{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T11:00:58Z","timestamp":1781175658950,"version":"3.54.1"},"reference-count":41,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T00:00:00Z","timestamp":1781136000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Bioeng. Biotechnol."],"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>The taekwondo roundhouse kick is a fundamental and performance-critical technique that requires precise lower-limb muscle coordination. However, previous studies have mainly focused on discrete electromyographic variables, providing limited insight into waveform-level variations across the kicking cycle, particularly between athletes of different age and training levels. Therefore, this study aimed to investigate lower-limb surface electromyographic (sEMG) waveform differences during the roundhouse kick between elite and youth taekwondo athletes using functional principal component analysis (FPCA).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Thirty-eight male taekwondo athletes were included (19 elite, 19 youth). Surface electromyography was recorded bilaterally from seven trunk and lower-limb muscles, including the rectus abdominis, gluteus maximus, rectus femoris, biceps femoris, semitendinosus, lateral gastrocnemius, and tibialis anterior, and three-dimensional kinematic data were collected synchronously during standardized roundhouse kicks. Time-normalized sEMG waveforms were analyzed using FPCA to identify dominant and secondary modes of variation. Group differences in principal component scores were tested using independent-samples comparisons, with Benjamini\u2013Hochberg false discovery rate correction applied across muscle \u00d7 component tests.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>After FDR correction, significant between-group differences were identified in four muscle\u2013component combinations. In the support leg, significant differences were observed in PC1 of the left tibialis anterior (p_FDR = 0.001, Cohen\u2019s d = 1.726) and left rectus femoris (p_FDR = 0.029, Cohen\u2019s d = 1.058), whereas the left lateral gastrocnemius differed in PC2 (p_FDR = 0.040, Cohen\u2019s d = 0.943). In the swing leg, the right biceps femoris differed in PC1 (p_FDR = 0.015, Cohen\u2019s d = 1.206).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Elite and youth taekwondo athletes showed distinct muscle-specific and phase-dependent neuromuscular organization during the roundhouse kick, particularly in support-leg control and swing-leg posterior-chain regulation. FPCA revealed whole-waveform differences that were not captured by conventional discrete measures, providing useful evidence for technique analysis, youth athlete development, and more targeted taekwondo training.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fbioe.2026.1844590","type":"journal-article","created":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T10:44:01Z","timestamp":1781174641000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Lower-limb muscle activation patterns during the taekwondo roundhouse kick in elite and youth athletes: a functional principal component analysis"],"prefix":"10.3389","volume":"14","author":[{"given":"Jianbo","family":"Sun","sequence":"first","affiliation":[{"name":"School of Health Sciences, Universiti Sains Malaysia","place":["Kota Bharu, Malaysia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingyuan","family":"Sun","sequence":"additional","affiliation":[{"name":"School of Health Sciences, Universiti Sains Malaysia","place":["Kota Bharu, Malaysia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gang","family":"Sun","sequence":"additional","affiliation":[{"name":"International Education College, Harbin University of Commerce","place":["Harbin, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liang","family":"Yin","sequence":"additional","affiliation":[{"name":"International Education College, Harbin University of Commerce","place":["Harbin, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shazlin","family":"Shaharudin","sequence":"additional","affiliation":[{"name":"School of Health Sciences, Universiti Sains Malaysia","place":["Kota Bharu, Malaysia"]},{"name":"Science of Learning in Education Centre, National Institute of Education, Nanyang Technological University","place":["Singapore, Singapore"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,11]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"3314","DOI":"10.1016\/j.jbiomech.2007.05.006","article-title":"Muscular coordination of knee motion during the terminal swing phase of normal gait","volume":"40","author":"Arnold","year":"2007","journal-title":"J. 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