What's with her muscles? Chun-li's supposed to be muscular at the legs, not the arms.

Oh, come on!
Try doing the Spinning Bird Kick without muscular arms.

You don't need strong arms to do it, just absence of gravity.

Well, the in-game version is kind of wicked, I prefer using this sequence as a reference: http://www.youtube.com/watch?v=FWk3dSCSlgg (around 5:00 mark).