I have been running for many years, but not competitively, about 10k a day for overall fitness etc. I have had IBS and bouts of ulcerative colitis for about 24 years, and I still manage. I never run first thing in the morning, but make sure my gut has done its thing first, I run most of my route through a large park with open public washrooms in summer and lots of trees and bushes year-round. In all the years, I can count on my hands the times I ever had an emergency requiring a BM stop while running.