Exoskeleton for upper limbs in meat processing industry: Influence on muscle activity and physical effort

Abstract

Background

Brazil is one of the leading global pork exporters, operating approximately 1100 slaughterhouses where manual labor often exposes workers to repetitive strain and poor postural conditions.

Objective

This study aimed to evaluate the effectiveness and usability of an exoskeleton in reducing upper-limb physical effort during dynamic, repetitive tasks common in meat processing lines.

Method

Seventeen workers performed 17 production tasks involving repeated arm elevations above 45°, both with and without the use of an exoskeleton. Muscle activity in the medial and anterior deltoids was measured using surface electromyography (sEMG). Subjective workload was assessed using the BORG scale and a usability questionnaire.

Results

Among the four muscles analyzed based on normalized mean values relative to maximum voluntary contraction (MVC), a statistically significant reduction in activity was observed in the right medial deltoid when using the exoskeleton (p = 0.0440). For normalized peak values, no muscle showed statistically significant reductions (left anterior deltoid, p = 0.3192; left medial deltoid, p = 0.0552; right anterior deltoid, p = 0.3708; right medial deltoid, p = 0.0552). However, Cohen's d indicated medium-to-large effect sizes for the right and left medial deltoids and the left anterior deltoid, suggesting reduced biomechanical demand during exoskeleton-assisted tasks.

Conclusion

The exoskeleton demonstrated potential to reduce the load on specific muscles, indicating possible ergonomic and industrial benefits. However, limitations include the need for anthropometric adjustments and additional operating space. These findings support the device's relevance and highlight the need for further research on optimization and industrial adaptation.