Gastric lesions secondary to long-distance running. Gastrointestinal disorders have been reported during long-distance running. The purpose of this study was to evaluate the effects of prolonged exercise on the upper digestive tract. Seven subjects were submitted to a standard endoscopic examination of the upper digestive tract before and after long-distance running (range 18-50 km). Mucosal biopsy specimens were taken during all endoscopies. After running, all runners had histologically pathological features in the stomach. Vascular lesions were present in the chorion in six subjects after running, with the intensity of the lesions ranging from congestion to hemorrhage. Postexercise histological examination also showed a decrease in mucosal secretion. These lesions secondary to prolonged exercise indicate the presence of hemodynamic perturbations in the upper digestive tract. 