Simulated Intelligent-System Interruptions: Effects on Back-Support Exoskeleton Performance and Muscle Activation

This study examined how interruptions, which are increasingly prevalent in modern intelligent work systems, influence the effectiveness of a back-support exoskeleton (BSE) during repetitive low-load lifting. Thirteen healthy male participants (age: 22.7 ± 1.7 years) performed a repetitive lifting task with and without a back-support exoskeleton (BSE) while concurrently engaging in a digit subtraction task that simulated cognitive interruptions characteristic of intelligent systems, presented at three frequencies (none, intermittent, and frequent). Task performance (number of lifting repetitions and placement accuracy), muscle activation of the erector spinae and upper trapezius, and subjective workload were assessed. Results showed that BSE use reduced the number of lifting repetitions by approximately 8% but did not affect placement accuracy. Consistent with its intended function, the BSE decreased erector spinae activation and subjective workload; however, it was also associated with progressively greater trapezius activation. Notably, BSE did not provide additional benefits under these cognitively demanding conditions, highlighting its limited effectiveness when attentional resources are constrained. These findings highlight that the value of BSEs depends not only on biomechanical support but also on work environments that effectively manage the dual-task demands introduced by intelligent systems.