This exercise is a modified version of the traditional sit-up. The balance disc provides assistance during the sit-up. It is also adds comfort to the lower back. Unlike traditional abdominal exercises that involve the hip flexor muscles (located in the upper thigh), the sit-up with balance disk considerably decreases hip flexor involvement. This allows for better isolation of the ab muscles.

First, place the balance disk in the center of a workout mat. Lie on your back in the sit-up position. Place the balance disk on the lower half of your back. Your knees should be bent. Your hands can be anywhere: across the chest, behind the head, in the air, etc. Hand positions are altered to affect weight distribution during the sit-up. Next, contract your abs by sitting up. Be sure to exhale and keep your head and chin up. To make this exercise more effective, try to maintain constant tension on the abdominal muscles throughout the movement. This can be done by sitting up just short of being completely upright. Slowly lower the body back down and repeat the exercise.