Be kind to your gut

There are a number of reasons why you might suffer from gastrointestinal problems while exercising. Happily there are a variety of techniques and tips you can deploy to prevent discomfort. GP and cyclist Andy Ward explains…


Anyone who has ridden a time trial will be familiar with that horrible wave of nausea that comes on at the finish. It’s possibly a sign that you’ve put the right amount of effort in, but if it comes on more frequently it can interfere with your enjoyment of the sport. Dehydration and low blood sugar can contribute, as can overeating before an event, and even anxiety. Low blood sodium can also cause nausea and is best avoided by drinking hypotonic sports drinks – simple water does not replace the sodium lost in sweat. 

The Runs

Stomach cramp and diarrhea are well know side effects of long-distance running, but unfortunately cyclists can be affected too, especially when riding hard. It is thought that blood is diverted to fuel the working muscles, which affects bowel function and causes cramps. As with nausea, dehydration can also have an effect. If you tend to suffer, avoid eating high-fibre foods in the 24 hours before an event. It is also worth experimenting with gels and drinks. If diarrhea is persistent, or associated with bleeding or weight loss, consult your doctor. 

Windy Days

Flatulence has a number of causes, not all of them cycling-related. In most cases, ‘excess’ flatulence is probably just a perception – passing wind up to 15 times a day is the average. The wind itself comes from swallowed air as a product of the digestive process. Gulping drinks, chewing gum and eating too quickly all increase the amount of swallowed air. Fructose, found in some sports drinks, causes the gut to produce more gas. Alcohol and caffeine also contribute, while some probiotics might help. 

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