Want to Ride Faster? Don’t Ignore Substrate Utilization

Summary

In this episode of the RCA podcast, host Cam Nicholls discusses the new substrate utilization feature in TrainingPeaks with head coach Ryan Thomas. They explore the importance of carbohydrate intake for cyclists, particularly during endurance rides, and how the new feature can help cyclists understand their fueling needs better. The conversation delves into the science behind substrate utilization, the significance of fat adaptation, and practical strategies for cyclists to optimize their performance through proper nutrition. Ryan emphasizes the need for accountability in fueling and the role of coaching in helping cyclists navigate these new insights.

Takeaways

Substrate utilization refers to the balance of carbohydrates and fats burned during exercise.
The new TrainingPeaks feature helps cyclists estimate their carbohydrate needs during rides.
Most amateur cyclists do not consume enough carbohydrates for optimal performance.
Carbohydrates are essential for recovery and performance in endurance sports.
The amount of carbohydrates needed can be higher than commonly recommended guidelines.
Context is crucial when determining carbohydrate intake for different ride intensities.
Fat adaptation varies among cyclists based on training status and fitness level.
Proper fueling strategies can prevent energy deficits and enhance training consistency.
Coaching can help cyclists understand and implement effective fueling strategies.
Awareness of carbohydrate needs can lead to better performance outcomes.

Chapters

00:00 Introduction to Substrate Utilization
03:01 Understanding the New TrainingPeaks Feature
06:05 Carbohydrate Needs for Cyclists
08:51 The Importance of Fueling During Rides
12:03 Fat Adaptation and Performance
15:02 Practical Applications of Carbohydrate Intake
17:50 Coaching and Support for Cyclists

 

Cam Nicholls (00:00.696)
Welcome back to the RCA podcast where today I am joined by the RCA's head coach, Ryan Thomas. And today we're gonna be talking about something that's a little bit technical, something that's new in the TrainingPeak software, but when you break it down, actually, it's, well, it is technical. It actually applies to all recreational and amateur road cyclists. And there was something interesting.

that Ryan put together for our Friday Training Trend newsletter about substrate utilization and essentially the amount of carbohydrates we're utilizing during our rides and there was one in particular that caught my attention about how many carbs we actually use as a general blanket during a one hour zone two ride. actually really surprised me and I know Ryan's gonna go into that detail today and I'm sure it'll surprise many of you. But before we go into that

level of detail, Ryan, can you tell me what is substrate utilization and this new feature in TrainingPeaks, which for those of you who are unaware, TrainingPeaks is a big training software platform, it's a calendar system we use for our members at the RCA to basically facilitate all their training. So tell us a little bit about this new feature and substrate utilization, Ryan.

Yeah, it's a really, really cool new feature that TrainingPeaks have brought in based on a whole bunch of research done by a well-renowned researcher and coach, Inigo Semmelan. He looked at, I think it was around 250 athletes, did a whole bunch of testing with them, lactate testing and metabolic cart testing, seeing how much fat and carbohydrate they burn in a specific ride and at a specific level. So,

what the substrate utilization actually looks at is how much carb versus fat calories that you're burning in your ride. So it's based on a prediction. So it's not a hundred percent accurate. If you went into your own metabolic cart test, it would be more accurate. But it's based off a whole bunch of testing that gives you a pretty good estimate for how many carbohydrates you're burning throughout your ride.

Ryan Thomas (02:15.572)
and how many carbohydrates predicted that you're gonna burn throughout that ride as well, which is the practical part for what we'll talk about in a minute. But very, very cool new feature that every single rider can use, and I think a lot of people will get a lot of value out of it, because majority of people that we see at the RCA aren't fueling their rides enough. And we can go through some specific examples, because it's actually more than you think you need.

Yeah, okay. So when you just drill in on this new feature and from a value perspective to people using Training Peaks, is it purely about them seeing how many they're burning and what they need to replace or is there more to it?

I think it's the accountability from a carb intake perspective. We know that carbs are your ultimate fuel and performance. If you're not having carbs before, during and after, you're missing out on a whole bunch of performance increases during that right end recovery and performance the following days. So that aspect, just making people aware that they actually need to take in a...

a lot of carbohydrate because most amateur or recreational cyclists do come into cycling and sugar is usually seen as like this bad thing that you shouldn't have sugar and it's in general life and if you're not an active person at 100 % you shouldn't be consuming a whole lot of simple sugar but as an endurance athlete or a high performance high intensity athlete you definitely need the carbohydrates and the sugar to be able to perform at a high level.

And I think this new feature gives people that accountability and specificity for what they should be doing.

Cam Nicholls (04:03.214)
Yeah, okay. So can you just give us a little breakdown then of what sort of catching some of our members off guard a little bit? Because obviously they've, know, lot of them have been speaking with, you know, coaches over the years from, you know, within our coaching group or within, you know, other coaching groups or some of them have watched a lot of YouTube content. Some of them have watched our very own Steph Cronin, you know, talk about, you know, how many carbs per hour they should at least be aiming for initially when they start.

leaning into the whole carb strategy for training world, know, starting with 30 grams an hour and then working towards 60 and then maybe going towards 90. So that kind of seems to be what are in people's heads. And then of course, you know, getting to, you know, what the pro level is getting to 125, 150 ridiculous. you know, knowing all that as as you know, know, evidence that we sort of see in the research and what we hear from sports dieticians, is that what is, you know,

the data showing us with this new feature in Training Peaks or is it catching some people off guard?

I think it's a slightly more than what the generalized data is, but there's a lot of context to this. just if we look at it from a pure data perspective and look at how many carbohydrate calories you burn in a ride and then how much you intake to keep up with that demand, it's a lot higher than what we see in the 30 or 60 grams of carbs an hour, for example. But the context makes a big difference here. And I think this is what's

A lot of people are going to be seeing this new feature and doing the calculations and like getting overwhelmed with it. And like you said, at the start of this, a one hour zone to ride, I'll go in that example right now because it's quite relevant. A one hour zone to ride for someone with the 250 watt threshold, roughly, which is a pretty normal for a recreational rider. You're looking at around 750 calories burnt.

Ryan Thomas (06:08.418)
carb calories burnt throughout that ride. So that's the cost on the body. There's a difference between kilojoules and calories. So this is where it becomes a bit technical. We're looking at calories, which is the cost on the body to produce the kilojoules, which is the mechanical work that the muscles actually do, which is measured in power. So the calories for that, 750 calories, what we need to do from that. So if you're looking at your own training peaks and you're

see 750 carb calories burnt for this ride or predicted for this ride. How do you actually figure out what you need to take in? And I'm taking this from the people at Training Peaks because they're the ones who created it and recommendation is that you need to intake roughly 50 % of the carbohydrate usage for that ride to maintain the physical output. So you don't just...

take 50 % of 750 calories because one carbohydrate, one gram of carbohydrate equals four calories. So we need to work backwards a little bit here. So what we need to do is that 750, you need to divide it by four to get the grams of carbohydrates that you're burning for that ride, which is around 180. And then you divide it by two, which you need to get 50 % of that number to maintain the physical output.

You can just divide it by eight is a quick way around that. But for a one hour zone two ride, average power of 160 watts, roughly 170 watts. Your body, the cost on your body is around 95 grams of carbohydrates. So that means that your body is using 95 grams of carbohydrates that you've taken in, whether it's before or during that ride to produce

a specific amount of mechanical work or power. Now that one hour, so the context behind that is you don't need to take in 95 grams of carbohydrates in that one hour ride. the reason for that and the recommendations for nutrition intake are based off duration and intensity. So you'll hear from Steph and you'll hear from other nutritionists and other

Ryan Thomas (08:26.862)
content online that over an hour and a half, you should be taking in more over three hours, you should be taking in a lot more. So, and the reason for that is we have a pretty high amount of calories and kilojoules in glycogen stores within our body to be able to produce that work without, with a limited cost for a one hour zone two ride. So you have 1500 to 2000 kilojoules of energy within your body to be able to.

produce work. So essentially that's quite a big ride. If you're looking at your own training peaks and you're thinking about how many kilojoules does it actually, how long does it take to burn that amount of kilojoules worth of energy or work, it's actually quite a long time. And probably for someone putting out 300 watts or two hours, it's probably a two hour ride for 2000 kilojoules. But if you're putting out 150, it's probably three hours to...

that would mean you are completely empty of stores if you didn't take any carbohydrates in. So the context here is really important. We don't expect you to be able to take in 94 grams of carbohydrates in a one hour session because you would have carbohydrates before and after that session to replace the 95 grams. And it's quite easy to replace 95 grams of carbohydrates from that ride as opposed to doing a three hour ride where your burns made it.

300, 350 grams of carbohydrates. So it's very difficult to get in your pre-ride meal. And during, you need to make sure you're getting a lot of that within there to be able to recover quickly and go again the next day.

Hmm interesting so the you know the barometer ride that I like to do when I'm training for events is the two-hour ride down the coast base focus sort of zone two I don't need anything because I feel like you know It's just one of the like I'm eating so much on my other rides when I'm training for an event I like to have rides where I'm not eating and I feel like I can get through that ride Without you know an effect on performance because it's not really a performance focus ride at zone two

Cam Nicholls (10:36.622)
And you know provided I have a good meal afterwards, I feel everything's okay, so I can still keep doing that zone to ride faster. That's okay

Ryan Thomas (10:48.946)
Yes, it really depends on what you've got the day before and the day after and what you're trying to get out of that ride from a physiological benefit. So for example, just quickly I just pulled up a two hour zone two ride of yours and you're burning your mechanical work for a two hour zone two ride at 180 watts, 200 watts for example is 1300 kilojoules worth of mechanical work.

that you're burning throughout that ride. the cost, the carbohydrate cost on your body for that ride is probably gonna be around the same, around 1300, 1200 maybe, because there'll be a bit of fat contribution in there as well. So divide that by four, you're getting 300 and then half of that 150. So 150 grams of carbs for that ride is what the cost is on your body. So what you should be trying to replace.

It's actually 300 because that's the amount you use, but you would need to replace 50 during that ride essentially. So if you're doing that in a fasted state and not feeling during, you need to be making up for it elsewhere to maintain your energy balance. And theoretically, if you don't do before and during, then you're in an energy deficit for the rest of the day and it just becomes a cycle. if you're, yeah, there's a cost and a benefit and there is

Some people are really big on their faster drives and higher fat contribution and high fat burning on those rides. But I think we need to remember, and this is why this is gonna raise a lot of flags. This new feature is we're actually, you're still burning a really high amount of carbohydrate even in a zone two ride. And I think people think that that's just like you're burning fat and then you switch to burning carbohydrates. There's no switch. It's not an on-off switch. You're burning a

high percentage of both throughout every intensity, just, the percentage changes as you increase the power. So the carbohydrate, you're using a lot of carbs still in a zone two, right? Is the takeaway there.

Cam Nicholls (12:56.042)
I also believe that the percentage changes as you get fitter. that two hours on the road down the coast that I talk about, I did that recently and I'm not fit at the moment. And I actually started to bonk because I hadn't had any fuel. I just had water in the water bottles. And I was starting to bonk. I said to the person I was riding with about an hour and 40 deep, was like, I think I need to stop and get like a Snickers bar or something like that. Whereas, like four or five months ago when I was training for an event, I would have

eaten that two hour ride for breakfast, pardon the pun, without having anything and being fine. So clearly the training, know, when you're particularly when doing a lot of zone two work, you do become better fat adapted. So that the switch, while it's not a switch, it does alter as you get fitter.

100 % yeah and that the fat utilization and where your fat max sits and the highest percentage of fat utilization across your power curve where that actually sits for each individual is very different based on training status physiology and that's why the in training peaks if you're looking at this feature another important point is you need to make sure that you have the right settings in your account to make sure to change the carb versus fat

in contribution because the more experienced athlete you are say, Tour de France level athletes, their Fat Max is going to be much further along with their power curve, relatively to a recreational athlete who's just starting. So like you said, Tour de France athletes could go on ride two, three hours without any carbohydrates at a really low level and be absolutely fine. But someone who has a really low Fat Max relatively to their threshold. So this is all relative to

the individual's threshold. The difference there is that today, for example, everyone's seen all that podcast where he's like 320, 340 Watts is his zone two or his fat max. That's very, very close to his threshold. And it's very high up his power curve because that's their ability because they train five, six hours zone two rides and they get really fat adapted and their ability to use fat as a fuel is really good. Whereas when you're only training an hour, hour and a half.

Ryan Thomas (15:12.39)
that fat utilization is very different and relatively to your threshold. that's, yeah, it's really important that you know what sort of level athlete and you adapt that in your settings.

Hmm, but I think it's an eye-opener. The reason why it was an eye-opener for me, and I know a lot of RCA members responded to that newsletter with similar thoughts, is that, you know, like we could be talking about intensity rides here versus zone two rides, but everyone's intensity ride looks quite different. Everyone's bunch ride looks quite different. The way everyone does threshold training can be quite different, whereas everyone's zone two, yeah, the actual zone two number.

might be quite different depending on the person's fitness level, but they're trying to target zone two and stay there for the entire ride. So it's a good workout to look at because everyone's, or most people are doing that sport workout specifically, but then recognize that, okay, when I am going into the world of intensity and I'm trying to perform and I'm trying to operate at my peak, knowing that

you know, unlike a car, you know, we can't perform optimally on three quarters of a tank or half a tank of fuel. You know, there's been research done on this, you know. If you're in a car and you've got like literally my car right now, it's got 40 kilometres left of fuel to go. I really need to go fill it up. But if I hit the, you know, put the pedal to the metal, like out the front here in Sunshine Beach, which I'm not gonna do, it's gonna take off the same way it would as if it was full. But.

know, physically, you know, our bodies don't operate like that. So we need to, particularly when we're trying to operate, you know, at intensity, get the most out of our high intensity interval training sessions, and then of course on event day, we need to try and stay towards the top of our capacity as much as we possibly can during those sessions so we can work in an optimal state. So knowing that, and then considering that we're potentially losing 100 grams of carbs per hour,

Cam Nicholls (17:19.008)
in a simple one hour zone two ride, it's like, well, our bodies are really using a lot of carbs when we're cycling, particularly at intensity. and knowing that we wanna try and keep it as optimal, the tank as high as possible during these sessions, for me it was like, okay, so now I reflect on the recent training that I was doing for an event and I was targeting 125 grams per hour.

You know, it seems extreme and it felt extreme and you know, it took a while to get to with the gut training but in actual fact, like, I'm still not getting anywhere near what I'm burning.

Yeah, I just started training for an event in 12 weeks time and I'm looking at it myself and it's actually made me the last two weeks since they updated it, it's made me consume more carbs. Like it's actually having an impact on myself and I knew how many carbs I needed to intake, but seeing the numbers there versus actually like just having a thing in the back of your mind saying, oh, I should have 90 or I should have hundred grams an hour today.

when I look at the session post or look at it before and it's like, I actually need to take in a whole lot of carbohydrates today. Like I'll actually plan out and I'll prepare to have a hundred grams of carbs an hour because I know that that's what I need for a three hour ride. If it's an hour, hour and a half, then not too, the impact is less. The cost on your body is less, but anything over that hour and a half period, if you're not hitting close to what you're burning, then I think you're going to be falling down a lot in.

in terms of your ability to progress and stay consistent with your high intensity training. I think that's the big difference here is that, yeah, okay, if you under feel one or two times during the week and you may not think it has a big impact or if you go and do that two hour ride fasted and under field, even if there is a little bit of high intensity in there and you've made, you've made get to the end of it and feel good and you eat after, but you at the end of the day, you're always playing catch up.

Ryan Thomas (19:28.344)
And that won't have an impact until three, four months down the line when you're actually starting to get into some really good quality, get really good fitness and you haven't prepared your body to be able to handle that or take on the carbohydrate and you're fatigued, you're always missing those two sessions a week, that consistency starts to fall down and you might get sick or injured or you need a rest when you shouldn't need a rest. That sort of stuff has a.

massive impact on your progression over a year to year, even six month period.

Exactly. And of course, you know, people might be listening to this and go, oh, it's just another thing that I need to look at and too many numbers and you know, one minute it's power, the next minute it's heart rate, the next minute it's, you know, chronic training load and now it's substrate utilization. But look, of course, if you're that person and you're like, you know, overwhelmed by all these numbers, but you're interested in them, that's the coach's job. So, you know, that's what Ryan is doing. That's what, you know, Cav, Ben, Carter, Georgie.

Danny all other RCA coaches are doing with their members and really pointing out the ones that are relevant during their one-to-one session so if you're interested in in stepping into this world and getting some support with some coaching make sure you head to the RCA website www.roadcyclingacademy.com check out the tab hire a coach and You can start working with a coach there. Thanks for your time Ryan and we'll catch everyone in the next podcast