're winning your age group, you're a super fast athlete, you're out there to win Kona, then it's a strategy that you can look at. But you're going to need to want to work with a sports dietitian so that you can dial that in for you and understand how to gut train properly.

Taryn Richardson  17:38

If you're not, if you're just an age grouper, out there for a good time, want to do really well, you know, because we like to do all those one-percenters and do all those things correctly, I definitely wouldn't try this as a strategy. There are probably bigger things that you need to do first, before you even go down this path. Like, what's your day-to-day nutrition look like? Have you got your recovery nutrition dialed in for what you need it to be? Have you periodised your day-to-day eating to your training load? Like, that's triathlon nutrition 101. It's one of the first things we cover in the Academy - is how to do that properly, because nobody knows how to do that. And that is where you're going to get better bang for your buck out of your training and racing.

Taryn Richardson  18:25

Before you even try and go down weird rabbit holes and try and, like, win at fueling per hour, you need to have your day-to-day nutrition right. So these elite athletes in this study, these elite mountain marathon runners, they have their day-to-day nutrition nailed. Tour de France riders have their day-to-day nutrition nailed. So they can hit these types of targets because they've dotted all the I's and crossed all the T's in all the other spaces. So I always talk about nutrition being that pyramid, right? We need to build a solid foundation with our day-to-day nutrition first. That is where you're going to get the best bang for your buck. And then we move up the pyramid a little bit further and start to dial in our more specific sports nutrition strategies. And then we top off the pyramid with more of our one-percenters there. Now, not a lot of athletes work that direction. They start at the tip and work backwards. They do all the one-percenters. They spend 20 grand on a carbon bike. They take weird supplements that don't do anything. But yet they don't have the proper recovery targets for them. They haven't periodised their nutrition to training. They're a bit afraid of carbohydrate. 

Taryn Richardson  19:43

So I really encourage you to take a step back from all of this stuff. And think about if you've got the foundations nailed first. And I really hope that's made you stop and think about where stuff comes from too. I've seen so many people talking about, or boasting about, hitting that 120 gram per hour target. And for 95% of you, it is probably a mistake because there are so many other things you need to do first. I'm not saying don't do it. But maybe just take a step back and make sure you've done everything else first, before you try and build up your fueling during training and racing. And you're going to need to do that systematically and strategically so that your guts can deal with it.

Taryn Richardson  20:31

All right, rant over. I hope you've enjoyed that episode. If you have any questions or you want to chat back about it, come and send me a DM on Instagram at dietitian.approved. And hey, if you want to catch me live, come and join me for Coffee and Questions. It's in the Dietitian Approved Crew Facebook group on the first Thursday of every month. Like if we can have a conversation about this, live on Facebook, that'd be pretty cool. I would love that anyway. All right. Thanks for listening. I will see you next week.

Taryn Richardson  21:05

Thanks for joining me for this episode of the Triathlon Nutrition Academy podcast. I would love to hear from you. If you have any questions or want to share with me what you've learned, email me at [email protected]. You can also spread the word by leaving me a review and taking a screenshot of you listening to the show. Don't forget to tag me on social media at @dietitian.approved so I can give you a shout out, too. If you want to learn more about what we do, head to dietitianapproved.com. And if you want to learn more about the Triathlon Nutrition Academy program, head to dietitianapproved.com/academy. Thanks for joining me and I look forward to helping you smashed in the fourth leg - nutrition!


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