Adolescent soccer player with unilateral lumbar spondylolysis has a small psoas major and a lumbopelvic depression during active straight leg raise

Adolescent soccer player with unilateral lumbar spondylolysis has a small psoas major and a lumbopelvic depression during active straight leg raise | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Adolescent soccer player with unilateral lumbar spondylolysis has a small psoas major and a lumbopelvic depression during active straight leg raise Toshiharu Tsutsui, Wataru Sakamaki, Suguru Torii This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6581181/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 21 Nov, 2025 Read the published version in BMC Sports Science, Medicine and Rehabilitation → Version 1 posted 14 You are reading this latest preprint version Abstract Background This study aimed to clarify trunk muscle morphology and clinical test characteristics in adolescent male soccer players with unilateral lumbar spondylolysis (uni-LS). Methods In total, 107 adolescent male soccer players were enrolled and categorized into a uni-LS group, based on magnetic resonance imaging (MRI), and an age-, height-, and weight-matched control group. MRI-derived cross-sectional areas (CSAs) of the L4/5 vertebrae were extracted, and the psoas major (PM), multifidus, and erector spinae muscles were analyzed. Active straight leg raise (ASLR) and hip extension tests were performed, and lumbopelvic depression was evaluated. Two-way analysis of variance was applied to determine trunk muscle CSA differences between groups, and the chi-square test was employed to evaluate the association between uni-LS and clinical findings. Results A significant main effect [F (1,36) = 7.6, p = 0.007] and interaction effect [F (1,36) = 4.1, p = 0.047] were found in the PM, indicating a smaller PM on the LS side in the uni-LS group. A significant association was also observed between uni-LS and ASLR on the LS side, with 13 of 16 players (81.2%) showing positive ASLR corresponding to the uni-LS group (p = 0.003). Conclusion A smaller PM and lumbopelvic depression during ASLR on the LS side characterize adolescent soccer players with uni-LS. Clinicians should consider these findings to help prevent LS progression or recurrence. lumbar injury bone stress spine physical function magnetic resonance imaging Figures Figure 1 Figure 2 Introduction Lumbar spondylolysis (LS), characterized by a pararticular defect, is caused by repeated lumbar spine extension and rotation [ 1 ] and is common in many sports [ 2 ]. The prevalence of LS in athletes is 2–5 times higher than that in the general population, where it is approximately 6% [ 3 , 4 ]. LS typically occurs during adolescence and results from chronic microtrauma to an immature and vulnerable lumbar spine. Once affected, athletes may need to restrict sports activities for extended periods, including wearing a corset for 2–3 months [ 5 ], which can reduce performance during adolescence and beyond. Given that approximately 80% of high school and college-aged soccer players with lower back pain have a history of LS [ 6 ], effective rehabilitation and prevention strategies during adolescence are essential. The primary approach to LS management is conservative treatment, aiming for bony union if pseudoarthrosis has not developed. Rehabilitation typically includes trunk exercises, brace use, and stretching, achieving an 80–90% bone union rate in early-stage LS [ 7 – 9 ]. Kasamasu et al. [ 10 ] reported that early and progressive-stage LS treated with brace wearing and trunk exercises achieved a 98.9% return-to-sport rate (mean return time: 4.7 ± 1.9 months), whereas pain management and athletic rehabilitation in terminal-stage LS achieved a 97.6% return rate (mean return time: 1.7 ± 1.8 months). These findings suggest that rest, spinal immobilization, and trunk exercises are vital components of return-to-sport protocols. However, no studies have detailed trunk muscle morphology and function in athletes with LS, leaving optimal muscle-targeted treatment and prevention strategies unclear. Identified factors inhibiting bone union in LS include pathology at L5, advanced LS stage, and contralateral progression [ 9 ]. Tatsumura et al. [ 11 ] speculated that unilateral LS (uni-LS) may increase mechanical stress on the contralateral side. Therefore, understanding the physical and clinical characteristics of uni-LS may help prevent LS progression and recurrence. The present study aimed to clarify trunk muscle morphology and clinical testing characteristics in uni-LS. Methods Participants In total, 107 male soccer players from the same competitive club were enrolled in this study. Players trained for 2–3 h, five days a week, after school and on weekends. Inclusion criteria required participants to be 12–14 years old at baseline. Exclusion criteria included not participating in soccer games or practices for 6 months. All measurements were performed at our institution. This study was approved by the ethics committee of the Waseda University (2021 − 218), and all participants and their parents provided signed informed consent. Data collection and procedures We measured body height and weight, assessed lumbar magnetic resonance imaging (MRI) and conducted core stability clinical tests. MRI scans were obtained using a 3.0-Tesla whole-body MRI system (GE Healthcare, Waukesha, WI, USA) with two imaging modes: short-tau inversion recovery (STIR) and computed tomography (CT)-like. Scanning parameters for STIR were as follows: repetition time/echo time, 1800/60 ms; slice thickness, 2 mm; field of view, 24 cm; matrix, 320 × 224 pixels; inversion time, 150 ms. The parameters for CT-like were as follows: repetition time/echo time, 4.5/2.1 ms; slice thickness, 0.80 mm; field of view, 24 cm; matrix, 384 × 384 pixels. Cross-sectional area of the trunk muscle Bilateral cross-sectional areas (CSAs) of the psoas major (PM), multifidus (MF), and erector spinae (ES) were measured using intermediate images of the L4/5 intervertebral disc (Fig. 1 ). A single examiner (T.T.) performed all analyses via image processing software (Osirix MD; Pixmeo). Intraclass correlation coefficients (1,1), calculated from three repeated measurements on ten participants, were 0.88 [95% confidence interval (CI), 0.85–0.92], 0.84 (95% CI, 0.80–0.89), and 0.82 (95% CI, 0.79–0.84) for the PM, MF, and ES, respectively. Clinical testing Active straight leg raise (ASLR) and hip extension (HE) tests were conducted to assess lumbopelvic stability during leg movement. ASLR involved raising one lower limb from a supine position, with subjective assessment of pelvic depression on the raised side (i.e., pelvic rotation to the right during right leg flexion). The examiner palpated the anterior superior iliac spine to detect pelvic depression. Similarly, HE involved lifting one lower limb from a prone position, with evaluation of pelvic depression on the elevated side (i.e., left pelvic rotation during right leg extension). Both ASLR and HE were assessed as binary outcomes (positive/negative). ASLR targeted 30° of hip flexion, and HE targeted 15° of hip extension. LS determination LS was diagnosed at the L5 level using both STIR and CT-like MRI modes. In STIR, bone marrow edema (BME) at the pars articularis was evaluated (Fig. 2 -A). In CT-like imaging, fracture stages were determined as early (hairline fracture, Fig. 2 -B), progressive (clear gap, Fig. 2 -C), and terminal (pseudoarthrosis, Fig. 2 -D). Participants were classified into the uni-LS group if findings were positive only on one side of the pars articularis. Statistical analysis SPSS Statistics 29 (SPSS, Inc., IBM, Japan) was used for all analyses. To form a control group matched to the uni-LS group, we selected participants with the same dominant leg. Of the 74 players without LS, 70 proceeded to the next analysis step. Propensity scores were calculated using multiple logistic regression with age, height, and weight as covariates. The uni-LS and control (without LS) groups were matched 1:1 by propensity score (caliper 0.2). An unpaired t -test was used to compare fundamental characteristics between the groups. Two-way analysis of variance was used to assess the effects of LS status (uni-LS vs. control) and side (LS vs. non-LS) on trunk muscle CSA, including the PM, MF, and ES. Based on prior research, vertebral region CSA was included as a covariate to control for body size effects [ 12 ]. The 2 × 2 main effects and interaction were examined; if a significant interaction was detected, post hoc Bonfferoni multiple comparisons were performed. To evaluate the relationship between LS and clinical test outcomes, we also used the chi-square test to analyze associations between uni-LS presence and binary ASLR and HE test results. Results Of the 19 soccer players with uni-LS, 15 and 4 had findings on the stepping and kicking sides, respectively. Among them, 4 were positive only for BME while 12, 3, and 0 were in the early, progressive, and terminal stages, respectively. Participant characteristics of the LS and control groups were shown in Table 1 . Table 1 Participant characteristics. Variable Unilateral LS (n = 19) Control (n = 19) P-value Age (years) 13.6 ± 0.8 13.6 ± 0.6 0.97 Height (cm) 161.9 ± 8.2 162.0 ± 10.8 0.95 Weight (kg) 51.5 ± 12.9 51.5 ± 11.4 0.99 LS, lumbar spondylolysis. Table 2 shows the differences in trunk muscle CSA between the uni-LS and control groups, including the PM, MF, and ES. A significant main effect [F (1,36) = 7.6, p = 0.007] and interaction effect [F (1,36) = 4.1, p = 0.047] were found in the PM, indicating a smaller PM on the LS side in the uni-LS group. No differences were observed between groups for the MF or ES. Table 2 Differences in trunk muscle CSA between players with unilateral LS and controls Variables Uni-LS group Control group Main effect (group) Interaction (group * side) LS side non-LS side LS side non-LS side F P F P PM CSA (cm 2 ) 12.8 (12.1 − 13.5) 14.3 (13.6 − 15.0) 14.5 (13.8 − 15.3) 14.6 (13.9 − 15.8) 7.6 0.007 4.1 0.047 MF CSA (cm 2 ) 8.6 (8.0 − 9.3) 10.8 (9.5 − 12.0) 8.7 (8.0 − 9.3) 9.2 (7.9 − 10.4) 2.4 0.12 2.8 0.10 ES CSA (cm 2 ) 7.8 (7.4 − 8.2) 8.7 (8.0 − 9.5) 8.1 (7.8 − 8.5) 8.6 (7.9 − 9.4) 0.1 0.72 0.5 0.47 Data are shown as means (95% confidence intervals) and adjusted by the covariate disc CSA. LS, lumbar spondylolysis; PM, psoas major; MF, multifidus; ES, erector spinae; CSA, cross sectional area Table 3 shows the association between LS presence and clinical testing. A significant relationship was found between uni-LS and ASLR on the LS side, with 13 of the 16 players (81.2%) who tested positive for ASLR on the LS side belonging to the uni-LS group (p = 0.003). Table 3 Relationships between lumbar spondylolysis (LS) and clinical testing. Clinical testing n LS, % (n) Odds ratio 95% CI P-value ASLR testing positive on LS side 16 81.2 (13) 2.67 1.34–5.32 0.003 negative on LS side 22 27.2 (6) positive on non-LS side 5 80 (4) 1.20 0.93–1.55 0.34 negative on non-LS side 33 45.4 (15) HE testing positive on LS side 8 50 (4) 1.00 0.72–1.39 1.00 negative on LS side 30 50 (15) positive on non-LS side 6 33.3 (2) 0.88 0.67–1.17 0.66 negative on non-LS side 32 53.1 (17) CI, confidence interval; ASLR, active straight leg raise; HE, hip extension. Discussion This study aimed to identify trunk muscle CSA characteristics and clinical test findings in adolescent male soccer players with uni-LS. Results revealed that the uni-LS group had a smaller PM CSA on the LS side and positive ASLR findings. These results suggest that evaluating PM and ASLR may be beneficial for physical therapists and athletic trainers in the clinical assessment and rehabilitation of adolescent players, especially those with uni-LS. Few studies have reported the prevalence of uni-LS using MRI in athletic cohorts. We identified 19 adolescent soccer players (17.7%) with uni-LS. Prior studies have shown that unilateral lumbar bone stress injury occurred in 40 (11.7%) of 342 adolescent athletes [ 13 ]. In our study, 3T MRI was used to detect early-stage hairline fractures to terminal-stage pseudoarthrosis in the pars articularis, as well as BME, via the CT-like mode [ 14 ]. The higher prevalence of uni-LS observed in our study may reflect the ability of this imaging method to detect both BME and fracture pathology [ 15 ]. Uni-LS is also more likely to occur on the nondominant side [ 16 ]. In our study, uni-LS was more frequently observed on the stepping side. Given that LS results from bony structural failure originating caudally in the pars articularis, repetitive stepping motions in soccer may create asymmetrical mechanical stress on the lumbar pars articularis. Our results also showed reduced PM CSA on the LS side in the uni-LS group. The PM originates from the upper lateral and transverse processes of the first to fourth lumbar vertebrae and lies posterior to the lumbar flexion–extension axis [ 17 ]. The lower PM flexes the lower lumbar spine, whereas the upper PM extends the upper spine, highlighting its role as a potential stabilizer of lumbar lordosis [ 17 , 18 ]. Additionally, adolescent athletes with LS often present with pronounced lumbar lordosis and sacral anteversion [ 13 , 19 , 20 ], which can increase compressive stress on the pars. Considering our L4/5 CSA measurements and prior research, the uni-LS group may have exhibited impaired lower lumbar flexion and reduced spinal stabilization on the LS side due to a smaller PM. The PM also contributes to contralateral lumbar rotation [ 21 ]. Thus, a smaller PM on the LS side may lead to increased lumbar rotation toward the LS side. Therefore, targeting PM function for lumbar spine rotation and lower spine flexion control may support uni-LS treatment and help prevent contralateral pathology. ASLR is widely used to evaluate muscle strength and function around the lumbopelvic region [ 22 ]. Poor lumbopelvic stability during lower limb raising can result in pelvic rotation and excessive lumbar movement. Park et al. [ 23 ] found that controlled ASLR reduced lumbar spine rotation by activating abdominal muscles. Liebenson et al. [ 24 ] also supported ASLR as a screen for lumbar spine stability, especially in rotation control and abdominal function. These findings support our interpretation that athletes with uni-LS may have impaired lumbopelvic and abdominal control on the LS side. Furthermore, as previous reports suggest that athletes with uni-LS have greater anterior pelvic tilt asymmetry compared with controls, correcting side-to-side ASLR differences may help reduce mechanical stress on the lumbar pars articularis. Limitations This study has several limitations. First, it had a cross-sectional design, making it unclear whether the smaller PM CSA observed in the uni-LS group was pre-existing or developed after onset. However, our findings suggest that reduced PM CSA may be a potential risk factor for recurrence. Second, trunk muscle behavior in the uni-LS group during movement remains unknown, as MRI was performed in a supine, resting position. Finally, we did not assess individual player workload. Although higher training frequency and shorter rest periods have been linked to lumbar injury [ 25 ], this limitation may have been minimized as all players trained within the same club. Declarations Ethics approval and consent to participate Ethics approval was granted by the Ethics Committee of the Waseda University (No. 2021-208) and written informed consent was obtained from all participants and their guardians. All methods were carried out in accordance with relevant guidelines and regulations. Consent for publication Not applicable Competing interests The authors declare that they have no competing interests. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author and the director of soccer club on reasonable request. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Author contributions TT, WS, and ST authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by TT, WS, and ST. The first draft of the manuscript was written by TT and TT, WS, and ST commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgements The authors sincerely thank the players who participated in this study. We also thank Nao Shinoda, the head coach of the junior soccer team in Tokyo. We also thank Kyoji Ohta and Hitomi Nakamura, the technical support in MR measurements. This work was supported by JSPS KAKENHI Grant Number. JP24K20617 and MIZUNO SPORTS PROMOTION FOUNDATION. References Leone A, Cianfoni A, Cerase A, et al. Lumbar spondylolysis: a review. Skeletal Radiol. 2011;40:683–700. https://doi.org/10.1007/s00256-010-0942-0 . Sakai T, Sairyo K, Suzue N, et al. Incidence and etiology of lumbar spondylolysis: review of the literature. J Orthop Sci. 2010;15:281–8. https://doi.org/10.1007/s00776-010-1454-4 . Beutler WJ, Fredrickson BE, Murtland A, et al. The natural history of spondylolysis and spondylolisthesis: 45-year follow-up evaluation. Spine. 2003;28:1027–35. https://doi.org/10.1097/01.BRS.0000061992.98108.A0 . Sonne-Holm S, Jacobsen S, Rovsing HC, et al. Lumbar spondylolysis: a life long dynamic condition? A cross sectional survey of 4.151 adults. Eur Spine J. 2007;16:821–8. https://doi.org/10.1007/s00586-006-0250-5 . Sakai T, Tezuka F, Yamashita K, et al. Conservative treatment for bony healing in pediatric lumbar spondylolysis. Spine. 2017;42:E716–20. https://doi.org/10.1097/BRS.0000000000001931 . Iwamoto J, Abe H, Tsukimura Y, Wakano K. Relationship between radiographic abnormalities of lumbar spine and incidence of low back pain in high school and college football players: a prospective study. Am J Sports Med. 2004;32:781–6. https://doi.org/10.1177/0363546503261721 . Nakashima H, Yoneda M, Kanemura T, et al. Conservative treatment of spondylolysis involving exercise initiated early and sports activities resumed with a lumbar-sacral brace. J Orthop Sci. 2022;27:360–5. https://doi.org/10.1016/j.jos.2021.01.013 . Kuroshima K, Miyazaki S, Hiranaka Y et al. (2023) Rate and duration of bone union for conservative treatment in pediatric lumbar spondylolysis. Spine. https://doi.org/10.1097/BRS.0000000000004849 Kuroshima K, Miyazaki S, Hiranaka Y, et al. Risk factors for nonunion after nonoperative treatment for pediatric lumbar spondylolysis: a retrospective case-control study. Am J Sports Med. 2024;52:2866–73. https://doi.org/10.1177/03635465241270293 . Kasamasu T, Ishida Y, Sato M, et al. Rates of return to sports and recurrence in pediatric athletes after conservative treatment for lumbar spondylolysis. Spine Surg Relat Res. 2022;6:540–4. https://doi.org/10.22603/ssrr.2021-0242 . Tatsumura M, Gamada H, Okuwaki S, et al. Factors associated with failure of bony union after conservative treatment of acute cases of unilateral lumbar spondylolysis. BMC Musculoskelet Disord. 2021;22:75. https://doi.org/10.1186/s12891-020-03940-9 . Sun X, Lei S-F, Deng F-Y, et al. Genetic and environmental correlations between bone geometric parameters and body compositions. Calcif Tissue Int. 2006;79:43–9. https://doi.org/10.1007/s00223-006-0041-3 . Tsutsui T, Iizuka S, Takei S, et al. Risk factors for symptomatic bilateral lumbar bone stress injury in adolescent soccer players: a prospective cohort study. Am J Sports Med. 2023;51:707–14. https://doi.org/10.1177/03635465221146289 . Ang EC, Robertson AF, Malara FA, et al. Diagnostic accuracy of 3-T magnetic resonance imaging with 3D T1 VIBE versus computer tomography in pars stress fracture of the lumbar spine. Skeletal Radiol. 2016;45:1533–40. https://doi.org/10.1007/s00256-016-2475-7 . Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014;44:749–65. https://doi.org/10.2519/jospt.2014.5334 . Sairyo K. Spondylolysis fracture angle in children and adolescents on CT indicates the facture producing force vector: a biomechanical rationale. Internet J Spine Surg. 2005;1:1–6. Penning L. Psoas muscle and lumbar spine stability: a concept uniting existing controversies. Eur Spine J. 2000;9:577–85. https://doi.org/10.1007/s005860000184 . Bogduk N, Pearcy M, Hadfield G. Anatomy and biomechanics of psoas major. Clin Biomech. 1992;7:109–19. https://doi.org/10.1016/0268-0033(92)90024-X . Tsutsui T, Kamikubo T, Sakamaki W, et al. Differences in lumbopelvic alignment in adolescent male soccer players with bilateral and unilateral lumbar bone stress injuries: an MRI evaluation. Orthop J Sports Med. 2024;12:23259671241229692. https://doi.org/10.1177/23259671241229692 . Wren TAL, Ponrartana S, Aggabao PC, et al. Increased lumbar lordosis and smaller vertebral cross-sectional area are associated with spondylolysis. Spine. 2018;43:833–8. https://doi.org/10.1097/BRS.0000000000002480 . Park RJ, Tsao H, Cresswell AG, Hodges PW. Changes in direction-specific activity of psoas major and quadratus lumborum in people with recurring back pain differ between muscle regions and patient groups. J Electromyogr Kinesiol. 2013;23:734–40. https://doi.org/10.1016/j.jelekin.2013.01.010 . Gatti R, Corti M, Cervi P, et al. Biomechanics of lower limb raising from the supine position. Eur Medicophysica. 2006;42:185–93. Park K, Ha S, Kim S, et al. Effects of the pelvic rotatory control method on abdominal muscle activity and the pelvic rotation during active straight leg raising. Man Ther. 2013;18:220–4. https://doi.org/10.1016/j.math.2012.10.004 . Liebenson C, Karpowicz AM, Brown SHM, et al. The active straight leg raise test and lumbar spine stability. PM&R. 2009;1:530–5. https://doi.org/10.1016/j.pmrj.2009.03.007 . Kountouris A, Sims K, Beakley D, et al. MRI bone marrow oedema precedes lumbar bone stress injury diagnosis in junior elite cricket fast bowlers. Br J Sports Med. 2019;53:1236–9. https://doi.org/10.1136/bjsports-2017-097930 . Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6581181","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":468216136,"identity":"f1c836b4-71a5-442e-b9c2-01d9b55f50a8","order_by":0,"name":"Toshiharu Tsutsui","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYBACfvbGBmYwA0QkFBChRbLncGMzmNEA0mJAhBaDG+kQLQYHwCQxLjuQ2P64oOZe4ubzqxM/PDBgkOcXO4BfB2PDwcbmGceKE7fdeLtZAugww5mzE/BrYWZsbGzmYUsAajm7AaQlweA2AS1sQD3NPP8SEjfPOLv5B1FaeNiAWnjbEhI38PduI84WCR7Gxtm8fQnGM27wbrNIMJAg7Bf7+88ffOb5liDb3392880fFTby/NIEtCDZB1YpQaxyEOA/QIrqUTAKRsEoGEkAAMeMSPeYn2+9AAAAAElFTkSuQmCC","orcid":"","institution":"Faculty of Sport Sciences, Waseda University","correspondingAuthor":true,"prefix":"","firstName":"Toshiharu","middleName":"","lastName":"Tsutsui","suffix":""},{"id":468216137,"identity":"34bb91e9-98c4-4ac2-8819-b35a8829bc09","order_by":1,"name":"Wataru Sakamaki","email":"","orcid":"","institution":"Graduate of Sport Sciences, Waseda University","correspondingAuthor":false,"prefix":"","firstName":"Wataru","middleName":"","lastName":"Sakamaki","suffix":""},{"id":468216138,"identity":"d799c680-2a3a-4a67-ad08-ff9c8c4edaf1","order_by":2,"name":"Suguru Torii","email":"","orcid":"","institution":"Faculty of Sport Sciences, Waseda University","correspondingAuthor":false,"prefix":"","firstName":"Suguru","middleName":"","lastName":"Torii","suffix":""}],"badges":[],"createdAt":"2025-05-03 00:08:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6581181/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6581181/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13102-025-01387-w","type":"published","date":"2025-11-21T15:58:31+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":84306788,"identity":"66936f02-53e8-4dd0-8589-d515bc66b5cc","added_by":"auto","created_at":"2025-06-10 11:30:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":766510,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of the cross-sectional areas PS, MF, and ES\u003c/p\u003e\n\u003cp\u003ePM, psoas major; MF, multifidus; ES, erector spinae\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-6581181/v1/fabea7feda092e5822e9e389.png"},{"id":84304169,"identity":"5124a137-3539-450f-ad71-45e1857dfec0","added_by":"auto","created_at":"2025-06-10 11:22:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":635635,"visible":true,"origin":"","legend":"\u003cp\u003eLumbar spondylolysis classification\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-6581181/v1/e55cf14e4dd62ef0a198b27e.png"},{"id":96650193,"identity":"8d37e5a0-1a71-4574-b652-5bb630a52bc3","added_by":"auto","created_at":"2025-11-24 16:09:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2385835,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6581181/v1/25430a0d-b4f5-4466-b2e9-58e947999e54.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Adolescent soccer player with unilateral lumbar spondylolysis has a small psoas major and a lumbopelvic depression during active straight leg raise","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLumbar spondylolysis (LS), characterized by a pararticular defect, is caused by repeated lumbar spine extension and rotation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] and is common in many sports [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The prevalence of LS in athletes is 2\u0026ndash;5 times higher than that in the general population, where it is approximately 6% [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. LS typically occurs during adolescence and results from chronic microtrauma to an immature and vulnerable lumbar spine. Once affected, athletes may need to restrict sports activities for extended periods, including wearing a corset for 2\u0026ndash;3 months [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], which can reduce performance during adolescence and beyond. Given that approximately 80% of high school and college-aged soccer players with lower back pain have a history of LS [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], effective rehabilitation and prevention strategies during adolescence are essential.\u003c/p\u003e \u003cp\u003eThe primary approach to LS management is conservative treatment, aiming for bony union if pseudoarthrosis has not developed. Rehabilitation typically includes trunk exercises, brace use, and stretching, achieving an 80\u0026ndash;90% bone union rate in early-stage LS [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Kasamasu et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] reported that early and progressive-stage LS treated with brace wearing and trunk exercises achieved a 98.9% return-to-sport rate (mean return time: 4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9 months), whereas pain management and athletic rehabilitation in terminal-stage LS achieved a 97.6% return rate (mean return time: 1.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 months). These findings suggest that rest, spinal immobilization, and trunk exercises are vital components of return-to-sport protocols. However, no studies have detailed trunk muscle morphology and function in athletes with LS, leaving optimal muscle-targeted treatment and prevention strategies unclear.\u003c/p\u003e \u003cp\u003eIdentified factors inhibiting bone union in LS include pathology at L5, advanced LS stage, and contralateral progression [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Tatsumura et al. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] speculated that unilateral LS (uni-LS) may increase mechanical stress on the contralateral side. Therefore, understanding the physical and clinical characteristics of uni-LS may help prevent LS progression and recurrence. The present study aimed to clarify trunk muscle morphology and clinical testing characteristics in uni-LS.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eIn total, 107 male soccer players from the same competitive club were enrolled in this study. Players trained for 2\u0026ndash;3 h, five days a week, after school and on weekends. Inclusion criteria required participants to be 12\u0026ndash;14 years old at baseline. Exclusion criteria included not participating in soccer games or practices for 6 months.\u003c/p\u003e \u003cp\u003eAll measurements were performed at our institution. This study was approved by the ethics committee of the Waseda University (2021\u0026thinsp;\u0026minus;\u0026thinsp;218), and all participants and their parents provided signed informed consent.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eData collection and procedures\u003c/h3\u003e\n\u003cp\u003eWe measured body height and weight, assessed lumbar magnetic resonance imaging (MRI) and conducted core stability clinical tests. MRI scans were obtained using a 3.0-Tesla whole-body MRI system (GE Healthcare, Waukesha, WI, USA) with two imaging modes: short-tau inversion recovery (STIR) and computed tomography (CT)-like. Scanning parameters for STIR were as follows: repetition time/echo time, 1800/60 ms; slice thickness, 2 mm; field of view, 24 cm; matrix, 320 \u0026times; 224 pixels; inversion time, 150 ms. The parameters for CT-like were as follows: repetition time/echo time, 4.5/2.1 ms; slice thickness, 0.80 mm; field of view, 24 cm; matrix, 384 \u0026times; 384 pixels.\u003c/p\u003e\n\u003ch3\u003eCross-sectional area of the trunk muscle\u003c/h3\u003e\n\u003cp\u003eBilateral cross-sectional areas (CSAs) of the psoas major (PM), multifidus (MF), and erector spinae (ES) were measured using intermediate images of the L4/5 intervertebral disc (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). A single examiner (T.T.) performed all analyses via image processing software (Osirix MD; Pixmeo). Intraclass correlation coefficients (1,1), calculated from three repeated measurements on ten participants, were 0.88 [95% confidence interval (CI), 0.85\u0026ndash;0.92], 0.84 (95% CI, 0.80\u0026ndash;0.89), and 0.82 (95% CI, 0.79\u0026ndash;0.84) for the PM, MF, and ES, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eClinical testing\u003c/h3\u003e\n\u003cp\u003eActive straight leg raise (ASLR) and hip extension (HE) tests were conducted to assess lumbopelvic stability during leg movement. ASLR involved raising one lower limb from a supine position, with subjective assessment of pelvic depression on the raised side (i.e., pelvic rotation to the right during right leg flexion). The examiner palpated the anterior superior iliac spine to detect pelvic depression. Similarly, HE involved lifting one lower limb from a prone position, with evaluation of pelvic depression on the elevated side (i.e., left pelvic rotation during right leg extension). Both ASLR and HE were assessed as binary outcomes (positive/negative). ASLR targeted 30\u0026deg; of hip flexion, and HE targeted 15\u0026deg; of hip extension.\u003c/p\u003e\n\u003ch3\u003eLS determination\u003c/h3\u003e\n\u003cp\u003eLS was diagnosed at the L5 level using both STIR and CT-like MRI modes. In STIR, bone marrow edema (BME) at the pars articularis was evaluated (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e-A). In CT-like imaging, fracture stages were determined as early (hairline fracture, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e-B), progressive (clear gap, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e-C), and terminal (pseudoarthrosis, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e-D). Participants were classified into the uni-LS group if findings were positive only on one side of the pars articularis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eSPSS Statistics 29 (SPSS, Inc., IBM, Japan) was used for all analyses. To form a control group matched to the uni-LS group, we selected participants with the same dominant leg. Of the 74 players without LS, 70 proceeded to the next analysis step. Propensity scores were calculated using multiple logistic regression with age, height, and weight as covariates. The uni-LS and control (without LS) groups were matched 1:1 by propensity score (caliper 0.2).\u003c/p\u003e \u003cp\u003eAn unpaired \u003cem\u003et\u003c/em\u003e-test was used to compare fundamental characteristics between the groups. Two-way analysis of variance was used to assess the effects of LS status (uni-LS vs. control) and side (LS vs. non-LS) on trunk muscle CSA, including the PM, MF, and ES. Based on prior research, vertebral region CSA was included as a covariate to control for body size effects [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The 2 \u0026times; 2 main effects and interaction were examined; if a significant interaction was detected, post hoc Bonfferoni multiple comparisons were performed. To evaluate the relationship between LS and clinical test outcomes, we also used the chi-square test to analyze associations between uni-LS presence and binary ASLR and HE test results.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eOf the 19 soccer players with uni-LS, 15 and 4 had findings on the stepping and kicking sides, respectively. Among them, 4 were positive only for BME while 12, 3, and 0 were in the early, progressive, and terminal stages, respectively. Participant characteristics of the LS and control groups were shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParticipant characteristics.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnilateral LS\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;19)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;19)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e13.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e13.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e161.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e162.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.95\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e51.5\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e51.5\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eLS, lumbar spondylolysis.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the differences in trunk muscle CSA between the uni-LS and control groups, including the PM, MF, and ES. A significant main effect [F (1,36)\u0026thinsp;=\u0026thinsp;7.6, p\u0026thinsp;=\u0026thinsp;0.007] and interaction effect [F (1,36)\u0026thinsp;=\u0026thinsp;4.1, p\u0026thinsp;=\u0026thinsp;0.047] were found in the PM, indicating a smaller PM on the LS side in the uni-LS group. No differences were observed between groups for the MF or ES.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDifferences in trunk muscle CSA between players with unilateral LS and controls\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"19\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c17\" colnum=\"17\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c18\" colnum=\"18\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c19\" colnum=\"19\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e \u003cp\u003eUni-LS group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c13\" namest=\"c9\"\u003e \u003cp\u003eControl group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e \u003cp\u003eMain effect\u003c/p\u003e \u003cp\u003e(group)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c17\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c19\" namest=\"c18\"\u003e \u003cp\u003eInteraction\u003c/p\u003e \u003cp\u003e(group * side)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eLS side\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003enon-LS side\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eLS side\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e \u003cp\u003enon-LS side\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c16\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c17\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c18\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c19\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePM CSA\u003c/p\u003e \u003cp\u003e(cm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(12.1\u0026thinsp;\u0026minus;\u0026thinsp;13.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e(13.6\u0026thinsp;\u0026minus;\u0026thinsp;15.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e14.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e(13.8\u0026thinsp;\u0026minus;\u0026thinsp;15.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e14.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e(13.9\u0026thinsp;\u0026minus;\u0026thinsp;15.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e7.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c16\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c18\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c19\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMF CSA\u003c/p\u003e \u003cp\u003e(cm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(8.0\u0026thinsp;\u0026minus;\u0026thinsp;9.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e(9.5\u0026thinsp;\u0026minus;\u0026thinsp;12.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e8.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e(8.0\u0026thinsp;\u0026minus;\u0026thinsp;9.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e9.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e(7.9\u0026thinsp;\u0026minus;\u0026thinsp;10.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c16\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c18\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c19\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eES CSA\u003c/p\u003e \u003cp\u003e(cm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(7.4\u0026thinsp;\u0026minus;\u0026thinsp;8.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e(8.0\u0026thinsp;\u0026minus;\u0026thinsp;9.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e8.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e(7.8\u0026thinsp;\u0026minus;\u0026thinsp;8.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e(7.9\u0026thinsp;\u0026minus;\u0026thinsp;9.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c16\"\u003e \u003cp\u003e0.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c18\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c19\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"19\" nameend=\"c19\" namest=\"c1\"\u003e \u003cp\u003eData are shown as means (95% confidence intervals) and adjusted by the covariate disc CSA.\u003c/p\u003e \u003cp\u003eLS, lumbar spondylolysis; PM, psoas major; MF, multifidus; ES, erector spinae; CSA, cross sectional area\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the association between LS presence and clinical testing. A significant relationship was found between uni-LS and ASLR on the LS side, with 13 of the 16 players (81.2%) who tested positive for ASLR on the LS side belonging to the uni-LS group (p\u0026thinsp;=\u0026thinsp;0.003).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRelationships between lumbar spondylolysis (LS) and clinical testing.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eClinical testing\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLS, % (n)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOdds\u003c/p\u003e \u003cp\u003eratio\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eASLR testing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epositive on LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.2 (13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.34\u0026ndash;5.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enegative on LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.2 (6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epositive on non-LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80 (4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.93\u0026ndash;1.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enegative on non-LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.4 (15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHE testing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epositive on LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50 (4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.72\u0026ndash;1.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enegative on LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50 (15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epositive on non-LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.3 (2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.67\u0026ndash;1.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enegative on non-LS side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.1 (17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eCI, confidence interval; ASLR, active straight leg raise; HE, hip extension.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study aimed to identify trunk muscle CSA characteristics and clinical test findings in adolescent male soccer players with uni-LS. Results revealed that the uni-LS group had a smaller PM CSA on the LS side and positive ASLR findings. These results suggest that evaluating PM and ASLR may be beneficial for physical therapists and athletic trainers in the clinical assessment and rehabilitation of adolescent players, especially those with uni-LS.\u003c/p\u003e \u003cp\u003eFew studies have reported the prevalence of uni-LS using MRI in athletic cohorts. We identified 19 adolescent soccer players (17.7%) with uni-LS. Prior studies have shown that unilateral lumbar bone stress injury occurred in 40 (11.7%) of 342 adolescent athletes [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In our study, 3T MRI was used to detect early-stage hairline fractures to terminal-stage pseudoarthrosis in the pars articularis, as well as BME, via the CT-like mode [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The higher prevalence of uni-LS observed in our study may reflect the ability of this imaging method to detect both BME and fracture pathology [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Uni-LS is also more likely to occur on the nondominant side [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In our study, uni-LS was more frequently observed on the stepping side. Given that LS results from bony structural failure originating caudally in the pars articularis, repetitive stepping motions in soccer may create asymmetrical mechanical stress on the lumbar pars articularis.\u003c/p\u003e \u003cp\u003eOur results also showed reduced PM CSA on the LS side in the uni-LS group. The PM originates from the upper lateral and transverse processes of the first to fourth lumbar vertebrae and lies posterior to the lumbar flexion\u0026ndash;extension axis [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The lower PM flexes the lower lumbar spine, whereas the upper PM extends the upper spine, highlighting its role as a potential stabilizer of lumbar lordosis [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Additionally, adolescent athletes with LS often present with pronounced lumbar lordosis and sacral anteversion [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], which can increase compressive stress on the pars. Considering our L4/5 CSA measurements and prior research, the uni-LS group may have exhibited impaired lower lumbar flexion and reduced spinal stabilization on the LS side due to a smaller PM. The PM also contributes to contralateral lumbar rotation [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Thus, a smaller PM on the LS side may lead to increased lumbar rotation toward the LS side. Therefore, targeting PM function for lumbar spine rotation and lower spine flexion control may support uni-LS treatment and help prevent contralateral pathology.\u003c/p\u003e \u003cp\u003eASLR is widely used to evaluate muscle strength and function around the lumbopelvic region [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Poor lumbopelvic stability during lower limb raising can result in pelvic rotation and excessive lumbar movement. Park et al. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] found that controlled ASLR reduced lumbar spine rotation by activating abdominal muscles. Liebenson et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] also supported ASLR as a screen for lumbar spine stability, especially in rotation control and abdominal function. These findings support our interpretation that athletes with uni-LS may have impaired lumbopelvic and abdominal control on the LS side. Furthermore, as previous reports suggest that athletes with uni-LS have greater anterior pelvic tilt asymmetry compared with controls, correcting side-to-side ASLR differences may help reduce mechanical stress on the lumbar pars articularis.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eThis study has several limitations. First, it had a cross-sectional design, making it unclear whether the smaller PM CSA observed in the uni-LS group was pre-existing or developed after onset. However, our findings suggest that reduced PM CSA may be a potential risk factor for recurrence. Second, trunk muscle behavior in the uni-LS group during movement remains unknown, as MRI was performed in a supine, resting position. Finally, we did not assess individual player workload. Although higher training frequency and shorter rest periods have been linked to lumbar injury [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], this limitation may have been minimized as all players trained within the same club.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics approval was granted by the Ethics Committee of the Waseda University (No. 2021-208) and written informed consent was obtained from all participants and their guardians. All methods were carried out in accordance with relevant guidelines and regulations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author and the director of soccer club on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTT, WS, and ST authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by TT, WS, and ST. The first draft of the manuscript was written by TT and TT, WS, and ST commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors sincerely thank the players who participated in this study. We also thank Nao Shinoda, the head coach of the junior soccer team in Tokyo. We also thank Kyoji Ohta and Hitomi Nakamura, the technical support in MR measurements. This work was supported by JSPS KAKENHI Grant Number. JP24K20617 and MIZUNO SPORTS PROMOTION FOUNDATION.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLeone A, Cianfoni A, Cerase A, et al. Lumbar spondylolysis: a review. Skeletal Radiol. 2011;40:683\u0026ndash;700. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00256-010-0942-0\u003c/span\u003e\u003cspan address=\"10.1007/s00256-010-0942-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSakai T, Sairyo K, Suzue N, et al. Incidence and etiology of lumbar spondylolysis: review of the literature. J Orthop Sci. 2010;15:281\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00776-010-1454-4\u003c/span\u003e\u003cspan address=\"10.1007/s00776-010-1454-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeutler WJ, Fredrickson BE, Murtland A, et al. The natural history of spondylolysis and spondylolisthesis: 45-year follow-up evaluation. Spine. 2003;28:1027\u0026ndash;35. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/01.BRS.0000061992.98108.A0\u003c/span\u003e\u003cspan address=\"10.1097/01.BRS.0000061992.98108.A0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSonne-Holm S, Jacobsen S, Rovsing HC, et al. Lumbar spondylolysis: a life long dynamic condition? A cross sectional survey of 4.151 adults. Eur Spine J. 2007;16:821\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00586-006-0250-5\u003c/span\u003e\u003cspan address=\"10.1007/s00586-006-0250-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSakai T, Tezuka F, Yamashita K, et al. Conservative treatment for bony healing in pediatric lumbar spondylolysis. Spine. 2017;42:E716\u0026ndash;20. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0000000000001931\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0000000000001931\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIwamoto J, Abe H, Tsukimura Y, Wakano K. Relationship between radiographic abnormalities of lumbar spine and incidence of low back pain in high school and college football players: a prospective study. Am J Sports Med. 2004;32:781\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/0363546503261721\u003c/span\u003e\u003cspan address=\"10.1177/0363546503261721\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakashima H, Yoneda M, Kanemura T, et al. Conservative treatment of spondylolysis involving exercise initiated early and sports activities resumed with a lumbar-sacral brace. J Orthop Sci. 2022;27:360\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jos.2021.01.013\u003c/span\u003e\u003cspan address=\"10.1016/j.jos.2021.01.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuroshima K, Miyazaki S, Hiranaka Y et al. (2023) Rate and duration of bone union for conservative treatment in pediatric lumbar spondylolysis. Spine. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0000000000004849\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0000000000004849\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuroshima K, Miyazaki S, Hiranaka Y, et al. Risk factors for nonunion after nonoperative treatment for pediatric lumbar spondylolysis: a retrospective case-control study. Am J Sports Med. 2024;52:2866\u0026ndash;73. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/03635465241270293\u003c/span\u003e\u003cspan address=\"10.1177/03635465241270293\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKasamasu T, Ishida Y, Sato M, et al. Rates of return to sports and recurrence in pediatric athletes after conservative treatment for lumbar spondylolysis. Spine Surg Relat Res. 2022;6:540\u0026ndash;4. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.22603/ssrr.2021-0242\u003c/span\u003e\u003cspan address=\"10.22603/ssrr.2021-0242\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTatsumura M, Gamada H, Okuwaki S, et al. Factors associated with failure of bony union after conservative treatment of acute cases of unilateral lumbar spondylolysis. BMC Musculoskelet Disord. 2021;22:75. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/s12891-020-03940-9\u003c/span\u003e\u003cspan address=\"10.1186/s12891-020-03940-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun X, Lei S-F, Deng F-Y, et al. Genetic and environmental correlations between bone geometric parameters and body compositions. Calcif Tissue Int. 2006;79:43\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00223-006-0041-3\u003c/span\u003e\u003cspan address=\"10.1007/s00223-006-0041-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsutsui T, Iizuka S, Takei S, et al. Risk factors for symptomatic bilateral lumbar bone stress injury in adolescent soccer players: a prospective cohort study. Am J Sports Med. 2023;51:707\u0026ndash;14. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/03635465221146289\u003c/span\u003e\u003cspan address=\"10.1177/03635465221146289\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAng EC, Robertson AF, Malara FA, et al. Diagnostic accuracy of 3-T magnetic resonance imaging with 3D T1 VIBE versus computer tomography in pars stress fracture of the lumbar spine. Skeletal Radiol. 2016;45:1533\u0026ndash;40. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00256-016-2475-7\u003c/span\u003e\u003cspan address=\"10.1007/s00256-016-2475-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWarden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014;44:749\u0026ndash;65. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2519/jospt.2014.5334\u003c/span\u003e\u003cspan address=\"10.2519/jospt.2014.5334\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSairyo K. Spondylolysis fracture angle in children and adolescents on CT indicates the facture producing force vector: a biomechanical rationale. Internet J Spine Surg. 2005;1:1\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePenning L. Psoas muscle and lumbar spine stability: a concept uniting existing controversies. Eur Spine J. 2000;9:577\u0026ndash;85. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s005860000184\u003c/span\u003e\u003cspan address=\"10.1007/s005860000184\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBogduk N, Pearcy M, Hadfield G. Anatomy and biomechanics of psoas major. Clin Biomech. 1992;7:109\u0026ndash;19. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0268-0033(92)90024-X\u003c/span\u003e\u003cspan address=\"10.1016/0268-0033(92)90024-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsutsui T, Kamikubo T, Sakamaki W, et al. Differences in lumbopelvic alignment in adolescent male soccer players with bilateral and unilateral lumbar bone stress injuries: an MRI evaluation. Orthop J Sports Med. 2024;12:23259671241229692. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/23259671241229692\u003c/span\u003e\u003cspan address=\"10.1177/23259671241229692\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWren TAL, Ponrartana S, Aggabao PC, et al. Increased lumbar lordosis and smaller vertebral cross-sectional area are associated with spondylolysis. Spine. 2018;43:833\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0000000000002480\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0000000000002480\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark RJ, Tsao H, Cresswell AG, Hodges PW. Changes in direction-specific activity of psoas major and quadratus lumborum in people with recurring back pain differ between muscle regions and patient groups. J Electromyogr Kinesiol. 2013;23:734\u0026ndash;40. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jelekin.2013.01.010\u003c/span\u003e\u003cspan address=\"10.1016/j.jelekin.2013.01.010\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGatti R, Corti M, Cervi P, et al. Biomechanics of lower limb raising from the supine position. Eur Medicophysica. 2006;42:185\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark K, Ha S, Kim S, et al. Effects of the pelvic rotatory control method on abdominal muscle activity and the pelvic rotation during active straight leg raising. Man Ther. 2013;18:220\u0026ndash;4. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.math.2012.10.004\u003c/span\u003e\u003cspan address=\"10.1016/j.math.2012.10.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiebenson C, Karpowicz AM, Brown SHM, et al. The active straight leg raise test and lumbar spine stability. PM\u0026amp;R. 2009;1:530\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.pmrj.2009.03.007\u003c/span\u003e\u003cspan address=\"10.1016/j.pmrj.2009.03.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKountouris A, Sims K, Beakley D, et al. MRI bone marrow oedema precedes lumbar bone stress injury diagnosis in junior elite cricket fast bowlers. Br J Sports Med. 2019;53:1236\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/bjsports-2017-097930\u003c/span\u003e\u003cspan address=\"10.1136/bjsports-2017-097930\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-sports-science-medicine-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ssmr","sideBox":"Learn more about [BMC Sports Science, Medicine and Rehabilitation](http://bmcsportsscimedrehabil.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ssmr/default.aspx","title":"BMC Sports Science, Medicine and Rehabilitation","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"lumbar injury, bone stress, spine, physical function, magnetic resonance imaging","lastPublishedDoi":"10.21203/rs.3.rs-6581181/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6581181/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThis study aimed to clarify trunk muscle morphology and clinical test characteristics in adolescent male soccer players with unilateral lumbar spondylolysis (uni-LS).\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eIn total, 107 adolescent male soccer players were enrolled and categorized into a uni-LS group, based on magnetic resonance imaging (MRI), and an age-, height-, and weight-matched control group. MRI-derived cross-sectional areas (CSAs) of the L4/5 vertebrae were extracted, and the psoas major (PM), multifidus, and erector spinae muscles were analyzed. Active straight leg raise (ASLR) and hip extension tests were performed, and lumbopelvic depression was evaluated. Two-way analysis of variance was applied to determine trunk muscle CSA differences between groups, and the chi-square test was employed to evaluate the association between uni-LS and clinical findings.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eA significant main effect [F (1,36)\u0026thinsp;=\u0026thinsp;7.6, p\u0026thinsp;=\u0026thinsp;0.007] and interaction effect [F (1,36)\u0026thinsp;=\u0026thinsp;4.1, p\u0026thinsp;=\u0026thinsp;0.047] were found in the PM, indicating a smaller PM on the LS side in the uni-LS group. A significant association was also observed between uni-LS and ASLR on the LS side, with 13 of 16 players (81.2%) showing positive ASLR corresponding to the uni-LS group (p\u0026thinsp;=\u0026thinsp;0.003).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eA smaller PM and lumbopelvic depression during ASLR on the LS side characterize adolescent soccer players with uni-LS. Clinicians should consider these findings to help prevent LS progression or recurrence.\u003c/p\u003e","manuscriptTitle":"Adolescent soccer player with unilateral lumbar spondylolysis has a small psoas major and a lumbopelvic depression during active straight leg raise","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-10 11:22:46","doi":"10.21203/rs.3.rs-6581181/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-09T10:10:52+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"272946400676242223417221583274267515316","date":"2025-06-08T12:09:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-07T08:54:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"112127371070370867723679988103515987513","date":"2025-06-07T07:27:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"175999079907582420312100963643305403694","date":"2025-06-06T15:56:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"103998490786753201230938988186649567080","date":"2025-06-06T12:42:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-06T04:45:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"250861576758926056848083589240456660980","date":"2025-06-06T04:33:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"160696790284987923687097202950425493271","date":"2025-06-05T11:49:16+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-05T11:40:12+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-05-14T07:15:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-12T10:25:26+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-12T10:21:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Sports Science, Medicine and Rehabilitation","date":"2025-05-03T00:03:37+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-sports-science-medicine-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ssmr","sideBox":"Learn more about [BMC Sports Science, Medicine and Rehabilitation](http://bmcsportsscimedrehabil.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ssmr/default.aspx","title":"BMC Sports Science, Medicine and Rehabilitation","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"99a42cc3-a48e-4014-a5fe-920ba5eedece","owner":[],"postedDate":"June 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-24T16:03:37+00:00","versionOfRecord":{"articleIdentity":"rs-6581181","link":"https://doi.org/10.1186/s13102-025-01387-w","journal":{"identity":"bmc-sports-science-medicine-and-rehabilitation","isVorOnly":false,"title":"BMC Sports Science, Medicine and Rehabilitation"},"publishedOn":"2025-11-21 15:58:31","publishedOnDateReadable":"November 21st, 2025"},"versionCreatedAt":"2025-06-10 11:22:46","video":"","vorDoi":"10.1186/s13102-025-01387-w","vorDoiUrl":"https://doi.org/10.1186/s13102-025-01387-w","workflowStages":[]},"version":"v1","identity":"rs-6581181","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6581181","identity":"rs-6581181","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}