Published on 1st January 2017


Gastrointestinal (GI) distress is a common but rarely talked about problem that is experienced by athletes at all levels.1 In fact, studies have shown that it affects between 30 and 65 per cent of runners, with the most frequent symptoms including cramping, bloating and loose bowel movements.2 Most people simply try to put up with it.

It’s thought that there are three main causes of GI problems:

  • Physiological (caused by reduced blood flow to the gut during exercise)
  • Mechanical (bouncing effect of running, for example)
  • Nutritional (such as excess intake of carbohydrate drinks)

Other contributors include alcohol consumption, anti-inflammatory medications, emotional stress, pathogenic bacteria, and excess pressure on the abdominal wall.3

Ultimately, these symptoms can impair performance and possibly prevent athletes from winning or even finishing a race. However, many nutritional steps can be taken to support the problem. These include:

  • Manipulating the fibre content of the diet during training
  • Adding in probiotics (‘friendly’ bacteria)
  • Using drinks containing multiple transportable carbohydrates4 (glucose plus fructose) as fuel during a race


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  1. de Oliviera E and Burini R (2014). Carbohydrate-dependent, exercise-induced gastrointestinal distress. Nutrients; 6:4191-4199.
  2. Simons S and Kennedy R (2004). Gastrointestinal problems in runners. Current Sports Medicine Reports. DOI: 10.1249/00149619-200404000-00011.
  3. Casey E, Mistry D and Macknight J (2005). Training room management of medical conditions: Sports gastroenterology. Clinics in Sports Med; 24:4191-4199.
  4. Jeukendrup A (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care; 4:452-457.