Some defaults in the positions are quite common and it's good to know them to be able to avoid them :

• unarched
• knees down
• legs apart
• legs flexed
• arms in front
• arms back
• no left-right symmetry

A person who has a position too tence and stiff emphasises little dissymmetries which otherwise would not be a problem.

Unarched :

The center of gravity is too high. This position is not stable because it isdifficult to keep the balance. The hips have to be pushed down and the head should be kept up.

Knees down :

The upper part of the body is in correct position but the student is not aware of the position of his legs. This is an example of a position where one can arch without being stable : one has to put the hips down instead of just arching his back. The toes have to be pointing to the sky in order to feel the legs, this will bring the knees back up.

Legs apart :

Unless you are a very lax woman, a too big split of the legs prevents one from putting his hip down. This results in an unstable position. The legs have to be put closer together and the hips pushed down.

Legs flexed :

Flexed legs cannot put any pressure on the air equalling the air pressure on the arms. The body is lifted in front, the effect is a backward slip. The legs have to be slightly stretched so that one can feel the air pressure on his tibias.

Arms in front :

Arms that are too much in front increases the air pressure in front which also causes a backward slip, and even rocking back and forth.

Arms back :

Without air pressure in front, the position rocks back and forth and is not comfortable. The hands have to be placed into eyesight to restore symmetry of the air pressure.