A reformer exercise apparatus has a generally rectangular frame having a head end and a foot end and including a pair of spaced apart parallel track members, a movable carriage mounted on the frame for movement along the track members between said head and foot ends against one or more springs connected between the carriage and the foot end of the frame and an elastic member anchor bar and carriage stop assembly to adjustably position the carriage and elastic members on the tracks to accommodate a wide range of user heights. The anchor bar and carriage stop assembly includes an anchor bar having each end disposed in an elongated slot formed in each track member. The elongated slot has spaced gear teeth defining spaced anchor bar stop or lock portions. The anchor bar can be moved between lock portions only when rotated to an unlocked position wherein the bar can operably slide along the slot.