Bi-directional resistance exercise apparatus designed to offer resistance to opposing muscle groups. The apparatus provides continuous and sequential resistance during the extension and flexion phases. The apparatus includes a controller including a graphic display. Resistance is provided by a variable resistance element such as a magnetic brake. A chair or other body supporting devices support the user depending on the exercise being performed. Force is applied by the user to a rotatable limb or torso retaining member and is transferred to the shaft of the magnetic brake. The brake applies variable resistance determined by the software instructions issued by the controller. The resistance levels can be pre-programmed or specifically selected by the user. The brake force varies instantaneously during the flexion and extension phases based on the angular position of the input shaft. A record of the exercise activity can be stored and displayed by the microprocessor controller.