For those that suffer from side stitches when running here's a possible solution. Sports that involve an up-and-down motion are most susceptible, though it does occur in cycling and swimming but not as often. It's also true that most stitches are on the right side of the abdomen, in the area of the liver, the heaviest organ in the abdominal area. The liver, stomach, and spleen all hang from ligaments attached to the diaphragm, a large, flat muscle in the core region that creates inhalation as it contracts. During running these organs bounce pulling down on the diaphragm, sometimes causing the side cramp known as a stitch.
Here's what to do. With a stitch on the right side, exhale when you’re left foot strikes the ground. This will transfer most of the jarring force away from the afflicted side allowing you to lessen the stress on the diaphragm. Hopefully you don’t have an ongoing issue with side stitches but if it occurs give it a try.