Gastrointestinal Problems During Exercise

Stomach problems that occur during exercise are common among athletes. This is especially true for distance runners and triathletes.


  • Heartburn.

  • Feeling sick to stomach (nausea).

  • Vomiting.

  • Diarrhea.

  • Bloating.

  • Stomach pain.

  • Rectal bleeding and gassiness (flatulence).

  • Cramping.

  • Urge to go the bathroom (defecate).


The treatment of problems (symptoms) from the upper GI (gastrointestinal) tract caused by exercise are helped by:

  • Avoiding solid foods for 3 to 4 hours before intense exercise.

  • Eating a diet high in carbohydrates and very low in protein and fat.

  • Medications from your caregiver are also available to help upper GI problems. Some of these include antacids to neutralize the acids in your stomach.


Bleeding from the GI tract may occur with intense exercise. It is especially common in marathon runners. The bleeding is thought to come mostly from the stomach. It may also come from the large bowel (colon). You should not assume the bleeding is caused by exercise. If you have any problems with gastrointestinal bleeding, it is extremely important to see your caregiver for evaluation to make sure there are not other causes of bleeding.


  • Once it is known that exercise is the cause of blood loss, maintaining adequate fluid intake to avoid dehydration may be helpful.

  • Wear good running shoes to cut down on jarring the body during workouts.

  • It is good to have your blood (hemoglobin) and the iron stores of your body checked periodically, to see if iron replacement may be necessary.

  • Take medications prescribed by your caregiver as directed.

Abdominal pain in athletes is common during intense activities. The cause is unknown. It may be due to spasms in the muscular division between the abdomen and chest (the diaphragm), or by air trapped in parts of the large bowel. Abdominal pain may be helped by avoiding large meals prior to exercise.

Runner's diarrhea is a very common complaint among runners. The diarrhea seems to be related to the intensity of the exercise. It is more common during competition than during regular exercise. There are many different possible causes of this and it may be a combination of all of them. Treatment of diarrhea may be difficult. A reduction in fiber intake a day and a half before competition may be helpful. If the problem persists, antidiarrheal medicine may be used.


  • Limit dietary fiber prior to competition.

  • Avoid solid foods at least three hours prior to a race.

  • Eat a pre-meal diet which is high in carbohydrates.

  • Avoid fat and protein intake during endurance events.

  • Drink fluids frequently during competition taking in two to three, 8 ounce glasses of fluid per hour. These should replace sodium, potassium, and carbohydrate in dilute solutions. Concentrated drinks may cause GI problems and aggravate existing conditions.