What is a side stitch while exercising?

This story has been updated. It was originally published on October 20, 2017.

Before the mile run each year in middle school, on the dreaded walk down from the classroom to the course, my classmates would argue over the best way to prevent a side stitch. More so than turning an ankle or coming in last, that repetitive stabbing pain is what the majority of us dreaded most. Our cures ranged across the map from taught techniques, like breathing in through the nose and out through the mouth and not eating for three hours prior, to my favorite: Punching yourself in the stomach at…