Kinematics of aimed movements in ecological immersive virtual reality: a comparative study with real world

Virtual reality (VR) has recently emerged as a promising technology to rehabilitate upper limb functions after stroke. To promote the recovery of functions, retraining physiological movement patterns is essential. However, it is still unclear whether VR can elicit functional movements that are similar to those performed in the real world (RW). This study aimed to investigate the kinematics of reach-to-grasp and transport movements performed in the real world and immersive VR by examining whether kinematic differences between the two conditions exist and their extent. A within-subject repeated-measures study was conducted. A realistic setup resembling a supermarket shelf unit was built in RW and VR. The analysis compared reaching and transport gestures in VR and RW, also considering potential differences due to: (i) holding the controller needed to interact with virtual items, (ii) hand dominance, and (iii) target positions. Ten healthy young adults were enrolled in the study. Motion data analysis showed that reach-to-grasp and transport required more time in VR, and that holding the controller had no effects. No major differences occurred between the two hands. Joint angles, except for thorax rotation, and hand trajectory curvature were comparable across conditions, suggesting that VR has the potentialities to retrain physiological movement patterns. Results were satisfying, though they did not demonstrate the superiority of ecological environments in eliciting natural gestures. Further studies should determine the extent of kinematic similarity required to obtain functional gains in VR-based upper limb rehabilitation.