Barbell russian twist: Grasp the bar near the very end again—this time with both hands. Stand with feet at shoulder width. Swing the bar to your left, pivoting your feet as needed, then swing to your right.
Dip/leg raise combo: Suspend yourself over the parallel bars at a dip station. Bend your knees slightly and raise your legs in front of you until they’re parallel to the floor. This will build you a magazine-worthy six-pack.