Lie on a gym mat on your back, draw your feet towards your bottom, bending your knees. Place your hands behind your head. Adopt the Neutral Spine Position. You must not let your back arch, the small of your back must not lift off the floor. You must use your stomach muscles to keep your back completely flat on the floor during the entire exercise.
With your hands still positioned behind your head, raise your head off the floor slightly. Use your stomach muscles to lift your head, shoulders and upper body off the floor and towards your knees. Keep your eyes on the ceiling so that you don't pull your head forwards. Pull your shoulders up and forwards as much as you are able, and when you have reached as far as you can, hold the position for 1 or 2 seconds before lowering your upper body and shoulders down to the floor.
Keep your stomach muscles engaged throughout so that you control the lowering of your body to the floor rather than letting it fall down to the floor. This will increase the effectiveness of the exercise by making the lowering of your body as much part of the exercise as raising it.
Don't let the back of your head touch the floor until you have finished the exercise.