Prepare the appropriate weight taking account of your fitness level.Kneel down on the mat and move the barbell behind your head and let it rest on your shoulders. Straighten up your torso while kneeling.
From the starting position sit slowly down on your heels and do not change the curve of your backbone. Then return back to the starting position. Do the required number of repetitions. Inhale while moving down and exhale while going up.
Make sure you keep your torso in the correct position and do not bend your spine at the waist. Choose an appropriate weight taking account of your fitness level.
If possible, do the motion with your side reflected in a mirror to monitor correct posture of your backbone.
This is actually a partial squat involving only some of the muscles that are used in squatting. The back should be straight, shoulder blades squeezed together (scapular retraction) and head facing forward during the whole exercise.