Assessment of evertor weakness in patients with chronic ankle instability: Functional versus isokinetic testing

The Effect of Additional Neuromuscular Training on Peri-Ankle Muscle Morphology and Function in Chronic Ankle Instability Subjects: A Randomized Controlled Trial

BACKGROUND

Lateral ankle sprain is one of the most common musculoskeletal issues during sports and activities of daily living. This study investigated the effect of combined neuromuscular training and conventional training (including strengthening, range of motion, and balance exercises) on muscle morphology, dynamic balance, perceived ankle instability, and functional capacity in persons with chronic ankle instability (CAI).

HYPOTHESIS

The combination of neuromuscular and conventional training programs might result in additional benefits on the morphology of muscle, dynamic balance, and functional capacity in subjects with CAI.

STUDY DESIGN

A single-blind parallel-arm randomized controlled trial.

LEVEL OF EVIDENCE

Level 2.

METHODS

A total of 34 participants with CAI were divided randomly into experimental (EG) and control groups (CG). The EG received conventional and neuromuscular training, while the CG underwent conventional training. Cross-sectional areas of the peroneus longus and tibialis anterior muscles were measured using ultrasonography. Measurements included reaching direction distance, ankle instability, and the foot and ankle outcome score, all evaluated before and immediately after 12 intervention sessions and 4 weeks later in the follow-up phase.

RESULTS

Repeated-measures analysis of variance (ANOVA) revealed significant improvement in the EG, particularly in the cross-sectional area of the tibialis anterior muscle on the injured side and the posteromedial reaching direction displacement of the Y balance test. Moreover, the EG's foot and ankle outcome scores increased significantly compared with the CG (P < 0.05). However, the group effect size ranged from minor to moderate (Hedges g, 0.40-0.73).

CONCLUSION

Combining neuromuscular and conventional training programs yields greater benefits than conventional training alone regarding tibialis anterior muscle morphology, posteromedial dynamic balance, and functional capacity in persons with CAI.

CLINICAL RELEVANCE

The combination of neuromuscular and conventional training programs could enhance muscle morphology, dynamic balance, perceived ankle instability, and functional capacity in persons with CAI.

Electromyographic Activity of Lower Limb Muscles during Ankle Destabilizing Tests

Ankle destabilizing devices were developed to improve the recruitment of the evertor muscles. Nevertheless, the activity of lower-leg muscles has never been compared to each other during functional tests performed with destabilization. The objectives were i) to compare the electromyographic activity between the lower-leg muscles during four functional tests performed with ankle destabilization, and ii) to determine sex-related differences in neuromuscular activation. Twenty-six healthy volunteers (13 males, 13 females) performed the modified Star Excursion Balance Test (mSEBT), unipedal balance and weight-bearing inversion and eversion tests with a destabilizing device, while recording electromyographic activity of the peroneus longus and brevis, tibialis anterior, gastrocnemius lateralis and gluteus medius. The activity of peroneal muscles was significantly greater than other muscles during all functional tests. Furthermore, the anterior direction of the mSEBT was the one implying the greatest activity of the peroneus longus muscle compared to the posteromedial (p=0.003) or posterolateral (p<0.001) directions. Finally, no significant sex-related differences in neuromuscular activity were reported. This study highlights the effectiveness of the destabilizing device to involve specifically the peroneal muscles when performing various functional tests. This device should be used by clinicians to be more specific to the stabilizers of the ankle joint during functional exercises.

Acute Neuromuscular Alterations of Ankle Evertors Induced by Short Trail Running: Sex-Related Considerations

Ravier, G, Dury, J, Grevillot, J, Girard, B, Bouzigon, R, and Michel, F. Acute neuromuscular alterations of ankle evertors induced by short trail running: sex-related considerations. J Strength Cond Res 37(10): 2008–2015, 2023—This study investigated the exercise-induced effects on the neuromuscular function of ankle evertors, balance control associated with trail running, and sex-related interactions. Fourteen male and 14 female medium-level runners completed a 16-km (400 D+) course. At rest and immediately after running, maximal voluntary isometric contraction (MVC) and rate of force development (RFD) for knee extension and ankle eversion, electromyographic (EMG) activity of peroneus muscles during MVC plateau (EMG) and the first 200 ms (EMG200), ankle angular velocity ( INV) during 20 weight-bearing inversion movements, and balance control during destabilizing single-leg task were evaluated. Repeated measures ANOVA-revealed changes in knee and ankle MVC (ankle: P = 0.0004, −12%) and RFD (ankle: P < 0.0001, −19%), EMG (P < 0.0001, −17%), EMG200 (P < 0.0001, −19%), and ankle INV (P < 0.0001, +35%) in response to trail running. Single-leg balance was not impaired. Sex-related differences were observed in EMG and EMG200 with higher values in men than in women. MVC and RFD were greater in men when expressed in absolute values, but not different relative to body mass. Single-leg balance and ankle INV did not differ between men and women. Finally, none of these variables showed any sex-related difference when considering pre-exercise to postexercise changes. This study demonstrated impairment in neuromuscular function of evertor muscles and ability in braking inversion in response to trail running. Sex-related differences were observed in neuromuscular activity but not in fatigability. These data suggest that coaches might implement strength exercises specifically designed for ankle lateral stability into their training program.

Kinetic Effects of 6 Weeks' Pilates or Balance Training in College Soccer Players with Chronic Ankle Instability

Lateral ankle sprain (LAS) is a common sports injury that frequently occurs in active individuals. LAS is characterized by a high recurrence rate, with a large proportion of patients progressing to chronic ankle instability (CAI). Pilates exercises have provided positive results in health care and in rehabilitation. This study compared Pilates training (PT) with traditional balance training (BT) in patients with CAI. Fifty-one college football players with CAI, divided into PT (n = 26) and BT (n = 25) groups, were included in the study. The groups performed PT or BT training as assigned, three times per week for 6 weeks. Isokinetic ankle strength, one-leg hop tests, Y-balance test (YBT), and foot and ankle outcome score (FAOS) were evaluated before and after training. There were considerable improvements in both the PT and BT groups after training. Group and time comparisons revealed that the PT group achieved better triple hop test results than the BT group, whereas the BT group exhibited a greater improvement in YBT posteromedial and posterolateral reach distances. In athletes with CAI, both PT and BT effectively improved symptoms and function. These findings suggest that ankle strength, balance, and core stability should be comprehensively evaluated and targeted in CAI rehabilitation programs.

Hip Abductor Muscle Fatigue Induces Different Strategies During Disrupted Postural Control

Background

Ankle sprain is one of the most common injuries in sport, and hip abductor muscle weakness has recently been reported as a predisposing factor. Currently, the influence of hip abductor muscle fatigue on ankle joint control has not been elucidated during an ankle disturbed balance exercise. This study aimed to determine the influence of hip abductor muscle fatigue on ankle joint control during a disturbed balance task, and to consider inter-individual variability in the kinematic and neuromuscular reorganizations implemented.

Methods

Twenty-six healthy subjects (13 males; 13 females) performed a unipedal postural balance task with eyes closed before and after a fatiguing exercise (up to a 50% decrease in strength) of the hip abductor muscles. Subjects completed balance task while equipped with an ankle destabilization device that allows inversion/eversion movements. Electromyographic (EMG) activity of the gastrocnemius lateralis (GastL), peroneus longus (PL) and brevis, tibialis anterior, and gluteus medius were recorded during task. Kinematics (e.g., frontal foot angulation) of the ankle complex were determined using inertial measurement units.

Results

In the overall group, no significant time, sex or interaction effect was observed for kinematic and EMG variables. However, when considering individual responses to hip fatigue, 14 subjects decreased the standard deviation of frontal angulation (−30%) suggesting enhancement of ankle joint control, while 12 subjects increased it (+46%). Normalized EMG for PL and GastL muscles changed with fatigue for both these groups. However, variations were significantly different between groups (p = 0.027 for PL and p = 0.006 for GastL). Indeed, the contribution of ankle muscles increased for the enhanced-stability group while no change for the impaired-stability group.

Conclusion

These results highlight that subject adopt different neuromuscular and kinematic ankle strategies to control ankle destabilization in response to hip abductor muscle fatigue. Frontal foot angulation variability seemed to be a valuable marker to detect the type of strategy employed. The strategy adopted by the impaired-stability group might have important implications when analyzing risk factors for ankle sprains. Further studies should consider individual responses to fatigue, to understand which factor could predispose athletes to use of one or other strategy.

Which Functional Tests and Self-Reported Questionnaires Can Help Clinicians Make Valid Return to Sport Decisions in Patients With Chronic Ankle Instability? A Narrative Review and Expert Opinion

Lateral ankle sprain is the most common injury in sports, with up to 40% of patients developing chronic ankle instability (CAI). One possible cause underlying this high rate of recurrence or feeling of giving way may be a premature return to sport (RTS). Indeed, except for time-based parameters, there are no specific criteria to guide clinicians in their RTS decisions in patients with CAI. A recent international consensus highlighted the relevance and importance of including patient-reported ankle function questionnaires combined with functional tests targeting ankle impairments in this population. Thus, the aim of this narrative review and expert opinion was to identify the most relevant functional performance tests and self-reported questionnaires to help clinicians in their RTS decision-making process following recurrent ankle sprains or surgical ankle stabilization. The PubMed (MEDLINE), PEDro, Cochrane Library and ScienceDirect databases were searched to identify published articles. Results showed that the single leg stance test on firm surfaces, the modified version of the star excursion balance test, the side hop test and the figure-of-8 test appeared to be the most relevant functional performance tests to target ankle impairments in patients with CAI. A combination of the Foot and Ankle Ability Measure (FAAM) and the Ankle Ligament Reconstruction-Return to Sport after Injury (ALR-RSI) questionnaires were the most relevant self-reported questionnaires to assess patient function in the context of CAI. Although these functional tests and questionnaires provide a solid foundation for clinicians to validate their RTS decisions in patient with CAI, objective scientific criteria with cut-off scores are still lacking. In addition to the proposed test cluster, an analysis of the context, in particular characteristics related to sports (e.g., fatigue, cognitive constraints), to obtain more information about the patient's risk of recurrent injury could be of added value when making a RTS decision in patients with CAI. In order to evaluate the strength of evertors under ecological conditions, it would also be interesting to assess the ability to control weight-bearing ankle inversion in a unipodal stance. Further studies are needed to assess the relevance of this proposed test cluster in RTS decision-making following lateral ankle sprain injury and CAI.

Fatigue of hip abductor muscles implies neuromuscular and kinematic adaptations of the ankle during dynamic balance

OBJECTIVE

Determine whether hip abductor muscle fatigue influenced ankle kinematic and muscle activity during ankle-destabilized tasks.

DESIGN

Cross-sectional study.

METHODS

Twenty-six healthy, active participants performed two tests (Star Excursion Balance Test, SEBT; Weight Bearing Inversion Test, WBIT) for assessment of dynamic balance and ability to control inversion. Participants were equipped with an ankle-destabilizing sandal in inversion and eversion to perform both tests, which were completed before and after a fatiguing exercise of hip abductor muscles (up to 50% reduction in strength). Electromyographic activity of peroneus longus (PL) and brevis (PB), tibialis anterior, gastrocnemius lateralis (GastL) and gluteus medius (GlutM) muscles were recorded. In addition, ankle kinematics were recorded using an inertial measurement unit.

RESULTS

Hip abductor fatigue induced a significant decrease in SEBT scores in three directions (p < 0.01). During SEBT, ankle supination decreased by 3.2° in the anterior and posteromedial directions (p < 0.01). Muscle activity of GastL increased during achievement of three directions (p < 0.05) in response to hip abductor fatigue. In posteromedial direction, PL (p < 0.001) and GlutM (p < 0.01) activity increased with fatigue. During WBIT, inversion angular velocity was not impacted by fatigue while, PB and GastL activity increased after fatiguing exercise (p < 0.005).

CONCLUSION

A decrease in SEBT performance and EMG adaptations with proximal fatigue attest to the importance of the hip abductor muscle in dynamic postural control. This could have important implications in building injury prevention programs. Changes in ankle supination may reflect a protective strategy of the joint in response to hip fatigue.

Assessment of Evertor Strength Following Inferior Extensor Retinaculum Flap Ligamentoplasty in Patients With Chronic Lateral Ankle Instability

The primary aim of our study was to evaluate the strength of ankle evertor muscles in patients who have undergone a lateral ankle ligamentoplasty (which combined tensioning of the primary ligament group and reinforcing it with a pediculated extensor retinaculum flap), using 2 measurement systems (isokinetic and the functional weightbearing test [MyoLux). Our hypothesis was the strength of evertor muscles on the treated side was comparable to that of the contralateral healthy side. This prospective study included 23 patients who had chronic ankle instability and underwent an inferior extensor retinaculum flap ligamentoplasty. Clinical and functional results were assessed using the American Orthopaedic Foot & Ankle Society and Karlsson scores. The evertor muscle strength was analyzed, in both treated and healthy contralateral ankles, using isokinetic testing (gold standard) - an open kinetic chain test and a functional closed kinetic chain test (MyoLux). Data were interpreted using the Stata 14.0 software. The American Orthopaedic Foot & Ankle Society score was 88.1 ± 4.5, and the Karlsson score was 89.6 ± 4.0. Isokinetic tests did not show any significant difference between the treated ankles and the healthy one. Functional tests measuring inversion control at the ankle did not demonstrate any functional differences between the 2 ankles. As confirmed by good functional scores and the lack of difference in evertor muscle strength, this study reports that the inferior extensor retinaculum flap ligamentoplasty is a satisfactory treatment of chronic ankle instability. In addition, the MyoLux is a reliable and effective test to properly assess proprioception at the ankle.

Tensiomyographic Neuromuscular Response of the Peroneus Longus and Tibialis Anterior with Chronic Ankle Instability

This study aimed to investigate the muscle contractile response of the peroneus longus (PL) and tibialis anterior (TA) in groups with and without chronic ankle instability (CAI) using tensiomyography. Twenty-three adults, 12 with CAI and 11 healthy participants, participated in this study. All subjects underwent a tensiomyographic assessment of the PL and TA to measure delay time, contraction time and maximal displacement. The ankle evertor and invertor normalized peak torques, maximum work done and muscle thickness of the PL and TA were calculated. The delay time and contraction time of the PL in the CAI side were significantly higher than those in the healthy group (p < 0.05); however, no significant difference could be detected in the TA between groups. Furthermore, there was no significant difference in the normalized peak torques, maximum work done and muscle thickness of the PL and TA between groups. The CAI side demonstrated a delayed muscle contractile response of the PL when compared with the healthy group although there was no difference in muscle strength and muscle size. Clinicians should consider the muscle contractile response of the PL for rehabilitation of the ankle evertor with CAI.

THE RELATIONSHIP BETWEEN SINGLE LEG BALANCE AND ISOMETRIC ANKLE AND HIP STRENGTH IN A HEALTHY POPULATION

Background

Impaired balance and strength commonly affect athletes with conditions like chronic ankle instability (CAI). Yet, clinical research surrounding the relationship between balance, strength, and CAI is still growing. Deeper investigation of these relationships is warranted to better inform clinical practice patterns when managing athletes with balance deficits.

Purpose

To investigate the relationship between single leg balance, ankle strength, and hip strength in healthy, active adults.

Study Design

Observational study.

Methods

Forty healthy participants (age 23.7 ± 4.9 years) were assessed for static balance, using a modified version of the Balance Error Scoring System (mBESS), as well as isometric strength of ankle and hip musculature via handheld dynamometry. Pearson's correlations were used to analyze relationships between balance and strength measures. Paired t-tests were utilized to compare dominant and non-dominant limb performance.

Results

Negligible to low, negative correlations were found between balance scores and hip extension strength (r = -0.24 to -0.38, p<0.05). High, positive correlations were found between ankle and hip strength measures (r = 0.75 to 0.84, p<0.05). When comparing dominant to non-dominant limbs, only minimal differences were noted in ankle eversion strength (mean difference = 6.0%, p<0.01) and hip extension strength (mean difference = 5.5%, p<0.01).

Conclusions

Minimal relationships were identified between static balance and isometric ankle and hip strength. Comparison of dominant and non-dominant limbs suggests that clinicians should expect relative symmetry in balance and strength in healthy adults. Thus, asymmetries found during clinical examination should raise suspicion of specific impairments that may lead to dysfunction.

Level of Evidence

2c.

Adaptation and psychometric evaluation of the simplified Chinese version of the identification of functional ankle instability questionnaire in Chinese-speaking patients with chronic ankle instability disorders

BACKGROUND

The aims of this study were to adapt the Identification of Functional Ankle Instability (IdFAI) questionnaire into a simplified Chinese version and to assess its reliability, validity, and responsiveness in Chinese-speaking patients with chronic ankle instability (CAI) disorders.

METHODS

The simplified Chinese version of the IdFAI (SC-IdFAI) questionnaire was developed with a five-step procedure involving cross-cultural translation and adaptation. Three questionnaires, including the SC-IdFAI, Medical Outcomes Study Short-Form 36 (SF-36), and Foot and Ankle Ability Measure (FAAM), were administered to the recruited patients. Then, the Cronbach's alpha value, intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimal detectable change (MDC), Spearman's correlation coefficient (r_s), effect size (ES), and standardized response mean (SRM) were calculated to evaluate the reliability, validity, and responsiveness of the SC-IdFAI questionnaire.

RESULTS

A total of 131, 119, and 86 patients with CAI successfully completed the first, second, and third rounds of the questionnaires, respectively. Good or excellent internal consistency and test-retest reliability were found for the overall scale and subscales of the SC-IdFAI questionnaire. The values for the SEM (1.346) and MDC (3.73) were low, indicating that small clinical changes can be detected by the SC-IdFAI questionnaire. The correlations of the SC-IdFAI with FAAM and SF-36 were generally in agreement with the a priori hypotheses (85%, 34/40), suggesting the SC-IdFAI questionnaire has good construct validity. Moreover, the results suggest that the SC-IdFAI (ES = 1.123 and SRM = 1.554) has an acceptable level of responsiveness.

CONCLUSION

The SC-IdFAI scale may be an effective tool, and it is responsive, reliable and valid for the assessment of Chinese patients suffering from CAI.

Criteria-Based Return to Sport Decision-Making Following Lateral Ankle Sprain Injury: a Systematic Review and Narrative Synthesis

OBJECTIVE

The aim of this systematic review was to identify prospective studies that used a criteria-based return to sport (RTS) decision-making process for patients with lateral ankle sprain (LAS) injury.

DESIGN

Systematic review and narrative synthesis.

DATA SOURCES

The PubMed (MEDLINE), Web of Science, PEDro, Cochrane Library, SPORTDiscus (EBSCO), ScienceDirect, and Scopus databases were searched to 23 November 2018.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies were included if they prospectively applied a criteria-based RTS decision-making process for patients with LAS injury, but were excluded if they merely gathered outcome measures at the RTS time point. Studies were also excluded if patients were recovering from ankle fracture, high ankle sprain, medial ankle sprain, chronic ankle instability or complex ankle injury.

RESULTS

No studies were identified that used a criteria-based RTS decision-making process for patients with LAS injury. We were unable to conduct a quantitative synthesis or meta-analysis, therefore we provide a narrative synthesis of relevant questionnaires, as well as clinical and functional assessments commonly used in studies retrieved in the search.

CONCLUSION

There are currently no published evidence-based criteria to inform RTS decisions for patients with an LAS injury. Based on our narrative synthesis, we propose a number of variables that could be used to develop a criteria-based RTS decision paradigm. Future research should aim to reach consensus on these variables and apply them to actual RTS decisions within prospective study designs. Furthermore, we suggest that complex systems theory and the RTS continuum could be used to inform the development of an RTS decision-making paradigm for athletes with LAS injury.

Comparison of the Strength and Electromyography of the Evertor Muscles With and Without Toe Flexion in Patients With Chronic Ankle Instability

BACKGROUND

Weakness of evertor strength is controversial in chronic ankle instability (CAI). Ankle evertor muscles are attached to the toe joints as well as to the metatarsal bone. Therefore, it is necessary to consider toe joint position for the measurement of evertor strength. The purpose of this study was to compare ankle evertor strength and muscle activity during eversion with and without toe flexion (TF) in individuals with CAI and individuals in a healthy group.

METHODS

Fifteen subjects with CAI and 15 healthy subjects participated in this study. Isometric ankle evertor strength and muscle activity of the peroneus longus (PL), peroneus brevis (PB), and extensor digitorum longus (EDL) were measured during eversion with and without TF.

RESULTS

The results indicated a significant interaction effect in evertor strength (P = .03) and no significant interaction effect on EMG of the PL (P = .08), PB (P = .12), and EDL (P = .28). However, measurements of muscle activity of the PL and PB between eversion with and without TF revealed a significant difference in the CAI group (P < .01) and no significant difference in the healthy group (PL: P = .07; PB: P = .13).

CONCLUSION

The results indicated that subjects with CAI had increased EDL compensation and reduced selective activation of the PL and PB during eversion.

CLINICAL RELEVANCE

Our findings suggest that clinicians should consider the activation of EDL when training the evertor of patients with CAI.

Ankle strength is not strongly associated with postural stability in patients awaiting surgery for chronic lateral ankle instability

PURPOSE

(1) To describe ankle strength and postural stability in patients with chronic lateral ankle instability and (2) to analyse the correlation between deficits in ankle strength and postural stability.

METHODS

Results of preoperative isokinetic and balance tests in 203 patients whose contralateral ankle was normal were retrospectively reviewed. Isokinetic peak torque values of eversion and inversion at 2 angular velocities (30°/s and 120°/s) were measured in the injured and normal ankles. In the balance test, the percent differences of 3 actual scores (overall, anterior-posterior, and medial-lateral) between the injured and normal ankles were calculated. Additional statistical analyses were performed to evaluate weakness of ankle strength, postural stability deficits, and their correlation.

RESULTS

Significant differences in 4 peak torque values and 4 relative peak torque values (peak torque/body weight) were found between the injured and normal ankles. All 8 values were significantly lower in the injured ankles. Weakness was severe during inversion and at 30°/s. In the balance test, 49 subjects (24.1%) had significant deficits in postural stability and 109 (53.7%) had favourable results. No strong association was found between weakness of ankle strength and deficits in postural stability.

CONCLUSIONS

Strength measurement alone is insufficient to evaluate preoperative functional deficits, and other functional tests are required to measure postural stability. The results of this study provide further evidence for a rehabilitation programme consisting of proprioceptive training as well as strengthening. The proprioceptive training must be an integral part of the rehabilitation programme in addition to strengthening exercise.

LEVEL OF EVIDENCE

Case series, Level IV.

An Updated Model of Chronic Ankle Instability

Lateral ankle sprains (LASs) are among the most common injuries incurred during participation in sport and physical activity, and it is estimated that up to 40% of individuals who experience a first-time LAS will develop chronic ankle instability (CAI). Chronic ankle instability is characterized by a patient's being more than 12 months removed from the initial LAS and exhibiting a propensity for recurrent ankle sprains, frequent episodes or perceptions of the ankle giving way, and persistent symptoms such as pain, swelling, limited motion, weakness, and diminished self-reported function. We present an updated model of CAI that aims to synthesize the current understanding of its causes and serves as a framework for the clinical assessment and rehabilitation of patients with LASs or CAI. Our goal was to describe how primary injury to the lateral ankle ligaments from an acute LAS may lead to a collection of interrelated pathomechanical, sensory-perceptual, and motor-behavioral impairments that influence a patient's clinical outcome. With an underpinning of the biopsychosocial model, the concepts of self-organization and perception-action cycles derived from dynamic systems theory and a patient-specific neurosignature, stemming from the Melzack neuromatrix of pain theory, are used to describe these interrelationships.

Predictors of chronic ankle instability: Analysis of peroneal reaction time, dynamic balance and isokinetic strength

BACKGROUND

Previous studies have reported the factors contributing to chronic ankle instability, which could lead to more effective treatments. However, factors such as the reflex response and ankle muscle strength have not been taken into account in previous investigations.

METHODS

Fifty recreational athletes with chronic ankle instability and 55 healthy controls were recruited. Peroneal reaction time in response to sudden inversion, isokinetic evertor muscle strength and dynamic balance with the Star Excursion Balance Test and the Biodex Stability System were measured. The relationship between the Cumberland Ankle Instability Tool score and performance on each test was assessed and a backward multiple linear regression analysis was conducted.

FINDINGS

Participants with chronic ankle instability showed prolonged peroneal reaction time, poor performance in the Biodex Stability System and decreased reach distance in the Star Excursion Balance Test. No significant differences were found in eversion and inversion peak torque. Moderate correlations were found between the Cumberland Ankle Instability Tool score and the peroneal reaction time and performance on the Star Excursion Balance Test. Peroneus brevis reaction time and the posteromedial and lateral directions of the Star Excursion Balance Test accounted for 36% of the variance in the Cumberland Ankle Instability Tool.

INTERPRETATION

Dynamic balance deficits and delayed peroneal reaction time are present in participants with chronic ankle instability. Peroneus brevis reaction time and the posteromedial and lateral directions of the Star Excursion Balance Test were the main contributing factors to the Cumberland Ankle Instability Tool score. No clear strength impairments were reported in unstable ankles.