to work your upper abs, perform lying exercises in which you raise your upper body ONLY off the floor (crunches, sit-ups).
to work your lower abs, perform lying exercises in which you raise your lower body ONLY off the floor (lying leg raises, bent knee raises, etc). if you have something sturdy to hang from, you may grasp the object, and while hanging, bring your knees in toward your chest, or keep your legs straight and bring them parallel to the floor.
to work you middle abs intensely, lying on your back, bring BOTH your upper body and lower body off the floor at the same time, making a “V” shape with your body.
to work your upper abs, perform lying exercises in which you raise your upper body ONLY off the floor (crunches, sit-ups).
to work your lower abs, perform lying exercises in which you raise your lower body ONLY off the floor (lying leg raises, bent knee raises, etc). if you have something sturdy to hang from, you may grasp the object, and while hanging, bring your knees in toward your chest, or keep your legs straight and bring them parallel to the floor.
to work you middle abs intensely, lying on your back, bring BOTH your upper body and lower body off the floor at the same time, making a “V” shape with your body.
hope this helps