EMG-derived cycle-time assessment of passive back-support exoskeletons in construction workers during repetitive masonry manual handling tasks

Work-related musculoskeletal disorders remain highly prevalent among construction workers due to repetitive manual handling and physically demanding tasks. While passive back-support exoskeletons have demonstrated biomechanical benefits, their impact on worker productivity remains insufficiently understood. This study assessed the immediate productivity impact of two passive back-support exoskeletons, BISKO (soft) and HAPO Back (rigid) on 23 professional masons performing a simulated masonry manual handling task involving 17.2 kg concrete masonry units. An EMG-based cycle time extraction methodology using bilateral lumbar erector spinae recordings was employed to objectively measure individual work cycle durations. Results from a repeated measures ANOVA revealed that both exoskeletons associated with mean cycle times relative to baseline, with BISKO showing a 7.77% increase and HAPO Back a 6.28% increase. No significant difference was found between exoskeleton designs. Notable individual variability was observed, with 22% of participants demonstrating productivity improvements. Correlation analyses indicated that older and more experienced workers tended to benefit more from exoskeleton use. These findings suggest that while passive exoskeletons are associated with an initial productivity cost, worker characteristics may warrant further investigation as a basis for targeted deployment, and expectations should prioritize long-term ergonomic benefits over immediate productivity gains.