scholarly journals Alterations in Knee Kinematics and Dynamic Stability Associated With Chronic Ankle Instability

2009 ◽  
Vol 44 (4) ◽  
pp. 350-355 ◽  
Author(s):  
Phillip A. Gribble ◽  
Richard H. Robinson
Keyword(s):  
Dynamic Stability ◽  
Repeated Measures ◽  
Knee Flexion ◽  
Ankle Instability ◽  
Plantar Flexion ◽  
Reaction Force ◽  
Rest Period ◽  
Chronic Ankle Instability ◽  
Therapeutic Interventions ◽  
Initial Contact

Abstract Chronic ankle instability (CAI) has been previously and separately associated with deficits in dynamic stability and proximal joint neuromuscular alterations, but how the 2 factors relate is unclear.Context: To examine the contributions of lower extremity kinematics during an assessment of dynamic stability in participants with CAI.Objective: Repeated-measures case-control design.Design: Research laboratory.Setting: Thirty-eight volunteers were categorized into groups of those with unilateral CAI (10 men, 9 women; age  =  20.3 ± 2.9 years, height  =  1.77 ± 0.1 m, mass  =  76.19 ± 13.19 kg) and those without (10 men, 9 women; age  =  23.1 ± 3.9 years, height  =  1.72 ± 0.1 m, mass  =  72.67 ± 16.0 kg).Patients or Other Participants: Participants performed 10 jump landings on each limb with a rest period between test limbs.Intervention(s): Ankle plantar flexion, knee flexion, and hip flexion were captured with an electromagnetic tracking device at the point of ground impact. Ground reaction force data were used to calculate time to stabilization in the anteroposterior and mediolateral planes.Main Outcome Measure(s): For the anteroposterior plane, we found a group-by-side interaction (P  =  .003), with the injured side of the CAI group demonstrating reduced dynamic stability. For knee flexion, a group main effect (P  =  .008) showed that the CAI group landed with less knee flexion than the control group.Results: Diminished dynamic stability and decreased knee flexion angle at initial contact were apparent in the CAI group and may play a role in contributing to CAI. This altered kinematic pattern may influence preventive and therapeutic interventions for those with CAI.Conclusions:

scholarly journals Hip Kinematics During a Stop-Jump Task in Patients With Chronic Ankle Instability

2011 ◽  
Vol 46 (5) ◽  
pp. 461-467 ◽  
Author(s):  
Cathleen N. Brown ◽  
Darin A. Padua ◽  
Stephen W. Marshall ◽  
Kevin M. Guskiewicz
Keyword(s):  
Ankle Sprain ◽  
Ankle Instability ◽  
Vertical Jump ◽  
Reaction Force ◽  
Chronic Ankle Instability ◽  
Maximum Speed ◽  
Initial Contact ◽  
Hip Kinematics ◽  
Hip Flexion ◽  
Kinematics And Kinetics

Context: Chronic ankle instability (CAI) commonly develops after lateral ankle sprain. Movement pattern differences at proximal joints may play a role in instability. Objective: To determine whether people with mechanical ankle instability (MAI) or functional ankle instability (FAI) exhibited different hip kinematics and kinetics during a stop-jump task compared with “copers.” Design: Cross-sectional study. Setting: Sports medicine research laboratory. Patients or Other Participants: Sixty-three recreational athletes, 21 (11 men, 10 women) per group, matched for sex, age, height, mass, and limb dominance. All participants reported a history of a moderate to severe ankle sprain. The participants with MAI and FAI reported 2 or more episodes of giving way at the ankle in the last year and decreased functional ability; copers did not. The MAI group demonstrated clinically positive anterior drawer and talar tilt tests, whereas the FAI group and copers did not. Intervention(s): Participants performed a maximum-speed approach run and a 2-legged stop jump followed by a maximum vertical jump. Main Outcome Measure(s): An electromagnetic tracking device synchronized with a force plate collected data during the stance phase of a 2-legged stop jump. Hip motion was measured from initial contact to takeoff into the vertical jump. Group differences in hip kinematics and kinetics were assessed. Results: The MAI group demonstrated greater hip flexion at initial contact and at maximum (P = .029 and P = .017, respectively) and greater hip external rotation at maximum (P = .035) than the coper group. The MAI group also demonstrated greater hip flexion displacement than both the FAI (P = .050) and coper groups (P = .006). No differences were noted between the FAI and coper groups in hip kinematic variables or among any of the groups in ground reaction force variables. Conclusions: The MAI group demonstrated different hip kinematics than the FAI and coper groups. Proximal joint motion may be affected by ankle joint function and laxity, and clinicians may need to assess proximal joints after repeated ankle sprains.

Knee Flexion Angle at Initial Contact During Jump Landing in Individuals With and Without Chronic Ankle Instability: A Critically-Appraised Topic

2019 ◽  
Vol 24 (4) ◽  
pp. 151-155
Author(s):  
Jacob T. Hartzell ◽  
Kyle B. Kosik ◽  
Matthew C. Hoch ◽  
Phillip A. Gribble
Keyword(s):  
Knee Flexion ◽  
Sagittal Plane ◽  
Ankle Instability ◽  
Knee Kinematics ◽  
Chronic Ankle Instability ◽  
Flexion Angle ◽  
Initial Contact ◽  
Knee Flexion Angle ◽  
Bottom Line ◽  
Jump Landing

Clinical Scenario: Chronic ankle instability (CAI) is characterized by the residual symptoms and feelings of instability that persist after an acute ankle sprain. Current literature has identified several neuromuscular impairments associated with CAI that may negatively impact sagittal plane knee kinematics during dynamic activities. This has led researchers to begin examining sagittal plane knee kinematics during jump landing tasks. Understanding changes in movement patterns at the knee may assist clinicians in designing rehabilitation plans that target both the ankle and more proximal joints, such as the knee. Clinical Question: What is the evidence to support the notion that patients with CAI have decreased sagittal plane knee flexion angle at initial contact during a jump-landing task compared to healthy individuals? Summary of Key Findings: The literature was systematically searched for level 4 evidence or higher. The search yielded two case-control studies which met the inclusion criteria. Based on limited evidence, there are mixed results for whether sagittal plane knee kinematic at initial contact differ between those with and without CAI. Clinical Bottom Line: There is weak evidence to support changes in sagittal plane knee kinematics at initial contact during a jump landing in individuals with CAI compared to healthy controls. Strength of Recommendation: In accordance with the Centre for Evidence-Based Medicine, a grade of C for level 4 evidence is recommended due to variable findings.

scholarly journals Altered Walking Neuromechanics in Patients With Chronic Ankle Instability

2019 ◽  
Vol 54 (6) ◽  
pp. 684-697 ◽  
Author(s):  
S. Jun Son ◽  
Hyunsoo Kim ◽  
Matthew K. Seeley ◽  
J. Ty Hopkins
Keyword(s):  
Lower Extremity ◽  
Muscle Activation ◽  
Comprehensive Evaluation ◽  
Ankle Instability ◽  
Plantar Flexion ◽  
Reaction Force ◽  
Chronic Ankle Instability ◽  
Control Group ◽  
Internal Joint ◽  
Knee Abduction

Context The literature on gait kinematics and muscle activation in chronic ankle instability (CAI) is limited. A comprehensive evaluation of all relevant gait measures is needed to examine alterations in gait neuromechanics that may contribute to recurrent sprain. Objective To compare walking neuromechanics, including kinematics, muscle activity, and kinetics (ie, ground reaction force [GRF], moment, and power), between participants with and those without CAI by applying a novel statistical analysis to data from a large sample. Design Controlled laboratory study. Setting Biomechanics laboratory. Patients or Other Participants A total of 100 participants with CAI (49 men, 51 women; age = 22.2 ± 2.3 years, height = 174.0 ± 9.7 cm, mass = 70.8 ± 14.4 kg) and 100 individuals without CAI serving as controls (55 men, 45 women; age = 22.5 ± 3.3 years, height = 173.1 ± 13.3 cm, mass = 72.6 ± 18.7 kg). Intervention(s) Participants performed 5 trials of walking (shod) at a self-selected speed over 2 in-ground force plates. Main Outcome Measure(s) Three-dimensional GRFs, lower extremity joint angles, internal joint moments, joint powers, and activation amplitudes of 6 muscles were recorded during stance. Results Compared with the control group, the CAI group demonstrated (1) increased plantar flexion or decreased dorsiflexion, increased inversion or decreased eversion, decreased knee flexion, decreased knee abduction, and increased hip-flexion angles; (2) increased or decreased inversion, increased plantar flexion, decreased knee extension, decreased knee abduction, and increased hip-extension moments; (3) increased vertical, braking, and propulsive GRFs; (4) increased hip eccentric and concentric power; and (5) altered muscle activation in all 6 lower extremity muscles. Conclusions The CAI group demonstrated a hip-dominant strategy by limiting propulsive forces at the ankle while increasing force generation at the hip. The different walking neuromechanics exhibited by the CAI group could represent maladaptive strategies that developed after the initial sprain or an injurious gait pattern that may have predisposed the participants to their initial injuries. Increased joint loading and altered kinematics at the foot and ankle complex during initial stance could affect the long-term health of the ankle articular cartilage.

Effects of a 4-Week Dynamic-Balance-Training Program Supplemented With Graston Instrument-Assisted Soft-Tissue Mobilization for Chronic Ankle Instability

2012 ◽  
Vol 21 (4) ◽  
pp. 313-326 ◽  
Author(s):  
Jessica L. Schaefer ◽  
Michelle A. Sandrey
Keyword(s):  
Soft Tissue ◽  
Postural Control ◽  
Outcome Measures ◽  
Repeated Measures ◽  
Ankle Instability ◽  
Dynamic Balance ◽  
Plantar Flexion ◽  
Balance Training ◽  
Chronic Ankle Instability ◽  
Soft Tissue Mobilization

Context:A dynamic-balance-training (DBT) program supplemented with the Graston instrument-assisted soft-tissue mobilization (GISTM) technique has not been evaluated collectively as a treatment in subjects with chronic ankle instability (CAI).Objective:To examine the effects of GISTM in conjunction with a DBT program on outcomes associated with CAI, including pain and disability, range of motion (ROM), and dynamic postural control.Design:Pretest/posttest, repeated measures.Setting:High school and a Division I mid-Atlantic university.Participants:Thirty-six healthy, physically active individuals (5 female, 31 male; age 17.7 ± 1.9 y; height 175.3 ± 14.6 cm) with a history of CAI as determined by an ankle-instability questionnaire volunteered to be in this study.Interventions:Subjects were randomly assigned to 1 of 3 intervention groups: both treatments (DBT/GISTM, n = 13), DBT and a sham GISTM treatment (DBT/GISTM-S, n = 12), or DBT and control—no GISTM (DBT/C, n = 11). All groups participated in a 4-wk DBT program consisting of low-impact and dynamic activities that was progressed from week to week. The DBT/GISTM and DBT/GISTM-S groups received the GISTM treatment or sham treatment twice a week for 8 min before performing the DBT program. Pretest and posttest measurements included the Foot and Ankle Ability Measure (FAAM), FAAM Sport, the visual analog scale (VAS), ankle ROM in 4 directions, and the Star Excursion Balance Test (SEBT) in 3 directions.Main Outcome Measures:FAAM and FAAM-Sport scores, VAS, goniometric ROM (plantar flexion, dorsiflexion, inversion, eversion), and SEBT (anterior, posteromedial, posterolateral).Results:Subjects in all groups posttest demonstrated an increase in FAAM, FAAM Sport, ROM, and SEBT in all directions but not in VAS, which decreased. No other results were significant.Conclusion:For subjects with CAI, dynamic postural control, ROM, pain and disability improved pretest to posttest regardless of group membership, with the largest effects found in most measures in the DBT/GISTM group.

scholarly journals Lower Extremity Biomechanics During a Drop-Vertical Jump in Participants With or Without Chronic Ankle Instability

2018 ◽  
Vol 53 (4) ◽  
pp. 364-371 ◽  
Author(s):  
C. Collin Herb ◽  
Kaitlyn Grossman ◽  
Mark A. Feger ◽  
Luke Donovan ◽  
Jay Hertel
Keyword(s):  
Lower Extremity ◽  
Motion Capture ◽  
Sagittal Plane ◽  
Ankle Instability ◽  
Vertical Jump ◽  
Plantar Flexion ◽  
Reaction Force ◽  
Chronic Ankle Instability ◽  
Vertical Ground Reaction Force ◽  
Drop Vertical Jump

Context:  Chronic ankle instability (CAI) is a condition characterized by range-of-motion, neuromuscular, and postural-control deficits and subjective disability, reinjury, and posttraumatic osteoarthritis. Differences have been reported in kinematics, kinetics, surface electromyography (EMG), and ground reaction forces during functional tasks performed by those with CAI. These measures are often collected independently, and the research on collecting measures simultaneously during a movement task is limited. Objective:  To assess the kinematics and kinetics of the lower extremity, vertical ground reaction force (vGRF), and EMG of 4 shank muscles during a drop–vertical-jump (DVJ) task. Design:  Controlled laboratory study. Setting:  Motion-capture laboratory. Patients or Other Participants:  Forty-seven young, active adults in either the CAI (n = 24) or control (n = 23) group. Intervention(s):  Three-dimensional motion capture was performed using an electromagnetic motion-capture system. Lower extremity kinematics, frontal- and sagittal-plane kinetics, vGRF, and EMG of the shank musculature were collected while participants performed 10 DVJs. Main Outcome Measure(s):  Means and 90% confidence intervals were calculated for all measures from 100 milliseconds before to 200 milliseconds after force-plate contact. Results:  Patients with CAI had greater inversion from 107 to 200 milliseconds postcontact (difference = 4.01° ± 2.55°), smaller plantar-flexion kinematics from 11 to 71 milliseconds postcontact (difference = 5.33° ± 2.02°), greater ankle sagittal-plane kinetics from 11 to 77 milliseconds postcontact (difference = 0.17 ± 0.09 Nm/kg) and from 107 to 200 milliseconds postcontact (difference = 0.23 ± 0.03 Nm/kg), and smaller knee sagittal-plane kinematics from 95 to 200 milliseconds postcontact (difference = 8.23° ± 0.97°) than control participants after landing. The patients with CAI had greater vGRF from 94 to 98 milliseconds postcontact (difference = 0.83 ± 0.03 N/kg) and peroneal activity from 17 to 128 milliseconds postcontact (difference = 10.56 ± 4.52 N/kg) than the control participants. Conclusions:  Patients with CAI presented with differences in their landing strategies that may be related to continued instability. Kinematic and kinetic changes after ground contact and greater vGRF may be related to a faulty landing strategy. The DVJ task should be considered for rehabilitation protocols in these individuals.

Does Chronic Ankle Instability Influence Knee Biomechanics of Females during Inverted Surface Landings?

2018 ◽  
Vol 39 (13) ◽  
pp. 1009-1017 ◽  
Author(s):  
Yumeng Li ◽  
Jupil Ko ◽  
Marika Walker ◽  
Cathleen Brown ◽  
Julianne Schmidt ◽  
...  
Keyword(s):  
Internal Rotation ◽  
Knee Flexion ◽  
Sagittal Plane ◽  
Ankle Instability ◽  
Knee Extension ◽  
Chronic Ankle Instability ◽  
Initial Contact ◽  
Knee Biomechanics ◽  
Peak Knee ◽  
Eccentric Work

AbstractThe primary purpose of the study was to determine whether atypical knee biomechanics are exhibited during landing on an inverted surface. A seven-camera motion analysis system and two force plates were used to collect lower extremity biomechanics from two groups of female participants: 21 subjects with chronic ankle instability (CAI) and 21 with pair-matched controls. Subjects performed ten landings onto inverted and flat platforms on the CAI/matched and non-test limbs, respectively. Knee and ankle joint angles, joint angular displacements, joint moments and eccentric work were calculated during the landing phase and/or at the initial contact. Paired t-tests were used to compare between-group differences (p<0.05). We observed that CAI group displayed a significantly increased knee flexion angle, knee flexion displacement, peak knee extension moment and internal rotation moment, and eccentric work in the sagittal plane, possibly due to altered ankle biomechanics. Participants with CAI employed some compensatory strategy to improve their ankle and postural stability during landing onto the tilted surface. The increased knee extension and internal rotation moments of CAI participants could potentially result in a greater ACL loading. In future studies, it may be worthwhile to measure or estimate the ACL loading to confirm whether CAI could relate to the mechanism of ACL injury.

scholarly journals Balance- and Strength-Training Protocols to Improve Chronic Ankle Instability Deficits, Part I: Assessing Clinical Outcome Measures

2018 ◽  
Vol 53 (6) ◽  
pp. 568-577 ◽  
Author(s):  
Emily A. Hall ◽  
Andrea K. Chomistek ◽  
Jackie J. Kingma ◽  
Carrie L. Docherty
Keyword(s):  
Strength Training ◽  
Repeated Measures ◽  
Performance Test ◽  
Functional Performance ◽  
Ankle Instability ◽  
Plantar Flexion ◽  
Chronic Ankle Instability ◽  
Control Group ◽  
Training Protocol ◽  
Training Protocols

Context:  Functional rehabilitation may improve the deficits associated with chronic ankle instability (CAI). Objective:  To determine if balance- and strength-training protocols improve the balance, strength, and functional performance deficits associated with CAI. Design:  Randomized controlled clinical trial. Setting:  Athletic training research laboratory. Patients or Other Participants:  Participants were 39 volunteers with CAI, which was determined using the Identification of Functional Ankle Instability Questionnaire. They were randomly assigned to 1 of 3 groups: balance-training protocol (7 males, 6 females; age = 23.5 ± 6.5 years, height = 175.0 ± 8.5 cm, mass = 72.8 ± 10.9 kg), strength-training protocol (8 males, 5 females; age = 24.6 ± 7.7 years, height = 173.2 ± 9.0 cm, mass = 76.0 ± 16.2 kg), or control (6 males, 7 females; age = 24.8 ± 9.0 years, height = 175.5 ± 8.4 cm, mass = 79.1 ± 16.8 kg). Intervention(s):  Each group participated in a 20-minute session, 3 times per week, for 6 weeks. The control group completed a mild to moderately strenuous bicycle workout. Main Outcome Measure(s):  Participants completed baseline testing of eccentric and concentric isokinetic strength in each ankle direction (inversion, eversion, plantar flexion, and dorsiflexion) and the Balance Error Scoring System (BESS), Star Excursion Balance Test (SEBT), and side-hop functional performance test. The same variables were tested again at 6 weeks after the intervention. Two multivariate repeated-measures analyses of variance with follow-up univariate analyses were conducted. The α level was set a priori at .05. Results:  We observed time-by-group interactions in concentric (P = .02) and eccentric (P = .01) inversion, eccentric eversion (P = .01), concentric (P = .001) and eccentric (P = .03) plantar flexion, BESS (P = .01), SEBT (P = .02), and side hop (P = .004). With pairwise comparisons, we found improvements in the balance- and strength-training protocol groups in concentric and eccentric inversion and concentric and eccentric plantar flexion and the BESS, SEBT, and side hop (all P values = .001). Only the strength-training protocol group improved in eccentric eversion. The control group did not improve in any dependent variable. Conclusions:  Both training protocols improved strength, balance, and functional performance. More clinicians should incorporate hop-to-stabilization exercises into their rehabilitation protocols to improve the deficits associated with CAI.

scholarly journals The Applications of Landing Strategies in Badminton Footwork Training on a Backhand Side Lateral Jump Smash

2020 ◽  
Vol 73 (1) ◽  
pp. 19-31
Author(s):  
Min-Hao Hung ◽  
Chi-Yao Chang ◽  
Kuo-Chuan Lin ◽  
Chia-Ling Hung ◽  
Chin-Shan Ho
Keyword(s):  
Ground Reaction Force ◽  
Repeated Measures ◽  
Knee Flexion ◽  
Reaction Force ◽  
Lower Limbs ◽  
Initial Contact ◽  
Target Area ◽  
Vertical Ground Reaction Force ◽  
Hip Abduction ◽  
Vertical Ground

AbstractPrevious research in badminton has associated unilateral landings following overhead strokes with the occurrence of knee injuries. Smashing involves tensing the abdomen muscles while swinging the racket rapidly and maintaining one’s balance while performing coordinated movements and steps; this process puts stress on the player’s lower limbs. However, few studies have compared the effects of different stroke training while performing various types of badminton strokes. This study investigated the influence of different stroke training on the smash action of badminton players. Three stroke training conditions were considered: shadow, target striking, and smashing. Sixteen male experienced badminton players were recruited for this study. One-way repeated-measures ANOVA with Bonferroni correction was used to identify the differences. At the initial contact with the ground, the knee flexion and knee valgus angles under the smash condition were significantly higher than target and shadow conditions. Under the smash condition, hip abduction was significantly higher than under the target and shadow conditions. Moreover, the hip abduction under the target condition was significantly higher than under the shadow condition. At the maximum knee flexion, the hip abduction under the smash and target conditions was significantly higher than under the shadow condition. Regarding the time from the moment of initial contact to the peak of vertical ground reaction force it was shorter under the smash condition than the target and shadow conditions. The vertical ground reaction force was higher under the smash condition than under the target and shadow conditions. The 50 ms impulse was higher under the smash condition than under the target and shadow conditions. The main findings of this study are that under the smash condition, the motion in the frontal plane increased, which produced higher loads on the joints in the lower limbs. Player performed the same footwork under the three conditions, but the landing strategies differed because of unique swing motions and techniques. The condition under which a player hits a shot to a target area can affect the landing. The results of this study suggest that target practice is more effective for improving the landing technique employed during actual shots than shadow practice.

Gluteal Activity During Gait in Patients With Chronic Ankle Instability Following Rehabilitation: A Randomized Controlled Trial

2021 ◽  
pp. 1-7
Author(s):  
Alexandra F. DeJong Lempke ◽  
Rachel M. Koldenhoven ◽  
Abbis H. Jaffri ◽  
Jay Hertel
Keyword(s):  
Randomized Controlled Trial ◽  
Repeated Measures ◽  
Gait Cycle ◽  
Ankle Instability ◽  
Controlled Trial ◽  
Gluteus Maximus ◽  
Gluteus Medius ◽  
Chronic Ankle Instability ◽  
Initial Contact ◽  
Randomized Controlled

Context: Ankle positioning gait biofeedback (GBF) has improved ankle inversion for patients with chronic ankle instability. However, the effects on proximal deficits remain unknown. The purpose of this study was to determine the effects of impairment-based rehabilitation with GBF and without biofeedback on gluteal activity during walking in patients with chronic ankle instability. Design: Randomized controlled trial. Methods: Eighteen patients with chronic ankle instability (14 women and 4 men; age 22 [4] y; height 171 [10] cm; mass 71.6 [13.8] kg) were recruited from a university setting, following International Ankle Consortium guidelines. Patients were randomly allocated to GBF or without biofeedback groups (N = 9 per group). Both groups performed 4 weeks of exercises and treadmill walking. The GBF group alone received feedback on frontal ankle positioning at initial contact during walking. Ultrasound videos of the gluteus maximus and medius were recorded during walking at baseline and follow-up by a blinded clinician. Gluteal activity ratios were obtained at each 10% of the gait cycle. Statistical parametric mapping repeated-measures analysis of variance were used to compare groups and time points. Results: Both groups demonstrated significantly increased gluteus medius activity across the gait cycle compared with baseline (P < .01, mean differences: 0.13–0.21, Hedge g: 0.97–1.89); however, there were no significant between-group differences. There were no statistically significant changes noted for the gluteus maximus. No adverse events were observed. Conclusions: Impairment-based rehabilitation led to increased gluteus medius activity, but GBF did not provide any additional improvement to this parameter. Clinicians may consider implementing impairment-based strengthening interventions to improve gluteus medius function during gait for patients with CAI.

scholarly journals People with chronic ankle instability benefit from brace application in highly dynamic change of direction movements

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Patrick Fuerst ◽  
Albert Gollhofer ◽  
Markus Wenning ◽  
Dominic Gehring
Keyword(s):  
Ankle Joint ◽  
Repeated Measures ◽  
Ankle Instability ◽  
Dynamic Change ◽  
Chronic Ankle Instability ◽  
Mechanical Resistance ◽  
Healthy Controls ◽  
Neuromuscular Activation ◽  
Ankle Inversion ◽  
Ankle Brace

Abstract Background The application of ankle braces is an effective method for the prevention of recurrent ankle sprains. It has been proposed that the reduction of injury rates is based on the mechanical stiffness of the brace and on beneficial effects on proprioception and neuromuscular activation. Yet, how the neuromuscular system responds to the application of various types of ankle braces during highly dynamic injury-relevant movements is not well understood. Enhanced stability of the ankle joint seems especially important for people with chronic ankle instability. We therefore aimed to analyse the effects of a soft and a semi-rigid ankle brace on the execution of highly dynamic 180° turning movements in participants with and without chronic ankle instability. Methods Fifteen participants with functional ankle instability, 15 participants with functional and mechanical ankle instability and 15 healthy controls performed 180° turning movements in reaction to light signals in a cross-sectional descriptive laboratory study. Ankle joint kinematics and kinetics as well as neuromuscular activation of muscles surrounding the ankle joint were determined. Two-way repeated measures analyses of variance and post-hoc t-tests were calculated. Results Maximum ankle inversion angles and velocities were significantly reduced with the semi-rigid brace in comparison to the conditions without a brace and with the soft brace (p ≤ 0.006, d ≥ 0.303). Effect sizes of these reductions were larger in participants with chronic ankle instability than in healthy controls. Furthermore, peroneal activation levels decreased significantly with the semi-rigid brace in the 100 ms before and after ground contact. No statistically significant brace by group effects were found. Conclusions Based on these findings, we argue that people with ankle instability in particular seem to benefit from a semi-rigid ankle brace, which allows them to keep ankle inversion angles in a range that is comparable to values of healthy people. Lower ankle inversion angles and velocities with a semi-rigid brace may explain reduced injury incidences with brace application. The lack of effect of the soft brace indicates that the primary mechanism behind the reduction of inversion angles and velocities is the mechanical resistance of the brace in the frontal plane.

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