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GI Problems in Running

Distance running probably induces more GI problems than any other sports (Cark, et al., 1989, Peters, et al., 1993, Moses, 1990).  Nausea is probably the most common one.

Nausea (Gastroesophageal reflux) can be induced by exercise even during fasting; eating food only makes it worse (Cark, et al., 1989, Kondo, et al., 2001).  The author's experience is that the combination of dehydration and carbohydrate intake surely produces nausea.  For example, taking sweet drink or food soon after a marathon or a hard 5-mile race in summer would cause nausea almost immediately for him.  Even taking Gatorade towards the end of a long run in summer can cause nausea.  This experience is consistent with a study on the relationship between nausea and glucose/electrolyte beverage ingestion (Davis, et al., 1988).  

Dehydration leads to a delayed liquid gastric emptying, but does not change orocaecal transit time, intestinal permeability or glucose uptake.  The delay in  liquid gastric emptying is significantly associated with an increase in exercise-induced nausea (van Nieuwenhoven, et al. 2000).  This explains the author's experience of nausea caused by taking sweet drink under dehydration, however it cannot explain another experience of the author.  The author drank multiple cups (up to 6) of soups that are a bit salty, sour and spicy soon after finishing three different marathons and he felt great after drinking the soups.  The author's speculation is that dehydration not only causes the loss of body water, but also produces electrolyte imbalance (such as sodium deficiency).  The soups may well help the restoration of the electrolyte balance. 

Ibuprofen but not aspirin ingestion during prolonged exercise may increase gastrointestinal permeability and lead to GI symptoms 

References:

Clark CS, et al. (1989) Gastroesophageal reflux induced by exercise in healthy volunteers.  JAMA 261(24):3599-601

Davis JM, et al. (1988)  Effects of ingesting 6% and 12% glucose/electrolyte beverages during prolonged intermittent cycling in the heat. Eur J Appl Physiol Occup Physiol 57(5):563-9

Kondo T, et al. (2001) Exercise-induced nausea is exaggerated by eating.  Appetite 36(2):119-25

Moses FM (1990) The effect of exercise on the gastrointestinal tract. Sports Med 19(3):159-72

Peters HP, et al. (1993) Gastrointestinal problems as a function of carbohydrate supplements and mode of exercise. Med Sci Sports Exerc 25(11):1211-24

Smetanka RD, et al.(1996) Intestinal permeability in runners in the 1996 Chicago marathon. Int J Sport Nutr. 9(4):426-33.

van Nieuwenhoven MA, et al. (2000) Effect of dehydration on gastrointestinal function at rest and during exercise in humans. Eur J Appl Physiol 83(6):578-84

 

(originally written on 5/5/2002)