I’ve had to slow down to a walk at times on long runs because my pooping impulse would get stimulated. Fortunately, I’ve never had to drop one in my shorts or go behind a bush.
As for that dude in the picture in #6: THAT’s determination (unless that’s from a slapstick movie). Hope there were showers at the finish line.
A marathoner I knew said he once saw a world champion female marathoner pull her shorts sideways, squat in the gutter and get right back to running, when she was stricken with diarrhea during a race.
Maybe it’s not uncommon when you’re pushing the body to the limits like that - lactic acid and prostaglandins and who knows what building up in the system.