The generally agreed site of a stitch is the diaphragm muscle and there are two main theories as to the cause. One is the Blood-Flow Theory, the other The Ligament Theory.
The premise is that, following ingestion of food or drink, blood flow is diverted away from the diaphragm to the stomach for digestive purposes.
The diaphragm is attached to the stomach by ligaments. Activity such as downhill running can cause the stomach to pull on these ligaments, causing the pain which runners recognise as stitch. However, it is clear that the extra weight in the stomach, albeit small, caused by taking on fluid could cause similar sensations.
How can we prevent or mitigate the onset of stitch?
- When running, contract your stomach muscles
- 'Belly breathe' so that your belly rises and falls, stabilising your stomach
- Press the point of pain with your hand and bend slightly forward
- Don't pound when running downhill
- Leave an appropriate period between eating/drinking and running
- During training or racing, if you must drink, take small amounts regularly, rather than one large quantity.
Hopefully these measures will help you when you experience one of the most annoying problems you may experience as a runner.