i know you're not supposed to work out the same muscle group on consecutive days to allow recovery since that's where your muscles actually build. my question is, does this also apply to crunches / sit-ups ? the reason i'm asking is that i have difficulty sleeping at night and so i heard somebody say to just do crunches / sit-ups while you're laying in bed until you're tired and you'll fall asleep.
so i was wondering if i do that, then i would be doing that every night. so does the same rule about not working out the same muscle group on consecutive days apply to crunches/sit-ups as well?