The Seated Barbell Twist is a great way to stretch and build your external oblique muscles. It is extremely simple but once you start you will begin to feel the stretch across the side of your abs. To do the Seated Barbell Twist you simply sit on a weight bench with either a length of pole or even a broom behind your neck. Grip the pole with your hands and keeping your chest upright and your lower torso rigid, begin to slowly twist to the left and then back to the right. It is advisable to exhale on the twist and inhale on the inward movement. As you twist and breathe you will feel your external oblique muscles (and your abs) contract. Repeat as long as you feel comfortable and then gradually build up the number of repetitions as your external oblique muscles become stronger.