{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T05:20:22Z","timestamp":1773724822951,"version":"3.50.1"},"update-to":[{"DOI":"10.1371\/journal.pcbi.1010466","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2022,9,21]],"date-time":"2022-09-21T00:00:00Z","timestamp":1663718400000}}],"reference-count":86,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2022,9,9]],"date-time":"2022-09-09T00:00:00Z","timestamp":1662681600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100006937","name":"National Center for Medical Rehabilitation Research","doi-asserted-by":"publisher","award":["NIH NCMRR R01HD091184"],"award-info":[{"award-number":["NIH NCMRR R01HD091184"]}],"id":[{"id":"10.13039\/100006937","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.ploscompbiol.org"],"crossmark-restriction":false},"short-container-title":["PLoS Comput Biol"],"abstract":"<jats:p>Hemiparesis, defined as unilateral muscle weakness, often occurs in people post-stroke or people with cerebral palsy, however it is difficult to understand how this hemiparesis affects movement patterns as it often presents alongside a variety of other neuromuscular impairments. Predictive musculoskeletal modeling presents an opportunity to investigate how impairments affect gait performance assuming a particular cost function. Here, we use predictive simulation to quantify the spatiotemporal asymmetries and changes to metabolic cost that emerge when muscle strength is unilaterally reduced and how reducing spatiotemporal symmetry affects metabolic cost. We modified a 2-D musculoskeletal model by uniformly reducing the peak isometric muscle force unilaterally. We then solved optimal control simulations of walking across a range of speeds by minimizing the sum of the cubed muscle excitations. Lastly, we ran additional optimizations to test if reducing spatiotemporal asymmetry would result in an increase in metabolic cost. Our results showed that the magnitude and direction of effort-optimal spatiotemporal asymmetries depends on both the gait speed and level of weakness. Also, the optimal speed was 1.25 m\/s for the symmetrical and 20% weakness models but slower (1.00 m\/s) for the 40% and 60% weakness models, suggesting that hemiparesis can account for a portion of the slower gait speed seen in people with hemiparesis. Modifying the cost function to minimize spatiotemporal asymmetry resulted in small increases (~4%) in metabolic cost. Overall, our results indicate that spatiotemporal asymmetry may be optimal for people with hemiparesis. Additionally, the effect of speed and the level of weakness on spatiotemporal asymmetry may help explain the well-known heterogenous distribution of spatiotemporal asymmetries observed in the clinic. Future work could extend our results by testing the effects of other neuromuscular impairments on optimal gait strategies, and therefore build a more comprehensive understanding of the gait patterns observed in clinical populations.<\/jats:p>","DOI":"10.1371\/journal.pcbi.1010466","type":"journal-article","created":{"date-parts":[[2022,9,9]],"date-time":"2022-09-09T17:07:19Z","timestamp":1662743239000},"page":"e1010466","update-policy":"https:\/\/doi.org\/10.1371\/journal.pcbi.corrections_policy","source":"Crossref","is-referenced-by-count":27,"title":["Patterns of asymmetry and energy cost generated from predictive simulations of hemiparetic gait"],"prefix":"10.1371","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3026-6307","authenticated-orcid":true,"given":"Russell T.","family":"Johnson","sequence":"first","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2229-4065","authenticated-orcid":true,"given":"Nicholas A.","family":"Bianco","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2679-2221","authenticated-orcid":true,"given":"James M.","family":"Finley","sequence":"additional","affiliation":[]}],"member":"340","published-online":{"date-parts":[[2022,9,9]]},"reference":[{"key":"pcbi.1010466.ref001","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1186\/1743-0003-3-17","article-title":"Quantification of functional weakness and abnormal synergy patterns in the lower limb of individuals with chronic stroke","volume":"3","author":"N Neckel","year":"2006","journal-title":"J Neuroeng Rehabil"},{"key":"pcbi.1010466.ref002","doi-asserted-by":"crossref","first-page":"564","DOI":"10.3389\/fneur.2018.00564","article-title":"Neural Constraints Affect the Ability to Generate Hip Abduction Torques When Combined With Hip Extension or Ankle Plantarflexion in Chronic Hemiparetic Stroke.","volume":"9","author":"N S\u00e1nchez","year":"2018","journal-title":"Frontiers in Neurology"},{"issue":"1","key":"pcbi.1010466.ref003","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1590\/S0004-282X2001000100007","article-title":"Hemiparetic cerebral palsy: etiological risk factors and neuroimaging.","volume":"59","author":"AM Piovesana","year":"2001","journal-title":"Arq NeuropsiquiatrMar"},{"issue":"3","key":"pcbi.1010466.ref004","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1001\/archneurol.2011.1930","article-title":"Classification of Cause of Motor Weakness in Traumatic Brain Injury Using Diffusion Tensor Imaging","volume":"69","author":"GS Choi","year":"2012","journal-title":"Archives of Neurology"},{"issue":"7","key":"pcbi.1010466.ref005","doi-asserted-by":"crossref","first-page":"633","DOI":"10.1080\/02699050010009568","article-title":"Combined motor disturbances following severe traumatic brain injury: an integrative long-term treatment approach","volume":"15","author":"O Keren","year":"2001","journal-title":"Brain Inj"},{"issue":"5","key":"pcbi.1010466.ref006","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1002\/mus.20285","article-title":"Pathophysiology of spastic paresis. 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