Q: What causes side stitches?

Km: I am unfamiliar with the term "side stitch"... is this the same as a side crampie? exercise related transient abdominal pain (ETAP)? Just kidding, but seriously, who uses these terms?! A side stitch is simply a muscle spasm of the diaphragm. There are a few theories about what causes this, but the largest contributing factor seems to be what you eat before you exercise. Namely, drinking reconstituted fruit juices or beverages high in carbohydrates and osmolality either right before or during exercise seemed to result in a higher prevalence of side stitches. Another viable theory speaks to over-stretching the ligaments that extend from the diaphragm to the internal organs, particularly the liver. Breathing while running, particularly when running fast, stretches these ligaments. People who exhale when their right foot hits the ground are more prone to side stitches, perhaps because this is the same side of the body that the liver is on. In order to prevent/relieve side stitches, try taking even, deep breaths. You can also try alternating your breathing pattern and stretching. Running downhill also seems to trigger side stitches because it places the entire body under more force.