Effects on muscular activity and usability of soft active versus rigid passive back exoskeleton during symmetric lifting tasks

Abstract

Low back injuries are globally prevalent among construction workers, leading to significant economic burdens. Despite various intervention strategies, their effectiveness remains uncertain. This study evaluates a lightweight active soft back exosuit (SV Exosuit) against a passive rigid exosuit (IX BACK) to assess muscle activity and usability. Fifteen healthy participants performed bending and lifting tasks under three conditions: no exosuit, with SV Exosuit, and with IX BACK. Electromyographic (EMG) signals from back extensors were collected, and subjective feedback was obtained using the NASA task load index (NASA-TLX). Results showed that the active exosuit significantly reduced mean and peak EMG levels, while the passive exoskeleton exhibited modest reductions, particularly during unloaded tasks. EMG pattern analysis indicated peak activity occurring within 30-40% of the motion cycle, with IX BACK causing delays in bending without load due to resistance. Overall, both devices alleviated muscle strain, with SV Exosuit providing superior support during loaded tasks. The findings suggest that SV Exosuit's lightweight and effective design make it a preferable option for construction tasks, highlighting the need for further research on its application in real-world settings.

Keywords: Back exoskeleton; Construction health; Exoskeleton comparison; Low back pain; Passive exoskeleton; Soft active exosuit.

Fig. 1

Overview of the (a) Safety vest exosuit (SV Exosuit), and (b) IX BACK.

Fig. 2

Position for surface EMG (sEMG) pairs to attach to the back extensors.

Fig. 3

Mean EMG (a) and peak EMG (b) comparisons across the three exosuit conditions.

Fig. 4

EMG curves in the bend down and lift up sessions under the three exosuit conditions.

Fig. 5

Subjective ratings on NASA-TLX items across the three back exosuit conditions. MD: mental demand; PD: physical demand; TD: temporal demand; P: performance, higher score for less successful; E: effort; F: and frustration.