November 16, 2023, edited by Francesco Rigodanza
This article is about sugar, and lots of it.
Because, if there is one thing for certain in endurance sports, it is that to go fast for many hours, our muscles need fuel, and the best fuel is sugar. Or carbohydrates, which are the same thing but have a name that sounds better. If you are aiming for performance, you need sugar, and lots of it.
Yes, but which kind? How much? How? Maltodextrins? Gels? Bread and Nutella? Glucose? Honey? Bananas?
Well, this has changed a lot in recent years. There is a bit of confusion, as often happens when a scientific field progresses rapidly and does not have time to communicate its ideas to the public in a clear and unambiguous way. So we need to take a brief look at the history of endurance fueling to understand the claims of sports champions like Mattehi Morijc after his latest victory at the 2023 Gravel World Championships: “I ate 120 grams of carbohydrates per hour.”
We need to make sense of these numbers. Because 120 grams is a lot.
The first gel
It all starts long before the 1990s, when athletes still had little knowledge of sports nutrition, and it was considered unimportant; secondary to training. So, they relied on jam sandwiches and other homemade foods, eating by feel. And the legendary bananas. Researchers knew that athletes needed 30-60 grams of carbohydrates per hour. And it was decided that these grams should consist of glucose.
Glucose? Sugars differ in size and complexity. Glucose and fructose are simple sugars, therefore easier to absorb (since the intestine has to do little to no work); sucrose (or regular sugar) is a bit more complex, while maltodextrins or starches are longer and harder to digest.
“What about the blood sugar spike?” The first thought that comes to mind when ingesting 30-60 grams of glucose is that this could cause very rapid absorption, resulting in a blood sugar spike capable of putting further stress on the body, in addition to using the newly consumed energy too quickly. And with this idea in the 1990s, instead of simple glucose, maltodextrins were preferred, which are nothing more than small glucose polymers obtained during starch processing.
The first “energy gel” was born in 1986. It was called “Leppin Squeezy.” And from there, within a few years, gels of all types became part of athletes’ performance and nausea.
And until just a few years ago, gels still resembled the 1986 Leppin Squeezy, about 20-30 g of maltodextrins mixed with some flavoring and a little thickener.
The 90-gram breakthrough
Once the sports world accepted that muscles need to burn a lot of energy and not bananas, research continued in an attempt to optimize performance as much as possible by increasing the levels of absorbable carbohydrates. Fructose began to be considered alongside glucose; another type of carbohydrate, which in the intestinal walls seems to have an absorption independent of that of glucose. It turned out that the right mix would allow even more carbohydrates to be absorbed: we moved from 30-60 g to 90 g. And to reach this quantity, the first modern products used an arbitrary mix of glucose (as maltodextrins)/fructose 2:1, that is, in 30 grams of gel, 20 g are maltodextrins, 10 g are fructose.
To be more precise, glucose absorption is around 60 g/hour. Fructose 50 g/hour. The two molecules weigh exactly the same. The ratio is 1 to 0.8.
At this point, it should be clear why the optimal mix is 1:0.8 glucose/fructose. Numbers that this sport has begun to feel.
And the blood sugar spike? Science has disregarded the blood sugar spike once it was noted how our body, sometimes, is not that stupid and under intense effort regulates itself to make the best use of every possible sugar molecule. Result: the blood sugar spike during endurance sports does not exist.
However, there is no big difference between using maltodextrins or glucose, even in terms of cost, and therefore by tradition maltodextrins are still favored as gel ingredients.
Too much or too little
We are only missing 120 g. We are still at 90 g. Which for now remains the most validated quantity. Which means that in the research conducted, it is checked that all the carbon atoms ingested at 90 g of sugar/h are then emitted as carbon dioxide (the C in CO2) by breathing. Up to 90 g, the body uses it all and therefore this allows to maximize effort by reducing the perception of fatigue and tiredness. Beyond this quantity, there is a risk that the extra carbohydrates accumulate in the intestine, unable to use that quantity, then generating a whole series of gastrointestinal problems familiar to many athletes.
It is 2020, and, given the shortage of races due to COVID, Spanish scientists, led by Aitor Viribay, now a nutritionist for the World Tour Ineos Granadier team and Kilian Jornet, two significant names, organize a 42 km mountain running race with international-level athletes (two world champions are mentioned in the study) dividing them into three groups based on sugar consumption per hour:
Group 1: 60 g/h
Group 2: 90 g/h
Group 3: 120g/h
By studying the muscle stress parameters, the researchers discover that group 3 reports significantly lower parameters than the other two, all supported by a lower perception of fatigue. So not only does more carbohydrates improve performance, but also, and by a lot, recovery.
Very interesting data, but too isolated and published in a journal of lesser scientific importance. However, word of mouth among athletes and nutritionists is stronger and more anarchic than academic communication, so slowly these famous “120 g/h” arrive in the world of cycling and trail running, revolutionizing performance in recent years (see averages in bike races or records in UltraTrail), forcing supplement companies to update gels with different and higher quantities of carbohydrates, competing to see who has the best composition.
120 g/h. It is the number and the slogan that now attracts attention, but, hoping to have convinced the reader of why we arrived at this number, there are still some notes to make about this whole sugary world:
- It is important how much you eat during, but it is even more important what you eat before and after, and this is talked about much less since it is a less marketable product. However, it would always be sugars.
- 90 g/h is the data with the most scientific value. On 120 g/h, research is still “in progress” and the attempts are made mainly by elite athletes.
- Carbohydrate absorption is something that requires a bit of training, you cannot go from zero to 120 in one day, but it is true that this training does not last forever. Even “training the gut” to assimilate more and more sugar is an easy slogan that is not always valid.
But how do you eat 90-120 g of sugar per hour? This in the next episode.
For further reading:
“New Horizons in Carbohydrate Research and Application for Endurance Athletes”, Sports Medicine, 2022, T. Podlogar et al., https://link.springer.com/article/10.1007/s40279-022-01757-1”
“Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers, International Journal of Sport Nutrition and Exercise Metabolism, 2019, AE Jeukendrup, https://journals.humankinetics.com/view/journals/ijsnem/29/2/article-p117.xml?ref=blog.supersapiens.com”
“Relationship of Carbohydrate Intake during a Single-Stage One-Day Ultra-Trail Race with Fatigue Outcomes and Gastrointestinal Problems: A Systematic Review, nt. J. Environ. Res. Public Health 2021, Aitor Viribay et al., https://doi.org/10.3390/ijerph18115737”
© photo: Camilla Pizzini, Luca Matassoni