An exercise device is disclosed. The exercise device includes an ankle rest structure and a housing. Within the housing, a drive mechanism is provided that is connected to the ankle rest structure. The drive mechanism moves the ankle rest in a reciprocating motion along a generally horizontal plane. The exercise device also includes a knee rest structure spaced away from the ankle rest and connected to the housing. In one embodiment, the knee rest is movable in a horizontal and vertical direction with respect to the housing.