Runner's diarrhea and other intestinal problems of athletes.

Lower gastrointestinal tract symptoms occur frequently in runners. The most common complaints are bowel urgency and diarrhea. Many etiologies have been proposed, including enteric fluid and electrolyte imbalance, autonomic nervous system stimulation, ischemia and mechanical trauma. The evaluation should include a review of the athlete's training program and diet, as well as a review of any preexisting gastrointestinal disease. A stool examination for occult blood should be performed in the athlete who complains of diarrhea. Treatment begins with a reduction in the intensity of workouts, followed by a gradual return to the previous level of training after the symptoms resolve. In most cases, symptoms do not recur. Dietary manipulation or antimotility agents may be helpful in some athletes. Bloody diarrhea, usually related to hemorrhagic gastritis, can be effectively treated with histamine H2-receptor antagonists.