Weighted One-Sided Crunch This abs exercise targets both the upper abs and the obliques. Lie with your knees bent and your feet flat on the floor, and hold a dumbbell with both hands by your right shoulder. Curl your torso up and rotate to the left. Lower yourself, finish the set on that side, then switch directions and repeat, holding the dumbbell next to your left shoulder. Perform three sets of eight repetitions to each side.