Hand Dynamics in Healthy Individuals and Spinal Cord Injury Patients During Real and Virtual Box and Block Test

Virtual reality (VR) is a promising tool in spinal cord injury (SCI) rehabilitation, particularly through virtual adaptations of functional tests like the Box and Block test (BBT). However, a comprehensive dynamic comparison between real and virtual BBT is lacking. This study investigates the kinematic and electromyographic (EMG) differences between healthy individuals and SCI patients performing both real (RBBT) and virtual (VBBT) versions of the BBT. An electromagnetic motion-tracking system, an instrumented glove, and surface EMG electrodes were used to capture hand trajectories, joint angles, and forearm muscle activation. The analysis included cycle-averaged and temporal kinematic and EMG parameters. Our findings reveal that both groups showed increased trajectory length and velocity peaks during the VBBT, with more pronounced increases in SCI patients. Unlike healthy individuals, SCI patients also showed increased finger and thumb flexion during VBBT. Cycle-averaged EMG values were lower in healthy participants during VBBT, likely due to reduced motor demands and lack of real grasping. Conversely, SCI patients exhibited higher muscle activity, suggesting impaired coordination and compensatory overactivation. Healthy individuals showed consistent temporal kinematic synergies and muscle activation, whereas they were altered in SCI patients, especially during reaching. These findings highlight the need for rehabilitation strategies to improve motor control and feedback integration.