Commonly, when a runner talks about a stitch, they report a sudden, sharp pain under the rib cage on one side, which impairs their performance and can make it difficult to take a deep breath.
“Most people feel this on the right side and a smaller proportion of runners get shoulder pain: this is because of the way nerves supply the diaphragm, so pain in this area is referred to the shoulder,” says Dr Rebecca Robinson, consultant in sports and exercise medicine, the Centre for Health and Human Performance.