Abstract: A physical therapy apparatus for use in conjunction with a treadmill provides an assistive force to a forward movement of the legs. A force assistance device is adapted to attach to the feet or legs of a patient positioned on a motorized treadmill to assist in walking therapy by providing an assistive force to a forward movement of the patient's feet or legs. An adjustment device may vary an interface of attachment, for example, the height or direction, between the force assistance device and the patient's feet or legs. A force arresting device may arrest the assistive force provided by the force assistance device during the forward movement of the patient's feet or legs. The force assistance device provides a substantially constant assistance force during the forward movement of the patient's feet or legs. The physical therapy device may also include a force adjustment device connected with the force assistance device to vary the magnitude of the assistive force.