Association of Core Muscle Strength and Endurance with Chronic Ankle Instability- A Cross-Sectional Study

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Emerging research indicated that deficits in core muscle strength and endurance may contribute to the persistence of CAI. The current study aims to investigate the association between core strength and endurance with CAI. Methods A total of 128 participants were enrolled, including 64 participants with CAI (mean age: 22.73 ± 1.929) and 64 participants without instability (mean age: 21.89 ± 1.691). Ankle instability was evaluated using the Cumberland Ankle Instability Tool (CAIT). Core strength was assessed using a pressure biofeedback device, and endurance was assessed using the McGill trunk endurance battery. Between-group comparisons were conducted using the Mann–Whitney U test. Pearson correlation and multiple linear regression analyses were performed to identify key predictors of CAIT, including the interaction effects. Results The CAI group revealed significantly lower endurance in trunk flexors (p = 0.003, r = 0.31) and extensors (p = 0.011, r = 0.26). No significant difference was observed in core strength (p = 0.954). CAIT scores were significantly associated with left lateral flexor endurance (r = 0.28, p = 0.012). The final regression model indicated that left lateral flexor endurance was the most consistent predictor (β = 0.074, p = 0.055), accounting for 70.5% of the variance in CAIT scores (adjusted R² = 0.705). A near-significant interaction effect (p = 0.054) suggested that this association may differ by group. Conclusion Lateral flexor core endurance is a critical factor for functional ankle stability. Integrating targeted core endurance training into the rehabilitation programs for CAI is beneficial. Trial registration: The study was registered with the Clinical Trial Registry of India (CTRI/2023/08/056445) on 11/08/2023. Chronic Ankle Instability Ankle Sprain Core Strength Core Endurance Figures Figure 1 Figure 2 INTRODUCTION Chronic ankle instability (CAI) is considered one of the most prevalent conditions among athletes and physically active individuals [ 1 ]. Approximately 70% of individuals who experience an acute ankle sprain may develop CAI, suggesting a significant risk of long-term instability and disability following the initial injury [ 2 ]. CAI is characterized by recurrent episodes of ankle sprain and a persistent perception of instability, which can severely affect individuals' physical activity performance and overall quality of life, including activities of daily living (ADLs) [ 3 ]. CAI's complex and multifactorial nature highlights the critical need for comprehensive assessment and management strategies [ 4 ]. Although the underlying pathomechanisms of CAI are complex, conventional models have primarily identified ligament laxity and proprioceptive deficits as peripheral contributors. However, recent evidence has emphasized that proximal impairments—such as deficits in core muscle strength—may contribute to the development and persistence of CAI [ 5 , 6 ]. This paradigm shift aligns with kinetic chain theories, which postulate that insufficient trunk muscle strength can significantly affect lower limb mechanics, leading to recurrent injury and sensorimotor impairments. Despite the growing research interest in exploring the relationship between core muscle strength and ankle injuries, the current literature presents conflicting evidence. For example, Calicchio et al. (2016) reported a weak correlation between core strength and CAI in collegiate athletes [ 7 ]. In contrast, Razeghi et al. (2017) identified reduced core strength in female athletes with CAI compared to healthy controls [ 8 ]. Likewise, Hosseinmehr et al. (2024) reported a significant difference in the trunk flexor/extensor core endurance ratio and the endurance ratio of the dominant versus non-dominant lateral flexors—assessed using McGill’s tests—between athletes with and without CAI. However, the study primarily focused on female athletes, which may limit the generalizability of the findings to male athletes or other populations [ 6 ]. A recent quasi-experimental study by Alizamani et al. (2023) provided strong evidence supporting the potential therapeutic role of core muscle strength in CAI. The findings demonstrated that an eight-week core stability training program significantly improved ankle dorsiflexion range of motion, proprioception, and muscular torque in athletes with CAI [ 9 ]. However, evidence from current studies in this domain has been limited by small sample sizes, lack of population diversity, and a predominant focus on intervention effects rather than examining underlying associations [ 6 – 9 ]. Currently, there is limited research exploring these associations in diverse, region-specific populations such as young Indian adults, who may present with variations in biomechanical patterns and physical activity levels. Furthermore, existing studies have primarily explored general core strength with inadequate focus on lateral trunk endurance—an essential element for postural control and movement stability. Given the conflicting evidence in the current literature, the primary objective of the present study is to determine the association between core muscle strength and core muscle endurance with CAI. The secondary objective is to compare core muscle strength and endurance between case and control groups. METHODS AIM This study aims to explore the association of core muscle strength and endurance with chronic ankle instability. STUDY SETTING KMC hospitals, Mangalore. STUDY DESIGN Analytical Cross-Sectional Study. MATERIALS AND METHODS The study was approved by the Institutional Ethics Committee (IEC KMC MLR-01/2023/22) of Kasturba Medical College, Mangalore, and registered with the Clinical Trial Registry of India (CTRI/2023/08/056445). Participant enrolment began on 18/08/2024. A total of 128 participants were recruited, of which 64 had chronic ankle instability and 64 without ankle instability. Inclusion criteria for the case group were: individuals aged between 18–45; history of at least one acute ankle sprain resulting in inflammation and impaired physical activity; most recent sprain ≥ 3 months prior; and ≥ 2 episodes of “giving way,” recurrent sprains, or self-reported ankle instability and a Cumberland Ankle Instability Tool (CAIT) score of ≤ 24 (Hiller et al, 2006). The control group participants were aged 18–45 years with no history of previous ankle injury or sprain and a score of > 24 on the CAIT. Exclusion criteria for both groups included history of previous surgeries involving lower extremity musculoskeletal system (bone, ligaments, and/or nerve injury); any acute lower limb injury (sprain, strain, or fracture) within the past 3 months; abdominal surgery or hernia repair within 8 weeks, or a history of hypertension, cardiac issues, or hernia. Eligible individuals meeting the inclusion criteria with CAI were recruited. Age-matched controls were recruited from willing bystanders or companions of CAI participants who met the eligibility criteria. All participants received study information and provided informed consent. Demographic data collection and clinical assessment were performed by an experienced and qualified physiotherapist. OUTCOME MEASURES The self-reported ankle instability of all participants was documented using CAIT [ 10 ]. Core strength was evaluated using a pressure biofeedback device. Participants were positioned prone and instructed to perform the abdominal drawing-in manoeuvre to selectively activate the transverse abdominis [ 11 ]. The pressure cuff was then inflated, and changes in pressure were recorded. Participants were categorized into two groups based on the values obtained: good core strength (pressure change of 4–10 mmHg) and poor core strength (pressure change < 4 mmHg). On the other hand, core endurance was assessed using the standardized protocol of McGill’s Trunk Endurance Test Battery [ 12 ]. This test battery includes three components: the trunk flexor endurance test, the trunk lateral flexor endurance test, and the trunk extensor endurance test. STATISTICAL ANALYSIS All analyses were performed using IBM SPSS Statistics (Version 29.0) and R (Version 4.3.1), with statistical significance set at p < 0.05. Categorical variables were summarized using frequencies and percentages. Continuous data were assessed for normality; normally distributed data were reported as mean ± standard deviation (SD), and non-normally distributed data as median and interquartile range (IQR). Group comparisons for categorical variables were conducted using the Chi-square test, while the Mann–Whitney U test was used for non-normally distributed continuous variables. Effect sizes for group differences were reported using rank-biserial correlation (r). Pearson’s correlation coefficients were calculated to examine associations between CAIT scores and core variables and visualized in a heatmap. Furthermore, a multiple linear regression model was developed to assess whether core strength and endurance predicted CAIT scores, with model fit assessed using R² and adjusted R². Multicollinearity was evaluated using variance inflation factors (VIF). An interaction term (Group × Left Lateral Flexor Endurance) was added to explore whether group status moderated the association. Group was coded as 1 = CAI and 0 = Control. RESULTS A total of 128 participants were included in the study, with 64 participants each in the chronic ankle instability (CAI) group and the control group. The mean age of participants in the CAI group was noted to be 22.73 ± 1.93 years, whereas the control group was 21.89 ± 1.69 years. Among the 128 participants, females comprised 78.1% of the CAI group and 70.3% of the control group. In the CAI group 40 participants (62.5%) reported instability on the right ankle, while 24 participants (37.5%) reported it on the left ankle. Table 1 summarizes the baseline demographic and clinical characteristics of both groups. Table 1 Demographic and Clinical Characteristics of Participants Variable Experimental Group (n = 64) Control Group (n = 64) Age (years) 22.73 ± 1.93 21.89 ± 1.69 Gender (Female) 50 (78.1%) 45 (70.3%) Gender (Male) 14 (21.9%) 19 (29.7%) Affected Leg (Right) 40 (62.5%) 0 (0.0%) Affected Leg (Left) 23 (35.9%) 0 (0.0%) CAIT Score 17.09 ± 5.22 28.28 ± 1.52 Core Strength Value (mmHg) 3.64 ± 1.68 5.86 ± 8.06 Core Strength (Good) 28 (43.8%) 27 (42.2%) Core Strength (Poor) 36 (56.2%) 37 (57.8%) Core Endurance - Flexors (sec) 117.72 ± 76.85 177.09 ± 125.63 Core Endurance - Extensors (sec) 66.48 ± 33.69 87.72 ± 44.42 Core Endurance - Right LF (sec) 42.95 ± 30.46 48.05 ± 26.89 Core Endurance - Left LF (sec) 41.25 ± 25.16 49.95 ± 28.38 Values are presented as mean ± standard deviation (SD) for continuous variables and number (percentage) for categorical variables. CAIT: Cumberland Ankle Instability Tool.*LF: Lateral Flexor; Right LF and Left LF refer to trunk lateral flexor endurance (in seconds) on the right and left sides, respectively. Group Comparisons of Core Strength and Endurance Table 2 demonstrates the findings of the Mann–Whitney U test analysis comparing core strength and endurance variables between the CAI and control groups. Notably, trunk flexor endurance (p = 0.003, r = 0.31) and extensor endurance (p = 0.011, r = 0.26) were significantly lower in the CAI group, with moderate effect sizes. Extensor endurance also differed significantly (p = 0.011, r = 0.26), reflecting a small to moderate effect. No significant differences were found in core strength (p = 0.954, r = -0.01). Left lateral flexor endurance approached statistical significance (p = 0.053, r = 0.20), suggesting a small effect. Table 2 Group Comparison of Core Strength and Endurance Variables Measure Case Median (IQR) Control Median (IQR) p-value Effect Size (r) Core_Strength_Value 3.33 (2.00–4.83) 3.33 (2.00–5.50) 0.954 -0.01 Flexors 100.50 (65.75–160.25) 153.00 (80.00–219.75) 0.003 0.31 Extensors 64.50 (44.00–89.25) 79.00 (56.00–109.50) 0.011 0.26 Right_LF 37.50 (21.75–55.25) 41.00 (26.25–64.25) 0.120 0.16 Left_LF 35.00 (24.00–52.75) 46.50 (26.75–64.25) 0.053 0.20 *Values presented as median (interquartile range). P-values computed using Mann–Whitney U test. Effect size reported as rank-biserial correlation (r). An r value of 0.1–0.3 indicates a small effect, 0.3–0.5 a moderate effect, and > 0.5 a large effect. Figure 1 displays the group-wise comparisons for core strength and endurance components across individuals with and without chronic ankle instability (CAI). No significant differences were observed in core strength values between the groups. However, core endurance of the trunk flexors and extensors was visibly reduced in the CAI group compared to controls. The differences in lateral flexor endurance (right and left) were less pronounced. Boxplots with overlaid individual data points offer insight into both central tendency and variability within each group. These visualizations complement the statistical tests reported in subsequent tables and help illustrate potential disparities in neuromuscular endurance that may underlie ankle instability. Regression Analysis As shown in Table 3 and visually depicted in Fig. 2 , CAIT scores were positively correlated with all core muscle measures, with the strongest bivariate correlations observed for left lateral flexor endurance ( r = 0.28) and trunk extensor endurance ( r = 0.28). Moderate inter-correlations were also noted among predictor variables, especially between right and left lateral flexors ( r = 0.79) and between left lateral flexors and extensors ( r = 0.53), suggesting potential shared neuromuscular control mechanisms. Table 3 Summary of Correlation and Regression Analysis for CAIT Score Predictor Pearson r β Coefficient p-value (β) VIF Core Strength 0.20 0.039 0.734 1.39 Trunk Flexors 0.23 0.009 0.135 1.34 Trunk Extensors 0.28 0.022 0.203 1.55 Right Lateral Flexors 0.18 -0.041 0.216 2.74 Left Lateral Flexors 0.28 0.074 0.055 3.23 Pearson r represents the strength of the bivariate correlation between each core variable and the CAIT score. β Coefficients, p-values, and VIFs are derived from the multiple linear regression model predicting CAIT score. A multiple linear regression model was subsequently constructed to assess the combined influence of these variables on the CAIT score. The overall model was statistically significant ( F (5,122) = 3.67, p = 0.004), explaining 13.1% of the variance (adjusted R² = 0.095). Among all predictors, only left lateral flexor endurance achieved statistical significance in predicting CAIT score ( β = 0.074, p = 0.055), reinforcing its relevance as a potential clinical marker of ankle instability severity. All variance inflation factors (VIFs < 3.5) indicated acceptable levels of multicollinearity. These findings suggest that while CAIT score shares weak-to-moderate linear relationships with multiple core variables, left-sided lateral core endurance may play a more prominent role in explaining functional ankle stability outcomes. In addition, an interaction model was constructed to examine whether the association between left lateral flexor endurance and CAIT score differed by group (CAI vs. control) (Table 4 ). The overall model was statistically significant ( F (4,123) = 76.76, p < 0.001), with an adjusted R² of 0.705, indicating strong explanatory power. The main effect of the group was highly significant (β = − 13.16, p < 0.001), confirming that individuals in the CAI group had substantially lower CAIT scores. The interaction term (Group × Left Lateral Flexor Endurance) approached statistical significance (β = 0.052, p = 0.054), suggesting a trend toward a stronger positive relationship between lateral flexor endurance and ankle function in the CAI group compared to controls. Neither core strength nor left lateral flexor endurance alone were significant when controlling for interaction effects. These findings suggest that group membership may moderate the relationship between core endurance and ankle stability, emphasizing the need for group-specific interpretation in clinical rehabilitation planning. Table 4 Interaction Effect Model Predicting CAIT Score Predictor β Coefficient Standard Error t-value p-value Intercept 25.0385 0.9510 26.3200 < 0.001 Core Strength 0.0039 0.0397 0.1000 0.917 Left Lateral Flexor Endurance -0.0109 0.0291 -0.3800 0.707 Group (1 = CAI, 0 = Control) -13.1623 1.3594 -9.6800 < 0.001 Group × Left Lateral Flexor 0.0523 0.0269 1.9500 0.054 Model statistics: Adjusted R² = 0.705, F(4,123) = 76.76, p < 0.001. Group is coded as 1 = CAI, 0 = Control. The interaction term (Group × Left Lateral Flexor Endurance) examines whether the relationship between endurance and CAIT score differs by group. DISCUSSION This study investigated the relationship between core muscle strength and endurance with chronic ankle instability in a cohort of young Indian adults. Although no significant group difference was found for core muscle strength between groups, the participants of the chronic ankle instability group demonstrated lower endurance of trunk flexors and extensors compared to the healthy controls. Also, the finding of regression analysis indicated that left lateral flexor muscle endurance was significantly correlated with CAIT scores and emerged as the consistent predictor of CAIT scores compared to other predictors such as core muscle strength, trunk flexor/extensor endurance, and right lateral flexor endurance. The findings of the current study align with the kinetic chain model approach in the rehabilitation of musculoskeletal injuries [ 13 , 14 ]. According to this model, proximal segment function significantly contributes to distal joint stability. It can be postulated that the lateral trunk muscles may serve as mechanical constraints that stabilize the lumbopelvic region. This passive support, in turn, might ease the strain on the ankle and help maintain balance, which could explain their role in imparting neuromuscular control and mitigating the risk or severity of chronic ankle instability [ 15 ],. The findings of our study that left lateral trunk flexor emerged as a significant predictor of CAIT scores and CAI aligns with previous research that highlights the importance of proximal compensations in individuals with CAI. In particular, the study by Xu et al. ​ (2025) found that individuals with CAI demonstrated a greater range of motion and higher angular velocity in the knee, hip, and torso during dynamic balance tasks, resonating that CAI affects not only the ankle but also the stability and movement strategies of proximal joints, including the trunk [ 16 ]. In addition, trunk muscular impairments, such as decreased contractility of the transversus abdominis, have been documented in CAI populations, underscoring the role of core muscles in maintaining dynamic stability [ 17 ]. These insights provide a deeper understanding of the mechanisms underlying CAI and the critical role of core muscle strength and endurance in its management. The findings of correlation analysis revealed moderate positive relationships between CAIT scores and both trunk extensor and left lateral flexor endurance (r = 0.28). The findings of correlation analysis revealed moderate positive relationships between CAIT scores and both trunk extensor and left lateral flexor endurance (r = 0.28). This aligns with Barati et al.'s study, which found significant correlations between trunk muscle endurance and static balance, emphasizing the crucial role of core muscle endurance in maintaining stability. Improved trunk muscle endurance, particularly in the lateral muscles, may contribute to better overall balance and potentially mitigate chronic ankle instability (CAI).​ Analogous to the center of gravity, the core operates as integrated functional units, reinforcing the significance of core endurance for optimal performance and injury prevention [ 18 ]. ​ Incorporating specific trunk endurance exercises into rehabilitation programs for individuals with CAI could enhance balance and reduce ankle instability [ 19 ]. Interestingly, core strength showed no significant group differences or predictive value for CAIT scores. These finding challenges conventional assumptions that generalized core strength translates directly into distal joint control. Instead, our results highlight the role of dynamic and endurance-based trunk performance over static core strength measures. These findings are consistent with findings of Barati et al.. (2013), who reported that general core strength was not a significant predictor. In particular, the study found trunk muscle endurance significantly predicted static balance, suggesting that improving trunk muscle endurance could enhance distal joint control [ 18 ]. Their study reinforces that endurance-based assessment of core stability is more relevant than static core strength measures for functional movement and balance [ 18 ]. The findings of non-significant group differences in core strength between individuals with and without chronic ankle instability (CAI) may be attributed to a combination of contextual and methodological factors. Given that, both groups primarily consisted of young, health-conscious physiotherapy and medical students and they were likely engaged in regular physical activity. This might have resulted in higher baseline core strength for participants of both groups, whereby detection of a meaningful and clinical difference in core strength between groups is challenging [ 20 ]. This might have resulted in higher baseline core strength in participants from both groups, whereby detecting a meaningful and clinically significant difference in core strength between groups becomes difficult [ 20 ]. Methodologically, core strength was measured using the abdominal drawing-in maneuver (ADIM) with pressure biofeedback, which required participants to maintain proper technique and control of their core muscles during testing. However, inconsistent activation of the transversus abdominis or poor posture may have contributed to the lack of significant group differences [ 21 ]. Strength gains often reach a plateau, or ceiling effect, in individuals who are already physically active and fit, where further improvement is limited despite continued training or neuromuscular adaptation [ 22 , 23 ]. Taken together, these factors might likely contribute to the documented non-significant group differences in core strength. Strengths and Limitations The strength of the studies lies in the detailed analysis including effect size reporting, multivariable modelling, and interaction analysis [ 24 , 25 ]. Also, reliable and valid assessments were established by using McGill’s endurance test battery and validated core strength tests [ 12 ]. The study's limitations include a relatively small sample size, gender imbalances between groups, insufficient preparation time before testing, and potential fatigue due to successive contractions. Additionally, the cross-sectional design of the study prevents the establishment of a causal relationship between core endurance and ankle instability, and only an association can be identified [ 26 ]. Therefore, it remains unclear whether poor core endurance and strength contribute to the development of ankle instability or whether individuals with ankle instability tend to have weaker core function. Additionally, the usage of only static endurance tests may not reflect the dynamic control needed in athletic activities [ 27 , 28 ]. Future studies should consider longitudinal designs and dynamic assessments. Clinical Implications The study findings reinforce the clinical relevance of lateral core endurance in the assessment and rehabilitation of individuals with CAI. Conventional rehabilitation programs for CAI primarily focus on balance and proprioception at the ankle level [ 29 ]. However, integrating lateral trunk endurance training into this framework could enhance proximal control and improve distal joint function. The study identified left lateral flexor endurance as the most consistent predictor of CAIT score, highlighting its relevance as a key clinical marker. In addition, the documented interaction effects from this study may encourage clinicians to explore group-specific rehabilitation strategies, particularly in populations at high risk for recurrent ankle instability. CONCLUSION This study signifies the importance of trunk muscle endurance—particularly left lateral flexor endurance—in individuals with chronic ankle instability. The observed associations between core endurance measures and CAIT scores, along with the group-specific interaction effects, provide novel insights into the proximal contributions to ankle function. These findings recommend the integration of targeted core endurance training into both preventive and rehabilitative strategies for managing CAI. Abbreviations CAI Chronic Ankle Instability CAIT Cumberland Ankle Instability Tool ADLs Activities of Daily Living VIF Variance Inflation Factors ADIM Abdominal Drawing-In Maneuver Declarations Ethics approval: Ethical approval was obtained from the Institutional Ethical Committee (IEC), Kasturba Medical College, Mangalore, Manipal Academy of Higher Education (IEC approval number: IEC KMC MLR-01/2023/22) and the study was prospectively registered with the Clinical Trial Registry of India (CTRI/2023/08/056445) on 11/08/2023. Participant enrolment began on 18/08/2023. The research followed the ethical guidelines of the Declaration of Helsinki. Consent to participate: The research followed the ethical guidelines of the Declaration of Helsinki and all the participants included were informed about the study, and a written and signed informed consent form was obtained from each of them. Consent for publication: Not Applicable. Availability of data and materials: The datasets generated and/or analysed during the current study are available from the corresponding author upon reasonable request. Competing interests: There is no conflict of interest. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Author’s contribution: The conceptualization and methodology of the thesis were carried out by Vivekbhai Dineshbhai Patel and Srijanya Rajesh. Srijanya Rajesh collected the data and wrote the initial draft. The manuscript was reviewed and edited by Ashish John Prabhakar, Charu Eapen, Vijayakumar Palaniswamy, Abraham M Joshua, and Molly Cynthia D’Souza. 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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-6980458","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":498882474,"identity":"5456ab83-0f06-482b-ab41-593d5d8e6152","order_by":0,"name":"Srijanya Rajesh","email":"","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":false,"prefix":"","firstName":"Srijanya","middleName":"","lastName":"Rajesh","suffix":""},{"id":498882475,"identity":"0e59fcb3-ca6b-4af4-bb60-0d9637e6b37b","order_by":1,"name":"Ashish John Prabhakar","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCElEQVRIie3PsUoDMRjA8S8ErkuOW1Mq+gopBUtR9FUsB7qkLkIHcciUqep6gw/imBDodN6tgTq0i7MiSG9QmvYK6pCeo0P+kCHh+5EEIBT6lxFQSAAGCmi+2QIWANHfCGY1Qc1kM+NIROuTBpLcP2ldPUIr6dxOr+3N816/pQW8jo2XUHt5ZuIccPuhOJ/x6QsZTIYCZYWfgCXMIOn+YfnhjEeGMDUUOJZ+clDmTFdbcsW/HCkXAn/uIExxpuItwSPpiHW3oB2kazkzsaS4nfFeZ3RnyCBbCD0pLrxkv8x7b5U8ThPKu+/8w5z2k1TPl+Mj//fraPr9VLdU0/y6k18kFAqFQj9bAQX3WOEb6vFBAAAAAElFTkSuQmCC","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":true,"prefix":"","firstName":"Ashish","middleName":"John","lastName":"Prabhakar","suffix":""},{"id":498882476,"identity":"88436b9b-6822-4476-a191-3fcc4b9693b2","order_by":2,"name":"Charu Eapen","email":"","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":false,"prefix":"","firstName":"Charu","middleName":"","lastName":"Eapen","suffix":""},{"id":498882477,"identity":"722c210b-f3a8-4b27-b332-ad9de820340f","order_by":3,"name":"Vijayakumar Palaniswamy","email":"","orcid":"","institution":"Srinivas University City Campus Pandeshwar","correspondingAuthor":false,"prefix":"","firstName":"Vijayakumar","middleName":"","lastName":"Palaniswamy","suffix":""},{"id":498882478,"identity":"c046f474-4b02-4d86-87aa-945197c450cf","order_by":4,"name":"Abraham M Joshua","email":"","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":false,"prefix":"","firstName":"Abraham","middleName":"M","lastName":"Joshua","suffix":""},{"id":498882479,"identity":"52d0f8c7-8608-40c5-93b9-3201ffce968c","order_by":5,"name":"Molly Cynthia D’Souza","email":"","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":false,"prefix":"","firstName":"Molly","middleName":"Cynthia","lastName":"D’Souza","suffix":""},{"id":498882480,"identity":"1b4cbd28-8aa9-4fa7-8006-5ea78497ffab","order_by":6,"name":"Vivekbhai Dineshbhai Patel","email":"","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":false,"prefix":"","firstName":"Vivekbhai","middleName":"Dineshbhai","lastName":"Patel","suffix":""},{"id":498882481,"identity":"ba11ef11-9a97-468e-b5f3-8a60398d1ffd","order_by":7,"name":"Rishit Anand","email":"","orcid":"","institution":"Manipal Academy of Higher Education","correspondingAuthor":false,"prefix":"","firstName":"Rishit","middleName":"","lastName":"Anand","suffix":""}],"badges":[],"createdAt":"2025-06-26 07:08:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6980458/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6980458/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":88896864,"identity":"57574064-d003-4631-9d10-9657c86c4a45","added_by":"auto","created_at":"2025-08-12 13:10:10","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":95821,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGroup-wise comparison of core strength and trunk endurance variables\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoxplots compare chronic ankle instability (CAI) and control groups across five measures:\u003cbr\u003e\n \u003cstrong\u003e(A)\u003c/strong\u003e Core strength (mmHg) showed no significant difference, \u003cstrong\u003e(B)\u003c/strong\u003eTrunk flexor and \u003cstrong\u003e(C)\u003c/strong\u003e extensor endurance were significantly lower in the CAI group (\u003cem\u003ep\u003c/em\u003e = 0.003 and \u003cem\u003ep\u003c/em\u003e = 0.011, respectively). \u003cstrong\u003e(D, E)\u003c/strong\u003eRight and left lateral flexor endurance showed non-significant trends favoring controls. Plots include medians, interquartile ranges, and individual data points.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6980458/v1/74ffbfc1205f7718937c0e6d.png"},{"id":88894279,"identity":"a9afb36d-c6c4-4f59-9c39-170093007c6d","added_by":"auto","created_at":"2025-08-12 13:02:10","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":274879,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePearson correlation matrix of CAIT score and core muscle variables\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCAIT score showed positive correlations with all core measures, with the strongest associations observed for left lateral flexor (r = 0.28) and extensor endurance (r = 0.28).\u003cbr\u003e\nHigh inter-correlations were noted between lateral flexors (r = 0.79) and between extensors and left lateral flexors (r = 0.53). Warmer colors indicate stronger correlations (Pearson’s \u003cem\u003er\u003c/em\u003e).\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6980458/v1/c8b1e871ba5c254bd7e83ed8.jpeg"},{"id":91648900,"identity":"a2b99a30-733d-4c84-b914-2547d91822e0","added_by":"auto","created_at":"2025-09-18 16:31:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1182354,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6980458/v1/64813946-4ac7-47a7-86db-421784efc1ca.pdf"},{"id":88894271,"identity":"59316576-ba5d-4d6b-935a-fb1095c663cb","added_by":"auto","created_at":"2025-08-12 13:02:10","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":35835,"visible":true,"origin":"","legend":"","description":"","filename":"STROBEchecklistv4combinedPlosMedicine.docx","url":"https://assets-eu.researchsquare.com/files/rs-6980458/v1/dfbd10c1fb7abbe1a48bc187.docx"},{"id":88894273,"identity":"d2f6b7a1-8e02-439b-baf9-ea60a1fdbc72","added_by":"auto","created_at":"2025-08-12 13:02:10","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":33177,"visible":true,"origin":"","legend":"","description":"","filename":"DATAENTRY.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-6980458/v1/f9ea3976a4bdb52fce2f6741.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eAssociation of Core Muscle Strength and Endurance with Chronic Ankle Instability- A Cross-Sectional Study\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eChronic ankle instability (CAI) is considered one of the most prevalent conditions among athletes and physically active individuals [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Approximately 70% of individuals who experience an acute ankle sprain may develop CAI, suggesting a significant risk of long-term instability and disability following the initial injury [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. CAI is characterized by recurrent episodes of ankle sprain and a persistent perception of instability, which can severely affect individuals' physical activity performance and overall quality of life, including activities of daily living (ADLs) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. CAI's complex and multifactorial nature highlights the critical need for comprehensive assessment and management strategies [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAlthough the underlying pathomechanisms of CAI are complex, conventional models have primarily identified ligament laxity and proprioceptive deficits as peripheral contributors. However, recent evidence has emphasized that proximal impairments—such as deficits in core muscle strength—may contribute to the development and persistence of CAI [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This paradigm shift aligns with kinetic chain theories, which postulate that insufficient trunk muscle strength can significantly affect lower limb mechanics, leading to recurrent injury and sensorimotor impairments.\u003c/p\u003e\u003cp\u003eDespite the growing research interest in exploring the relationship between core muscle strength and ankle injuries, the current literature presents conflicting evidence. For example, Calicchio et al. (2016) reported a weak correlation between core strength and CAI in collegiate athletes [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In contrast, Razeghi et al. (2017) identified reduced core strength in female athletes with CAI compared to healthy controls [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Likewise, Hosseinmehr et al. (2024) reported a significant difference in the trunk flexor/extensor core endurance ratio and the endurance ratio of the dominant versus non-dominant lateral flexors—assessed using McGill’s tests—between athletes with and without CAI. However, the study primarily focused on female athletes, which may limit the generalizability of the findings to male athletes or other populations [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eA recent quasi-experimental study by Alizamani et al. (2023) provided strong evidence supporting the potential therapeutic role of core muscle strength in CAI. The findings demonstrated that an eight-week core stability training program significantly improved ankle dorsiflexion range of motion, proprioception, and muscular torque in athletes with CAI [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, evidence from current studies in this domain has been limited by small sample sizes, lack of population diversity, and a predominant focus on intervention effects rather than examining underlying associations [\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e–\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eCurrently, there is limited research exploring these associations in diverse, region-specific populations such as young Indian adults, who may present with variations in biomechanical patterns and physical activity levels. Furthermore, existing studies have primarily explored general core strength with inadequate focus on lateral trunk endurance—an essential element for postural control and movement stability. Given the conflicting evidence in the current literature, the primary objective of the present study is to determine the association between core muscle strength and core muscle endurance with CAI. The secondary objective is to compare core muscle strength and endurance between case and control groups.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003e\u003cstrong\u003eAIM\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eThis study aims to explore the association of core muscle strength and endurance with chronic ankle instability.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eSTUDY SETTING\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eKMC hospitals, Mangalore.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eSTUDY DESIGN\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eAnalytical Cross-Sectional Study.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003ch3\u003eMATERIALS AND METHODS\u003c/h3\u003e\u003cp\u003e The study was approved by the Institutional Ethics Committee (IEC KMC MLR-01/2023/22) of Kasturba Medical College, Mangalore, and registered with the Clinical Trial Registry of India (CTRI/2023/08/056445). Participant enrolment began on 18/08/2024.\u003c/p\u003e\u003cp\u003eA total of 128 participants were recruited, of which 64 had chronic ankle instability and 64 without ankle instability. Inclusion criteria for the case group were: individuals aged between 18–45; history of at least one acute ankle sprain resulting in inflammation and impaired physical activity; most recent sprain ≥ 3 months prior; and ≥ 2 episodes of “giving way,” recurrent sprains, or self-reported ankle instability and a Cumberland Ankle Instability Tool (CAIT) score of ≤ 24 (Hiller et al, 2006). The control group participants were aged 18–45 years with no history of previous ankle injury or sprain and a score of \u0026gt; 24 on the CAIT. Exclusion criteria for both groups included history of previous surgeries involving lower extremity musculoskeletal system (bone, ligaments, and/or nerve injury); any acute lower limb injury (sprain, strain, or fracture) within the past 3 months; abdominal surgery or hernia repair within 8 weeks, or a history of hypertension, cardiac issues, or hernia.\u003c/p\u003e\u003cp\u003eEligible individuals meeting the inclusion criteria with CAI were recruited. Age-matched controls were recruited from willing bystanders or companions of CAI participants who met the eligibility criteria. All participants received study information and provided informed consent. Demographic data collection and clinical assessment were performed by an experienced and qualified physiotherapist.\u003c/p\u003e\u003cp\u003e\u003cb\u003eOUTCOME MEASURES\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe self-reported ankle instability of all participants was documented using CAIT [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Core strength was evaluated using a pressure biofeedback device. Participants were positioned prone and instructed to perform the abdominal drawing-in manoeuvre to selectively activate the transverse abdominis [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The pressure cuff was then inflated, and changes in pressure were recorded. Participants were categorized into two groups based on the values obtained: good core strength (pressure change of 4–10 mmHg) and poor core strength (pressure change \u0026lt; 4 mmHg). On the other hand, core endurance was assessed using the standardized protocol of McGill’s Trunk Endurance Test Battery [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. This test battery includes three components: the trunk flexor endurance test, the trunk lateral flexor endurance test, and the trunk extensor endurance test.\u003c/p\u003e\u003ch2\u003eSTATISTICAL ANALYSIS\u003c/h2\u003e\u003cp\u003eAll analyses were performed using IBM SPSS Statistics (Version 29.0) and R (Version 4.3.1), with statistical significance set at p \u0026lt; 0.05. Categorical variables were summarized using frequencies and percentages. Continuous data were assessed for normality; normally distributed data were reported as mean ± standard deviation (SD), and non-normally distributed data as median and interquartile range (IQR). Group comparisons for categorical variables were conducted using the Chi-square test, while the Mann–Whitney U test was used for non-normally distributed continuous variables. Effect sizes for group differences were reported using rank-biserial correlation (r). Pearson’s correlation coefficients were calculated to examine associations between CAIT scores and core variables and visualized in a heatmap. Furthermore, a multiple linear regression model was developed to assess whether core strength and endurance predicted CAIT scores, with model fit assessed using R² and adjusted R². Multicollinearity was evaluated using variance inflation factors (VIF). An interaction term (Group × Left Lateral Flexor Endurance) was added to explore whether group status moderated the association. Group was coded as 1 = CAI and 0 = Control.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 128 participants were included in the study, with 64 participants each in the chronic ankle instability (CAI) group and the control group. The mean age of participants in the CAI group was noted to be 22.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93 years, whereas the control group was 21.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.69 years. Among the 128 participants, females comprised 78.1% of the CAI group and 70.3% of the control group. In the CAI group 40 participants (62.5%) reported instability on the right ankle, while 24 participants (37.5%) reported it on the left ankle. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the baseline demographic and clinical characteristics of both groups.\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\u003e\u003cb\u003eDemographic and Clinical Characteristics of Participants\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\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\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\u003eExperimental Group (n\u0026thinsp;=\u0026thinsp;64)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl Group (n\u0026thinsp;=\u0026thinsp;64)\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=\"left\" colname=\"c2\"\u003e\u003cp\u003e22.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.69\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGender (Female)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e50 (78.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e45 (70.3%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGender (Male)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14 (21.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19 (29.7%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAffected Leg (Right)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40 (62.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0.0%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAffected Leg (Left)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23 (35.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0.0%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCAIT Score\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17.09\u0026thinsp;\u0026plusmn;\u0026thinsp;5.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e28.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Strength Value (mmHg)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.86\u0026thinsp;\u0026plusmn;\u0026thinsp;8.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Strength (Good)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28 (43.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27 (42.2%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Strength (Poor)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e36 (56.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37 (57.8%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Endurance - Flexors (sec)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e117.72\u0026thinsp;\u0026plusmn;\u0026thinsp;76.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e177.09\u0026thinsp;\u0026plusmn;\u0026thinsp;125.63\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Endurance - Extensors (sec)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e66.48\u0026thinsp;\u0026plusmn;\u0026thinsp;33.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e87.72\u0026thinsp;\u0026plusmn;\u0026thinsp;44.42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Endurance - Right LF (sec)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e42.95\u0026thinsp;\u0026plusmn;\u0026thinsp;30.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e48.05\u0026thinsp;\u0026plusmn;\u0026thinsp;26.89\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Endurance - Left LF (sec)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41.25\u0026thinsp;\u0026plusmn;\u0026thinsp;25.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e49.95\u0026thinsp;\u0026plusmn;\u0026thinsp;28.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003eValues are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) for continuous variables and number (percentage) for categorical variables. CAIT: Cumberland Ankle Instability Tool.*LF: Lateral Flexor; Right LF and Left LF refer to trunk lateral flexor endurance (in seconds) on the right and left sides, respectively.\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\u003e\u003cb\u003eGroup Comparisons of Core Strength and Endurance\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e demonstrates the findings of the Mann\u0026ndash;Whitney U test analysis comparing core strength and endurance variables between the CAI and control groups. Notably, trunk flexor endurance (p\u0026thinsp;=\u0026thinsp;0.003, r\u0026thinsp;=\u0026thinsp;0.31) and extensor endurance (p\u0026thinsp;=\u0026thinsp;0.011, r\u0026thinsp;=\u0026thinsp;0.26) were significantly lower in the CAI group, with moderate effect sizes. Extensor endurance also differed significantly (p\u0026thinsp;=\u0026thinsp;0.011, r\u0026thinsp;=\u0026thinsp;0.26), reflecting a small to moderate effect. No significant differences were found in core strength (p\u0026thinsp;=\u0026thinsp;0.954, r = -0.01). Left lateral flexor endurance approached statistical significance (p\u0026thinsp;=\u0026thinsp;0.053, r\u0026thinsp;=\u0026thinsp;0.20), suggesting a small effect.\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\u003eGroup Comparison of Core Strength and Endurance Variables\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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMeasure\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase Median (IQR)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl Median (IQR)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eEffect Size (r)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore_Strength_Value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.33 (2.00\u0026ndash;4.83)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.33 (2.00\u0026ndash;5.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.954\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlexors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e100.50 (65.75\u0026ndash;160.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e153.00 (80.00\u0026ndash;219.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.31\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExtensors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e64.50 (44.00\u0026ndash;89.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e79.00 (56.00\u0026ndash;109.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRight_LF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e37.50 (21.75\u0026ndash;55.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41.00 (26.25\u0026ndash;64.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeft_LF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e35.00 (24.00\u0026ndash;52.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e46.50 (26.75\u0026ndash;64.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.053\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e\u003cp\u003e*Values presented as median (interquartile range). P-values computed using Mann\u0026ndash;Whitney U test. Effect size reported as rank-biserial correlation (r). An r value of 0.1\u0026ndash;0.3 indicates a small effect, 0.3\u0026ndash;0.5 a moderate effect, and \u0026gt;\u0026thinsp;0.5 a large effect.\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\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e displays the group-wise comparisons for core strength and endurance components across individuals with and without chronic ankle instability (CAI). No significant differences were observed in core strength values between the groups. However, core endurance of the trunk flexors and extensors was visibly reduced in the CAI group compared to controls. The differences in lateral flexor endurance (right and left) were less pronounced. Boxplots with overlaid individual data points offer insight into both central tendency and variability within each group. These visualizations complement the statistical tests reported in subsequent tables and help illustrate potential disparities in neuromuscular endurance that may underlie ankle instability.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eRegression Analysis\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and visually depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, CAIT scores were positively correlated with all core muscle measures, with the strongest bivariate correlations observed for left lateral flexor endurance (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.28) and trunk extensor endurance (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.28). Moderate inter-correlations were also noted among predictor variables, especially between right and left lateral flexors (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.79) and between left lateral flexors and extensors (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.53), suggesting potential shared neuromuscular control mechanisms.\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\u003eSummary of Correlation and Regression Analysis for CAIT Score\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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePredictor\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePearson r\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eβ Coefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep-value (β)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eVIF\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Strength\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.039\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.734\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTrunk Flexors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.009\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.135\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.34\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTrunk Extensors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.022\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.203\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRight Lateral Flexors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.041\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2.74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeft Lateral Flexors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.074\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.055\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e\u003cp\u003ePearson r represents the strength of the bivariate correlation between each core variable and the CAIT score. β Coefficients, p-values, and VIFs are derived from the multiple linear regression model predicting CAIT score.\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\u003e\u003c/p\u003e\u003cp\u003eA multiple linear regression model was subsequently constructed to assess the combined influence of these variables on the CAIT score. The overall model was statistically significant (\u003cem\u003eF\u003c/em\u003e(5,122)\u0026thinsp;=\u0026thinsp;3.67, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004), explaining 13.1% of the variance (adjusted \u003cem\u003eR\u0026sup2;\u003c/em\u003e = 0.095). Among all predictors, only left lateral flexor endurance achieved statistical significance in predicting CAIT score (\u003cem\u003eβ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.074, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.055), reinforcing its relevance as a potential clinical marker of ankle instability severity. All variance inflation factors (VIFs\u0026thinsp;\u0026lt;\u0026thinsp;3.5) indicated acceptable levels of multicollinearity. These findings suggest that while CAIT score shares weak-to-moderate linear relationships with multiple core variables, left-sided lateral core endurance may play a more prominent role in explaining functional ankle stability outcomes.\u003c/p\u003e\u003cp\u003eIn addition, an interaction model was constructed to examine whether the association between left lateral flexor endurance and CAIT score differed by group (CAI vs. control) (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e The overall model was statistically significant (\u003cem\u003eF\u003c/em\u003e(4,123)\u0026thinsp;=\u0026thinsp;76.76, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with an adjusted R\u0026sup2; of 0.705, indicating strong explanatory power. The main effect of the group was highly significant (β = \u0026minus;\u0026thinsp;13.16, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), confirming that individuals in the CAI group had substantially lower CAIT scores. The interaction term (Group \u0026times; Left Lateral Flexor Endurance) approached statistical significance (β\u0026thinsp;=\u0026thinsp;0.052, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.054), suggesting a trend toward a stronger positive relationship between lateral flexor endurance and ankle function in the CAI group compared to controls. Neither core strength nor left lateral flexor endurance alone were significant when controlling for interaction effects. These findings suggest that group membership may moderate the relationship between core endurance and ankle stability, emphasizing the need for group-specific interpretation in clinical rehabilitation planning.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInteraction Effect Model Predicting CAIT Score\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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePredictor\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eβ Coefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eStandard Error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003et-value\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\u003eIntercept\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25.0385\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.9510\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26.3200\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCore Strength\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.0039\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.0397\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.917\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeft Lateral Flexor Endurance\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.0109\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.0291\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.3800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.707\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup (1\u0026thinsp;=\u0026thinsp;CAI, 0\u0026thinsp;=\u0026thinsp;Control)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-13.1623\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.3594\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-9.6800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup \u0026times; Left Lateral Flexor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.0523\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.0269\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.9500\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.054\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e\u003cp\u003eModel statistics: Adjusted R\u0026sup2; = 0.705, F(4,123)\u0026thinsp;=\u0026thinsp;76.76, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001. Group is coded as 1\u0026thinsp;=\u0026thinsp;CAI, 0\u0026thinsp;=\u0026thinsp;Control. The interaction term (Group \u0026times; Left Lateral Flexor Endurance) examines whether the relationship between endurance and CAIT score differs by group.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study investigated the relationship between core muscle strength and endurance with chronic ankle instability in a cohort of young Indian adults. Although no significant group difference was found for core muscle strength between groups, the participants of the chronic ankle instability group demonstrated lower endurance of trunk flexors and extensors compared to the healthy controls. Also, the finding of regression analysis indicated that left lateral flexor muscle endurance was significantly correlated with CAIT scores and emerged as the consistent predictor of CAIT scores compared to other predictors such as core muscle strength, trunk flexor/extensor endurance, and right lateral flexor endurance.\u003c/p\u003e\u003cp\u003eThe findings of the current study align with the kinetic chain model approach in the rehabilitation of musculoskeletal injuries [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. According to this model, proximal segment function significantly contributes to distal joint stability. It can be postulated that the lateral trunk muscles may serve as mechanical constraints that stabilize the lumbopelvic region. This passive support, in turn, might ease the strain on the ankle and help maintain balance, which could explain their role in imparting neuromuscular control and mitigating the risk or severity of chronic ankle instability [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e],.\u003c/p\u003e\u003cp\u003eThe findings of our study that left lateral trunk flexor emerged as a significant predictor of CAIT scores and CAI aligns with previous research that highlights the importance of proximal compensations in individuals with CAI. In particular, the study by Xu et al. ​ (2025) found that individuals with CAI demonstrated a greater range of motion and higher angular velocity in the knee, hip, and torso during dynamic balance tasks, resonating that CAI affects not only the ankle but also the stability and movement strategies of proximal joints, including the trunk [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In addition, trunk muscular impairments, such as decreased contractility of the transversus abdominis, have been documented in CAI populations, underscoring the role of core muscles in maintaining dynamic stability [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. These insights provide a deeper understanding of the mechanisms underlying CAI and the critical role of core muscle strength and endurance in its management.\u003c/p\u003e\u003cp\u003eThe findings of correlation analysis revealed moderate positive relationships between CAIT scores and both trunk extensor and left lateral flexor endurance (r\u0026thinsp;=\u0026thinsp;0.28). The findings of correlation analysis revealed moderate positive relationships between CAIT scores and both trunk extensor and left lateral flexor endurance (r\u0026thinsp;=\u0026thinsp;0.28). This aligns with Barati et al.'s study, which found significant correlations between trunk muscle endurance and static balance, emphasizing the crucial role of core muscle endurance in maintaining stability. Improved trunk muscle endurance, particularly in the lateral muscles, may contribute to better overall balance and potentially mitigate chronic ankle instability (CAI).​ Analogous to the center of gravity, the core operates as integrated functional units, reinforcing the significance of core endurance for optimal performance and injury prevention [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. ​ Incorporating specific trunk endurance exercises into rehabilitation programs for individuals with CAI could enhance balance and reduce ankle instability [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eInterestingly, core strength showed no significant group differences or predictive value for CAIT scores. These finding challenges conventional assumptions that generalized core strength translates directly into distal joint control. Instead, our results highlight the role of dynamic and endurance-based trunk performance over static core strength measures. These findings are consistent with findings of Barati et al.. (2013), who reported that general core strength was not a significant predictor. In particular, the study found trunk muscle endurance significantly predicted static balance, suggesting that improving trunk muscle endurance could enhance distal joint control [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Their study reinforces that endurance-based assessment of core stability is more relevant than static core strength measures for functional movement and balance [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe findings of non-significant group differences in core strength between individuals with and without chronic ankle instability (CAI) may be attributed to a combination of contextual and methodological factors. Given that, both groups primarily consisted of young, health-conscious physiotherapy and medical students and they were likely engaged in regular physical activity. This might have resulted in higher baseline core strength for participants of both groups, whereby detection of a meaningful and clinical difference in core strength between groups is challenging [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. This might have resulted in higher baseline core strength in participants from both groups, whereby detecting a meaningful and clinically significant difference in core strength between groups becomes difficult [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Methodologically, core strength was measured using the abdominal drawing-in maneuver (ADIM) with pressure biofeedback, which required participants to maintain proper technique and control of their core muscles during testing. However, inconsistent activation of the transversus abdominis or poor posture may have contributed to the lack of significant group differences [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Strength gains often reach a plateau, or ceiling effect, in individuals who are already physically active and fit, where further improvement is limited despite continued training or neuromuscular adaptation [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Taken together, these factors might likely contribute to the documented non-significant group differences in core strength.\u003c/p\u003e\u003cp\u003e\u003cb\u003eStrengths and Limitations\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe strength of the studies lies in the detailed analysis including effect size reporting, multivariable modelling, and interaction analysis [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Also, reliable and valid assessments were established by using McGill\u0026rsquo;s endurance test battery and validated core strength tests [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The study's limitations include a relatively small sample size, gender imbalances between groups, insufficient preparation time before testing, and potential fatigue due to successive contractions. Additionally, the cross-sectional design of the study prevents the establishment of a causal relationship between core endurance and ankle instability, and only an association can be identified [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Therefore, it remains unclear whether poor core endurance and strength contribute to the development of ankle instability or whether individuals with ankle instability tend to have weaker core function. Additionally, the usage of only static endurance tests may not reflect the dynamic control needed in athletic activities [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Future studies should consider longitudinal designs and dynamic assessments.\u003c/p\u003e\u003cp\u003e\u003cb\u003eClinical Implications\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe study findings reinforce the clinical relevance of lateral core endurance in the assessment and rehabilitation of individuals with CAI. Conventional rehabilitation programs for CAI primarily focus on balance and proprioception at the ankle level [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. However, integrating lateral trunk endurance training into this framework could enhance proximal control and improve distal joint function. The study identified left lateral flexor endurance as the most consistent predictor of CAIT score, highlighting its relevance as a key clinical marker. In addition, the documented interaction effects from this study may encourage clinicians to explore group-specific rehabilitation strategies, particularly in populations at high risk for recurrent ankle instability.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThis study signifies the importance of trunk muscle endurance\u0026mdash;particularly left lateral flexor endurance\u0026mdash;in individuals with chronic ankle instability. The observed associations between core endurance measures and CAIT scores, along with the group-specific interaction effects, provide novel insights into the proximal contributions to ankle function. These findings recommend the integration of targeted core endurance training into both preventive and rehabilitative strategies for managing CAI.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"574\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 36.4111%;\"\u003e\n \u003cp\u003eCAI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63.5889%;\"\u003e\n \u003cp\u003eChronic Ankle Instability\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 36.4111%;\"\u003e\n \u003cp\u003eCAIT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63.5889%;\"\u003e\n \u003cp\u003eCumberland Ankle Instability Tool\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 36.4111%;\"\u003e\n \u003cp\u003eADLs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63.5889%;\"\u003e\n \u003cp\u003eActivities of Daily Living\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 36.4111%;\"\u003e\n \u003cp\u003eVIF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63.5889%;\"\u003e\n \u003cp\u003eVariance Inflation Factors\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 36.4111%;\"\u003e\n \u003cp\u003eADIM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63.5889%;\"\u003e\n \u003cp\u003eAbdominal Drawing-In Maneuver\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval:\u003c/strong\u003e Ethical approval was obtained from the Institutional Ethical Committee (IEC), Kasturba Medical College, Mangalore, Manipal Academy of Higher Education (IEC approval number: IEC KMC MLR-01/2023/22)\u0026nbsp;and\u0026nbsp;the\u0026nbsp;study\u0026nbsp;was\u0026nbsp;prospectively\u0026nbsp;registered\u0026nbsp;with the Clinical\u0026nbsp;Trial Registry of India\u0026nbsp;(CTRI/2023/08/056445) on 11/08/2023. Participant enrolment began on 18/08/2023. The research followed the ethical\u0026nbsp;guidelines\u0026nbsp;of\u0026nbsp;the\u0026nbsp;Declaration\u0026nbsp;of\u0026nbsp;Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate:\u0026nbsp;\u003c/strong\u003eThe research followed the ethical guidelines of the Declaration of Helsinki and\u0026nbsp;all the participants included were informed about the study, and a written and signed informed consent form was obtained from each of them.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e Not Applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eThe datasets generated and/or analysed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e There is no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This 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’s contribution:\u0026nbsp;\u003c/strong\u003eThe conceptualization and methodology of the thesis were carried out by\u0026nbsp;Vivekbhai Dineshbhai Patel and\u0026nbsp;Srijanya Rajesh.\u0026nbsp;Srijanya Rajesh collected the data and wrote the initial draft. The manuscript was reviewed and edited by Ashish John Prabhakar, Charu Eapen, Vijayakumar Palaniswamy, Abraham M Joshua, and Molly Cynthia D’Souza. The overall supervision of the thesis was done by Ashish John Prabhakar and Abraham M Joshua. Rishit Anand analyzed the data, reviewed the draft of the article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u003c/strong\u003e We would like to thank the Manipal Academy of Higher Education, Manipal, India, and all the participants of this study.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAlizamani S, I Ghasemi G, Lenjannejadian S. Effects of Core Stability Training on Stable-and Unstable-surface on sensorimotor function of Ankle in Athletes with Chronic Ankle Instability. Studies in Sport Medicine. 2023;15(35):41-64.\u003c/li\u003e\n\u003cli\u003eHerzog MM, Kerr ZY, Marshall SW, Wikstrom EA. Epidemiology of ankle sprains and chronic ankle instability. Journal of athletic training. 2019;54(6):603-10.\u003c/li\u003e\n\u003cli\u003eGribble PA, Bleakley CM, Caulfield BM, Docherty CL, Fourchet F, Fong DT. Evidence review for the 2016 International Ankle Consortium consensus statement on the prevalence, impact and long-term consequences of lateral ankle sprains. British journal of sports medicine. 2016;50(24):1496-505.\u003c/li\u003e\n\u003cli\u003eHertel J. Functional instability following lateral ankle sprain. Sports medicine. 2000;29:361-71.\u003c/li\u003e\n\u003cli\u003eAlghadir AH, Iqbal ZA, Iqbal A, Ahmed H, Ramteke SU. Effect of chronic ankle sprain on pain, range of motion, proprioception, and balance among athletes. International journal of environmental research and public health. 2020;17(15):5318.\u003c/li\u003e\n\u003cli\u003eHosseinimehr SH, Mazhari Z. The Endurance Ratio of Core Stability Global Muscles and Postural Control in Female Athletes with and Without Chronic Ankle Instability. Journal of Motor Control and Learning. 2024;6(3).\u003c/li\u003e\n\u003cli\u003eCalicchio, A., Ludwig, G., \u0026amp; DeBeliso, M. Is there a relationship between core muscular strength and chronic ankle instability? Journal of Physical Education Research. 2016 June;2(3):48-58.\u003c/li\u003e\n\u003cli\u003eRazeghi A, Rahnama N, Shokri E, Ghanbari A. Evaluation of Endurance of Core Muscles in Female Athletes with Chronic Ankle Instability. Journal of Paramedical Sciences \u0026amp; Rehabilitation 2017 Mar 21 6(1):47\u0026ndash;57.\u003c/li\u003e\n\u003cli\u003eAlizamani S, Ghasemi G, Lenjan Nejadian S. Effects of eight-week core stability training on stable- and unstable-surface on ankle muscular strength, proprioception, and dorsiflexion in athletes with chronic ankle instability. Journal of Bodywork and Movement Therapies. 2023;45(15):148-154.\u003c/li\u003e\n\u003cli\u003eHiller CE, Refshauge KM, Bundy AC, Herbert RD, Kilbreath SL. The Cumberland ankle instability tool: a report of validity and reliability testing. Archives of physical medicine and rehabilitation. 2006;87(9):1235-41.\u003c/li\u003e\n\u003cli\u003eGage MJ. The effects of abdominal training on postural control, lower extremity kinematics, kinetics, and muscle activation. Brigham Young University; 2009.\u003c/li\u003e\n\u003cli\u003eMcGill SM, Childs A, Liebenson C. Endurance times for low back stabilization exercises: clinical targets for testing and training from a normal database. Archives of physical medicine and rehabilitation. 1999;80(8):941-4.\u003c/li\u003e\n\u003cli\u003ePutnam CA. Sequential motions of body segments in striking and throwing skills: descriptions and explanations. Journal of biomechanics. 1993;26:125-35.\u003c/li\u003e\n\u003cli\u003eFeltner ME, Dapena J. Three-dimensional interactions in a two-segment kinetic chain. Part I: General model. Journal of Applied biomechanics. 1989;5(4):403-19.\u003c/li\u003e\n\u003cli\u003eCefai CM, Shaw JW, Cushion EJ, Cleather DJ. An arm swing enhances the proximal-to-distal delay in joint extension during a countermovement jump. Scientific Reports. 2024;14(1):20371.\u003c/li\u003e\n\u003cli\u003eXu X, Bowtell J, Fong DT, Young WR, Williams GK. Kinematics of balance controls in people with chronic ankle instability during unilateral stance on a moving platform. Scientific Reports. 2025;15(1):1126.\u003c/li\u003e\n\u003cli\u003eMcCann RS, Johnson K, Suttmiller AM. Lumbopelvic stability and trunk muscle contractility of individuals with chronic ankle instability. International Journal of Sports Physical Therapy. 2021;16(3):741.\u003c/li\u003e\n\u003cli\u003eBarati A, Safarcherati A, Aghayari A, Azizi F, Abbasi H. Evaluation of relationship between trunk muscle endurance and static balance in male students. Asian journal of sports medicine. 2013;4(4):289.\u003c/li\u003e\n\u003cli\u003eOkada T, Huxel KC, Nesser TW. Relationship between core stability, functional movement, and performance. The Journal of Strength \u0026amp; Conditioning Research. 2011;25(1):252-61.\u003c/li\u003e\n\u003cli\u003eBagherian S, Ghasempoor K. A cross-sectional study of functional movement quality in school-aged children. BMC pediatrics. 2022;22(1):399.\u003c/li\u003e\n\u003cli\u003eStorheim K, Holm I, Gunderson R, Brox JI, B\u0026oslash; K. The effect of comprehensive group training on cross-sectional area, density, and strength of paraspinal muscles in patients sick-listed for subacute low back pain. Clinical Spine Surgery. 2003;16(3):271-9.\u003c/li\u003e\n\u003cli\u003eWillardson JM. Core stability training: applications to sports conditioning programs. The Journal of Strength \u0026amp; Conditioning Research. 2007;21(3):979-85.\u003c/li\u003e\n\u003cli\u003eGribble PA, Robinson RH, Hertel J, Denegar CR. The effects of gender and fatigue on dynamic postural control. Journal of sport rehabilitation. 2009;18(2):240-57.\u003c/li\u003e\n\u003cli\u003eSullivan GM, Feinn R. Using effect size\u0026mdash;or why the P value is not enough. Journal of graduate medical education. 2012;4(3):279-82.\u003c/li\u003e\n\u003cli\u003eVittinghoff E, Glidden DV, Shiboski SC, McCulloch CE. Regression methods in biostatistics: linear, logistic, survival, and repeated measures models. Springer Science \u0026amp; Business Media; 2012.\u003c/li\u003e\n\u003cli\u003eMann CJ. Observational research methods. Research design II: cohort, cross sectional, and case-control studies. Emergency medicine journal. 2003;20(1):54-60.\u003c/li\u003e\n\u003cli\u003eZazulak BT, Hewett TE, Reeves NP, Goldberg B, Cholewicki J. Deficits in neuromuscular control of the trunk predict knee injury risk: prospective biomechanical-epidemiologic study. The American journal of sports medicine. 2007;35(7):1123-30.\u003c/li\u003e\n\u003cli\u003eLeetun DT, Ireland ML, Willson JD, Ballantyne BT, Davis IM. Core stability measures as risk factors for lower extremity injury in athletes. Medicine \u0026amp; Science in Sports \u0026amp; Exercise. 2004;36(6):926-34.\u003c/li\u003e\n\u003cli\u003eMcKeon PO, Donovan L. A perceptual framework for conservative treatment and rehabilitation of ankle sprains: an evidence-based paradigm shift. Journal of athletic training. 2019;54(6):628-38.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Chronic Ankle Instability, Ankle Sprain, Core Strength, Core Endurance","lastPublishedDoi":"10.21203/rs.3.rs-6980458/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6980458/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eChronic Ankle Instability (CAI) accounts for over 40% of cases following an ankle sprain, often leading to debilitating and long-term consequences. Emerging research indicated that deficits in core muscle strength and endurance may contribute to the persistence of CAI. The current study aims to investigate the association between core strength and endurance with CAI.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eA total of 128 participants were enrolled, including 64 participants with CAI (mean age: 22.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.929) and 64 participants without instability (mean age: 21.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.691). Ankle instability was evaluated using the Cumberland Ankle Instability Tool (CAIT). Core strength was assessed using a pressure biofeedback device, and endurance was assessed using the McGill trunk endurance battery. Between-group comparisons were conducted using the Mann\u0026ndash;Whitney U test. Pearson correlation and multiple linear regression analyses were performed to identify key predictors of CAIT, including the interaction effects.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThe CAI group revealed significantly lower endurance in trunk flexors (p\u0026thinsp;=\u0026thinsp;0.003, r\u0026thinsp;=\u0026thinsp;0.31) and extensors (p\u0026thinsp;=\u0026thinsp;0.011, r\u0026thinsp;=\u0026thinsp;0.26). No significant difference was observed in core strength (p\u0026thinsp;=\u0026thinsp;0.954). CAIT scores were significantly associated with left lateral flexor endurance (r\u0026thinsp;=\u0026thinsp;0.28, p\u0026thinsp;=\u0026thinsp;0.012). The final regression model indicated that left lateral flexor endurance was the most consistent predictor (β\u0026thinsp;=\u0026thinsp;0.074, p\u0026thinsp;=\u0026thinsp;0.055), accounting for 70.5% of the variance in CAIT scores (adjusted R\u0026sup2; = 0.705). A near-significant interaction effect (p\u0026thinsp;=\u0026thinsp;0.054) suggested that this association may differ by group.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eLateral flexor core endurance is a critical factor for functional ankle stability. Integrating targeted core endurance training into the rehabilitation programs for CAI is beneficial.\u003c/p\u003e\u003ch2\u003eTrial registration:\u003c/h2\u003e\u003cp\u003eThe study was registered with the Clinical Trial Registry of India (CTRI/2023/08/056445) on 11/08/2023.\u003c/p\u003e","manuscriptTitle":"Association of Core Muscle Strength and Endurance with Chronic Ankle Instability- A Cross-Sectional Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-12 13:02:05","doi":"10.21203/rs.3.rs-6980458/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"edb2fc8f-83a4-413f-8ea5-2693013d8d0f","owner":[],"postedDate":"August 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-18T16:23:35+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-12 13:02:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6980458","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6980458","identity":"rs-6980458","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}