Inter-limb Functional Asymmetry and the Development of Pain in Collegiate Volleyball Players: A Preliminary Study

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We therefore aimed to explore the association between inter-limb asymmetry in performance-based tests and the development of lower extremity pain in collegiate volleyball players over a competitive season. Methods In this preliminary study, 26 male collegiate volleyball players (mean age = 20.6 ± 1.0 years) underwent preseason testing, including the star excursion balance test (anterior direction), side hop test, and single-leg hop for distance. Pain status was tracked on a biweekly basis using an online survey with an 11-point numerical rating scale. Based on reporting frequency, some athletes were classified into the pain group (pain reported on ≥ 80% of surveys) or into the no-pain group (pain reported on 0%). Inter-limb asymmetry was calculated as |1 − (left/right)| for each performance test. Results There was significantly greater asymmetry in the star excursion balance test in the pain group (n = 9; 0.29 ± 0.25) than in the no-pain group (n = 10; 0.04 ± 0.03, p = 0.040). Overall trends towards higher asymmetry were seen in the pain group, but no significant differences between the groups were observed in the side hop test asymmetry index (pain group: 0.13 ± 0.12, no-pain group: 0.06 ± 0.04, p = 0.203) or single-leg hop asymmetry index (pain group: 0.16 ± 0.17, no-pain group: 0.04 ± 0.05, p = 0.117). Conclusion Greater inter-limb asymmetry in dynamic balance was associated with frequent pain in a group of volleyball athletes. Our preliminary findings suggest that functional asymmetry screening, especially in dynamic balance, might be useful for early detection of athletes who may be at risk of developing non-traumatic pain. Trial Registration UMIN000054720 asymmetry athletes pain volleyball Introduction Injury prevention has long been considered important in the preservation of athlete health and the enhancement of performance sustainability. In high-impact sports such as volleyball, this principle holds particular relevance: athletes are repeatedly exposed to mechanical stressors including vertical jumping, abrupt landings, lateral cutting maneuvers, and overhead arm actions. Together, these are thought to impose cumulative loading on both the lower and upper extremities over time. Recent longitudinal epidemiological investigations targeting male collegiate volleyball players revealed the substantial burden of musculoskeletal injuries in this population. Notably, a five-year cohort study of Japanese university athletes identified lower-limb injuries (particularly those of overuse origin) as the predominant concern, with patellar tendinopathy and ankle sprains accounting for the majority of reported cases, and approximately 40% of all lower extremity complaints were attributed to the knees alone [ 1 ]. Elsewhere, in a prospective study of elite male volleyball players, 75% of participants reported symptoms consistent with ‘jumper’s knee’ across a competitive season, and the incidence of clinically significant patellar tendinopathy reached 30% of athletes per season. These figures underscore the pervasive and recurrent nature of knee pathology in these athletes [ 2 ]. Similarly, in a recent multicenter survey of university and professional volleyball players spanning multiple countries, 93% of male athletes experienced pain during at least one phase of the season [ 3 ]. Among the symptomatic regions, the knees were most commonly affected (31%), followed by the lumbar spine (21%) and the shoulders (19%), suggesting a broader, systemic vulnerability that often does not meet classical injury thresholds yet has profound implications for training capacity, biomechanics, and injury susceptibility. The etiology of these injuries is thought to be multifactorial and context-specific, but there has been recent attention toward the role of modifiable intrinsic risk factors. Functional asymmetries in neuromuscular control, unilateral strength, joint stability, and sensorimotor integration are notable among them, and they may collectively contribute to altered movement patterns, imbalanced loading, and micro-traumatic accumulation over time [ 4 , 5 ]. These asymmetries may remain subclinical in many cases, but accumulating evidence suggests that inter-limb asymmetries may reflect latent neuromuscular dysfunction. This could potentially lead to unequal force absorption and compromised frontal plane stability during athletic movements, thereby predisposing athletes to microtrauma, compensatory mechanics, pain, and ultimately, musculoskeletal injuries [ 6 ]. The predictive value of asymmetry indices has been widely explored, but results remain inconsistent due to methodological heterogeneity, so rigorous longitudinal analyses in well-defined athletic populations are required. To operationalize the identification of such asymmetries in field settings, several functional performance tests have gained widespread application in sports science and rehabilitation contexts. The star excursion balance test (SEBT) has been extensively validated for its ability to capture dynamic postural control across multiple planes. Prospective studies have indicated that anterior reach asymmetries > 4 cm or limb symmetry indices < 90% are predictive of increased risk for ankle sprains, anterior cruciate ligament injuries, and generalized lower extremity dysfunction [ 7 , 8 ]. Meanwhile, unilateral hop tests, such as the single-leg hop for distance and the 10-repetition side hop, have been established as robust indicators of explosive power, neuromuscular coordination, and load-absorption capacity. In clinical and return-to-sport protocols, limb symmetry index thresholds < 85–90% are frequently cited as markers of incomplete functional restoration or elevated risk for re-injury [ 9 , 10 ]. Despite their widespread use, it remains unclear whether baseline inter-limb asymmetries, as quantified by these field-based assessments, are prospectively associated with the development of musculoskeletal pain across an entire competitive season in male volleyball athletes. This gap is thought to be especially notable given that pain (though distinct from structural injury) can itself lead to altered kinematics, reduced proprioceptive acuity, and a cascade of compensatory strategies that predispose the athlete to more serious pathology. This study therefore examines whether pre-season asymmetries in performance-based functional tests—specifically the SEBT (anterior direction), single-leg hop for distance, and side hop test—are associated with the development of self-reported pain in male collegiate volleyball players throughout a full competitive season. By dividing athletes into pain and no-pain groups based on repeated biweekly questionnaire responses and comparing their baseline asymmetry indices, we aim to assess the prognostic value of inter-limb performance asymmetry as a low-cost, non-invasive screening tool for identifying athletes at elevated risk of pain-related musculoskeletal compromise. Methods Participants This preliminary study enrolled 27 male collegiate volleyball players (mean age = 20.6 ± 1.0 years) from a University of Commerce volleyball team. All athletes were actively participating in competitive team activities, and prior to enrollment, they all provided written informed consent. Sample Size Estimation This study was conducted as a preliminary investigation to explore potential associations between inter-limb functional asymmetry and pain development in collegiate volleyball players. Due to logistical constraints, no formal a priori sample size calculation was performed. Instead, the sample size was guided by recommendations for preliminary studies in the literature, which suggest 12–15 participants per group as an acceptable minimum to estimate variability and to inform future research [ 11 ]. The current study slightly fell below these benchmarks, but these findings are still thought to provide meaningful trends to inform larger-scale investigations. Study Design Baseline performance assessments were conducted during the preseason. Thereafter, participants completed pain surveillance questionnaires on a biweekly basis throughout the volleyball season. Based on the frequency of reported pain, some participants were divided into groups for comparative analysis: a pain group (reported pain in ≥ 80% of the questionnaires), and a no-pain group (no pain across all survey points). Participants with inconsistent or incomplete survey responses were excluded from the final analysis. Pain assessment Pain status was assessed every two weeks using a web-based questionnaire administered via Google Forms. Athletes reported the presence or absence of pain, the anatomical site of the pain, and the severity of pain using an 11-point numerical rating scale, ranging from 0 (no pain) to 10 (worst imaginable pain). Performance assessment All performance evaluations were conducted on a non-slip gymnasium floor under the supervision of trained examiners. A standardized warm-up consisting of dynamic mobility drills and submaximal jumping was completed prior to testing. The order of test execution was randomized across participants. Sufficient rest periods were provided between tests to minimize fatigue. Each test was performed bilaterally, and both raw values and inter-limb asymmetry were calculated. To quantify inter-limb asymmetry, we calculated the absolute asymmetry index (AI) for each test using the following formula: Asymmetry Index = |1 − (Left / Right)| , as commonly used in sports performance literature [ 5 ]. Higher values indicate greater asymmetry between limbs. Considerable variation in asymmetry calculation methods across studies has been reported, but ratio-based indices are thought to remain among the most interpretable and clinically applicable formats [ 6 ]. Star excursion balance test The SEBT was administered in the anterior direction only, which has been shown to strongly correlate with composite reach scores and dynamic balance capabilities [ 12 ]. Participants performed three trials per leg while maintaining single-leg stance and reaching forward with the contralateral leg. Reach distance was measured in centimeters and normalized by leg length, defined as the distance from the anterior superior iliac spine to the distal tip of the medial malleolus [ 13 ]. The mean of three valid attempts per limb was calculated, and the inter-limb asymmetry was then computed using the above AI formula. Side hop test To assess lateral agility and neuromuscular control, participants performed a 10-repetition side hop test. A 30-cm-wide line was marked with tape on the floor. Participants completed 10 consecutive lateral hops over the line on one leg, as quickly as possible. Two valid trials per leg were recorded, with the fastest time retained for analysis. Trials were invalidated if the participant lost balance or failed to cross the line [ 14 , 15 ]. Asymmetry in side hop performance was calculated using the absolute difference in hop time between limbs. Single-leg hop for distance Unilateral lower-limb power was assessed using the single-leg hop for distance test [ 16 ]. Athletes performed a maximal forward hop on one leg, attempting to land and stabilize on the same leg. Distance was measured from the toe at takeoff to the heel at landing. Trials were repeated if the contralateral foot touched the ground or if postural control was lost. Two valid trials per leg were recorded, with the greater distance used for analysis. Asymmetry was calculated using the absolute ratio-based index as described. Data Analysis All performance data were processed to compute raw scores for both limbs and inter-limb asymmetry indices. SEBT scores were normalized to leg length and expressed as percentages (%LL). Data distributions were tested for normality using the Shapiro–Wilk test. Independent t-tests were applied to normally distributed variables, while Mann–Whitney U tests were used for non-parametric data. Categorical variables were compared using chi-squared tests. Statistical significance was set at p < 0.05. All statistical analyses were performed using IBM SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA). Results Of the 27 enrolled volleyball players, one athlete was excluded from the study due to injury at baseline, resulting in a total of 26 participants being included in the final analysis. Nine athletes were allocated to the pain group and 10 to the no-pain group, based on biweekly pain surveillance conducted throughout the competitive season. Seven participants were excluded due to incomplete or ambiguous reporting. There were no significant differences between the groups in age, height, weight, or passive joint range of motion (all p -values > 0.05) (Table 1 ). Table 1 Group Comparisons of Demographic Characteristics, Pain Location, and Lower Extremity Performance Measures Between Athletes With and Without Pain Outcome All N = 19 Pain Group N = 9 No Pain Group N = 10 p value Age (years) 20.6 ± 1.0 20.8 ± 1.0 20.4 ± 1.1 0.31 BMI (kg/m2) 21.1 ± 1.8 22.6 ± 1.7 20.1 ± 0.9 0.14 Pain intensity 4.1 ± 1.9 4.1 ± 1.9 0 < 0.05 Pain location % Low back 5 (26.3) 5 (55.6) 0 knee 6 (31.6) 6 (66.7) 0 ankle 1 (5.2) 1 (11.1) 0 Single Hop (Right) (cm) 182.3 ± 21.8 181.9 ± 25.1 182.6 ± 19.8 0.24 Single Hop (Left) (cm) 194.0 ± 53.9 180.8 ± 20.4 207.2 ± 73.5 0.46 Normalized Single Hop (Right) 0.95 ± 0.08 1.01 ± 0.17 0.94 ± 0.09 0.24 Normalized Single Hop (Left) 0.98 ± 0.11 0.99 ± 0.13 0.96 ± 0.06 0.45 Side Hop (Right) (sec) 7.3 ± 1.2 7.0 ± 1.6 7.6 ± 0.6 0.44 Side Hop (Left) (sec) 7.8 ± 0.8 7.9 ± 1.0 7.8 ± 0.6 0.14 Normalized SEBT (Right) 0.6 ± 0.1 0.7 ± 0.2 0.6 ± 0.1 0.84 Normalized SEBT (Left) 0.6 ± 0.1 0.6 ± 0.1 0.6 ± 0.1 0.39 Hip Flexion (Right) 123.1 ± 10.9 121.8 ± 14.6 124.3 ± 6.2 0.67​ Hip Flexion (Left) 123.8 ± 8.5 122.50 ± 10.7 125.0 ± 6.0 0.57​ Hip Extension (Right) 18.8 ± 7.4 21.2 ± 9.2 16.2 ± 4.4 0.19​ Hip Extension (Left) 21.6 ± 8.9 26.2 ± 9.5 16.8 ± 5.3 0.08​ Hip External Rotation (Right) 45.6 ± 10.1 43.1 ± 11.0 48.1 ± 9.1 0.35​ Hip External Rotation (Left) 45.0 ± 9.8 43.1 ± 11.63 46.8 ± 8.0 0.47​ Hip Internal Rotation (Right) 38.8 ± 9.6 33.1 ± 3.72 44.3 ± 10.5 0.07​ Hip Internal Rotation (Left) 38.4 ± 7.9 36.2 ± 3.54 40.6 ± 10.5 0.29​ Ankle Dorsiflexion (Right) 16.9 ± 8.3 18.8 ± 9.9 15.0 ± 6.6 0.39​ Ankle Dorsiflexion (Left) 15.6 ± 7.7 16.8 ± 10.0 14.3 ± 5.0 0.54​ Ankle Plantarflexion (Right) 44.1 ± 7.6 41.9 ± 9.6 46.2 ± 4.4 0.27​ Ankle Plantarflexion (Left) 43.8 ± 8.5 42.5 ± 7.1 45.0 ± 10.0 0.57​ Ankle Inversion (Right) 22.5 ± 7.8 24.9 ± 7.5 20.1 ± 5.3 0.17​ Ankle Inversion (Left) 23.1 ± 10.1 25.6 ± 7.8 20.6 ± 12.1 0.34​ Ankle Eversion (Right) 11.9 ± 5.7 13.1 ± 4.6 10.6 ± 6.8 0.4​ Ankle Eversion (Left) 13.4 ± 6.5 15.6 ± 6.2 11.2 ± 6.4 0.19​ Average ± SD, SEBT: the Star Excursion Balance Test Functional performance and asymmetry Analysis revealed marked inter-limb asymmetry in the pain group across functional tasks. In SEBT, the AI, calculated as |1 − [Left/Right]|, was significantly greater in the pain group (0.29 ± 0.25) than in the no-pain group (0.04 ± 0.03; p = 0.04), despite these groups demonstrating comparable normalized reach distances. These results suggest that dynamic postural control may be less consistent between limbs among athletes who developed pain (Table 2 ). In the side hop test, the pain group exhibited greater asymmetry (AI: 0.13 ± 0.12 vs. 0.06 ± 0.04), but this difference was without statistical significance ( p = 0.203). Hop duration appeared to be longer in the pain group, but timing data were not consistently recorded and thus are not reported. In the single-leg hop for distance, the pain group again demonstrated numerically greater asymmetry (AI: 0.16 ± 0.17) than the no-pain group (0.04 ± 0.05), with a moderate effect size (Cohen’s d = 0.75), although this difference did not reach statistical significance ( p = 0.12). Collectively, we suggest these findings indicate that athletes who developed pain during the season exhibited significantly greater inter-limb asymmetry in dynamic balance (SEBT). There were non-significant but moderate-to-large trends toward greater asymmetry in lateral agility and unilateral power. Table 2 Comparison of Inter-Limb Asymmetry Indices in Dynamic Balance, Lateral Agility, and Unilateral Power Between Pain and No-Pain Groups Outcome Pain Group No Pain Group p value SEBT asymmetric ratio 0.29 ± 0.25 0.04 ± 0.03 0.04 Side hop test asymmetric ratio 0.13 ± 0.12 0.06 ± 0.04 0.20 Single hop test asymmetric ratio 0.16 ± 0.17 0.04 ± 0.05 0.12 SEBT: the Star Excursion Balance Test Discussion Athletes who reported persistent pain demonstrated significantly greater asymmetry in dynamic balance, as measured by the SEBT. Although asymmetries in lateral agility (side hop test) and unilateral power (single-leg hop for distance) did not reach statistical significance, the observed effect sizes nonetheless suggest potentially meaningful trends. These results partially align with those in existing literature. A previous systematic review of 28 prospective studies concluded that inter-limb asymmetry is a potential risk factor for sports injuries [ 6 ], though findings vary significantly due to heterogeneity in test protocols, injury definitions, and asymmetry calculations. This methodological variability may also explain the non-significant differences observed in the present hop-based assessments. In particular, while not statistically significant, the side hop test revealed a trend toward performance decrement and asymmetry in the pain group. This finding is consistent with published research into soccer and basketball populations, where lateral hop asymmetry has been linked to compromised knee valgus control and altered neuromuscular mechanics [ 15 ]. Furthermore, although a reported study focused on single-leg hop for distance [ 17 ], they emphasized that distance alone may not detect underlying functional deficits—particularly in knee power absorption and landing control—which are crucial during high-load, multidirectional movements such as the side hop. The underlying mechanisms linking asymmetry to pain development are thought to be multifactorial. Asymmetrical loading may impair frontal-plane stability and lead to uneven force distribution, neuromuscular compensation, and cumulative microtrauma [ 6 ]. These mechanisms are thought to be particularly salient in volleyball, a sport characterized by frequent single-leg landings, rapid lateral shifts, and high plyometric demand. Asymmetries in dynamic balance may reflect proprioceptive deficits, whereas disparities in hop performance may signify impairments in joint power, rate of force development, or neuromuscular coordination. In addition, functional asymmetries may impair movement efficiency, requiring increased neuromuscular effort and metabolic cost to maintain performance. Over time, such compensation may manifest as chronic overuse symptoms, particularly in commonly affected areas such as the patellar tendon, ankle ligaments, and lumbar spine. The findings from this study underscore the value of preseason asymmetry screening. Tests like SEBT and side hop are low-cost, field-based tools capable of detecting latent functional imbalances. Standardized asymmetry indices (e.g., |1 − [Left/Right]|) provide an objective means of monitoring athletes longitudinally. However, the lack of consensus on asymmetry definitions (absolute, percentage, ratio-based) remains a barrier to cross-study comparison [ 6 ]. Establishing standardized metrics and reporting reliability indices (e.g., ICC, coefficient of variation) will be critical for advancing the clinical utility of asymmetry-based screening. Limitations and future directions This study has several limitations. The sample size was modest and restricted to a single collegiate volleyball team, limiting generalizability. Pain was assessed via self-report rather than clinical diagnosis, which may have introduced potential bias. Also, failure to account for limb dominance or standardized injury classification may further complicate interpretation [ 6 ]. Despite these limitations, the observed asymmetry trends and the use of validated performance assessments provide preliminary evidence that may inform future prospective studies. To clarify the predictive validity of these indices in volleyball and other sports contexts, larger multicenter investigations that incorporate biomechanical and clinical markers, alongside asymmetry profiling, are warranted. Conclusion Greater inter-limb asymmetry in dynamic balance was found to be associated with frequent pain in a group of volleyball athletes. Functional asymmetry screening, especially in dynamic balance, might be useful for early detection of athletes at risk. Declarations Acknowledgements: We would like to acknowledge Ben for his assistance with English proofreading and editing. Conflict of Interest disclosure: The authors have no conflicts of interest to declare. Ethics approval: This study was approved by the Ethics Committee of Osaka Kawasaki Rehabilitation University (Approval No. OKRU-2024-012). Informed consent: Written informed consent was obtained from all individual participants aged 18 years or older included in the study. 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Cite Share Download PDF Status: Published Journal Publication published 05 Jan, 2026 Read the published version in Sport Sciences for Health → Version 1 posted Editorial decision: Revision requested 17 Nov, 2025 Reviews received at journal 12 Nov, 2025 Reviews received at journal 11 Nov, 2025 Reviewers agreed at journal 07 Nov, 2025 Reviews received at journal 04 Nov, 2025 Reviewers agreed at journal 04 Nov, 2025 Reviewers agreed at journal 30 Oct, 2025 Reviewers invited by journal 30 Oct, 2025 Editor assigned by journal 18 Aug, 2025 Submission checks completed at journal 18 Aug, 2025 First submitted to journal 14 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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18:50:48","extension":"html","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":86585,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7369965/v1/f83b11d9e5e47c6b8f2eff39.html"},{"id":100069343,"identity":"4d59d7ea-9b9b-4fb1-a809-8054654bd210","added_by":"auto","created_at":"2026-01-12 16:13:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":891825,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7369965/v1/460ba44b-2b05-420d-88a8-e103633e97f9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Inter-limb Functional Asymmetry and the Development of Pain in Collegiate Volleyball Players: A Preliminary Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eInjury prevention has long been considered important in the preservation of athlete health and the enhancement of performance sustainability. In high-impact sports such as volleyball, this principle holds particular relevance: athletes are repeatedly exposed to mechanical stressors including vertical jumping, abrupt landings, lateral cutting maneuvers, and overhead arm actions. Together, these are thought to impose cumulative loading on both the lower and upper extremities over time. Recent longitudinal epidemiological investigations targeting male collegiate volleyball players revealed the substantial burden of musculoskeletal injuries in this population. Notably, a five-year cohort study of Japanese university athletes identified lower-limb injuries (particularly those of overuse origin) as the predominant concern, with patellar tendinopathy and ankle sprains accounting for the majority of reported cases, and approximately 40% of all lower extremity complaints were attributed to the knees alone [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eElsewhere, in a prospective study of elite male volleyball players, 75% of participants reported symptoms consistent with \u0026lsquo;jumper\u0026rsquo;s knee\u0026rsquo; across a competitive season, and the incidence of clinically significant patellar tendinopathy reached 30% of athletes per season. These figures underscore the pervasive and recurrent nature of knee pathology in these athletes [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSimilarly, in a recent multicenter survey of university and professional volleyball players spanning multiple countries, 93% of male athletes experienced pain during at least one phase of the season [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Among the symptomatic regions, the knees were most commonly affected (31%), followed by the lumbar spine (21%) and the shoulders (19%), suggesting a broader, systemic vulnerability that often does not meet classical injury thresholds yet has profound implications for training capacity, biomechanics, and injury susceptibility.\u003c/p\u003e\u003cp\u003eThe etiology of these injuries is thought to be multifactorial and context-specific, but there has been recent attention toward the role of modifiable intrinsic risk factors. Functional asymmetries in neuromuscular control, unilateral strength, joint stability, and sensorimotor integration are notable among them, and they may collectively contribute to altered movement patterns, imbalanced loading, and micro-traumatic accumulation over time [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These asymmetries may remain subclinical in many cases, but accumulating evidence suggests that inter-limb asymmetries may reflect latent neuromuscular dysfunction. This could potentially lead to unequal force absorption and compromised frontal plane stability during athletic movements, thereby predisposing athletes to microtrauma, compensatory mechanics, pain, and ultimately, musculoskeletal injuries [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The predictive value of asymmetry indices has been widely explored, but results remain inconsistent due to methodological heterogeneity, so rigorous longitudinal analyses in well-defined athletic populations are required.\u003c/p\u003e\u003cp\u003eTo operationalize the identification of such asymmetries in field settings, several functional performance tests have gained widespread application in sports science and rehabilitation contexts. The star excursion balance test (SEBT) has been extensively validated for its ability to capture dynamic postural control across multiple planes. Prospective studies have indicated that anterior reach asymmetries\u0026thinsp;\u0026gt;\u0026thinsp;4 cm or limb symmetry indices\u0026thinsp;\u0026lt;\u0026thinsp;90% are predictive of increased risk for ankle sprains, anterior cruciate ligament injuries, and generalized lower extremity dysfunction [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Meanwhile, unilateral hop tests, such as the single-leg hop for distance and the 10-repetition side hop, have been established as robust indicators of explosive power, neuromuscular coordination, and load-absorption capacity. In clinical and return-to-sport protocols, limb symmetry index thresholds\u0026thinsp;\u0026lt;\u0026thinsp;85\u0026ndash;90% are frequently cited as markers of incomplete functional restoration or elevated risk for re-injury [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDespite their widespread use, it remains unclear whether baseline inter-limb asymmetries, as quantified by these field-based assessments, are prospectively associated with the development of musculoskeletal pain across an entire competitive season in male volleyball athletes.\u003c/p\u003e\u003cp\u003eThis gap is thought to be especially notable given that pain (though distinct from structural injury) can itself lead to altered kinematics, reduced proprioceptive acuity, and a cascade of compensatory strategies that predispose the athlete to more serious pathology.\u003c/p\u003e\u003cp\u003eThis study therefore examines whether pre-season asymmetries in performance-based functional tests\u0026mdash;specifically the SEBT (anterior direction), single-leg hop for distance, and side hop test\u0026mdash;are associated with the development of self-reported pain in male collegiate volleyball players throughout a full competitive season. By dividing athletes into pain and no-pain groups based on repeated biweekly questionnaire responses and comparing their baseline asymmetry indices, we aim to assess the prognostic value of inter-limb performance asymmetry as a low-cost, non-invasive screening tool for identifying athletes at elevated risk of pain-related musculoskeletal compromise.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eParticipants\u003c/h2\u003e\u003cp\u003eThis preliminary study enrolled 27 male collegiate volleyball players (mean age\u0026thinsp;=\u0026thinsp;20.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 years) from a University of Commerce volleyball team. All athletes were actively participating in competitive team activities, and prior to enrollment, they all provided written informed consent.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSample Size Estimation\u003c/h3\u003e\n\u003cp\u003eThis study was conducted as a preliminary investigation to explore potential associations between inter-limb functional asymmetry and pain development in collegiate volleyball players. Due to logistical constraints, no formal a priori sample size calculation was performed. Instead, the sample size was guided by recommendations for preliminary studies in the literature, which suggest 12\u0026ndash;15 participants per group as an acceptable minimum to estimate variability and to inform future research [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The current study slightly fell below these benchmarks, but these findings are still thought to provide meaningful trends to inform larger-scale investigations.\u003c/p\u003e\n\u003ch3\u003eStudy Design\u003c/h3\u003e\n\u003cp\u003eBaseline performance assessments were conducted during the preseason. Thereafter, participants completed pain surveillance questionnaires on a biweekly basis throughout the volleyball season. Based on the frequency of reported pain, some participants were divided into groups for comparative analysis: a pain group (reported pain in \u0026ge;\u0026thinsp;80% of the questionnaires), and a no-pain group (no pain across all survey points). Participants with inconsistent or incomplete survey responses were excluded from the final analysis.\u003c/p\u003e\n\u003ch3\u003ePain assessment\u003c/h3\u003e\n\u003cp\u003ePain status was assessed every two weeks using a web-based questionnaire administered via Google Forms. Athletes reported the presence or absence of pain, the anatomical site of the pain, and the severity of pain using an 11-point numerical rating scale, ranging from 0 (no pain) to 10 (worst imaginable pain).\u003c/p\u003e\n\u003ch3\u003ePerformance assessment\u003c/h3\u003e\n\u003cp\u003eAll performance evaluations were conducted on a non-slip gymnasium floor under the supervision of trained examiners. A standardized warm-up consisting of dynamic mobility drills and submaximal jumping was completed prior to testing. The order of test execution was randomized across participants. Sufficient rest periods were provided between tests to minimize fatigue. Each test was performed bilaterally, and both raw values and inter-limb asymmetry were calculated. To quantify inter-limb asymmetry, we calculated the absolute asymmetry index (AI) for each test using the following formula:\u003c/p\u003e\u003cp\u003e\u003cb\u003eAsymmetry Index = |1 \u0026minus; (Left / Right)|\u003c/b\u003e,\u003c/p\u003e\u003cp\u003eas commonly used in sports performance literature [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Higher values indicate greater asymmetry between limbs. Considerable variation in asymmetry calculation methods across studies has been reported, but ratio-based indices are thought to remain among the most interpretable and clinically applicable formats [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eStar excursion balance test\u003c/h2\u003e\u003cp\u003eThe SEBT was administered in the anterior direction only, which has been shown to strongly correlate with composite reach scores and dynamic balance capabilities [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Participants performed three trials per leg while maintaining single-leg stance and reaching forward with the contralateral leg. Reach distance was measured in centimeters and normalized by leg length, defined as the distance from the anterior superior iliac spine to the distal tip of the medial malleolus [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The mean of three valid attempts per limb was calculated, and the inter-limb asymmetry was then computed using the above AI formula.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSide hop test\u003c/h3\u003e\n\u003cp\u003eTo assess lateral agility and neuromuscular control, participants performed a 10-repetition side hop test. A 30-cm-wide line was marked with tape on the floor. Participants completed 10 consecutive lateral hops over the line on one leg, as quickly as possible. Two valid trials per leg were recorded, with the fastest time retained for analysis. Trials were invalidated if the participant lost balance or failed to cross the line [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Asymmetry in side hop performance was calculated using the absolute difference in hop time between limbs.\u003c/p\u003e\n\u003ch3\u003eSingle-leg hop for distance\u003c/h3\u003e\n\u003cp\u003eUnilateral lower-limb power was assessed using the single-leg hop for distance test [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Athletes performed a maximal forward hop on one leg, attempting to land and stabilize on the same leg. Distance was measured from the toe at takeoff to the heel at landing. Trials were repeated if the contralateral foot touched the ground or if postural control was lost. Two valid trials per leg were recorded, with the greater distance used for analysis. Asymmetry was calculated using the absolute ratio-based index as described.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eData Analysis\u003c/h2\u003e\u003cp\u003eAll performance data were processed to compute raw scores for both limbs and inter-limb asymmetry indices. SEBT scores were normalized to leg length and expressed as percentages (%LL). Data distributions were tested for normality using the Shapiro\u0026ndash;Wilk test. Independent t-tests were applied to normally distributed variables, while Mann\u0026ndash;Whitney U tests were used for non-parametric data. Categorical variables were compared using chi-squared tests. Statistical significance was set at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05. All statistical analyses were performed using IBM SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eOf the 27 enrolled volleyball players, one athlete was excluded from the study due to injury at baseline, resulting in a total of 26 participants being included in the final analysis. Nine athletes were allocated to the pain group and 10 to the no-pain group, based on biweekly pain surveillance conducted throughout the competitive season. Seven participants were excluded due to incomplete or ambiguous reporting. There were no significant differences between the groups in age, height, weight, or passive joint range of motion (all \u003cem\u003ep\u003c/em\u003e-values\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (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\u003eGroup Comparisons of Demographic Characteristics, Pain Location, and Lower Extremity Performance Measures Between Athletes With and Without Pain\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOutcome\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAll\u003c/p\u003e\u003cp\u003eN\u0026thinsp;=\u0026thinsp;19\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePain Group\u003c/p\u003e\u003cp\u003eN\u0026thinsp;=\u0026thinsp;9\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNo Pain Group\u003c/p\u003e\u003cp\u003eN\u0026thinsp;=\u0026thinsp;10\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\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\u003e\u003cb\u003eAge (years)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.31\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBMI (kg/m2)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePain intensity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePain location %\u003c/b\u003e\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\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLow back\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5 (26.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (55.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eknee\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6 (31.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6 (66.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eankle\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (5.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (11.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSingle Hop (Right) (cm)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e182.3\u0026thinsp;\u0026plusmn;\u0026thinsp;21.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e181.9\u0026thinsp;\u0026plusmn;\u0026thinsp;25.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e182.6\u0026thinsp;\u0026plusmn;\u0026thinsp;19.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSingle Hop (Left) (cm)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e194.0\u0026thinsp;\u0026plusmn;\u0026thinsp;53.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e180.8\u0026thinsp;\u0026plusmn;\u0026thinsp;20.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e207.2\u0026thinsp;\u0026plusmn;\u0026thinsp;73.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormalized Single Hop (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormalized Single Hop (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSide Hop (Right) (sec)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSide Hop (Left) (sec)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormalized SEBT (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.84\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormalized SEBT (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip Flexion (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e123.1\u0026thinsp;\u0026plusmn;\u0026thinsp;10.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e121.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e124.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.67​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip Flexion (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e123.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e122.50\u0026thinsp;\u0026plusmn;\u0026thinsp;10.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e125.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.57​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip Extension (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.19​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip Extension (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.6\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e26.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.08​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip External Rotation (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e45.6\u0026thinsp;\u0026plusmn;\u0026thinsp;10.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e43.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e48.1\u0026thinsp;\u0026plusmn;\u0026thinsp;9.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.35​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip External Rotation (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e45.0\u0026thinsp;\u0026plusmn;\u0026thinsp;9.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e43.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e46.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.47​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip Internal Rotation (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e38.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e33.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e44.3\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.07​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHip Internal Rotation (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e38.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e40.6\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.29​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Dorsiflexion (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e18.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e15.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.39​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Dorsiflexion (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.54​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Plantarflexion (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e44.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e46.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.27​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Plantarflexion (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e43.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e42.5\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e45.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.57​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Inversion (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22.5\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.17​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Inversion (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23.1\u0026thinsp;\u0026plusmn;\u0026thinsp;10.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20.6\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.34​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Eversion (Right)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.4​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnkle Eversion (Left)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.19​\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eAverage\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, SEBT: the Star Excursion Balance Test\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eFunctional performance and asymmetry\u003c/h2\u003e\u003cp\u003eAnalysis revealed marked inter-limb asymmetry in the pain group across functional tasks. In SEBT, the AI, calculated as |1 \u0026minus; [Left/Right]|, was significantly greater in the pain group (0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25) than in the no-pain group (0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04), despite these groups demonstrating comparable normalized reach distances. These results suggest that dynamic postural control may be less consistent between limbs among athletes who developed pain (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn the side hop test, the pain group exhibited greater asymmetry (AI: 0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12 vs. 0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04), but this difference was without statistical significance (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.203). Hop duration appeared to be longer in the pain group, but timing data were not consistently recorded and thus are not reported.\u003c/p\u003e\u003cp\u003eIn the single-leg hop for distance, the pain group again demonstrated numerically greater asymmetry (AI: 0.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17) than the no-pain group (0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05), with a moderate effect size (Cohen\u0026rsquo;s d\u0026thinsp;=\u0026thinsp;0.75), although this difference did not reach statistical significance (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.12).\u003c/p\u003e\u003cp\u003eCollectively, we suggest these findings indicate that athletes who developed pain during the season exhibited significantly greater inter-limb asymmetry in dynamic balance (SEBT). There were non-significant but moderate-to-large trends toward greater asymmetry in lateral agility and unilateral power.\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\u003eComparison of Inter-Limb Asymmetry Indices in Dynamic Balance, Lateral Agility, and Unilateral Power Between Pain and No-Pain Groups\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\u003eOutcome\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePain Group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNo Pain Group\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\u003e\u003cb\u003eSEBT asymmetric ratio\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.04\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSide hop test asymmetric ratio\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSingle hop test asymmetric ratio\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e0.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.12\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSEBT: the Star Excursion Balance Test\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\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eAthletes who reported persistent pain demonstrated significantly greater asymmetry in dynamic balance, as measured by the SEBT. Although asymmetries in lateral agility (side hop test) and unilateral power (single-leg hop for distance) did not reach statistical significance, the observed effect sizes nonetheless suggest potentially meaningful trends.\u003c/p\u003e\u003cp\u003eThese results partially align with those in existing literature. A previous systematic review of 28 prospective studies concluded that inter-limb asymmetry is a potential risk factor for sports injuries [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], though findings vary significantly due to heterogeneity in test protocols, injury definitions, and asymmetry calculations. This methodological variability may also explain the non-significant differences observed in the present hop-based assessments.\u003c/p\u003e\u003cp\u003eIn particular, while not statistically significant, the side hop test revealed a trend toward performance decrement and asymmetry in the pain group. This finding is consistent with published research into soccer and basketball populations, where lateral hop asymmetry has been linked to compromised knee valgus control and altered neuromuscular mechanics [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Furthermore, although a reported study focused on single-leg hop for distance [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], they emphasized that distance alone may not detect underlying functional deficits\u0026mdash;particularly in knee power absorption and landing control\u0026mdash;which are crucial during high-load, multidirectional movements such as the side hop.\u003c/p\u003e\u003cp\u003eThe underlying mechanisms linking asymmetry to pain development are thought to be multifactorial. Asymmetrical loading may impair frontal-plane stability and lead to uneven force distribution, neuromuscular compensation, and cumulative microtrauma [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. These mechanisms are thought to be particularly salient in volleyball, a sport characterized by frequent single-leg landings, rapid lateral shifts, and high plyometric demand. Asymmetries in dynamic balance may reflect proprioceptive deficits, whereas disparities in hop performance may signify impairments in joint power, rate of force development, or neuromuscular coordination.\u003c/p\u003e\u003cp\u003eIn addition, functional asymmetries may impair movement efficiency, requiring increased neuromuscular effort and metabolic cost to maintain performance. Over time, such compensation may manifest as chronic overuse symptoms, particularly in commonly affected areas such as the patellar tendon, ankle ligaments, and lumbar spine.\u003c/p\u003e\u003cp\u003eThe findings from this study underscore the value of preseason asymmetry screening. Tests like SEBT and side hop are low-cost, field-based tools capable of detecting latent functional imbalances. Standardized asymmetry indices (e.g., |1 \u0026minus; [Left/Right]|) provide an objective means of monitoring athletes longitudinally. However, the lack of consensus on asymmetry definitions (absolute, percentage, ratio-based) remains a barrier to cross-study comparison [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Establishing standardized metrics and reporting reliability indices (e.g., ICC, coefficient of variation) will be critical for advancing the clinical utility of asymmetry-based screening.\u003c/p\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eLimitations and future directions\u003c/h2\u003e\u003cp\u003eThis study has several limitations. The sample size was modest and restricted to a single collegiate volleyball team, limiting generalizability. Pain was assessed via self-report rather than clinical diagnosis, which may have introduced potential bias. Also, failure to account for limb dominance or standardized injury classification may further complicate interpretation [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDespite these limitations, the observed asymmetry trends and the use of validated performance assessments provide preliminary evidence that may inform future prospective studies. To clarify the predictive validity of these indices in volleyball and other sports contexts, larger multicenter investigations that incorporate biomechanical and clinical markers, alongside asymmetry profiling, are warranted.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eGreater inter-limb asymmetry in dynamic balance was found to be associated with frequent pain in a group of volleyball athletes. Functional asymmetry screening, especially in dynamic balance, might be useful for early detection of athletes at risk.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u0026nbsp;\u003c/strong\u003eWe would like to acknowledge Ben for his assistance with English proofreading and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest disclosure:\u0026nbsp;\u003c/strong\u003eThe authors have no conflicts of interest to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval:\u0026nbsp;\u003c/strong\u003eThis study was approved by the Ethics Committee of Osaka Kawasaki Rehabilitation University (Approval No. OKRU-2024-012).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent:\u0026nbsp;\u003c/strong\u003eWritten informed consent was obtained from all individual participants aged 18 years or older included in the study. The study procedures were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMuramoto Y, Kuruma H (2022) The Effectiveness of Trunk and Balance Warm-up Exercises in Prevention, Severity, and Length of Limitation From Overuse and Acute Lower Limb Injuries in Male Volleyball Players. 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British Journal of Sports Medicine 54:139\u0026ndash;153. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/bjsports-2018-099918\u003c/span\u003e\u003cspan address=\"10.1136/bjsports-2018-099918\" 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":"sport-sciences-for-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ssfh","sideBox":"Learn more about [Sport Sciences for Health](http://link.springer.com/journal/11332)","snPcode":"11332","submissionUrl":"https://submission.nature.com/new-submission/11332/3","title":"Sport Sciences for Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"asymmetry, athletes, pain, volleyball","lastPublishedDoi":"10.21203/rs.3.rs-7369965/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7369965/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\u003cp\u003eFunctional asymmetry is a potential risk factor for musculoskeletal pain in athletes, but how it affects volleyball players has not been widely investigated. We therefore aimed to explore the association between inter-limb asymmetry in performance-based tests and the development of lower extremity pain in collegiate volleyball players over a competitive season.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eIn this preliminary study, 26 male collegiate volleyball players (mean age\u0026thinsp;=\u0026thinsp;20.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 years) underwent preseason testing, including the star excursion balance test (anterior direction), side hop test, and single-leg hop for distance. Pain status was tracked on a biweekly basis using an online survey with an 11-point numerical rating scale. Based on reporting frequency, some athletes were classified into the pain group (pain reported on \u0026ge;\u0026thinsp;80% of surveys) or into the no-pain group (pain reported on 0%). Inter-limb asymmetry was calculated as |1 \u0026minus; (left/right)| for each performance test.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThere was significantly greater asymmetry in the star excursion balance test in the pain group (n\u0026thinsp;=\u0026thinsp;9; 0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25) than in the no-pain group (n\u0026thinsp;=\u0026thinsp;10; 0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.040). Overall trends towards higher asymmetry were seen in the pain group, but no significant differences between the groups were observed in the side hop test asymmetry index (pain group: 0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12, no-pain group: 0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.203) or single-leg hop asymmetry index (pain group: 0.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17, no-pain group: 0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.117).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eGreater inter-limb asymmetry in dynamic balance was associated with frequent pain in a group of volleyball athletes. Our preliminary findings suggest that functional asymmetry screening, especially in dynamic balance, might be useful for early detection of athletes who may be at risk of developing non-traumatic pain.\u003c/p\u003e\u003ch2\u003eTrial Registration\u003c/h2\u003e\u003cp\u003eUMIN000054720\u003c/p\u003e","manuscriptTitle":"Inter-limb Functional Asymmetry and the Development of Pain in Collegiate Volleyball Players: A Preliminary Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-11 18:50:43","doi":"10.21203/rs.3.rs-7369965/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-17T09:45:50+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-12T09:15:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-12T03:40:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"133818764658151034851053473833699758066","date":"2025-11-08T04:52:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-04T06:05:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"11684091805819720949449427303373277048","date":"2025-11-04T05:08:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"204935315904086635840733281199921909197","date":"2025-10-30T13:28:00+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-30T13:20:57+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-18T08:46:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-18T08:45:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"Sport Sciences for Health","date":"2025-08-14T05:12:42+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"sport-sciences-for-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ssfh","sideBox":"Learn more about [Sport Sciences for Health](http://link.springer.com/journal/11332)","snPcode":"11332","submissionUrl":"https://submission.nature.com/new-submission/11332/3","title":"Sport Sciences for Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"b10b831f-e609-478c-8819-1a28deafff49","owner":[],"postedDate":"November 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-12T16:04:17+00:00","versionOfRecord":{"articleIdentity":"rs-7369965","link":"https://doi.org/10.1007/s11332-025-01614-4","journal":{"identity":"sport-sciences-for-health","isVorOnly":false,"title":"Sport Sciences for Health"},"publishedOn":"2026-01-05 15:58:33","publishedOnDateReadable":"January 5th, 2026"},"versionCreatedAt":"2025-11-11 18:50:43","video":"","vorDoi":"10.1007/s11332-025-01614-4","vorDoiUrl":"https://doi.org/10.1007/s11332-025-01614-4","workflowStages":[]},"version":"v1","identity":"rs-7369965","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7369965","identity":"rs-7369965","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}