Abstract: An apparatus for weight training is attached to a weightlifting device, such as a barbell or a selectorized weightlifting device. A second weight to be lifted is then coupled to the apparatus. The apparatus is adjusted for the varying skeletal configurations of various individual users. Within one portion of the exercise stroke of the invention, the resistance to lifting continuously varies between that of the weight lifting device and the sum of the weightlifting device and second weight. Thus, the effect of the lifting stroke is increased for each exercise stroke.

Abstract: A progressive resistance mechanism suitable for use with a weightlifting machine as provided having a base, a plurality of spaced vertical guide members, a carriage vertically reciprocating along the guide members and a plurality of weight stacks restingly supported by the base. An apertured selector post is slidably disposed through each stack and has a first pin for attaching a selected subset of weights from the stack for upward movement. A second pin on each selector post is provided for locking a slidable collar at selected positions on the post above the carriage. The collars may thus be set at different distances above the carriage. The upward-travelling carriage engages each collar in sequence to serially lift the associated weight stacks. The user thereby experiences progressively increasing weight resistance during the course of a single repetition.