Why can we get a stitch during exercise?

THAT'S THE WHY:Have you ever been running around or swimming and suddenly felt a horrible pain in your side that can range from crampy to stabbing? You're not alone: getting a "stitch" can be a common enough experience.

A 2005 study of a 14km race in Sydney found that 27 per cent of respondents to a questionnaire had felt a stitch – with many saying it impacted on their performance – and the pain was more common among runners (rather than walkers) and in people who had eaten a relatively large amount in the hour or two before the event.

Why do we get stitches sometimes during exertion? The phenomenon, more formally labelled “exercise-related transient abdominal pain” (try saying that while you have a stitch), hasn’t received a huge amount of attention in the scientific or medical literature, but there are some suggested possibilities.

One proposes that the pain arises when blood is shunted away from the diaphragm – the sheet of muscle under the lungs – and gets diverted to other muscles during exercise. Another suggests the unpleasant sensation comes from ligaments attached to the diaphragm being tugged. Another points the finger at irritation of part of the peritoneum, a membrane around the abdominal organs.

Whatever the cause, studies tend to find that stitches are more common among younger people and in those who exercise soon after eating or drinking a large amount.