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Stomach problems while running – Why problems with the stomach occur and what to do about them

Unfortunately, running and the stomach don’t always get along. It is not uncommon for athletes to suffer from cramps or other gastrointestinal problems during training, which can have a negative impact on training or competition. In endurance competitions, these problems are sometimes one of the main reasons for performance losses or athletes dropping out. In our blog article, we take a look at this sensitive topic.

It is very likely that most runners have experienced the uncomfortable feeling of stomach problems during intense physical exertion. The greater the effort, the greater the risk. Because when we run, we put a strain on our stomach and all the organs in it through the pounding vertical movements we make with our steps. Only through constant training can we acclimate our body to these impacts and cushion them more gently. The symptoms affect both the upper and lower abdomen and range from heartburn, acid regurgitation, cramps, nausea, vomiting to diarrhea. These are not random phenomena, but there are several reasons why we sometimes suffer from this type of pain or discomfort.

Causes of problems:

Physiological explanation

First of all, the main cause lies in the way our body works: physical exertion and digestion do not match. In fact, this pain is brought on by “the forced redirection of blood flow from the gastrointestinal tract to the muscles”. What does this mean? When we run, the available oxygen is used to supply energy to the muscles. As a result, all other systems in our body, including digestion, are put on the back burner, and blood flow (and therefore oxygen supply) to the diaphragm is drastically reduced. For this reason, it is virtually impossible to take a sip or eat anything during intense exercise.

Excitement is also a physiological element that must be taken into account. Many runners have intestinal problems on the day of a race because the excitement becomes too great.


The second aspect to highlight is hydration: it has been shown that an athlete who drinks something before the race has a higher risk of experiencing stomach problems during or after the race. So you have to know what to drink and when. Amateurs and novice runners suffer the most from this symptom because they lack experience. But people who drink too little can also suffer from gastrointestinal symptoms such as nausea and vomiting. This is due to the delayed gastric emptying that occurs during high intensity exercise (75% of VO2max). Therefore, avoid hypertonic drinks (sugary drinks like Coca-Cola) and prefer isotonic drinks (or gels) instead. We also recommend dividing the increase of drinks and gels into small portions, as this allows them to be emptied from the stomach more quickly, they provide the body with energy accordingly without overloading the digestion.


In terms of nutrition, we can give some advice, although tolerance is always a personal matter and therefore it is advisable to test the products during training to ensure that they are compatible with the body. In this way, the personally tested products can be safely brought to the competition without unpleasant surprises.

If you have problems with your stomach, it is advisable to limit high-fiber products (such as whole grains, vegetables and legumes) in the two days before the race and to avoid fruits, milk and dairy products in the last 24 hours.

Carbohydrates can be consumed 2 or 3 days before the race, but without overdoing it. The last meal before the race should be taken at least 3 hours before the load, depending on the digestion time (this meal should contain little fat). Simple carbohydrates such as cornflakes or white bread are preferable. Of course, it is best to avoid foods that are difficult to digest such as onions, garlic, peppers, beans, lettuce, leeks or dried fruits, as well as fried and breaded foods.

On the day of the competition, it is important to eat a good breakfast, not to eat foods that make you “heavy” and not to drink coffee, tea, sugar or milkshakes. For efforts that last longer than two hours, it is recommended to add salt to drinks (about 2 grams per liter) to get a sodium supplement. When taking gels, diluting them with a little water can facilitate digestion.

We recommend creating a nutrition plan before participating in a race to be sure to eat right – with precise planning that will help avoid stomach upset during the race! Here are some articles on nutrition.

Taking medication

Medications also need to be discussed. Taking medication seems to be a simple and effective way to solve gastrointestinal problems, but the effect is often counterproductive. We therefore advise avoiding anti-inflammatory drugs such as aspirin or ibuprofen, as well as cortisone. Instead, it may be useful to try medications such as ranitidine or acid blockers, which can reduce acid production in the body. Before doing so, however, ask a doctor for advice.

Caffeine, nicotine and alcohol are more likely to cause symptoms. Avoid taking them before physical activity, as they promote bowel movements.

High temperatures

Another cause of gastrointestinal problems is high temperatures. Intense heat also affects gastric emptying, resulting in less blood flow to the intestines.

Pain relief

There are some techniques for pain relief that are more or less effective. First, take a break from running (complicated if you are in a race), then tighten the abdomen and breathe with lips half-closed. It is useful to tense the abdominal muscles and the breaths should be frequent and constant. Breathing through the abdomen rather than the chest can help. An alternative is to stretch your arms above your head for a few minutes.

In terms of diet, there are some foods that have a “healing” effect. Low-fiber vegetables such as tomatoes, olives or zucchini are good. Fruits such as grapes or grapefruits are also recommended, as they contain less than one gram of fiber per serving. In addition, refined carbohydrates such as pasta or white rice, which already contain crushed rice, facilitate digestion. A mint tea stimulates digestion and can help half an hour before a run. Ginger also prevents flatulence and fights nausea ( you can take it in the form of herbal tea or as a dietary supplement).


In conclusion, it should be emphasized that preventing stomach problems is not an exact science. Each of the mentioned tips can help and it is necessary to determine individually which measures are useful for which situation. To obtain this information, it is necessary to practice, experiment and adapt in order to finally reach a balance.


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