I was on a Company run and one of my guys couldn't hold it in anymore. He jumped out of formation and popped a squat in the bean field. Wiped with one of his socks then caught up with the formation.

They say that running is the best cure for constipation and they were right in saying so. That being said, I lace my key into my shoe-laces so I don't have to frantically undo a knot as I try not to crap my shorts. It's more secure and it doesn't hamper your quick-draw. Just undo one of the laces from the top hole, thread the lace through the hole in the key, tuck it against the tongue and the other part of the shoe and then retie the shoe. Works like a charm.

My advice would be to try and synchronize your pooping schedule. I know it sounds funny but it works. Just try to time it so you go whenever you know you won't be running, thats what I do. As for the feeling like you have to go during a workout, most of the time its just a false alarm (obviously it wasn't in your case). When I run, most of the time I get "that" feeling, particularly during fast stuff. Almost always its either gas, or just a false alarm.