Weightlifting 101

Keeping the head position static throughout the sn**ch is a mistake - the head position should be active.

(A) The function of the head in the first and second pull is to improve the posture of the upper body in order to improve your ability to generate power - and for that reason the chin has to be a bit up while you look straight ahead or slightly up.

(B) The function of the head in the lockout, on the other hand, is no longer to improve the posture, but instead to improve the lockout. In order to do that you need the head through the window and for the chin to be slightly tucked.

It is in the third pull, i.e. when you pull yourself under the barbell - that you have to move your head from A to B.