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...

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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
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Online Access:https://www.cambridge.org/core/product/identifier/S263171762510008X/type/journal_article
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author Seemab Zakir
Lorenzo Grazi
Francesco Giovacchini
Nicola Vitiello
Emilio Trigili
Simona Crea
author_facet Seemab Zakir
Lorenzo Grazi
Francesco Giovacchini
Nicola Vitiello
Emilio Trigili
Simona Crea
author_sort Seemab Zakir
collection DOAJ
description 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.
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issn 2631-7176
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publishDate 2025-01-01
publisher Cambridge University Press
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series Wearable Technologies
spelling doaj-art-67103a13541d477b98bcb2031dc8d3872025-08-20T03:46:37ZengCambridge University PressWearable Technologies2631-71762025-01-01610.1017/wtc.2025.10008Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistanceSeemab Zakir0https://orcid.org/0009-0004-3715-9792Lorenzo Grazi1https://orcid.org/0000-0003-4899-9346Francesco Giovacchini2Nicola Vitiello3Emilio Trigili4Simona Crea5https://orcid.org/0000-0001-9833-4401The BioRobotics Institute, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, Italy Department of Excellence in Robotics & AI, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, ItalyThe BioRobotics Institute, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, Italy Department of Excellence in Robotics & AI, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, ItalyIUVO S.r.l., Pontedera, ItalyThe BioRobotics Institute, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, Italy Department of Excellence in Robotics & AI, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, ItalyThe BioRobotics Institute, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, Italy Department of Excellence in Robotics & AI, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, ItalyThe BioRobotics Institute, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, Italy Department of Excellence in Robotics & AI, https://ror.org/025602r80 Scuola Superiore Sant’Anna , Pisa, ItalyUpper-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.https://www.cambridge.org/core/product/identifier/S263171762510008X/type/journal_articleexoskeletonsbiomechanicshuman-robot interaction
spellingShingle Seemab Zakir
Lorenzo Grazi
Francesco Giovacchini
Nicola Vitiello
Emilio Trigili
Simona Crea
Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
Wearable Technologies
exoskeletons
biomechanics
human-robot interaction
title Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
title_full Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
title_fullStr Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
title_full_unstemmed Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
title_short Evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
title_sort evaluation of fatigue progression during overhead tasks and the effects of exoskeleton assistance
topic exoskeletons
biomechanics
human-robot interaction
url https://www.cambridge.org/core/product/identifier/S263171762510008X/type/journal_article
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AT francescogiovacchini evaluationoffatigueprogressionduringoverheadtasksandtheeffectsofexoskeletonassistance
AT nicolavitiello evaluationoffatigueprogressionduringoverheadtasksandtheeffectsofexoskeletonassistance
AT emiliotrigili evaluationoffatigueprogressionduringoverheadtasksandtheeffectsofexoskeletonassistance
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