Endurance runners can improve their performance by drinking carbohydrates, such as sugar, during exercise. It works best around three quarters of a liter of water with 40 grams of carbohydrates; about 7 sugar cubes. More than that has no positive effect and may cause abdominal discomfort. If the effort lasts less than half an hour, drinking carbohydrates has no positive effect.

Most studies on the benefits of carbohydrate intake during exercise are conducted in cyclists. Whether the identified effects also apply for runners is not always clear. Runners get a lot more abdominal discomfort than cyclists after consuming carbohydrates. So Patrick Wilson has therefore made an overview of studies on the effects of carbohydrate drinks on running performance.


Especially when a running performance takes more than a half hour, a carbohydrate drink proves to be useful. Runners can reach a better performance from two to ten percent when they take only water or a drink without carbohydrates. With carbs, runners can run faster especially during the latter part of the race. It was found that a well-balanced drink with 60 grams of carbohydrates, 0.06 grams of sodium and 0.09 grams of caffeine per hour can provide a time saving at marathon runners for eleven minutes compared with runners who were allowed to choose what and how much they drank.


A carbohydrate beverage does not lead to a better performance when runners run for a relatively short time, less than 8 minutes. This could be because runners intensify efforts at shorter distances and therefore suffer from abdominal discomfort earlier. When runners drink much more the risk of stomach problems increases. The consumption of different types of carbohydrates, such as fructose and glucose, was only found to be better than a single sort when the effort took a long time (more than 2 hours) and the athletes took a lot of carbohydrates (more than 78 grams per hour). It further appears that a carbohydrate gel instead of a beverage does not improve performance at relatively short distances (up to 21 kilometers).


In general, runners can benefit from a drink containing carbohydrates, if the race is long enough, and if they do not drink much more than they like themselves and thereby develop abdominal discomfort.