{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T23:36:43Z","timestamp":1781739403016,"version":"3.54.5"},"reference-count":29,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,9,23]],"date-time":"2025-09-23T00:00:00Z","timestamp":1758585600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JFMK"],"abstract":"<jats:p>Background: Hamstring tightness is highly prevalent in young adults and may negatively affect neuromuscular performance. Despite growing interest in the biomechanical and neuromuscular consequences of reduced flexibility, few studies have examined its effect on muscle activation in healthy individuals. This study aimed to compare thigh muscle activation during functional tasks in healthy young males with and without hamstring tightness. Methods: Thirty healthy male participants (18\u201326 years) were assigned to two groups based on the Active Knee Extension test: normal flexibility (&lt;20\u00b0) and hamstring tightness (\u226520\u00b0). Surface electromyography (sEMG) was used to assess the activation (%MVIC) of the biceps femoris and semitendinosus muscles during four functional exercises: unilateral standing knee flexion, unilateral bridge, elastic-band knee flexion, and Nordic curl. Independent t-tests were used to compare muscle activation between groups. Results: Participants with hamstring tightness showed significantly lower activation of the semitendinosus during the unilateral bridge (p = 0.036) and Nordic curl (p = 0.024). Additionally, biceps femoris activation during the Nordic curl was reduced in the tightness group compared to the normal group (p = 0.044). No significant differences were observed in other exercises. Conclusions: Hamstring tightness is associated with reduced activation of key posterior thigh muscles during exercises that require high eccentric or isometric demands. These neuromuscular alterations may impair performance and increase the risk of injury in functional tasks. Clinically, assessing and addressing hamstring flexibility may support muscle recruitment efficiency and injury prevention strategies in young physically active populations.<\/jats:p>","DOI":"10.3390\/jfmk10040363","type":"journal-article","created":{"date-parts":[[2025,9,23]],"date-time":"2025-09-23T08:09:42Z","timestamp":1758614982000},"page":"363","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Impact of Hamstring Tightness on Muscle Activation in Healthy Young Adults"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7001-9004","authenticated-orcid":false,"given":"Eduardo","family":"Guzm\u00e1n-Mu\u00f1oz","sequence":"first","affiliation":[{"name":"Escuela de Kinesiologi\u0301a, Facultad de Salud, Universidad Santo Toma\u0301s, Talca 3460000, Chile"},{"name":"Pedagogi\u0301a en Educacio\u0301n Fi\u0301sica, Facultad de Educacio\u0301n, Universidad Auto\u0301noma de Chile, Talca 3460000, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Camila","family":"Zurita-Leiva","sequence":"additional","affiliation":[{"name":"Escuela de Kinesiologi\u0301a, Facultad de Salud, Universidad Santo Toma\u0301s, Talca 3460000, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Felipe","family":"G\u00f3mez-Araya","sequence":"additional","affiliation":[{"name":"Escuela de Kinesiologi\u0301a, Facultad de Salud, Universidad Santo Toma\u0301s, Talca 3460000, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7013-3894","authenticated-orcid":false,"given":"Yeny","family":"Concha-Cisternas","sequence":"additional","affiliation":[{"name":"Escuela de Kinesiologi\u0301a, Facultad de Salud, Universidad Santo Toma\u0301s, Talca 3460000, Chile"},{"name":"Vicerrectori\u0301a de Investigacio\u0301n e Innovacio\u0301n, Universidad Arturo Prat, Iquique 1100000, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7239-960X","authenticated-orcid":false,"given":"Antonio","family":"Castillo-Paredes","sequence":"additional","affiliation":[{"name":"Grupo AFySE, Investigaci\u00f3n en Actividad F\u00edsica y Salud Escolar, Escuela de Pedagog\u00eda en Educaci\u00f3n F\u00edsica, Facultad de Educaci\u00f3n, Universidad de Las Am\u00e9ricas, Santiago 8370040, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0004-3089","authenticated-orcid":false,"given":"Felipe","family":"Montalva-Valenzuela","sequence":"additional","affiliation":[{"name":"Escuela de Entrenador en Actividad F\u00edsica y Deporte, Facultad de Ciencias Humanas, Universidad Bernardo O\u2019Higgins, Santiago 8370040, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9311-6576","authenticated-orcid":false,"given":"Rodrigo","family":"Y\u00e1\u00f1ez-Sep\u00falveda","sequence":"additional","affiliation":[{"name":"Faculty Education and Social Sciences, Universidad Andr\u00e9s Bello, Vi\u00f1a del Mar 2520000, Chile"},{"name":"School of Medicine, Universidad Esp\u00edritu Santo, Samborond\u00f3n 092301, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6726-9798","authenticated-orcid":false,"given":"Emilio","family":"Jofr\u00e9-Sald\u00eda","sequence":"additional","affiliation":[{"name":"Escuela de Ciencias de la Actividad F\u00edsica, Facultad de Ciencias de la Rehabilitaci\u00f3n y Calidad de Vida, Universidad San Sebasti\u00e1n, Santiago 8370040, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6003-5107","authenticated-orcid":false,"given":"Iv\u00e1n","family":"Molina-M\u00e1rquez","sequence":"additional","affiliation":[{"name":"Escuela de Educaci\u00f3n F\u00edsica, Facultad de Educaci\u00f3n, Universidad Adventista de Chile, Chill\u00e1n 3780000, Chile"},{"name":"Programa Doctorado en Ciencias de la Actividad F\u00edsica, Universidad Cat\u00f3lica del Maule, Talca 3460000, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8409-6526","authenticated-orcid":false,"given":"Manuel","family":"Vasquez-Mu\u00f1oz","sequence":"additional","affiliation":[{"name":"Centro de Observaci\u00f3n y An\u00e1lisis de Datos en Salud, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Santiago 8580745, Chile"},{"name":"Escuela de Medicina, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Santiago 8580745, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1016\/j.jcot.2020.08.021","article-title":"Hamstring origin\u2013anatomy, angle of origin and its possible clinical implications","volume":"13","author":"Azzopardi","year":"2021","journal-title":"J. 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