Abstract: A portable exercise device (20) having a force measuring system (28) and a length adjuster (30). The exercise device includes a pulley/securing device assembly (22) and a cord (24) having a gripping structure (26) at each of its ends. The pulley/securing device assembly has a pulley (38) for engaging the cord and a securing device (34) for securing the exercise device to a door (46). The force measuring system engages one of the gripping structures and determines magnitude of a tensile force (68) applied to that gripping member. The force measuring system is in communication with an electronic display (88′) that displays the magnitude of the tensile force to a user (27).