The intestine is an extraordinarily important sports-organ, and together with the stomach forms part of the gastrointestinal tract. Nervousness or elevated stress levels before a competition can literally cause an “upset stomach”. The wrong nutrition can further make the gastrointestinal tract rebel. Complaints of varying severity include feelings of fullness, bloating, flatulence, stomach cramps, nausea / sickness, vomiting, or diarrhoea.

Gastrointestinal problems aren’t uncommon during competitions for endurance athletes, and often result in not being able to achieve maximal efforts. Nils Daimer, Triathlete on the Erdinger Alkoholfrei Perspektivteam has also had these negative experiences before: “During this year I had two races where I just couldn’t give everything I had due to stomach issues. My stomach felt like it was being blown up from inside. Insufficient intake of fluid was one of the causes“. In addition to a fluid deficit (dehydration), the consumption of foods that are difficult and hard to digest (these especially include foods rich in fat and high in fibre) in the last few hours leading up to an intense exercise increases the risk of digestion issues. It’s therefore better to avoid sandwiches with salami, or fried potatoes / chips with sausages and co.









At pasta-parties before races I generally avoid bolognese sauces, as typically this is a very fatty option. I prefer an easy to digest tomato sauce”, the successful trail runner Stephan Hugenschmidt shares. Whereas pro mountain biker Katrin Schwing always avoids sparkling water before a race to help avoiding feeling unwell in the stomach region. Contrary to popular belief, a gluten-free diet (avoiding grains such as wheat, rye, barley, oats, spelt, kamut) before or during intense exercise does not prevent problems with digestion in healthy athletes that don’t suffer from diagnosed gluten intolerance such as celiac disease. “I was involved in the first study looking at a diet with gluten versus a gluten-free diet in non-celiac endurance athletes. We found absolutely no differences in gastrointestinal comfort or performance”, Dr Trent Stellingwerff, expert in the field of Physiology and Sports Nutrition from the Canadian Institute of Sport and consultant for several Olympic athletes confirms.

The tolerance for foods and drinks is individually different. Therefore, on several occasions, every athlete should mimic their race place in training, which includes nutritional and fluid timing and amounts to find out what can be tolerated best. The main rule is: no experiments on race day! “It is essential through trial and error to find a protocol for eating and drinking. Only through doing this can I develop my own strategy further, and find out what is best suited for me during a race”, says Nils Daimer. It’s also important not to forget these ‘rituals’ shortly before the start: Eat and drink only what you’re used to. This helps you feel prepared to race and calms you down. “I’m always angry with myself if I eat or drink something different to what I’d planned shortly before a race”, Katrin Schwing describes.

The right carbohydrate strategy during competition not only supports maximal performance, but also prevents gastrointestinal distress. The saying “for success train both the body and the gut” is therefore correct. The expert Dr Trent Stellingwerff explains: “Gradually increasing the quantity of carbohydrate intake during training can enhance the ability of the gastrointestinal tract to absorb more carbohydrates and to decrease symptoms of discomfort. For prolonged endurance events (>3 hours) up to 90g of carbohydrates per hour are recommended. A 2:1 carbohydrate mix of glucose and fructose (e.g. C2Max) enhances carbohydrate delivery to the muscles. In comparison to carbohydrates supplies made solely out of glucose, this can not only improve performance, but also minimize gastrointestinal discomfort. Therefore, a carbohydrate and fluid strategy should be tried out and tested 3-5 weeks before an important race, so that subsequently the best possible strategy can be developed.”

7 practical tips to help avoid gastrointestinal problems

  • Never try something new on race day!
  • Gradually increase the carbohydrate and fluid intake over several weeks before a race, so that the gastrointestinal tract also gets ‘trained’, and the best possible individual strategy can be developed.
  • Avoid Aspirin or other painkillers with anti-inflammatory properties, such as e.g. Ibuprofen, as these increase the risk for gastrointestinal problems.
  • Consume the last big meal 3-4 hours before the race: easy to digest, low in fat and fibre (e.g. pasta with tomato sauce, sandwiches / bread rolls with ham or jam), combined with sufficient fluid.
  • The closer in time you get to the race, the smaller the portions should become. Up to 60 minutes before: carbohydrate snacks (e.g. ENERGIZE Wafer) with sufficient to drink. In cases of high levels of competition nervousness, liquid food, such as sports drinks or POWERGELs dissolved in water, can usually be tolerated better than solid snacks.
  • Avoid a fluid deficit (dehydration): begin with a good fluid balance, and make sure to follow an appropriate and individual drinking strategy.
  • Use proven methods to manage stress through nervousness and fear of competition. For example, food rituals and typically followed behaviours can give reassurance and feelings of security.

i.a. used references:

  • De Oliveira, E.P., Burini, R.C., & Jeukendrup, A. (2014). Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Med, 44 Suppl 1:S79-85. Lis, D., Stellingwerff, T., Kitic, C.M., Ahuja, K.D., & Fell, J. (2015). No effects of a short-term gluten-free diet on performance in nonceliac athletes. Med Sci Sports Exerc. (Epub ahead of print) Peters, H.P. et al. (1999). Gastrointestinal symptoms in long-distance runners, cyclists, and triathletes: prevalence, medication, and etiology. Am J Gastroenterol, 94(6):1570-81.

© Corinne Mäder Reinhard, Senior EU Sport Nutrition Manager PowerBar. International Olympic Committee post-graduate Diploma in Sports Nutrition