# Biomechanical effects of soft and rigid passive back occupational exoskeletons during load-carrying and static trunk bending tasks in the aeronautics industry

## TL;DR

This study examines how different types of back exoskeletons affect muscle activity, movement, and discomfort during tasks in the aeronautics industry.

## Contribution

The study compares the biomechanical effects of four specific passive back exoskeletons in a simulated aeronautics task setting.

## Key findings

- Laevo FLEX and CORFOR reduced lumbar erector spinae muscle activity during static tasks by 8–18%.
- Laevo FLEX significantly reduced biceps femoris activity across all tasks by 8–17%.
- Rigid exoskeletons decreased perceived back discomfort, while BionicBack altered trunk kinematics.

## Abstract

The manufacturing industry, notably the aeronautics sector, involves tasks presenting risks of low back pain. One of the preventive strategies could be the use of passive back exoskeletons, which have demonstrated benefits during activities involving trunk bending. This study aims to evaluate the effects of four passive back exoskeletons on trunk neuromuscular activity, kinematics, and perceived discomfort during polishing tasks simulated in a laboratory setting. Nineteen participants performed four tasks (two static bending tasks and two load-carrying tasks) without and with two soft (CORFOR and BionicBack) and two rigid (BackX and Laevo FLEX) exoskeletons. The results showed varying effects depending on the tested exoskeleton model, beyond the distinction between rigid and soft designs. Reductions in lumbar erector spinae (LES) neuromuscular activity were observed with Laevo FLEX and CORFOR during static tasks compared to the condition without exoskeleton (8–18%; p < .05). However, reductions in LES muscle activity were not significant during load carrying. Biceps femoris neuromuscular activity was significantly lower in the four tasks when using the Laevo FLEX, with reductions ranging from 8 to 17% (p < .01). The two rigid exoskeletons decreased perceived back discomfort across all tasks (p < .05). Finally, the BionicBack exoskeleton significantly altered participants’ kinematics across all four tasks, reducing both trunk range of motion and average flexion (p < .05). The Laevo FLEX exoskeleton was the only one to significantly reduce both neuromuscular activity and perceived back discomfort, while causing no adverse effects, appearing advantageous when polishing in the aeronautical industry.