{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T22:12:15Z","timestamp":1789769535536,"version":"4.0.1"},"reference-count":22,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T00:00:00Z","timestamp":1770163200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background\/Objectives: Persistent strength deficits and psychological impairments may compromise return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR). We investigate the relationship between thigh muscle isokinetic strength recovery at six months after ACLR and long-term psychological outcomes related to RTS in competitive male soccer players. Methods: Sixty male soccer players who underwent primary ACLR with bone\u2013patellar tendon\u2013bone autograft were retrospectively analyzed. Isokinetic testing of quadriceps and hamstrings was performed one week before surgery and six months post-surgery at 90\u00b0\/s and 180\u00b0\/s. Limb symmetry index (LSI) was calculated both pre- and post-operatively. At long-term follow-up (mean \u2248 4 years after RTS), athletes completed questionnaires assessing RTS status, ACL re-injuries, sport-related perceptions, and kinesiophobia using the Tampa Scale for Kinesiophobia (TSK). Statistical analyses were conducted to explore associations between post-operative LSI and TSK scores and to compare psychological and neuromuscular outcomes between athletes with and without ACL re-injury. Results: Absolute quadriceps and hamstring peak torque values significantly increased from pre- to post-surgery, with quadriceps strength deficits persisting only in the operated limb. However, quadriceps LSI significantly decreased post-operatively, while hamstring LSI remained stable. Pearson correlation analysis revealed a weak positive association between post-operative quadriceps LSI at 90\u00b0\/s and TSK scores (r = 0.34). Overall, RTS rate was 91.7%, but a second ACL injury occurred in 18.2% of athletes. No significant differences were observed between re-injured and non-re-injured athletes in TSK scores or post-operative LSI values at either angular velocity (all p &gt; 0.29). High kinesiophobia (TSK \u2265 37) was present in 56.7% of the cohort at long-term follow-up. Conclusions: Despite significant strength gains, quadriceps limb symmetry worsened six months after ACLR, with deficits confined to the operated limb, suggesting persistent neuromuscular inhibition. These physical deficits coexist with long-term kinesiophobia despite high RTS rates. The weak associations between strength symmetry and psychological outcomes highlight the multifactorial nature of RTS and support the need for an integrated physical, psychological, and neuro-cognitive approach to rehabilitation and RTS decision-making.<\/jats:p>","DOI":"10.3390\/jcm15031243","type":"journal-article","created":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T14:55:11Z","timestamp":1770216911000},"page":"1243","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Isokinetic Strength Recovery and Fear of Re-Injury After ACL Reconstruction in Male Soccer Players: A Retrospective Cohort Study"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-9337-8717","authenticated-orcid":false,"given":"Matteo","family":"Interlandi","sequence":"first","affiliation":[{"name":"\u201dPerformance\u201d Rehabilitation and Medical Center, 53100 Siena, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luca","family":"Santini","sequence":"additional","affiliation":[{"name":"\u201dPerformance\u201d Rehabilitation and Medical Center, 53100 Siena, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sebastiano","family":"Zuppardo","sequence":"additional","affiliation":[{"name":"\u201dPegaso\u201d Rehabilitation and Medical Center, 58100 Grosseto, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Franco","family":"Merlo","sequence":"additional","affiliation":[{"name":"\u201dPerformance\u201d Rehabilitation and Medical Center, 53100 Siena, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giovanni","family":"Grazzini","sequence":"additional","affiliation":[{"name":"Easytech Research Department, 50032 Borgo San Lorenzo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gilberto","family":"Martelli","sequence":"additional","affiliation":[{"name":"\u201dPerformance\u201d Rehabilitation and Medical Center, 53100 Siena, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.1136\/bjsports-2014-093962","article-title":"Isokinetic muscle strength and readiness to return to sport following anterior cruciate ligament reconstruction: Is there an association? A systematic review and a protocol recommendation","volume":"49","author":"Undheim","year":"2015","journal-title":"Br. J. Sports Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"678","DOI":"10.1002\/pmrj.12815","article-title":"Evidence for isokinetic and functional testing in return-to-sport decisions following anterior cruciate ligament surgery","volume":"14","author":"Frontera","year":"2022","journal-title":"PM&R"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1059","DOI":"10.1007\/s40279-016-0479-z","article-title":"Neuromuscular Risk Factors for Knee and Ankle Ligament Injuries in Male Youth Soccer Players","volume":"46","author":"Read","year":"2016","journal-title":"Sports Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1177\/1941738115578112","article-title":"Deficits in quadriceps strength and activation following anterior cruciate ligament reconstruction: A systematic review","volume":"7","author":"Lepley","year":"2015","journal-title":"Sports Health"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2299","DOI":"10.1007\/s00167-022-07296-6","article-title":"Fear of reinjury following primary anterior cruciate ligament reconstruction: A systematic review","volume":"31","author":"Mir","year":"2023","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1120","DOI":"10.1136\/bjsports-2012-091203","article-title":"A systematic review of the psychological factors associated with returning to sport following injury","volume":"47","author":"Ardern","year":"2013","journal-title":"Br. J. Sports Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5848","DOI":"10.1007\/s00167-023-07630-6","article-title":"Psychosocial interventions seem to reduce kinesiophobia after anterior cruciate ligament reconstruction, but a higher level of evidence is needed: A systematic review and meta-analysis","volume":"31","author":"Naderi","year":"2023","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1154","DOI":"10.1136\/bjsports-2018-099982","article-title":"Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review","volume":"53","author":"Burgi","year":"2019","journal-title":"Br. J. Sports Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1697","DOI":"10.1016\/j.arthro.2011.09.009","article-title":"Factors used to determine return to unrestricted sports activities after anterior cruciate ligament reconstruction","volume":"27","author":"Noyes","year":"2011","journal-title":"Arthroscopy"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1177\/19417381221094780","article-title":"Biopsychosocial Factors Associated With Return to Preinjury Sport After ACL Injury Treated Without Reconstruction: NACOX Cohort Study 12-Month Follow-up","volume":"15","author":"Slater","year":"2022","journal-title":"Sports Health A Multidiscip. Approach"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"955","DOI":"10.4085\/1062-6050-0543.21","article-title":"Psychological Readiness to Return to Sport After Anterior Cruciate Ligament Reconstruction in the Adolescent Athlete","volume":"57","author":"Webster","year":"2022","journal-title":"J. Athl. Train."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"87","DOI":"10.4085\/1062-6050-45.1.87","article-title":"Quadriceps activation following knee injuries: A systematic review","volume":"45","author":"Hart","year":"2010","journal-title":"J. Athl. Train."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1016\/j.semarthrit.2009.10.001","article-title":"Quadriceps arthrogenic muscle inhibition: Neural mechanisms and treatment perspectives","volume":"40","author":"Rice","year":"2010","journal-title":"Semin. Arthritis Rheum."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"McPherson, A.L., Schilaty, N.D., Anderson, S., Nagai, T., and Bates, N.A. (2023). Arthrogenic muscle inhibition after anterior cruciate ligament injury: Injured and uninjured limb recovery over time. Front. Sports Act. Living, 21.","DOI":"10.3389\/fspor.2023.1143376"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"172","DOI":"10.1016\/j.jshs.2020.07.005","article-title":"How does anterior cruciate ligament reconstruction affect the functioning of the brain and spinal cord? A review of neurophysiological changes","volume":"10","author":"Krishnan","year":"2021","journal-title":"J. Sport Health Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"549","DOI":"10.1177\/19417381211029265","article-title":"Neurocognitive and neurophysiological functions related to ACL injury: A framework for neurocognitive approaches in rehabilitation and return-to-sport tests","volume":"14","author":"Piskin","year":"2022","journal-title":"Sports Health"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1177\/0363546514559707","article-title":"Comparison of physical impairment, functional, and psychosocial measures based on fear of reinjury\/lack of confidence and return-to-sport status after ACL reconstruction","volume":"43","author":"Lentz","year":"2015","journal-title":"Am. J. Sports Med."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4498","DOI":"10.3390\/jcm13154498","article-title":"Correlation between anterior cruciate ligament\u2013return to sport after injury score at six months after anterior cruciate ligament reconstruction and mid-term functional outcomes","volume":"13","author":"Gerfroit","year":"2024","journal-title":"J. Clin. Med."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1053\/j.otsm.2015.09.006","article-title":"Psychological aspects of anterior cruciate ligament injuries","volume":"24","author":"Ardern","year":"2016","journal-title":"Oper. Tech. Sports Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1136\/bjsm.2010.076364","article-title":"Return to sport following anterior cruciate ligament reconstruction surgery: A systematic review and meta-analysis of the state of play","volume":"45","author":"Ardern","year":"2011","journal-title":"Br. J. Sports Med."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"946","DOI":"10.1136\/bjsports-2015-095908","article-title":"Likelihood of ACL graft rupture: Not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture","volume":"50","author":"Kyritsis","year":"2016","journal-title":"Br. J. Sports Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"804","DOI":"10.1136\/bjsports-2016-096031","article-title":"Simple decision rules can reduce reinjury risk after anterior cruciate ligament reconstruction: The Delaware\u2013Oslo ACL cohort study","volume":"50","author":"Grindem","year":"2016","journal-title":"Br. J. Sports Med."}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/3\/1243\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T15:00:52Z","timestamp":1770217252000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/3\/1243"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,4]]},"references-count":22,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["jcm15031243"],"URL":"https:\/\/doi.org\/10.3390\/jcm15031243","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,4]]}}}