Stand upright with your feet shoulder width apart and knee joints slightly bent.
Place a barbell on end in front of you, with the the end of the barbell immobilized on a non-slip mat.
Place weights on the top end of the barbell and then grip the top of the barbell with your arms out straight.
Move the barbell from side to side, keeping your lower back stable in the neutral position.
You should only rotate through the shoulders and spine, not through your legs.
