Review article: the pathophysiology and management of gastrointestinal symptoms during physical exercise, and the role of splanchnic blood flow

Abstract

Summary Background The prevalence of exercise‐induced gastrointestinal (GI) symptoms has been reported up to 70%. The pathophysiology largely remains unknown. Aim 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.

The Gastrointestinal Circulation: Physiology and Pathophysiology

“…The magnitude of the reduction in splanchnic blood flow during exercise appears to be dependent on different factors, including age, exercise intensity, the increase in total body oxygen consumption (VO 2 ), heart rate, plasma norepinephrine concentration, time after food ingestion, and ambient temperature (95,209,255,398,488,503). Intensity-dependent increases in plasma vasopressin and angiotensin II levels accompany the increased splanchnic vascular resistance during exercise (37,502).…”

Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance

“…Gastrointestinal symptoms are a common feature of endurance exercise, and appear to be more pronounced in running or endurance events that contain a running element (e.g., triathlon) compared to other exercise modes (e.g., cycling) (Pfeiffer et al 2012;ter Steege and Kolkman 2012). For example, severe gastrointestinal symptoms have been reported in 85% and 73% of ultramarathon runners during multi-stage and 24 h ultra-marathons, respectively.…”

“…Epithelial injury is a key feature of exercise-induced gastrointestinal syndrome, which appears to originate from splanchnic hypoperfusion and subsequent gastrointestinal ischaemia (Evennett et al 2009;Grootjans et al 2016;ter Steege and Kolkman 2012;van Wijck et al 2011;van Wijck et al 2012). Despite evidence of increased epithelial injury after GC1 (144%) and GC2…”

“…The cause/s of gastrointestinal symptoms during running appear to be multifactorial in origin and stem from 'exercise-induced gastrointestinal syndrome', in which the primary driving D r a f t 5 factors are: 1) splanchnic hypoperfusion and subsequent intestinal epithelial injury, increased intestinal permeability, systemic responses (i.e., endotoxaemia and cytokinaemia), and impaired intestinal nutrient absorption; and 2) stress induced increases in sympathetic drive and subsequent reductions in enteric nervous system activity, which alters intestinal motility and absorption capacity (Gill et al 2015a;Gill et al 2015b;Grootjans et al 2016;Leipers 2015;ter Steege and Kolkman 2012;van Wijck et al 2012). …”

The Effect of Intra-Dialytic Exercise on Inflammation and Blood Endotoxin Levels

“…Increased gut permeability related to intense exercise is thought to occur due to a combination of fluid depletion, hyperthermia, ischaemia and free radical stress [3]. Ischaemia occurs due to decreased blood flow to the splanchnic circulation during exercise, and many athletes report gastrointestinal symptoms such as abdominal pain, nausea and vomiting during and after exercise [4]. Similarly, many haemodialysis (HD) patients experience gastrointestinal complaints after dialysis and also experience intestinal ischaemia and contraction of the splanchnic circulation during dialysis and ultrafiltration [5].…”