Dear Yahoo!:
What causes a "stitch" in your side during exercise?
Jack
Dear Jack:
A side stitch is a piercing sensation just below the ribcage, usually
felt when you're running. In the past, several different theories tried
to explain the cause: trapped gas, swollen liver, stomach muscle
cramps. However a recent and fairly conclusive theory holds that strain
on the ligaments connecting the liver to the diaphragm is the cause.
The liver "hangs" from the diaphragm by fibrous bands called ligaments.
Running exerts a steady downward force on your liver, stretching these
ligaments. In addition, when you exhale (usually as your left foot hits
the ground), your diaphragm is pushed up. That means your liver falls
with gravity as your diaphragm rises, placing considerable strain on
those poor ligaments.
The result? A stitch. The cure? Stop running immediately and press your
hand just below the pain. This should raise your liver up, relieving
the strain on the ligaments. Inhale and exhale evenly as you press
down.
As a preventive measure, take deep, full breaths while running. If you
take shallow breaths, your diaphragm is consistently raised, which
wreaks havoc on your ligaments. Exercise is great, but remember to be
kind to the rubber bands keeping your organs in place.