Abstract: An apparatus is provided for specifically exercising the lower abdominal muscles, upper abdominal muscles, or both the lower and upper abdominal muscles together in combination of a human user. The apparatus includes a frame which accommodates the upper torso of a user and a resistance member pivotally connected to the frame on a latitudinal axis. The resistance member is capable of pivotal rotation about the axis, and includes a mechanism for varying the resistance of such pivotal rotation. As such, the knees of the user can be raised and lowered above horizontal without interference.