Abstract: The machine of the present invention can have frame that supports an I-beam in either a vertical or horizontal manner. The I-beam can support a mounting plate and gear racks. A gear box housing is movable with respect to the I-beam under operation of a motor that turns a shaft so that pinion gears engage the gear racks to translate relative to the gear racks. A pivot assembly is fixed with respect to the gear box so that when force is applied to the carriage, it causes a change in torque loading in the gear box that is measurable by a force gauge mounted between the pivot assembly and the gear box housing. The motor is controlled by a controller to be operable to move the carriage and user engagement components carried by the carriage, such as a foot plate and/or manually grasped handles, so as to require user exertion to resist such movement.