{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,28]],"date-time":"2026-10-28T00:58:05Z","timestamp":1793149085849,"version":"4.5.0"},"reference-count":21,"publisher":"Public Library of Science (PLoS)","issue":"8","license":[{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>\n                    Lower limb strength imbalance and inter-limb asymmetry are relevant neuromuscular screening markers in women\u2019s football, yet data from national-champion squads in Eastern Europe remain limited. The aim of this study was to characterise lower limb isometric knee strength, hamstring-to-quadriceps (H:Q) ratios, and bilateral and unilateral squat jump (SJ) and countermovement jump (CMJ) performance, and to describe their distribution by playing position, in elite Bulgarian female football players. Nineteen players from FC NSA Sofia Women (Bulgarian Women\u2019s Football Champions, 2024\/25; age 20.9\u2009\u00b1\u20094.3 years; height 168.4\u2009\u00b1\u20094.7 cm; body mass 60.5\u2009\u00b1\u20098.0 kg; body mass index 21.3\u2009\u00b1\u20092.7 kg\u00b7m\n                    <jats:sup>\u22122<\/jats:sup>\n                    ) were assessed on a single testing day using a handheld dynamometer (Kineo Intelligent Load) and an optical jump system (Optojump Next). Mean H:Q ratios were 0.58\u2009\u00b1\u20090.10 (left, 95% CI [0.52, 0.64]) and 0.55\u2009\u00b1\u20090.07 (right, 95% CI [0.51, 0.60]); the right-limb mean was statistically below the 0.60 reference threshold (t(13) = \u22122.40, p\u2009=\u20090.032, d\u2009=\u2009\u22120.64). Thirteen of fourteen assessed players (92.9%, 95% CI [68.5\u201398.7%]) presented at least one limb with an H:Q ratio below 0.60. Mean bilateral SJ and CMJ were both 29.2 cm, producing a near-zero elasticity index (0.99\u2009\u00b1\u200910.6%). Unilateral asymmetry exceeding 10% was observed in 52.9% of players for SJ (95% CI [31.0\u201373.8%]) and 35.3% for CMJ (95% CI [17.3\u201358.7%]). Positional profiles are reported descriptively only, given the small subgroup sizes. The findings support routine neuromuscular screening of lower limb strength balance and unilateral jump performance in elite women\u2019s football, and indicate that conditioning programmes should address both hamstring and quadriceps capacity rather than hamstring strength in isolation.\n                  <\/jats:p>","DOI":"10.1371\/journal.pone.0350952","type":"journal-article","created":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T17:27:41Z","timestamp":1787938061000},"page":"e0350952","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Lower limb muscle strength, inter-limb asymmetry, and vertical jump performance in elite female football players: A cross-sectional study"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-4893-5056","authenticated-orcid":true,"given":"Danail Georgiev","family":"Ivanov","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1402-5121","authenticated-orcid":true,"given":"Petar","family":"Peev","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,8,28]]},"reference":[{"key":"pone.0350952.ref001","unstructured":"FIFA. Women\u2019s football member associations survey report. Zurich: FIFA; 2023."},{"issue":"1","key":"pone.0350952.ref002","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1007\/s00167-010-1172-7","article-title":"The epidemiology of anterior cruciate ligament injury in football (soccer): a review of the literature from a gender-related perspective","volume":"19","author":"M Wald\u00e9n","year":"2011","journal-title":"Knee Surg Sports Traumatol Arthrosc"},{"issue":"1","key":"pone.0350952.ref003","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1111\/sms.12860","article-title":"A comparison of injuries in elite male and female football players: a five-season prospective study","volume":"28","author":"J Larruskain","year":"2018","journal-title":"Scand J Med Sci Sports"},{"issue":"12","key":"pone.0350952.ref004","doi-asserted-by":"crossref","DOI":"10.1016\/j.arthro.2007.07.003","article-title":"A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen","volume":"23","author":"CC Prodromos","year":"2007","journal-title":"Arthroscopy"},{"issue":"2","key":"pone.0350952.ref005","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1177\/0363546505284183","article-title":"Anterior cruciate ligament injuries in female athletes: Part 1, mechanisms and risk factors","volume":"34","author":"TE Hewett","year":"2006","journal-title":"Am J Sports Med"},{"issue":"2","key":"pone.0350952.ref006","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1177\/03635465980260021201","article-title":"A new concept for isokinetic hamstring: quadriceps muscle strength ratio","volume":"26","author":"P Aagaard","year":"1998","journal-title":"Am J Sports Med"},{"issue":"1","key":"pone.0350952.ref007","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1097\/JSM.0b013e318190bddb","article-title":"The relationship of hamstrings and quadriceps strength to anterior cruciate ligament injury in female athletes","volume":"19","author":"GD Myer","year":"2009","journal-title":"Clin J Sport Med"},{"issue":"9","key":"pone.0350952.ref008","doi-asserted-by":"crossref","first-page":"2579","DOI":"10.1519\/JSC.0000000000002608","article-title":"The relationship between asymmetry and athletic performance: a critical review","volume":"33","author":"SJ Maloney","year":"2019","journal-title":"J Strength Cond Res"},{"issue":"10","key":"pone.0350952.ref009","doi-asserted-by":"crossref","first-page":"1135","DOI":"10.1080\/02640414.2017.1361894","article-title":"Effects of inter-limb asymmetries on physical and sports performance: a systematic review","volume":"36","author":"C Bishop","year":"2018","journal-title":"J Sports Sci"},{"issue":"1","key":"pone.0350952.ref010","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1016\/S0003-9993(97)90005-8","article-title":"Reference values for extremity muscle strength obtained by hand-held dynamometry from adults aged 20 to 79 years","volume":"78","author":"RW Bohannon","year":"1997","journal-title":"Arch Phys Med Rehabil"},{"issue":"6","key":"pone.0350952.ref011","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1519\/SSC.0000000000000264","article-title":"Asymmetries of the lower limb: the calculation conundrum in strength training and conditioning","volume":"38","author":"C Bishop","year":"2016","journal-title":"Strength Cond J"},{"issue":"2","key":"pone.0350952.ref012","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1007\/BF00422166","article-title":"A simple method for measurement of mechanical power in jumping","volume":"50","author":"C Bosco","year":"1983","journal-title":"Eur J Appl Physiol Occup Physiol"},{"issue":"10","key":"pone.0350952.ref013","doi-asserted-by":"crossref","first-page":"1197","DOI":"10.1016\/S0021-9290(00)00064-6","article-title":"Stretch-shortening cycle: a powerful model to study normal and fatigued muscle","volume":"33","author":"PV Komi","year":"2000","journal-title":"J Biomech"},{"issue":"2","key":"pone.0350952.ref014","doi-asserted-by":"crossref","first-page":"556","DOI":"10.1519\/JSC.0b013e3181ccb18d","article-title":"Validity and Reliability of Optojump Photoelectric Cells for Estimating Vertical Jump Height","volume":"25","author":"JF Glatthorn","year":"2010","journal-title":"J Strength Cond Res"},{"issue":"5","key":"pone.0350952.ref015","doi-asserted-by":"crossref","first-page":"1220","DOI":"10.1519\/JSC.0000000000000766","article-title":"Lower-extremity strength ratios of professional soccer players according to field position","volume":"29","author":"CV Ruas","year":"2015","journal-title":"J Strength Cond Res"},{"issue":"2","key":"pone.0350952.ref016","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1111\/j.1600-0838.2008.00780.x","article-title":"Muscular strength, functional performances and injury risk in professional and junior elite soccer players","volume":"19","author":"C Lehance","year":"2009","journal-title":"Scand J Med Sci Sports"},{"issue":"4","key":"pone.0350952.ref017","doi-asserted-by":"crossref","first-page":"1156","DOI":"10.1519\/JSC.0b013e3182610999","article-title":"Vertical jump performance in Italian male and female national team soccer players","volume":"27","author":"C Castagna","year":"2013","journal-title":"J Strength Cond Res"},{"issue":"4","key":"pone.0350952.ref018","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1123\/ijspp.7.4.340","article-title":"Speed and countermovement-jump characteristics of elite female soccer players, 1995-2010","volume":"7","author":"TA Haugen","year":"2012","journal-title":"Int J Sports Physiol Perform"},{"issue":"3","key":"pone.0350952.ref019","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0229440","article-title":"Inter-limb asymmetries are associated with decrements in physical performance in youth elite team sports athletes","volume":"15","author":"A Fort-Vanmeerhaeghe","year":"2020","journal-title":"PLoS One"},{"issue":"10","key":"pone.0350952.ref020","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0140822","article-title":"Assessment of lower limb muscle strength and power using hand-held and fixed dynamometry: a reliability and validity study","volume":"10","author":"BF Mentiplay","year":"2015","journal-title":"PLoS One"},{"key":"pone.0350952.ref021","volume-title":"Isokinetics: muscle testing, interpretation and clinical applications","author":"Z Dvir","year":"2004","edition":"2"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0350952","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T17:27:45Z","timestamp":1787938065000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0350952"}},"subtitle":[],"editor":[{"given":"Julio Alejandro Henriques Castro","family":"da Costa","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,8,28]]},"references-count":21,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8,28]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0350952","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,28]]}}}