Gastrointestinal bleeding and the athlete.

GI bleeding occurs with prolonged exercise and is probably mediated by visceral ischemia. It may produce acute hemorrhage, more chronic symptoms with anemia, or result in guaiac-positive conversion with little clinical disease. Hemorrhagic gastritis and colitis are the most frequently recognized lesions, and are usually transient and reversible. Acid suppression with cimetidine may be effective in selected patients with recurrent HG, but effective therapy for most patients with this form of GI bleeding is still uncertain. Awareness of the association between GI bleeding and exercise should stimulate further investigations into the pathophysiology and therapy.