A reformer exercise apparatus has a head end and a foot end and a pair of spaced apart parallel track members, a movable carriage mounted on the track members for movement between the head and foot end. One or more springs are connected between the carriage and an elastic member anchor bar and carriage stop assembly at the foot end. The anchor bar and carriage stop assembly adjustably positions the carriage, the anchor bar and the elastic members on the tracks to accommodate a wide range of user heights. Each end of the anchor bar is disposed in an elongated slot formed in each track member. The elongated slot has spaced gear teeth shaped openings 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, coupled to the carriage, can slide along the track within the slot. In addition, the assembly maintains the carriage and anchor bar a predetermined distance apart when the anchor bar is in the unlocked position and maintains a minimum distance between the anchor bar and the carriage when the anchor bar is in the locked position.