A torsion bar resistance unit and a variable resistance unit system having at least one selectably engageable torsion bar is disclosed. A resistance training machine having a plurality of selectably engageable torsion bars coupled to a lever is disclosed wherein a rotational resistance load is based on which of the plurality of torsion bars are rotatably locked and the force applied to the lever. Also disclosed is a user interface that allows a user to selectively engage any of the plurality of torsion bars, output the total resistance load and the translation distance on an output screen.