Endurance athletes who take carbohydrates in a gel instead of a drink can often suffer from stomach and intestinal complaints. German research shows that performance does not differ if a sportsman takes carbohydrate gels or beverages.


It is generally known that the ingestion of carbohydrates can improve endurance performance. The most common method to take carbohydrates during exercise is through carbohydrate drinks. There are many athletes, mostly cyclists and triathletes who take carbohydrates by consuming so-called gels. Sareban and colleagues, however, argue that little is known about the differences in the effects of carbohydrate drinks and gels on both performance and any gastrointestinal problems. Therefore, they have investigated possible differences between the two forms.


In this study 9 duration trained athletes averaging 38 years and an average VO2max of 59 ml / kg.min participated. They carried out twice a simulated triathlon in a laboratory. Participants swam for an hour at the speed corresponding to 90% of the speed of their personal record of the 400m. Then they cycled 180 minutes on average 204 watts and finally the participants ran one hour as fast as they could. The participants were allowed to swim more slowly or cycle at lower power if they risked the chance that the effort could not be sustained. During the cycling and running athletes took a total of 81 g carbohydrates. Once they did so in the form of gels and once via a carbohydrate drink.

The carbohydrates that were used were fructose and maltodextrin, and the participants were given on both test days the same amount of liquid. The researchers also looked at the performance in the various components and asked whether the participants had experienced gastrointestinal problems.

It turns out that the way of carbohydrates intake does not have any influence on performance. In the final run an average of 12 km was reached by the participants after taking both gels and beverages. The blood sugar level was similar between the two conditions and never came below 4 mmol / L. There was a big difference in the experience of gastrointestinal problems. Seven of the nine participants reported having suffered bloating after taking gels.

Nausea and vomiting
Bowel problems and diarrhea

One participant even had to go to the toilet between the biking and running. When drinking carbohydrate beverages not one of the participants had any stomach or intestinal problems.


Although it does not matter for performance whether an endurance athlete takes a carbohydrate drink or gel, it may have an effect on the experienced gastrointestinal problems. Taking gels can increase the risk of stomach problems considerably, and it is not unthinkable that in the end, for example during a long cycling race, this will lead to a negative effect on performance.  The advice is to consume carbohydrates by means of a drink instead of gels.

The most important advice: If an athlete for example still wants to make use of gels it is wise to first try this in a training situation.

When I was working for pro cycling teams many riders used carbohydrate gels during the races without any problem. These riders were accustomed to using gels and besides that they drank a lot of water at the same time.