Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance

Upper-limb occupational exoskeletons reduce injuries during overhead work. Previous studies focused on muscle activation with and without exoskeletons, but their impact on shoulder fatigue remains unclear. Additionally, no studies have explored how exoskeleton support levels affect fatigue. This stu...

Full description

Saved in:
Bibliographic Details
Main Authors: Seemab Zakir, Lorenzo Grazi, Francesco Giovacchini, Nicola Vitiello, Emilio Trigili, Simona Crea
Format: Article
Language:English
Published: Cambridge University Press 2025-01-01
Series:Wearable Technologies
Subjects:
Online Access:https://www.cambridge.org/core/product/identifier/S263171762510008X/type/journal_article
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Upper-limb occupational exoskeletons reduce injuries during overhead work. Previous studies focused on muscle activation with and without exoskeletons, but their impact on shoulder fatigue remains unclear. Additionally, no studies have explored how exoskeleton support levels affect fatigue. This study investigates the effects of assistive profiles on muscular and cardiovascular fatigue. Electromyographic (EMG) and electrocardiographic signals were collected to compute EMG median frequency (MDF), heart rate (HR), and heart rate variability (HRV). Fatigue was assessed using three MDF and HR metrics: relative change ( $ {\mathrm{MDF}}_{\Delta } $ , $ {\mathrm{HR}}_{\Delta } $ ), slope ( $ {\mathrm{MDF}}_{\mathrm{slope}} $ , $ \mathrm{H}{\mathrm{R}}_{\mathrm{slope}} $ ), and intercept ( $ {\mathrm{MDF}}_{\mathrm{intercept}} $ , $ \mathrm{H}{\mathrm{R}}_{\mathrm{intercept}} $ ) of the linear regression. Results showed $ {\mathrm{MDF}}_{\Delta } $ decreased 64% (p = 0.0020) with higher assistance compared to no exoskeleton; $ {\mathrm{HR}}_{\Delta } $ decreased 40% (p < 0.0273) with lower assistance, $ {\mathrm{MDF}}_{\mathrm{slope}} $ decreased up to 67% (p = 0.0039) and $ \mathrm{H}{\mathrm{R}}_{\mathrm{slope}} $ by 43% (p < 0.0098) with higher and medium assistance. HRV metrics included root mean square of successive differences (RMSSD) and low-frequency to high-frequency power ratio (LF/HF). RMSSD indicated parasympathetic dominance, while rising LF/HF ratio suggested physiological strain. Findings support occupational exoskeletons as ergonomic tools for reducing fatigue.
ISSN:2631-7176