1. Lie with a Bosu ball under your hips, your knees bent and your hands by your temples.
2. Curl up into a crunch, twisting your torso to the right.
3. At the same time, lift your right knee and touch it to your left elbow while straightening your left leg
4. Go back to the start and repeat the action on the opposite side

The crunch twist targets your upper abs and obliques, while the unstable surface gives your car an extra workout.

1. Lie back back as far as you can with the ball under your lower back
2. Curl your shoulders up and twist your torso to one side.
3. Lower slowly to start and repeat to other side