The development of humanoids with bimanual manipulator arms may facilitate assistive robots to perform physical therapy with older adults living at home. As we assume the human-human interaction to be the gold standard of physical therapy, we propose a kinematics analysis to derive guidelines for implementing physical therapy assisted by humanoids. Therefore, a pilot study was carried out involving three physical therapists and two participants acting as exemplary patients. The study analyzes the therapists' movement strategy, including the position and orientation of the therapists' bodies in relation to the participants and the placement of the therapists' hands on the upper limb segment of the participants, as well as the inter- and intravariability during the performance of a ROM (range of motion) assessment. The results demonstrate that while physical therapists exhibit variation in their interaction strategies, they still achieve a consistently low level of variability in their manipulation space.