{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:59:35Z","timestamp":1760241575893,"version":"build-2065373602"},"reference-count":46,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2018,5,17]],"date-time":"2018-05-17T00:00:00Z","timestamp":1526515200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Guangdong Science and Technology Plan Project (Application Technology Research Foundation)","award":["2015B020233006","2017B020210011"],"award-info":[{"award-number":["2015B020233006","2017B020210011"]}]},{"name":"Science and Technology Program of Guangzhou","award":["201604020108"],"award-info":[{"award-number":["201604020108"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Introduction: The variability and complexity of handgrip forces in various modulations were investigated to identify post-stroke changes in force modulation, and extend our understanding of stroke-induced deficits. Methods: Eleven post-stroke subjects and ten age-matched controls performed voluntary grip force control tasks (power-grip tasks) at three contraction levels, and stationary dynamometer holding tasks (stationary holding tasks). Variability and complexity were described with root mean square jerk (RMS-jerk) and fuzzy approximate entropy (fApEn), respectively. Force magnitude, Fugl-Meyer upper extremity assessment and Wolf motor function test were also evaluated. Results: Comparing the affected side with the controls, fApEn was significantly decreased and RMS-jerk increased across the three levels in power-grip tasks, and fApEn was significantly decreased in stationary holding tasks. There were significant strong correlations between RMS-jerk and clinical scales in power-grip tasks. Discussion: Abnormal neuromuscular control, altered mechanical properties, and atrophic motoneurons could be the main causes of the differences in complexity and variability in post-stroke subjects.<\/jats:p>","DOI":"10.3390\/e20050377","type":"journal-article","created":{"date-parts":[[2018,5,17]],"date-time":"2018-05-17T11:47:45Z","timestamp":1526557665000},"page":"377","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Characterization of the Stroke-Induced Changes in the Variability and Complexity of Handgrip Force"],"prefix":"10.3390","volume":"20","author":[{"given":"Pengzhi","family":"Zhu","sequence":"first","affiliation":[{"name":"School of Engineering, Sun Yat-sen University, Guangzhou 510275, China"},{"name":"Guangdong Medical Devices Quality Surveillance and Test Institute, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuanyu","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Engineering, Sun Yat-sen University, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jingtao","family":"Liang","sequence":"additional","affiliation":[{"name":"School of Engineering, Sun Yat-sen University, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yu","family":"Ye","sequence":"additional","affiliation":[{"name":"School of Engineering, Sun Yat-sen University, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huihua","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tiebin","family":"Yan","sequence":"additional","affiliation":[{"name":"Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3662-116X","authenticated-orcid":false,"given":"Rong","family":"Song","sequence":"additional","affiliation":[{"name":"School of Engineering, Sun Yat-sen University, Guangzhou 510275, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,5,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"643","DOI":"10.1016\/j.humov.2004.10.005","article-title":"Deficits of anticipatory grip force control after damage to peripheral and central sensorimotor systems","volume":"23","author":"Hagl","year":"2004","journal-title":"Hum. 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