Abstract

Physical activity can cause gastrointestinal symptoms, including chest pain (due to oesophageal spasm), belching, heartburn, nausea, vomiting, abdominal cramps and diarrhoea. Modifications of gastric emptying, digestive motility, secretions and intestinal absorption rate, as well as the brisk decrease of splanchnic blood flow, are the putative causes of the exercise-induced digestive symptoms. Symptoms are particularly common in long distance runners, athletes engaged in multidisciplinary sports, young people and untrained individuals. Their occurrence can be seen as a protective mechanism, which heralds and, therefore, can prevent the development of organ damage and life threatening conditions, such as digestive bleeding, heat stroke and shock. Gut training (a gradually increasing training load which, however, is maintained below the threshold of the workload inducing symptoms) protects the athlete from the occurrence of digestive disturbs, allowing him to eventually achieve high training loads. Training also accelerates the gastric emptying and the intestinal transit time without adversely affecting the absorption rate of nutrients, making it possible to match the increased energy demand of exercise with the diet (compensatory hyperphagia), without suffering from abdominal discomfort.