This exercise works the lower of your abdominal muscle and when performed correctly can eliminate the use of other muscles to cheat the movement.

1 Lie flat on a bench and reach back to hold on to the underside of the bench behind your head. Bend your legs at the knee, raising your feet off the bench so that your knees are over your hips.

2 Slowly draw your abdominal muscles toward your spine, then slowly exhale and push your spine into the bench - start with your lower back and make the movement flow up your spine until your hips roll up off the bench.

3 Imagine that the bench is made of soft plastic and try to leave an imprint of your spine in it.

4 When you have rolled the full length of your spine, inhale slowly and return to the starting position, pushing your spine into the bench as you roll back down.