sudas: I've only heard of two gals who could blow themselves. The first was a yoga instructor. She demonstrated for her best students and offered to give lessons. The second was a 10-13 y.o. gymnast. She said her mom walked in on her and scolded her, but she keeps doing it. I suppose those Asian contortionist girls could do it also, but they're not telling and it's rude to ask.
In all cases we're talking about years of training. That kind of training could do weird stuff to your abdomen. Guys with serious skill show a musled belly that's bent inward, gross! Ladies don't show their bellies. Perhaps the organs move up like for wearing a corset.