Note: Welcome to my notes about carbohydrate intake in endurance running events. I am not a nutritionist or dietician. Everything in this blog entry is a collation of notes I’ve taken from professionals. I highly recommend you go to the original sources (references at the end) to get the full information in the original contexts.Carb mouth rinse can see some performance benefit neurological response (not energy to muscle).
(McCubbin & Gaskell, 2022)
As your effort becomes longer, your carbohydrate needs become greater.
Under 1 hour you don't need much.
1-2 hours about 30g of carbohydrates per hour.
2-3 hours about 60g per hour.
Over 2 1/2 hours you can push to 90g per hour, but you must practice this in training and get used to it and pay careful attention to the type of carbohydrates you consume.
Mixing carbohydrates makes use of the two transporters in the gut.
Glucose (or maltodextrin or starch broken down to glucose) - the first 60g comes from glucose.
Fructose - after the first 60g, additional grams of carbohydrates can come from fructose. Fructose is often not absorbed that well, so be careful. Introduce it gradually, learning what your gut can tolerate.
It doesn't really matter whether you're getting your carbohydrates from drinks, gels, bars as long as you drink the same volume of fluid. Whether it’s a drink or gels mixed with fluid in your stomach, it doesn’t matter. A bar that has little else but carbohydrates behaves the same as a gel. If there’s protein, fat, and/or fibre in it, however, you’ll slow down gastric emptying, so you need to read labels, think about what else you’re consuming, and be careful.
You need to work out what your carbohydrate and fluid requirements are for an event. There is a calculator to help you work this out at: https://www.fuelthecore.com/
You don't need to modify the amount of grams of carbohydrates per hour during exercise based on your weight as the 60g per hour limitation of what can be absorbed and used appears to apply regardless of size.
You only need to train your gut to tolerate more than 60g of carbohydrates once per week. Eg on a long run push your intake. Over 5-6 weeks you will see improvements on what you can take in. That doesn't mean absorption has improved, it just means intake and how that feels improves.
In events it's best to start eating straight away while your gut is still working well and absorbing well.
Best to start eating straight away. Gut is still working well, absorbing well.
McCubbin, A, & Gaskell, S. (2022, June 23). How much carbohydrate should I consume during training or a race? | Prof. Asker Jeukendrup. The Long Munch. [Audio podcast]. Retrieved from https://thelongmunch.podbean.com/e/ep39a/
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