[header] How to do reverse crunches [title] Lie flat on your back. [step] Fully extend your legs, with your toes pointing upward and keeping your gaze focused on the ceiling. Your body should form a straight line from head to toe. 
[substeps] Relax your shoulders and neck to minimize the tension in your upper body. Stretching out on a lightly cushioned surface like a yoga mat or a carpeted section of the floor can make performing the exercise more comfortable.