Just so you know, the pose you've put her in is physically impossible for the sake of showing both her bottom and breasts at the same time. I think you have beautiful art, but it would be even more beautiful if the glaring break in her spine was replaced with a humanly possible pose She would look even stronger and even cooler!
Lots of women have tried doing it for the purpose of proving that it's impossible. Even a professional contortionist was unable to do it. People look a lot better and stronger in realistic poses anyway.
I also have to disagree - except with you, not Garitoaga. Are you even looking at the pose? You make it sound like her chest and butt are parallel facing the camera, which sure, would be impossible. But she's only twisted to 90 degrees. We're just able to see both her chest and butt because of the angle we happen to be facing her, where as someone parallel to her chest would only get a side on of her butt. And claiming a "processional contortionist" couldn't do that? Please. Run a Youtube search of the phrase "torso twist" and you'll find a video by the same name from an amateur contortionist who pulls off a much harder angle off with ease. No spine breaks, and definitely no pain. This pose and picture is fine; and I'm talking both meanings of the word.
Checked out a video as you suggested and I am still not convinced. As I am looking at the pose and it looks painful and difficult as well as weird. Sure, people can get close to achieving the pose. But it's with practice, stretching and flexibility in a relaxed and slow manner - not while they're trying to chop something in half with a heavy sword. Why don't you try and pose like that in the mirror? First try it being stationary and you'll find it uncomfortable (you have to be able to see both buttcheeks and both nipples). Now try it while jumping and lifting something up in the air... It's just not practical - aside from looking broken, the pose serves to weaken the character's action (attacking with the sword) because it doesn't follow the rest of her body. It's an established rule for making good poses that you create a line of action which doesn't randomly break off for no reason, but supplements the action of the character. It's incredibly obvious the pose was done in such a way simply for the sake of showing both butt and breasts of the character. In my opinion, it is degrading to women although I recognise that a lot of artists will do it because it's very common in art/comics etc. to draw women with broken spines for the sake of making them as "sexy" as possible. I would just like to see more women drawn with correct anatomy as is allowed for male characters, so that the female characters can look strong rather than ridiculous.