Abstract: An exercise machine having a user interface engaged by a user to perform exercises using the exercise machine is disclosed in which an electric, direct current (DC), servo control motor is used as the force producing element to which the user interface is mechanically connected and in which a digital data processor, operatively connected to the electric motor, is used for monitoring the position and direction of movement of the linkage relative to the electric DC servo motor and for controlling the electric DC servo motor to operate as one of a generator or a motor depending upon the determined position and direction of movement of the linkage is disclosed. The force exerted by the electric motor, whether it is operating as a motor or a generator, is dependant upon the position and direction of movement of the mechanical linkage as well as upon the force exerted by the user on the mechanical linkage, and other parameters, depending upon which one of three modes of operation is selected.