Does anyone else get diarrhea after running? Is there a connection?

Yes. Diarrhea can occur after an intense session or a long run. Your body diverts blood away from your gut/intestines to supply your working muscles. This often leads to intestinal distress, and diarrhea in some runners. At a race, 'nerves' and race-anxiety can also cause diarrhea, commonly referred to as the 'runner's trots'. Use caution with gels and hydration mixes, since they can also be culprits.