Hip rotation: external/lateral versus internal/medial

[tyciol]

To get the side splits, if I understand right, we require the ability to turn out our hips, which points the knee external (outwards) called lateral rotation. I am not sure on the exact degrees (I think read somewhere 45 is abduction other 45 is rotation, though how this sums confuses me a bit).

I am not sure exactly how it works, like if we can only turn out a full 90 degrees with hips in a flexed position or if it is also possible to get that amount of turnout while in a hip-extended position, such as ballet dancers are said to do.

Moreso though I am wonder, if we can improve our rotation of hips in that direction so incredibly, is it possible to improve them so much in the other direction? I do not know this, I wonder if perhaps the things we hear about hip construction not allowing turnout which you say are not true might be true for turnIN?

I have seen evidence that some people can do this though, like this Japanese cosplayer:
Snow sitting

I am not sure the subtleties though. Like if this is something we can only expect some women to be able to do because of their differences in pelvic construction to males, or something only possible for hypermobile people who have longer ligament or something like that whereas our ligaments are short and tight and would not allow this, or the ball socket of the femur in pelvis is not constructed to allow it? I have no idea, like maybe all this is just my being in denial about not properly stretching my external rotators and contracting internal rotators to do it.

There seem to be subtleties, like in the picture, the hips are flexed (seated) so I do not know if it makes a difference as to how far internally the leg could rotate at the hip if the hips were extended, such in this physiotherapy photographs illustrated in this Tnation article (bout halfway down) http://www.tmuscle.com/free_online_arti ... rom_a_to_z