Carbs, carbs, and more carbs.

It takes a hell of a lot of energy to ride a Grand Tour. We’re talking about three weeks of racing, more than 80 hours and 3,400 km in the saddle, and something like 50,000 metres of climbing. That’s a lot of pasta and rice.

But how much exactly? And to drill down further, how much carbohydrate are we talking about? After all, if you’re going to do any sort of intense exercise, let alone race a Grand Tour, you’re going to need carbohydrates.

A new research paper sheds light on this very subject, following one rider throughout the 2021 Vuelta a España. It’s apparently “the first report to detail the distribution of CHO [carbohydrate] intake on a meal-by-meal and stage-by-stage basis during a Grand Tour.”

Let’s find out what the study showed.

As is normally the case with studies like this, the researchers don’t identify the rider involved. But there are some clues:

“The male athlete was 26 years old with six years’ experience as a professional cyclist, the last three years at UCI WorldTour level. The athlete’s role within the team at the 2021 Vuelta a España (his 6th Grand Tour) was as a ‘domestique’, supporting the team’s general classification leader during hilly and mountain stages.”

Reckon you know who it is? Keep reading for the answer in just a moment.

The 2021 Vuelta comprised 21 stages with two individual time trials, six flat stages, four hilly stages, and nine mountain stages. For all but the final stage, our mystery rider collected a bunch of data which he sent on to the researchers each day.

Every morning he measured his mass in a “voided and fasted state with minimal clothing”. After each day’s riding, his power meter data was used to calculate his total on-bike exercise energy expenditure. (The researchers assumed a “gross efficiency” of 21.7% – that is, as per previous research, the inefficiencies of the human body mean a rider burns roughly four to five times as much energy as they end up pushing through the pedals).

The rider also completed a daily food diary, recording how much he ate and drank during the day, including for breakfast, pre-race snacks, during each stage, and after each stage. The amounts he ate were carefully monitored. In the words of one of the researchers, Dr Samuel Impey: “the rider would take a photo of all the rice cakes, gels, bars etc. that they started with. They would then let us know any other foods they took on-bike after the stage. Diet was assessed by the rider, weighing all their foods at meals.”

All of that information was then collated by the researchers, one of whom is actually a staff member on the rider’s team.

Before we go on, did you work out who the rider was? If you guessed Nick Schultz of BikeExchange-Jayco, you’d be right. So how did Schultz feel about the effort of recording all his food and drink consumption in detail?

“For me it wasn’t very difficult to take note of everything in so much detail,” he told CyclingTips. “The only meal that required much thought on my behalf was breakfast. Otherwise it was just weighing out the guidelines provided by the nutrition team and a few snacks here and there. I also really believed in this method and was motivated to participate as I saw benefit on the performance side.” 

So what did the researchers find from all of Schultz’s data?

On an average day, Schultz burned roughly 3,500 kCal (14,640 kJ) on the bike, with his easiest day being 560 kCal (2,340 kJ) on the second rest day and the hardest being 5,830 kCal (24,400 kJ) on stage 20 – the final mountain stage. For context, an active adult male might burn something like 2,400 kCal (10,000 kJ) in an entire day (Again, Schultz’s energy expenditures above only relate to his time on the bike – just a fraction of his day.)

On average, Schultz consumed a total of 812 g of carbohydrate per day of the Vuelta, or 12.2 g per kilogram of body mass. That’s the equivalent of about 20 cups – or more than 3 kg(!) – of cooked pasta, per day. 

Unsurprisingly, his highest absolute and relative carbohydrate intakes occurred on mountain stages, followed by hilly stages, then flat stages, then the time trials. And as you’d expect, his carbohydrate intake was considerably lower on the rest days.

The breakdown of Schultz’s carbohydrate intake throughout each day is interesting too. On average, he consumed 197 g of CHO at dinner, with a similar amount (189 g average) immediately post stage. Perhaps surprisingly, his breakfast average was lower with 124 g. 

As for food he consumed in-race, Schultz’s CHO intake ranged from 185 g to a whopping 508 g per stage. That breaks down to an average of between 41 and 106 g/hour of CHO. Ingesting 100 g of CHO per hour is getting towards the upper limit of what most pro athletes are able to tolerate. (Notably, Mathieu van der Poel was taking in up to 120 g/hour during his Tour of Flanders win earlier this year). Your average amateur athlete – and certainly non-athletes – would certainly struggle to process 100 g of CHO in an hour.

If you’re wondering about what Schultz ate on the bike, here’s a breakdown of the types of foods and their contribution to his CHO intake:

Those high-concentration CHO drinks are particularly interesting. During “strategic sections” of the Vuelta, Schultz increased his carbohydrate intake via concentrated CHO drinks that included roughly 90 g of CHO per 500 mL. For context, a bottle of Gatorade only has a third as much carbs: 30 g of carbohydrate per 500 mL (36 g for a 600 mL bottle).

As the researchers write, sometimes the intensity of the racing makes it hard to pull out, eat, and digest solid food. “This strategy delivered additional CHO during parts of the race where energy expenditure was high and the athlete’s opportunity/ability to consume foods was limited,” they wrote.

Interestingly, and as you can see in table 1 above, Schultz’s weight actually increased throughout the Vuelta. It started at 66.8 kg and dipped to 65 kg by stage 4, but after fluctuating and reaching as high as 69 kg, he ended the race at 67.8 kg – 1 kg heavier than he started.

Take a look at the chart immediately above. Note that just as Schultz’s energy expenditure varied each day – according to the demands of the terrain and the racing – so too did the way he fuelled (and refuelled) for each day’s racing.

As the researchers write, these findings “highlights the application of a periodised approach to CHO intake to match the highly variable event demands.”

You might have heard of periodisation before. Indeed you might have read about it here on CyclingTips. In essence it’s the idea that an athlete should adjust their food intake to match their expected energy requirements, rather than sticking to a set (or arbitrary) intake each day.

So if a rider has a particularly hard day coming up (a big mountain stage, for example), they might increase their energy intake relative to a normal day. An easier day (like a time trial or flat sprint stage) might prompt a reduction in daily energy intake. In the words of nutritionist and long-time CyclingTips contributor Dr Alan McCubbin: 

“By providing the appropriate amount of carbohydrate before the longer or harder sessions, you’ll be able to maximise your performance in those sessions and achieve the desired intensities. But by reducing the carbs and total energy on the rest days (or even lighter training days) you can help reduce the total energy eaten across the week. This can help enormously for those struggling to balance the need to reduce body fat whilst still having enough fuel to get through their bigger rides.”

The magnitude of Schultz’s CHO intake throughout the race is noteworthy. Depending on who you listen to, current sport nutrition guidelines suggest athletes should consume between 8-12 g/kg of carbohydrate to fuel 4-5 hours of moderate exercise. Schultz’s consumption (12.2 g/kg on average) is in line with the top end of that range, but according to the authors of this latest paper, the current guidelines “fail to capture the substantial day-by-day variation in CHO intake employed by athletes during these multi-day events.”

For example, you can see from the range of Schultz’s CHO intakes at his various meals that the amount was varying from day to day rather than staying constant:

As the researchers write, “this variation was dependent on the physical demands of the current stage in combination with the anticipated demands of the next stage.”

The least carbohydrate Schultz consumed in one day was 340 g (5.2 g/kg), on the first rest day. His biggest day was the mountainous stage 18 with nearly 5,000 m of climbing; a day in which he consumed a total of 1,118 g (17.7 g/kg) of CHO. That’s around 150% of the recommended amount and the equivalent of roughly 28 cups of cooked pasta. More than 4.2 kg of the stuff.

Here’s how his consumption broke down across that massive day:

For context, an average adult male might eat somewhere in the range of 225 to 325 g of carbohydrates in an entire day. 

The researchers highlight that, during the Vuelta, Schultz got most of his daily CHO intake post-stage and at dinner. Interestingly, this is in contrast to findings from previous studies at the Vuelta. One study from 2018 showed the riders got most of their CHO at breakfast (we broke this study down around the time it came out). That study showed that the riders ate an average of 199 g of carbs at breakfast. By contrast, Schultz’s biggest breakfast included 152 g.

Another paper from back in the late ‘90s, found riders ate similar amounts of CHO at dinner and breakfast.

Perhaps Schultz’s numbers are evidence of changing attitudes to fuelling in elite cycling; a push towards fuelling for the present and following day, rather than simply relying on breakfast to provide most of the day’s necessary fuel. Or maybe it’s something else, as the researchers note: “These observations potentially relate to individual rider and cultural preferences surrounding meal provision.” Maybe some people just prefer to eat more at breakfast.

The researchers continue: “additional research [is] required to determine which feeding pattern is optimal for Grand Tour performance.”

Nutrition advice might have changed over the years, but it’s still not entirely clear what the perfect fuelling strategy looks like.

So what can we take away from this? For starters, as the researchers reiterate, real-world CHO intakes can range well beyond best-practice recommendations, and a single figure for those recommendations doesn’t really work across the board. Those recommendations should really be adapted to reflect the dynamic nature of racing. Most, if not all, professional cycling teams will be doing this already.

While the 2018 study mentioned above looked at a whole team (Movistar) rather than just one rider, it would be interesting to see more research with full teams, looking at CHO requirements for different riders across those teams.

I asked Impey what he thought they might find from such a study.

“The major difference between riders would likely be their role in the team,” he said. “So a climber would have slightly different requirements than a sprinter for example, depending on the stage type.

“For example on a flat stage a GC rider will be sat in the bunch out of any wind etc. which means their total kCal output for the stage is going to be much lower than a domestique who may have to sit on the front to protect a GC rider – meaning they will have a much bigger kCal output for the same stage. A sprinter will have to ensure they are in the front group in the right position to be able to sprint. The dynamics of how this happens can be very changeable – depending on the team they have around them.

“In the same way, a sprinter coming over a climb in the grupetto will have a lower kCal output compared to the climbers who are chasing a result.” 

Future research aside, it’s just interesting to get a sense of the volume of food the professionals need to eat in a given race day and more specifically, how much carbohydrate. In short: a whole lot.

While Schultz hasn’t looked through the published paper, he can certainly see the value in a detailed approach to race nutrition.

“I haven’t had a detailed look at the study released,” he said. “I do however pay close attention to the advice provided and am constantly asking questions and learning from the nutrition team. Feedback from the experts helped me understand what was happening with my sensations and provided me with a platform to fuel correctly which I strongly believe contributed to my consistency throughout three weeks of racing.”