{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T04:02:39Z","timestamp":1780372959672,"version":"3.54.1"},"reference-count":40,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,8,12]],"date-time":"2021-08-12T00:00:00Z","timestamp":1628726400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100017596","name":"Natural Science Basic Research Program of Shaanxi Province","doi-asserted-by":"publisher","award":["2021JM-441"],"award-info":[{"award-number":["2021JM-441"]}],"id":[{"id":"10.13039\/501100017596","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>This study aimed to investigate the degree of regularity of surface electromyography (sEMG) signals during muscle fatigue during dynamic contractions and muscle recovery after cupping therapy. To the best of our knowledge, this is the first study assessing both muscle fatigue and muscle recovery using a nonlinear method. Twelve healthy participants were recruited to perform biceps curls at 75% of the 10 repetitions maximum under four conditions: immediately and 24 h after cupping therapy (\u2212300 mmHg pressure), as well as after sham control (no negative pressure). Cupping therapy or sham control was assigned to each participant according to a pre-determined counter-balanced order and applied to the participant\u2019s biceps brachii for 5 min. The degree of regularity of the sEMG signal during the first, second, and last 10 repetitions (Reps) of biceps curls was quantified using a modified sample entropy (Ems) algorithm. When exercise was performed immediately or 24 h after sham control, Ems of the sEMG signal showed a significant decrease from the first to second 10 Reps; when exercise was performed immediately after cupping therapy, Ems also showed a significant decrease from the first to second 10 Reps but its relative change was significantly smaller compared to the condition of exercise immediately after sham control. When exercise was performed 24 h after cupping therapy, Ems did not show a significant decrease, while its relative change was significantly smaller compared to the condition of exercise 24 h after sham control. These results indicated that the degree of regularity of sEMG signals quantified by Ems is capable of assessing muscle fatigue and the effect of cupping therapy. Moreover, this measure seems to be more sensitive to muscle fatigue and could yield more consistent results compared to the traditional linear measures.<\/jats:p>","DOI":"10.3390\/e23081036","type":"journal-article","created":{"date-parts":[[2021,8,12]],"date-time":"2021-08-12T02:40:14Z","timestamp":1628736014000},"page":"1036","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Effects of Muscle Fatigue and Recovery on Complexity of Surface Electromyography of Biceps Brachii"],"prefix":"10.3390","volume":"23","author":[{"given":"Fuyuan","family":"Liao","sequence":"first","affiliation":[{"name":"Department of Biomedical Engineering, Xi\u2019an Technological University, Xi\u2019an 710021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xueyan","family":"Zhang","sequence":"additional","affiliation":[{"name":"Rehabilitation Engineering Lab, Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3762-7651","authenticated-orcid":false,"given":"Chunmei","family":"Cao","sequence":"additional","affiliation":[{"name":"Division of Sports Science and Physical Education, Tsinghua University, Beijing 100084, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Isabella Yu-Ju","family":"Hung","sequence":"additional","affiliation":[{"name":"Department of Nursing, Chung Hwa University of Medical Technology, Tainan 717302, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanni","family":"Chen","sequence":"additional","affiliation":[{"name":"Xi\u2019an Children\u2019s Hospital and The Affiliated Children\u2019s Hospital of Xi\u2019an Jiaotong University, Xi\u2019an 710021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7149-4034","authenticated-orcid":false,"given":"Yih-Kuen","family":"Jan","sequence":"additional","affiliation":[{"name":"Rehabilitation Engineering Lab, Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/S0165-0270(97)02251-6","article-title":"Measurement of human muscle fatigue","volume":"74","author":"Vollestad","year":"1997","journal-title":"J. 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