A protocol for the comparison of reaching gesture kinematics in physical versus immersive virtual reality

Virtual environments are increasingly being used for upper limb rehabilitation in post-stroke patients. However, still there is no clear evidence that the movements performed in virtual reality are comparable to those performed in the physical world from the kinematic point-of-view. The goal of the proposed study is thus to determine if aimed reaching movements made in a 3D ecological and immersive virtual environment - displayed through a Head Mounted Display (HMD) - are comparable to movements performed in the real world. The study foresees the realization of two comparable environmental settings representing the shelf of a supermarket. Three different groups of subjects (healthy young adults, healthy elderly, and post-stroke subjects, n=15 each) are asked to reach 5 times toward 9 targets in 3 different conditions: virtual reality, physical reality, and physical reality while holding a controller. Their movements are tracked with a stereo-photogrammetric motion capture system; movement times, peak velocities, and joint angles are then extracted for analysis. This protocol will allow comparing reaching movements, and also excluding of the effects related to holding a controller. A preliminary trial reveled the feasibility of the protocol, thus the experiment will be carried out in the next months. If results will be encouraging, VR should be considered in rehabilitative treatments as a useful means to elicit patients' motivation, but also appropriate movement synergies, thus promoting a better recovery of upper limb functions.