Sit on the floor with your knees bent and heels on the floor. Hold a dumbbell with both hands in front of your chest.
As you inhale, lift your feet off the floor. As you exhale, lean back until you feel your abs engaged. It is really important, and difficult, to keep your back straight; don't let it round. If this is too difficult, keep your heels on the floor.
Twist to the left side and lower the dumbbell to the floor. Then twist to the right side and lower the dumbbell to the floor. This completes one repetition.