Repetitive exoskeleton use induces persistent coordination changes in wearers

Abstract Exoskeletons are redefining occupational ergonomics, offering a promising solution to mitigate musculoskeletal strain in repetitive tasks. However, their long-term effects on motor control remain poorly understood. This study investigates whether repeated short-duration exposure to an upper-limb exoskeleton induces persistent changes in motor performance. Over five consecutive days, 24 participants performed reaching tasks under one of three conditions: (1) low-magnitude gravitational support from a robotic exoskeleton, (2) exposure to a viscous force field in the same exoskeleton, or (3) no exoskeleton exposure. Spontaneous movements performed before daily exposure were analyzed in order to characterize the evolution in upper limb kinematics. While no significant changes in task duration or overall joint range of motion were observed, substantial alterations in patterns of shoulder-elbow coordination were seen to emerge. Participants exposed to gravitational support, outside of the exoskeleton, progressively decreased shoulder involvement while increasing elbow contribution, with temporal synchronization evolving over time. In contrast, those exposed to the viscous field exhibited initial disruptions in shoulder-elbow synchrony, which gradually subsided throughout the five-day protocol. These findings challenge the assumption that exoskeleton effects vanish upon removal, demonstrating instead that repeated exposure to small-magnitude force fields can induce lasting changes in motor coordination. Given the growing adoption of exoskeletons in industrial and healthcare settings, understanding these prolonged motor modifications is critical. If unaccounted for, such changes could inadvertently elevate musculoskeletal risks rather than mitigate them.