Connect an ankle strap attachment to a low pulley cable and position a mat on the floor in front of it. Sit down with your feet toward the pulley and attach the cable to your ankles. Lie down, elevate your legs and bend your knees at a 90-degree angle. Your legs and the cable should be aligned. If not, adjust the pulley up or down until they are. With your hands behind your head, bring your knees inward to your torso and elevate your hips off the floor. Pause for a moment and in a slow and controlled manner drop your hips and bring your legs back to the starting 90-degree angle. You should still have tension on your abs in the resting position. Repeat the same movement to failure.