Review article: the pathophysiology and management of gastrointestinal symptoms during physical exercise, and the role of splanchnic blood flow.
BACKGROUND
The prevalence of exercise-induced gastrointestinal (GI) symptoms has been reported up to 70%. The pathophysiology largely remains unknown.


OBJECTIVE
To review the physiological and pathophysiological changes of the GI-tract during physical exercise and the management of the most common gastrointestinal symptoms.


METHODS
Search of the literature published in the English and Dutch languages using the Pubmed database to review the literature that focused on the relation between splanchnic blood flow (SBF), development of ischaemia, postischaemic endotoxinemia and motility.


RESULTS
During physical exercise, the increased activity of the sympathetic nervous system (SNS) redistributes blood flow from the splanchnic organs to the working muscles. With prolonged duration and/or intensity, the SBF may be decreased by 80% or more. Most studies point in the direction of increased SNS-activity as central driving force for reduction in SBF. A severely reduced SBF may frequently cause GI ischaemia. GI-ischaemia combined with reduced vagal activity probably triggers changes in GI-motility and GI absorption derangements. GI-symptoms during physical exercise may be prevented by lowering the exercise intensity, preventing dehydration and avoiding the ingestion of hypertonic fluids.


CONCLUSIONS
Literature on the pathophysiology of exercise-induced GI-symptoms is scarce. Increased sympathetic nervous system activity and decreased splanchnic blood flow during physical exercise seems to be the key factor in the pathogenesis of exercise-induced GI-symptoms, and this should be the target for symptom reduction.
Department of Gastroenterology, University Medical Centre Groningen, The Netherlands. rinzetersteege@hotmail.com
R W F
RW
ter Steege
J J
JJ
Kolkman
D004032:Diet; D015444:Exercise / Q000502:physiology*; D005765:Gastrointestinal Agents / Q000627:therapeutic use; D005767:Gastrointestinal Diseases / Q000503:physiopathology* / Q000628:therapy*; D005769:Gastrointestinal Motility / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000098:blood supply / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D013152:Splanchnic Circulation / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*
D005765:Gastrointestinal Agents