Are situps, curlups, and crunches all the same thing?
If no, what is the difference?
If yes, why the name changes?
I feel that situps and curlups are different, although that might just be because my teacher called them by different names back in elementary school, in an effort to get us lazy folk to try situps. "Curlups. That sounds so much easier!"
They are sort of the same thing. But you will find that different grops fo people do them differently:
Footballers do sit ups and raise their upper bodies as far off the floor as possible, often very quickly and with their feet somehow held down.
Curlups are often done by yoga and pilates instrcutors - done slowly under a lot of control and involving an emphasis on the curl rather than the up!
Crunches are what most group fitness instructors use - they are somewhere in the middle (sorry no pun intended there).
If you read the post under this one 'exercise question for stef' you'll find a long thread someone very kindly glued together of all the abdominal exercises I had posted a couple of years ago.
These exercises are all you'll ever need to know about working those abs for fitness and strength. Anything else is modification of these exercises for fashion or variety. Nothing wring with that but sometimes the basics are just what we need.
NB China?!?! I don't think I've responded to China before. I'll try to take a squiz at your links.