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Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage

Due to the increasing load in backpacks and other load carriage systems over the last decades, load carriage system designs have to be adapted accordingly to minimize discomfort and to reduce the risk of injury. As subject studies are labor-intensive and include further challenges such as intra-subj...

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Autores principales: Wettenschwiler, Patrick D., Annaheim, Simon, Lorenzetti, Silvio, Ferguson, Stephen J., Stämpfli, Rolf, Psikuta, Agnes, Rossi, René M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491328/
https://www.ncbi.nlm.nih.gov/pubmed/28662084
http://dx.doi.org/10.1371/journal.pone.0180069
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author Wettenschwiler, Patrick D.
Annaheim, Simon
Lorenzetti, Silvio
Ferguson, Stephen J.
Stämpfli, Rolf
Psikuta, Agnes
Rossi, René M.
author_facet Wettenschwiler, Patrick D.
Annaheim, Simon
Lorenzetti, Silvio
Ferguson, Stephen J.
Stämpfli, Rolf
Psikuta, Agnes
Rossi, René M.
author_sort Wettenschwiler, Patrick D.
collection PubMed
description Due to the increasing load in backpacks and other load carriage systems over the last decades, load carriage system designs have to be adapted accordingly to minimize discomfort and to reduce the risk of injury. As subject studies are labor-intensive and include further challenges such as intra-subject and inter-subject variability, we aimed to validate an instrumented dummy as an objective laboratory tool to assess the mechanical aspects of discomfort. The validation of the instrumented dummy was conducted by comparison with a recent subject study. The mechanical parameters that characterize the static and dynamic interaction between backpack and body during different backpack settings were compared. The second aim was to investigate whether high predictive power (coefficient of determination R(2)>0.5) in assessing the discomfort of load carriage systems could be reached using the instrumented dummy. Measurements were conducted under static conditions, simulating upright standing, and dynamic conditions, simulating level walking. Twelve different configurations of a typical load carriage system, a commercially available backpack with a hip belt, were assessed. The mechanical parameters were measured in the shoulder and the hip region of the dummy and consisted of average pressure, peak pressure, strap force and relative motion between the system and the body. The twelve configurations consisted of three different weights (15kg, 20kg, and 25kg), combined with four different hip belt tensions (30N, 60N, 90N, and 120N). Through the significant (p<0.05) correlation of the mechanical parameters measured on the dummy with the corresponding values of the subject study, the dummy was validated for all static measurements and for dynamic measurements in the hip region to accurately simulate the interaction between the human body and the load carriage system. Multiple linear regressions with the mechanical parameters measured on the dummy as independent variables and the corresponding subjective discomfort scores from the subject study as the dependent variable revealed a high predictive power of the instrumented dummy. The dummy can explain 75% or more of the variance in discomfort using average pressures as predictors and even 79% or more of the variance in discomfort using strap forces as predictors. Use of the dummy enables objective, fast, and iterative assessments of load carriage systems and therefore reduces the need for labor-intensive subject studies in order to decrease the mechanical aspects of discomfort during load carriage.
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spelling pubmed-54913282017-07-18 Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage Wettenschwiler, Patrick D. Annaheim, Simon Lorenzetti, Silvio Ferguson, Stephen J. Stämpfli, Rolf Psikuta, Agnes Rossi, René M. PLoS One Research Article Due to the increasing load in backpacks and other load carriage systems over the last decades, load carriage system designs have to be adapted accordingly to minimize discomfort and to reduce the risk of injury. As subject studies are labor-intensive and include further challenges such as intra-subject and inter-subject variability, we aimed to validate an instrumented dummy as an objective laboratory tool to assess the mechanical aspects of discomfort. The validation of the instrumented dummy was conducted by comparison with a recent subject study. The mechanical parameters that characterize the static and dynamic interaction between backpack and body during different backpack settings were compared. The second aim was to investigate whether high predictive power (coefficient of determination R(2)>0.5) in assessing the discomfort of load carriage systems could be reached using the instrumented dummy. Measurements were conducted under static conditions, simulating upright standing, and dynamic conditions, simulating level walking. Twelve different configurations of a typical load carriage system, a commercially available backpack with a hip belt, were assessed. The mechanical parameters were measured in the shoulder and the hip region of the dummy and consisted of average pressure, peak pressure, strap force and relative motion between the system and the body. The twelve configurations consisted of three different weights (15kg, 20kg, and 25kg), combined with four different hip belt tensions (30N, 60N, 90N, and 120N). Through the significant (p<0.05) correlation of the mechanical parameters measured on the dummy with the corresponding values of the subject study, the dummy was validated for all static measurements and for dynamic measurements in the hip region to accurately simulate the interaction between the human body and the load carriage system. Multiple linear regressions with the mechanical parameters measured on the dummy as independent variables and the corresponding subjective discomfort scores from the subject study as the dependent variable revealed a high predictive power of the instrumented dummy. The dummy can explain 75% or more of the variance in discomfort using average pressures as predictors and even 79% or more of the variance in discomfort using strap forces as predictors. Use of the dummy enables objective, fast, and iterative assessments of load carriage systems and therefore reduces the need for labor-intensive subject studies in order to decrease the mechanical aspects of discomfort during load carriage. Public Library of Science 2017-06-29 /pmc/articles/PMC5491328/ /pubmed/28662084 http://dx.doi.org/10.1371/journal.pone.0180069 Text en © 2017 Wettenschwiler et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Wettenschwiler, Patrick D.
Annaheim, Simon
Lorenzetti, Silvio
Ferguson, Stephen J.
Stämpfli, Rolf
Psikuta, Agnes
Rossi, René M.
Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
title Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
title_full Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
title_fullStr Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
title_full_unstemmed Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
title_short Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
title_sort validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491328/
https://www.ncbi.nlm.nih.gov/pubmed/28662084
http://dx.doi.org/10.1371/journal.pone.0180069
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