{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T06:11:31Z","timestamp":1792131091250,"version":"4.4.0"},"reference-count":36,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2021,6,24]],"date-time":"2021-06-24T00:00:00Z","timestamp":1624492800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Purpose: The main objective of this study was to evaluate the level of muscle strength by using isokinetic and isometric measurements\u2014more specifically, the force ratio between the knee flexors and extensors (values of the torques). Methods: An experimental group of elite volleyball players (n = 14) were compared to a control group (n = 14) of healthy non-athletes of comparable ages. Torque measurements were obtained under three concentric conditions (angular velocities of 60 \u00b0\/s, 180 \u00b0\/s, and 300 \u00b0\/s) and one static condition by utilizing the Biodex System 3. Results: In all trials, the volleyball players achieved significantly higher peak torque (PT) values for both the extensors and flexors (p &lt; 0.05) than those of the control group. However, the strength ratio of the flexors and extensors (H\/Q) in the experimental group was only 83% of the standard reported in the literature. The most developed and dominating muscles in the knee joints of the volleyball players were the extensors, which accounted for the low strength ratio and dynamic instability of this joint. Conclusion: Based on a proper assessment of the strength ratio of the knee flexors and extensors, properly selected and implemented resistance training can improve the maximum strength and power production and reduce the incidence of injuries in volleyball.<\/jats:p>","DOI":"10.3390\/ijerph18136780","type":"journal-article","created":{"date-parts":[[2021,6,24]],"date-time":"2021-06-24T11:01:38Z","timestamp":1624532498000},"page":"6780","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Isokinetic and Isometric Assessment of the Knee Joint Extensors and Flexors of Professional Volleyball Players"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8465-468X","authenticated-orcid":false,"given":"Piotr","family":"Wilkosz","sequence":"first","affiliation":[{"name":"Department of Physiotherapy, Stanislaw Staszic University of Applied Science in Pila, ul. Podchorazych 10, 64-920 Pila, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6478-6116","authenticated-orcid":false,"given":"Jaroslaw","family":"Kabacinski","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, Poznan University of Physical Education, Kr\u00f3lowej Jadwigi 27\/39, 61-871 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6750-4316","authenticated-orcid":false,"given":"Krzysztof","family":"Mackala","sequence":"additional","affiliation":[{"name":"Department of Track and Field, University School of Physical Education, ul. Paderewskiego 35, 51-612 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michal","family":"Murawa","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, Poznan University of Physical Education, Kr\u00f3lowej Jadwigi 27\/39, 61-871 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John","family":"Ostarello","sequence":"additional","affiliation":[{"name":"Department of Kinesiology, California State University, Hayward, CA 94542, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Agata","family":"Rzepnicka","sequence":"additional","affiliation":[{"name":"Public Medical Center \u2018Doktor Krasicki\u2019 in Gdynia, ul. Zakr\u0119t od Oksywia 3, 81-244 Gdynia, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lukasz","family":"Szczesny","sequence":"additional","affiliation":[{"name":"VeloLAB Physiotherapy Biomechanics Lukasz Szczesny, ul. Starodworska 3, 80-137 Gdansk, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1163-3973","authenticated-orcid":false,"given":"Anna","family":"Fryzowicz","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, Poznan University of Physical Education, Kr\u00f3lowej Jadwigi 27\/39, 61-871 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jacek","family":"Maczynski","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, Poznan University of Physical Education, Kr\u00f3lowej Jadwigi 27\/39, 61-871 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lechoslaw B.","family":"Dworak","sequence":"additional","affiliation":[{"name":"Faculty of Health Sciences, Calisia University, ul. Nowy \u015awiat 4, 62-800 Kalisz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1858","DOI":"10.1519\/JSC.0b013e3181b45c6a","article-title":"An Analysis of Playing Positions in Elite Men\u2019s Volleyball: Considerations for Competition Demands and Physiologic Characteristics","volume":"23","author":"Sheppard","year":"2009","journal-title":"J. Strength Cond. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1080\/17461390300073310","article-title":"The value of strength-diagnostic for the structure of jump training in volleyball","volume":"3","author":"Voigt","year":"2003","journal-title":"Eur. J. Sport Sci."},{"key":"ref_3","unstructured":"Esper, A. (2013). Jumps Performed by Male Volleyball Players of a Team of the Argentine League. Rev. Digit Educ. F\u00edsica y Deport, 8. 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