Internal Medicine

Diarrhea after exercise

introduction

Diarrhea after exercise describes the discontinuation of thin stool, possibly in combination with an increased urge to defecate and an increased stool frequency, which is directly temporally related to a sporting activity. The complaints can already appear during exercise or only manifest shortly after it has ended.

In technical jargon, the symptom is called exercise-induced Diarrhea designated. The expression too runners diarrhea (in German: runner's diarrhea) is used. 10-50% of runners are affected. This makes it clear that diarrhea that occurs regularly after exercise is frequently observed, especially in endurance sports, especially running.

Causes of diarrhea after exercise

The exact pathophysiology that leads to the occurrence of diarrhea in endurance sports has not yet been conclusively clarified. Several factors seem to play a role:

decreased blood flow to the intestinal mucosa during exercise;
Shortened colon transit time (the time it takes for the food pulp to pass through the intestine to be excreted);
increased fluid secretion into the intestinal lumen;
mechanical shock in the context of sporting activity;
Diet before and during endurance exercise.

In the case of a certain form of diarrhea after exercise, transient hemorrhagic colitis, which results in bloody diarrhea and severe abdominal pain, the symptoms are caused by insufficient blood flow in the intestine (intestinal mucosal ischemia). This arises because the blood is redistributed in favor of the muscles during exercise.

Diagnosis of diarrhea after exercise

The diagnosis of diarrhea after exercise is made clinically, i.e. based on the symptoms. If diarrhea recurs in close temporal connection with exercise, it can be assumed that there is exercise-induced diarrhea.

Other possible causes such as food intolerance, such as lactose intolerance or food allergies, should be ruled out beforehand. Blood tests or a breath test (to rule out lactose intolerance) can be used for this.

If there are pronounced symptoms such as bloody diarrhea or severe abdominal pain, further diagnostic examinations may be necessary in order to be able to rule out diseases such as appendicitis or chronic inflammatory bowel disease. Possible examination methods for this are blood sampling, abdominal ultrasound and colonoscopy.

For more information on diagnosing diarrhea after exercise, see: Course of a colonoscopy

Concomitant symptoms

Exercise-induced diarrhea is often accompanied by other gastrointestinal symptoms such as abdominal pain, nausea and vomiting. The consistency of the stool is fluid and the stool frequency increases more than 3 times a day.
In some cases blood is stuck in the stool. In mild cases of occasional diarrhea after exercise, accompanying symptoms may be absent.

You can read more about this in our next article: Stomach cramps with diarrhea

Diarrhea with stomach pain

In addition to diarrhea, competitive and ambitious recreational athletes also experience so-called gastroesophageal reflux more often than in the normal population, i.e. a backflow of stomach acid into the esophagus.
The gastric acid irritates the lining of the esophagus. This creates a burning sensation in the stomach area and behind the breastbone, as well as heartburn and acid regurgitation.

Read more on the subject at: Diarrhea and stomach pain

Diarrhea with abdominal pain

Abdominal pain is a common symptom associated with exercise-induced diarrhea. The different pathophysiological changes in the gastrointestinal tract are responsible for this. Various factors such as an improper diet before or during endurance sports or the use of certain medications can make abdominal pain worse.

Are you interested in this topic? Read more about this under: Abdominal pain and diarrhea

How can I avoid diarrhea after exercise?

In the case of pronounced symptoms, physical training should first be reduced in terms of extent and intensity until the symptoms cease. This should be followed by a slow build-up of training.

In addition, proper nutrition is crucial before and - in the case of endurance sports lasting several hours - during physical activity. In particular, dietary supplements that are explicitly offered for athletes and contain concentrated foods such as carbohydrates or minerals, as well as energy-rich drinks, are suspected of triggering the symptoms.

High-fat meals that remain in the gastrointestinal tract for a long time should also be avoided several hours before starting endurance training. In general, the last large meal should be taken 2-3 hours before the start of the training session.
Easily digestible, carbohydrate-rich foods should be preferred to fatty, high-fiber foods. These include, for example, rice, pasta or potatoes. Light snacks such as bananas, yoghurt or white bread can also be consumed in small quantities shortly before training.

Adequate hydration must be ensured before, during and after exercise.

If these measures are not sufficient, there are several drug options. Loperamide is an active ingredient that reduces bowel movements and thus counteracts diarrhea. If the focus is on stomach pain, anticonvulsant medication such as Buscopan® can be used.
If bloody diarrhea occurs repeatedly, this indicates a source of bleeding in the gastrointestinal tract. In athletes, damage to the mucous membrane in the stomach is more common. In this case, acid-inhibiting drugs such as Pantozol® are recommended. We also point out that any medication intake must always be discussed with a specialist.

Duration of diarrhea after exercise

The duration of diarrhea after exercise varies greatly from person to person and depends heavily on the level of training as well as the intensity and duration of exercise. Basically, diarrhea is defined as a thin stool with a stool frequency of at least 3 times a day.

For some recreational athletes, the symptoms only occur in the context of unusual excessive physical activity and have completely disappeared after a few hours. Other endurance athletes regularly experience diarrhea and accompanying symptoms after training.

With the treatment strategies mentioned, diarrhea after exercise can be contained in many cases.

Also read: How to stop diarrhea quickly