On the surface it seemed like an easy question. A friend was getting back into running and asked me why he was getting cramps or side stitches a mile into his run. I started to reply then stopped. I knew what he was talking about. Just about everyone has gotten that familiar acute pain in their side while running at some point. But when was the last time it had happened to me? It had been a while. And what really did cause those cramps? That simple question didn’t have a simple answer.