To do the Full Body Crunch, lie on your back with your legs out straight. You can place your hands behind your head or across your chest. Lift your feet up off the ground and tuck your knees in toward your chest as you crunch your upper body up. Keep a space between your chin and your chest as you lift your shoulder blades up off the ground.
Crunch both your lower and upper body together then relax your upper body back down as you kick your legs out straight. Do not touch your heels to the ground until all reps are complete.
Beginners may need to keep their feet up higher in the air while more advanced exercisers will kick their legs out close to the ground, keeping them only an inch or two up off the ground.
After you kick your legs out, crunch everything back together.