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In 1997 during the Hawaiian Ironman I pushed my body to the limit. I was vomiting, had diarrhea and stomach cramps, but I just had to finish the race. Just 50 metres from the finish line I collapsed. Shortly after, I had to have surgery to remove one third of my large bowel, as it had died.

Chris Legh, quoted from

The gut is not an athletic organ. During exercise, blood is directed away from the splanchnic vessels and to the exercising muscles. The gut therefore becomes relatively ischemic, and it is this which causes the majority of gastrointestinal symptoms during exercise. These symptoms may be divided into those relating to the upper gut and those relating to the lower gut (Table 51.1). Bleeding is another important clinical presentation, as discussed below.

Table 51.1

Gastrointestinal symptoms associated with exercise

Physiological changes that alter gastrointestinal function during exercise include reduced blood flow to the abdominal viscera, gastrointestinal hormonal changes, and alterations to gastric emptying rates and intestinal motility. Also, vigorous diaphragmatic movements, abdominal contractions, and intestinal jarring can all cause abdominal symptoms.1

Although the incidence of gastrointestinal symptoms is increased with exercise, the presence of symptoms in a sportsperson should not automatically be assumed to be solely related to exercise. Sportspeople as well as non-sportspeople suffer from common conditions, such as hiatus hernia and peptic ulceration, inflammatory bowel disease, polyps, and cancer. Physical activity confers a 25% reduction in colon cancer risk.2 Clinical judgment is required to appreciate when these conditions must be considered in the sportsperson with gastrointestinal symptoms.

A summary of the management of common gastrointestinal symptoms is shown in Table 51.2.

Table 51.2

Treatment of common gastrointestinal problems

Upper gastrointestinal symptoms

Heartburn, reflux, nausea, vomiting, and upper abdominal pain are the most common upper gastrointestinal tract symptoms related to exercise. Gastroesophageal reflux is a common complaint among sportspeople and can even cause asthma-like symptoms.3 Twenty per cent of patients with established reflux consider exercise to be the major contributor to their symptoms.

The mechanism by which exercise causes reflux is not well understood, ...

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