Evaluation of the subjective and objective benefits of occupational soft and rigid back support exoskeletons in simulated automotive assembly tasks

Despite extensive research demonstrating the benefits of back-support exoskeletons (BSEs), most objective evidence on the effectiveness of BSEs is based on short-term outcomes from static/non-functional tasks, which may not fully represent the complexities and dynamics inherent in real-world scenarios. To address this gap, the current study examined the effects of BSEs on both objective and subjective physical demands in simulated automotive assembly performed on a semi-assembled 2018 BMW X5 vehicle, under three conditions: control (no-exoskeleton), and using two different passive BSEs (soft vs. rigid), in a convenience sample of 18 healthy adults. Across the job that included a wide variety of tasks, using the soft BSE significantly reduced peak trunk flexion, and both BSEs restricted axial rotation, which was compensated by increased trunk lateral bending (with the rigid BSE having a more pronounced effect). Using both BSEs also led to decreased median trunk extensor muscle activity. However, at the task-specific level, the soft device showed higher efficacy. The main effects of both BSEs on perceived exertion were significant, with a small increase in the exoskeleton condition compared to control, and it was also associated with a significant decrease in perceived 'comfort' and 'performance' over time. These findings highlight that objective biomechanical effects and subjective responses may reflect different, complementary aspects of BSE use during complex industrial task simulations and over longer exposure durations.