Hi! I've had no trouble running and hiking. It took some time though, to recover from surgery. I felt I didn't fully recover for a year. My only problem when it comes to exercise is heavy lifting and other activities that strains my stomach very directly, I have to avoid that, mostly because of the risk of hernia. (But if you get a j-pouch I guess that's no problem?) And of course there are things I haven't even tried yet, but I have been running and hiking a lot. Well, not ultramarathons, but still... :p I don't struggle with dehydration, I thought that would be a bigger issue, but to me it's not. I do have water with electrolytes when I exercise though
I have a loop ileostomy.