Abstract: A direct drive rehabilitation and fitness apparatus and method having a range limiter disk cooperating with an inclined cam surface, the method of construction requiring the range limiter disk to be directly coupled to the inclined cam surface through a drive shaft for converting rotational motion of the limiter disk into translational motion of the drive shaft for providing vertical movement of a weight stack. The method of construction provides that the range limiter disk be fitted with an adjustment pin for limiting the range of motion of an actuator arm and that a shaft supporting the weight stack communicate with a cam follower for riding along the translating inclined cam surface. The apparatus and method permit opposing patterns of movement with the range limiter disk by repositioning the adjustment pin thus making possible concentric and eccentric movements of opposing muscle groups.