Neuromechanical Effects of a Soft Shoulder Exoskeleton in Overhead Industrial Tasks: Evidence from Multimodal Physiological Evaluation

Overhead industrial work frequently causes shoulder work-related musculoskeletal disorders. These tasks require not only localized muscle activation but also integrated central nervous system regulation for motor control. Although soft e x oskeletons have demonstrated effectiveness in reducing peripheral musculoskeletal load, their impact on central nervous system regulation remains poorly understood. This study aimed to investigate the biomechanical benefits and corticomuscular coupling of a soft e x oskeleton during industrial tasks. Fifteen healthy males performed standardized screwing and lifting tasks under exoskeleton-assisted and unassisted conditions. Multimodal physiological signals were acquired through: surface electromyography for muscle activation, functional near-infrared spectroscopy for corte x hemodynamics and ratings of perceived e x ertion for subjective perception. Corticomuscular coupling was analyzed based on hemodynamic and electromyographic metrics. The anterior deltoid activity decreased by 25.0% during lifting, while biceps brachii effort in screwing tasks was reduced by 46.1% and ratings of perceived exertion were mitigated during the early phase of screwing operations. Concurrently, wearing the exoskeleton during lifting significantly lowered cortical activation compared with the screwing tasks. The exoskeleton task-specifically enhanced corticomuscular coupling within sensorimotor pathways during precision screwing task, while reducing dorsolateral prefrontal pathways during lifting. Therefore, this study demonstrates that the soft shoulder exoskeleton has the potential to simultaneously provide biomechanical support and corticomuscular coupling adaptation, thereby enhancing motor control and mitigating work-related musculoskeletal disorders.