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How to optimize your endurance sports performance with Gut Training: dietary strategies for effective digestion

Training is the basis. Also eat. During long distance events, whether trail running, triathlon or cycling, the goal is to meet your needs without causing any digestive disorders. For this, there is also a training, also called the Gut training which means “eating training” ou “intestinal training”. In endurance sports, eating is essential, however it is not always easy. Sometimes the intestinal disorders appear and the effort becomes more difficult (cramps, bloating, feelings of heaviness, desire to vomit, etc.). As endurance athletes engaged in demanding disciplines such as trail running, triathlon or ultra cycling, you know better than anyone the crucial importance of nutrition to maximize your performance. But did you know that the secret to achieving your goals could lie in something called Gut Training ? Gut Training is a way to reduce gastrointestinal discomfort in athletes who wish to ingest high levels of exogenous carbohydrates during exercise. It is the optimization of the functioning of your intestine in order to improve your tolerance to carbohydrates during the most demanding events.


  • Better understand digestive disorders

The digestive disorders constitute a complex challenge for endurance athletes, capable of transforming their hours of training into a resounding success or a grueling ordeal. Factors such as previous meals, the state of the intestinal microbiota, diet and hydration during the test play a crucial role in this phenomenon.

A study of 63 marathon runners revealed that 54% of them suffered from digestive disorders, among whom 20% reported post-workout diarrhea. In addition, 13% of runners had traces of blood in their stools.

Another study focused on triathletes highlighted differences in the prevalence of digestive disorders depending on the type of endurance activity practiced. For example, 49% of the subjects interviewed reported digestive disorders, mainly during running. Furthermore, it was observed that 93% people who vomited had consumed hypertonic drinks, While 100% of those who vomited had eaten within 3 hours before the race, and 100% of those experiencing stomach aches had consumed whole grains, rich in fiber.

These studies highlight the significant impact of running on digestive disorders. Indeed, although these unpleasantness can occur in all endurance activities such as cross-country skiing, cycling or athletic walking, they are much more common in running due to the repeated shocks that the body experiences with each stride.

Digestive disorders caused by exercise are thus two to three times more common in running, due to the repercussion of shock waves on the digestive tract, which notably increases the prevalence of diarrhea and digestive bleeding. This impact is all the more pronounced during prolonged efforts such as trails or ultra trails. A possible strategy to remedy this is to refuel during climbs and avoid doing so at the top of mountains, where shocks are greater and vibrations transmitted to the viscera are exacerbated.

Digestive disorders caused by exercise are multifactorial.This may be due to: stress or the anxiety of the ordeal, the position (especially on the bike), rebound movements (while running), history of digestive disorders (if you have had them in the past), blood flow during exercise (the blood goes towards the muscles during exercise rather than towards the intestine), theexercise intensity, hormones, heat and nutrition.

Indeed, we often believe that digestive disorders come only from nutrition, but all the other factors mentioned above can intervene. Nutrition can indeed induce digestive disorders notably the consumption of fibers, the consumption of fats, Dehydration, poor absorption of carbohydrates, eating a large meal before exercise, very sweet tastes and lactose. It is possible to act quickly on reducing fiber and fat consumption before exercise, as well as eating a large meal and avoiding lactose. There poor absorption of carbohydrates As for it, it must train to be better tolerated.

  • What are the benefits of bowel training?

The endurance sports are very demanding for the body when you feel physical suffering but also for all the organs and in particular the intestine who suffers numerous attacks during exercise. The point of training your intestine is to:

-Reduce or eliminate digestive disorders during exercise
-Improve the transport and utilization of nutrients

If you feel discomfort in the stomach or intestine during exercise, the Gut training is an effective way to:

-Reduce intestinal discomfort
-Improve gastric emptying
-Reduce bloating
-Tolerate larger volumes
-Improve the speed at which you can absorb carbohydrates

  • How to implement a good intestinal workout?


Two approaches are possible:

  1. Bowel training: Just like physical training, it is possible to strengthen the intestine. The stomach is an adaptable organ, meaning that with proper training it can better tolerate carbohydrate ingestion. This practice, often called "stomach training," has two main benefits: the stomach can expand to accommodate a larger amount of food, and a full stomach is better tolerated and less uncomfortable, improving comfort during the effort.
  2. Carbohydrate consumption: The improvement in gastric emptying varies depending on the nutrients (better glucose tolerance if glucose is used and better fructose tolerance if fructose is used). Better absorption of glucose in the intestine may reduce negative feedback, which could promote more efficient gastric emptying and better utilization of carbohydrates during exercise.

  • And in practice, how to do it?

Intestinal problems during races are not inevitable and can be largely reduced, or even avoided, thanks to a few simple tips.

  • Avoid new foods before the competition and stick to familiar ones.
  • Reduce fiber consumption a few days before the event to avoid intestinal irritation, if you are sensitive to these problems, reduce their consumption a few days before the event.
  • Test regularly use nutrition and hydration products under the same conditions as during the race to evaluate their effect on you. Studies have shown that athletes unaccustomed to ingesting fluids and foods during exercise are more likely to develop gastrointestinal symptoms.
  • Familiarize yourself with the tastes and textures and take note of the effects of refreshments so there are no surprises on your race day.
  • Respect your nutritional plan to maintain a regular diet and avoid the risks associated with intuitive eating.
  • Include high-carb days in your training if you follow a low-carb or high-fat diet with the aim ofimprove stomach tolerance and comfort.
  • Experience a short-term reduction in FODMAP if you suffer from gastrointestinal disorders.
  • Practice drinking during training. Hydrate yourself sufficiently before and during exercise to prevent dehydration.
  • Limit medication use and consult a gastroenterologist if gastrointestinal complaints persist.

Before a race:

  • Maintain a diet rich in energy and carbohydrates before the competition to maximize glycogen reserves.
  • Limit the consumption of insoluble fiber and eat the pre-competitive meal at least 3 hours before warming up. Favor fast proteins and limit fats. Avoid overeating before and during exercise.
  • Current recommendations recommend a carbohydrate intake of up to approximately 60 g for exercises lasting up to 2 hours. When exercise lasts more than 2 h, slightly higher amounts of carbohydrates (90 g/h) are recommended. These carbohydrates must consist of a mixture of several carbohydrates (glucose:fructose (2:1) or maltodextrin:fructose (2:1)).
  • In a hot environment, it is useful to start hydration before exercise to stimulate gastric emptying.
  • Experiment repeatedly the nutrition and hydration plan for the race.
  • Start the race well hydrated. Look for clear urine.

These tips are essential for setting up a good bowel training and promote a optimal performance during your sporting activities.


In conclusion, optimizing performance requires appropriate nutrition and efficient digestion. THE Gut Training, or bowel training, is a promising strategy for reduce digestive disorders et maximize nutrient absorption during exercise. By understanding the multiple factors that impact gut health, you can implement specific dietary and hydration practices to prevent gastrointestinal discomfort. By combining physical training with stomach training and an appropriate nutritional strategy, you can improve comfort during exercise and optimize your performance on the long term.


Halvorsen, F.A., Lyng, J., & Ritland, S. (1986). Gastrointestinal bleeding in marathon runners. Scandinavian Journal of Gastroenterology, 21(4), 493-497.

Rehrer, N.J., van Kemenade, M., Meester, W., Brouns, F., & Saris, W.H.M. (1992). Gastrointestinal complaints in relation to dietary intake in triathletes. International Journal of Sport Nutrition and Exercise Metabolism, 2(1), 48-59.

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