That, too. I mean, sometimes people get what is euphemistically referred to as runner's diarrhea when they first start exercising, as it shocks their gut, which is not used to motility. DH and I have a joke that even looking at our cycling shoes causes the need to go! For me, it's more the anxiety of starting a ride.
I could go on and on, but it's no different than types of riders. There was this well known man named Ken Alan who taught workshops for instructors. One of the funniest things I heard him, say was a categorization of group fitness clients; The A's, B's, C's, and D's. He said what everyone thought. I correctly classified myself as a "B" and I continue to find the "A's" as distasteful as I did in 1987.