Archerelle

Hi! Question: I am looking for the specific muscles activated in the described exercise and also, how it might possibly affect turn out. Here is the exercise: Sit on the floor, erect on the sitz bones. Lengthen the spine. Pull your feet in towards your body, keeping your knees as close to the floor as possible. Allow your big toes to touch. Remaining tall, pull your sits bones together, squeeze - hold for ten seconds and release. Repeat. I was told these work the lower pelvic muscles related to core and can assist in turn out/rotation of the hips desired for ballet. After doing a few of the exercises, I see and feel a result. I cannot figure out which muscles are being used and how it affects the rotation of the hip. ?? Can anyone help? Many thanks, R.