Endurance Athletes at Heightened Risk for Gut Problems

ANAHEIM, Calif. – Gastrointestinal problems are now some of the most common medical complaints in endurance athletes, according to an expert presenting today at the American College of Sports Medicine’s 15th-annual Health & Fitness Summit & Exposition.

While overuse injuries are the most common medical issue in endurance athletes, Lauren Simon, M.D., M.P.H., FACSM, reported that gastrointestinal (GI) disturbances are also very common. Research indicates that between 30 and 81 percent of distance runners experience some type of GI disturbance.

Three common GI disturbances in endurance athletes are:

  • Gastroesophageal Reflux Disease (GERD). GERD is the regurgitation of stomach contents and acid up the esophagus, and it is thought to be the most common cause of upper GI symptoms in athletes. Athletes with GERD may have symptoms of heartburn, regurgitation, dyspepsia and sour taste in mouth.
  • Exercise-induced GI bleeding. This bleeding can occur in the upper or lower GI tract and may result from intense exercise. Athletes with bloody stools, diarrhea and abdominal pain should see a doctor, as they could be experiencing decreased blood supply to part of their abdomen.
  • Diarrhea. Diarrhea and the urge to defecate are common problems in distance runners and endurance athletes.

To reduce incidence of GI disorders, athletes should try altering their training regimen or dietary intake using some of the following practical suggestions:

  • Start by lowering the intensity level of exercise and then gradually increase activity.
  • Void and defecate before exercise.
  • Avoid intense exercise within three hours of a meal.
  • Avoid high-fiber or high-fat foods before exercise.
  • Limit caffeine for one to two hours before exercise.
  • Stay hydrated.

Simon recommended seeing a doctor if GI problems persist or worsen after exercise, interfere with exercise, decrease performance or accompany fever, weight loss, dizziness or bleeding.

“Really, any gastrointestinal disorder that interferes with an athlete’s training or competition warrants medical attention,” said Simon.


The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 40,000 international, national and regional members and certified professionals are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.