Side stitches are pains that occur usually in your abdomen or just under your ribs (most often on the right side) when running. In the past it was thought that the pain was due to an unconditioned diaphragm, food allergies (often milk), gas, or having just eaten before running. Side stitches happen more often with beginning runners or when a runner is out of shape.
Today it is believed that the side stitch occurs due to the lack of oxygen (ischemia) in a portion of the colon. There is a piece of the colon that, at times, may not receive an adequate blood supply. During rigorous exercise, when blood is shunted away from the gut and diverted to the limbs to supply the muscles, pain is experienced in this portion of the colon that is starved for oxygen.
Controlling Side Stitches
When caused by lack of conditioning, the best thing to do for side stitches is to run slower and longer. Breathe fuller and try belly breathing, in which you allow your stomach to relax and push out as you inhale and then contract slightly as you exhale fully. Breathe rhythmically and make sure that you are not holding your breath.
Another breathing tactic consists of exhaling against resistance through pursed lips. Combined with belly breathing, this may be the best approach. Applying direct pressure to the side stitch sometimes helps. Another way of gaining temporary relief is to stretch your arms up while inhaling, imagining your breath coming in and soothing the side stitch.