Abstract: An apparatus for exercising the abdominal and lower back muscles of a human exerciser is provided in which a frame supports a seat and a pivotable barrier. The exerciser adjusts the seat and the pivotable barrier along the length of the frame. A resilient member connects the pivotable barrier to the frame and opposes rotation of the barrier in a direction away from the seat. By opposing this rotation, the resilient member permits the user of the apparatus to exercise his abdominal muscles when he pushes against the barrier when he faces the barrier and to exercise his lower back muscles when he pushes against the barrier when he faces away from the barrier.