Abstract: An exercise apparatus in which the resistance force experienced by the exerciser may be varied is provided. The apparatus includes a support frame within which a weight support carriage having detachable weight members is supported for vertical movement. A shaft is rotatably mounted on the frame and an exercise bearing member which may be engaged by a user is secured to the shaft as well as a cable wheel having a peripheral cable guide track. A length of cable is secured at one end to the weight support carriage, reeved through cable guides and movably attached at its other end to the cable wheel. A supplemental cam member having a varying thickness is received within the guide track and is movable therein along guide members. The position of the supplemental cam member may be fixed at predetermined points along the guide track in order that the cable must ride thereon, thereby providing exercise resistance or force which varies with the thickness of the supplemental cam member.