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Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking

Variability is ubiquitous in human movement, arising from internal and external noise, inherent biological redundancy, and from the neurophysiological control actions that help regulate movement fluctuations. Increased walking variability can lead to increased energetic cost and/or increased fall ri...

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Detalles Bibliográficos
Autores principales: Dingwell, Jonathan B., Cusumano, Joseph P.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409060/
https://www.ncbi.nlm.nih.gov/pubmed/25910253
http://dx.doi.org/10.1371/journal.pone.0124879
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author Dingwell, Jonathan B.
Cusumano, Joseph P.
author_facet Dingwell, Jonathan B.
Cusumano, Joseph P.
author_sort Dingwell, Jonathan B.
collection PubMed
description Variability is ubiquitous in human movement, arising from internal and external noise, inherent biological redundancy, and from the neurophysiological control actions that help regulate movement fluctuations. Increased walking variability can lead to increased energetic cost and/or increased fall risk. Conversely, biological noise may be beneficial, even necessary, to enhance motor performance. Indeed, encouraging more variability actually facilitates greater improvements in some forms of locomotor rehabilitation. Thus, it is critical to identify the fundamental principles humans use to regulate stride-to-stride fluctuations in walking. This study sought to determine how humans regulate stride-to-stride fluctuations in stepping movements during treadmill walking. We developed computational models based on pre-defined goal functions to compare if subjects, from each stride to the next, tried to maintain the same speed as the treadmill, or instead stay in the same position on the treadmill. Both strategies predicted average behaviors empirically indistinguishable from each other and from that of humans. These strategies, however, predicted very different stride-to-stride fluctuation dynamics. Comparisons to experimental data showed that human stepping movements were generally well-predicted by the speed-control model, but not by the position-control model. Human subjects also exhibited no indications they corrected deviations in absolute position only intermittently: i.e., closer to the boundaries of the treadmill. Thus, humans clearly do not adopt a control strategy whose primary goal is to maintain some constant absolute position on the treadmill. Instead, humans appear to regulate their stepping movements in a way most consistent with a strategy whose primary goal is to try to maintain the same speed as the treadmill at each consecutive stride. These findings have important implications both for understanding how biological systems regulate walking in general and for being able to harness these mechanisms to develop more effective rehabilitation interventions to improve locomotor performance.
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spelling pubmed-44090602015-05-12 Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking Dingwell, Jonathan B. Cusumano, Joseph P. PLoS One Research Article Variability is ubiquitous in human movement, arising from internal and external noise, inherent biological redundancy, and from the neurophysiological control actions that help regulate movement fluctuations. Increased walking variability can lead to increased energetic cost and/or increased fall risk. Conversely, biological noise may be beneficial, even necessary, to enhance motor performance. Indeed, encouraging more variability actually facilitates greater improvements in some forms of locomotor rehabilitation. Thus, it is critical to identify the fundamental principles humans use to regulate stride-to-stride fluctuations in walking. This study sought to determine how humans regulate stride-to-stride fluctuations in stepping movements during treadmill walking. We developed computational models based on pre-defined goal functions to compare if subjects, from each stride to the next, tried to maintain the same speed as the treadmill, or instead stay in the same position on the treadmill. Both strategies predicted average behaviors empirically indistinguishable from each other and from that of humans. These strategies, however, predicted very different stride-to-stride fluctuation dynamics. Comparisons to experimental data showed that human stepping movements were generally well-predicted by the speed-control model, but not by the position-control model. Human subjects also exhibited no indications they corrected deviations in absolute position only intermittently: i.e., closer to the boundaries of the treadmill. Thus, humans clearly do not adopt a control strategy whose primary goal is to maintain some constant absolute position on the treadmill. Instead, humans appear to regulate their stepping movements in a way most consistent with a strategy whose primary goal is to try to maintain the same speed as the treadmill at each consecutive stride. These findings have important implications both for understanding how biological systems regulate walking in general and for being able to harness these mechanisms to develop more effective rehabilitation interventions to improve locomotor performance. Public Library of Science 2015-04-24 /pmc/articles/PMC4409060/ /pubmed/25910253 http://dx.doi.org/10.1371/journal.pone.0124879 Text en © 2015 Dingwell, Cusumano http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Dingwell, Jonathan B.
Cusumano, Joseph P.
Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking
title Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking
title_full Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking
title_fullStr Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking
title_full_unstemmed Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking
title_short Identifying Stride-To-Stride Control Strategies in Human Treadmill Walking
title_sort identifying stride-to-stride control strategies in human treadmill walking
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409060/
https://www.ncbi.nlm.nih.gov/pubmed/25910253
http://dx.doi.org/10.1371/journal.pone.0124879
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