I'm considering a treadmill tomorrow if the sidewalks are icy here after today's nor'easter. I'm not a minimalist, but I've noticed in the past that trainers seem too bulky and cushioned for a treadmill, which is usually bouncy. So, I'm considering flats for it. Not that it will do much damage even if I find this uncomfortable, but has anyone tried using flats for treadmills, but not roads (except for races of course)?