Aetiology of running-related gastrointestinal dysfunction - How far is thefinishing line?

30 to 65% of long distance runners experience gastrointestinal (GI) symptom s related to exercise. Several hypotheses have been postulated; however, th e aetiology and pathophysiology are far from clear. The mechanical effect of running on the viscera must be involved in the dev elopment of GI symptoms in this sport. Reduction of splanchnic blood now du e to visceral vasoconstriction is another widely supported theory; neverthe less, it does not explain many of the clinical findings. Examination of the GI tract during exercise is a difficult task, and measurements of both oro caecal and whole-gut transit time have shown equivocal results. GI hormones , and especially prostaglandins, may be of crucial importance for the produ ction of symptoms. Intestinal absorption, secretion and permeability may al so be altered during exercise, provoking intestinal dysfunction. Factors su ch as stress, diet, dehydration, infections and other factors need to be an alysed in order to present a global view of the hypotheses regarding the ae tiology of this common and often overlooked problem.