Age-related differences in the kinematics of aimed movements in immersive virtual reality: a preliminary study

Immersive virtual reality (VR) represents a viable technology to support rehabilitation and promote the recovery of upper limb functions after stroke. Nonetheless, it has not been determined yet if VR can elicit movements that share the same kinematic characteristics of those occurring in the real world (RW), thus positively impacting arm use in daily life. A previous study enrolling young adults showed promising results: joints' ranges of motion were preserved, although movement times were longer and peak velocity lower in VR. Starting from these results, this work aimed at comparing young and older adults' (i.e., an age-matched sample to stroke survivors) upper limb kinematics while performing aimed movements in RW and immersive VR. The presented study was a within-subject repeated-measures design in which participants had to reach, grasp and transport grocery items from a simplified supermarket shelf unit. The VR condition was performed using an HTC Vive head-mounted display; its controller was used to interact with virtual objects. Three conditions were tested: VR, RW, and RW while holding the controller (RWC, to account for carrying a weight). Ten healthy young adults (26.7 +/- 5.46) and three older adults (69.0 +/- 2.0) were enrolled. The collected data showed that older adults moved slower, more curved, and reached lower peak velocity during both reaching and transfer in VR compared to young adults. Arm ranges of motion seemed to be preserved, whereas thorax movements were different. We hypothesized that these differences might be dependent on age-related vision and cognitive decline, lack of familiarity with VR technology, and lack of force feedback. Further studies are needed to address these issues and confirm or reject our hypotheses.