Introduction
Diarrhea after sport describes the stoppage of thin bowel movements, possibly in combination with an increased urge to defecate and an increased frequency of bowel movements, which is directly related to a sporting activity. The symptoms can already occur during the sporting activity or only manifest themselves shortly after it has ended. In technical jargon, the symptom is called stress-induced diarrhea.
The term runners diarrhea is also used. 10-50% of runners are affected. This shows that regularly occurring diarrhea after sport is frequently observed in endurance sports, especially running.
Causes of diarrhea after exercise
The exact pathophysiology leading to the occurrence of diarrhea in endurance sports is not yet fully understood. Several factors seem to play a role: In a certain form of diarrhea after sport, transient hemorrhagic colitis, which leads to bloody diarrhea and severe abdominal pain, reduced blood flow to the intestine (intestinal mucosal ischemia) is the cause of the symptoms. This is caused by the fact that during physical exercise the blood is redistributed to the muscles.
- Reduced blood circulation of the intestinal mucosa during sports;
- Shortened colon transit time (the period during which the food pulp passes through the intestine to be excreted);
- Increased fluid secretion into the intestinal lumen;
- Mechanical vibration in the course of sports activity;
- Nutrition before and during endurance training.
Diagnosis of diarrhea after sport
The diagnosis of diarrhea after sport is made clinically, i.e. based on the symptoms. If diarrhea recurs in close temporal relation to sport, it can be assumed that a stress-induced diarrhea is present. Other possible causes such as food intolerances, for example lactose intolerance or food allergies, should be excluded beforehand.
Blood tests or a breath test (to exclude lactose intolerance) are recommended. If there are pronounced symptoms such as bloody diarrhea or severe abdominal pain, further diagnostic tests may be necessary to exclude diseases such as appendicitis or chronic inflammatory bowel disease. Possible examination procedures for this are blood sampling, abdominal ultrasound and colonoscopy.
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