When you do any sort of exercise, your trainer will tell you 'exhale on the effort' ... When you inhale, your pelvic floor relaxes; when you exhale, your pelvic floor contracts. And so, actually, that contraction stabilizes the pelvic floor. So, whatever intra-abdominal pressure you're causing to increase from the exercise, whether it's a squat or a crunch or whatever, you're increasing your abdominal pressure. Your pelvic floor is then contracting to help stabilize that.