Exercised-induced gastrointestinal syndrome

RICARDO COSTA: So what is exercise-induced gastrointestinal syndrome? So when you start exercising, the body undergoes some natural changes to prepare the body for the actual exercise stress. And because of these natural changes, the gastrointestinal tract can be perturbed. When you start exercising, two main things occur. First of all, you have an increase in sympathetic drive. So you have an increase in sympathetic nervous system and a reduction in your parasympathetic nervous system. And this has a tendency to reduce the overall function of the gastrointestinal tract. So that means you have a reduction in your gastric emptying, intestinal motility, and this can impair the transport mechanisms of nutrients along the intestinal wall.

So that means if consume food during exercise, when it hits the intestine, the uptake of those nutrients into the body and into circulation may be impaired because of the disturbances to these transport mechanisms. So that can lead to some malabsorption. Simultaneously, we have a change in the blood flow to the gastrointestinal tract, meaning that when you start exercising, the blood flow moves into the muscles to provide muscles with the oxygen, removal of carbon dioxide, but also provide them with nutrients for the energy needs. This is at the expense of the blood flow to what we call the splanchnic around the gastrointestinal tract. So that creates a situation of ischaema.

So the problem with ischaema along the gastrointestinal tract, it will lead to damage and injury to cells along the intestine. So more specifically, along the epithelium, you’ve got important cells, such as goblet cells, paneth cells, and your enterocytes. The damage will create local inflammation, and that will increase your pro-inflammatory cytokines at the intestine epithelium. Both, with the damage and the increase in your localised inflammation, this prompts the increase in intestinal permeability, meaning that the tight-junctions which hold all the cells of the epithelium together start to open, and, therefore, there’s more space for the bacterial content of the intestine to leech into normal circulation.

If this occurs, we’ll have the immune system going into action and producing a systemic inflammatory response to try and protect the internal body. In normal, healthy people, that’s not a problem because the body has the ability to counteract that systemic response in the form of anti-inflammatory agents such as Interleukin 10. Many people that aren’t fit for purpose or may be ill or immuno-compromised, this is where the systemic response can lead to health implications.