Altered Plantar-Receptor Stimulation Impairs Postural Control in Those With Chronic Ankle Instability

2012 ◽  
Vol 21 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Patrick O. McKeon ◽  
Alex J. Stein ◽  
Christopher D. Ingersoll ◽  
Jay Hertel
Keyword(s):  
Postural Control ◽  
Outcome Measures ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Physically Active ◽  
Plantar Surface ◽  
Eyes Closed ◽  
Eyes Open ◽  
Sensorimotor Mechanisms ◽  
Control Sham

Context:Postural control as assessed via time-to-boundary (TTB) measures has been shown to be impaired in those with chronic ankle instability (CAI). Foot orthotics have been shown to improve postural control, although it is not clear if this is via mechanical or sensorimotor mechanisms.Objective:To assess the effect of textured shoe inserts that provide no mechanical support on postural control as assessed by TTB measures in subjects with CAI.Design:A crossover design to examine the effects of a textured insole on postural control in individuals with unilateral CAI. The independent variables were vision (eyes open, eyes closed) and texture (textured insole, sham insole, control).Setting:Laboratory.Participants:20 physically active individuals, 12 men, 8 women, age 18–45 y (21.5 ± 5.51) with self-reported CAI.Intervention:Each subject balanced in shod single-limb stance with eyes open and eyes closed under 3 conditions (control, sham, and textured insole). The order of testing under the 3 shoe conditions and 2 vision conditions was counterbalanced.Main Outcome Measures:The mean of TTB minima and the standard deviation of TTB minima in the mediolateral (ML) and anteroposterior directions.Results:There were significant reductions in TTB ML magnitude and variability found in the textured condition compared with the control and sham conditions. In the textured condition, subjects failed significantly more trials than any other condition.Conclusions:Stimulating the plantar surface of the foot, via a textured insole, has an effect in the broad spectrum of postural-control maintenance in individuals with CAI.

scholarly journals Comparative Effectiveness of Plantar-Massage Techniques on Postural Control in Those With Chronic Ankle Instability

2017 ◽  
Vol 52 (7) ◽  
pp. 629-635 ◽  
Author(s):  
Erik A. Wikstrom ◽  
Kyeongtak Song ◽  
Ashley Lea ◽  
Nastassia Brown
Keyword(s):  
Postural Control ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Balance Test ◽  
Physically Active ◽  
Lateral Ankle ◽  
Massage Treatment ◽  
Eyes Open ◽  
University Setting ◽  
Stimulation Of

Context:  One of the major concerns after an acute lateral ankle sprain is the potential for development of chronic ankle instability (CAI). The existing research has determined that clinician-delivered plantar massage improves postural control in those with CAI. However, the effectiveness of self-administered treatments and the underlying cause of any improvements remain unclear. Objectives:  To determine (1) the effectiveness of a self-administered plantar-massage treatment in those with CAI and (2) whether the postural-control improvements were due to the stimulation of the plantar cutaneous receptors. Design:  Crossover study. Setting:  University setting. Patients or Other Participants:  A total of 20 physically active individuals (6 men and 14 women) with self-reported CAI. Intervention(s):  All participants completed 3 test sessions involving 3 treatments: a clinician-delivered manual plantar massage, a patient-delivered self-massage with a ball, and a clinician-delivered sensory brush massage. Main Outcome Measure(s):  Postural control was assessed using single-legged balance with eyes open and the Star Excursion Balance Test. Results:  Static postural control improved (P ≤ .014) after each of the interventions. However, no changes in dynamic postural control after any of the interventions were observed (P > .05). No differences were observed between a clinician-delivered manual plantar massage and either a patient-delivered self-massage with a ball or a clinician-delivered sensory brush massage in any postural-control outcome. Conclusions:  In those with CAI, single 5-minute sessions of traditional plantar massage, self-administered massage, and sensory brush massage each resulted in comparable static postural-control improvements. The results also provide empirical evidence suggesting that the mechanism for the postural-control improvements is the stimulation of the plantar cutaneous receptors.

Effect of a 2-Week Joint-Mobilization Intervention on Single-Limb Balance and Ankle Arthrokinematics in Those With Chronic Ankle Instability

2014 ◽  
Vol 23 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Matthew C. Hoch ◽  
David R. Mullineaux ◽  
Richard D. Andreatta ◽  
Robert A. English ◽  
Jennifer M. Medina-McKeon ◽  
...  
Keyword(s):  
Postural Control ◽  
Outcome Measures ◽  
Repeated Measures ◽  
Center Of Pressure ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Talocrural Joint ◽  
Joint Mobilization ◽  
Multiple Treatment ◽  
Eyes Open

Context:A single talocrural joint-mobilization treatment has improved spatiotemporal measures of postural control but not ankle arthrokinematics in individuals with chronic ankle instability (CAI). However, the effects of multiple treatment sessions on these aspects of function have not been investigated.Objective:To examine the effect of a 2-wk anterior-to-posterior joint-mobilization intervention on instrumented measures of single-limb-stance static postural control and ankle arthrokinematics in adults with CAI.Design:Repeated measures.Setting:Research laboratory.Participants:12 individuals with CAI (6 male, 6 female; age 27.4 ± 4.3 y, height 175.4 ± 9.78 cm, mass 78.4 ± 11.0 kg).Intervention:Subjects received 6 treatments sessions of talocrural grade II joint traction and grade III anterior-to-posterior joint mobilization over 2 wk.Main Outcome Measures:Instrumented measures of single-limb-stance static postural control (eyes open and closed) and anterior and posterior talar displacement and stiffness were assessed 1 wk before the intervention (baseline), before the first treatment (preintervention), 24–48 h after the final treatment (postintervention), and 1 wk later (1-wk follow-up). Postural control was analyzed as center-of-pressure velocity, center-of-pressure range, the mean of time-to-boundary minima, and standard deviation of time-to-boundary minima in the anteroposterior and mediolateral directions for each visual condition.Results:No significant differences were identified in any measures of postural control (P > .08) or ankle arthrokinematics (P > .21).Conclusions:The 2-wk talocrural joint-mobilization intervention did not alter instrumented measures of single-limb-stance postural control or ankle arthrokinematics. Despite the absence of change in these measures, this study continues to clarify the role of talocrural joint mobilization as a rehabilitation strategy for patients with CAI.

Progressive Visual Occlusion and Postural Control Responses in Individuals With and Without Chronic Ankle Instability

2021 ◽  
pp. 1-6
Author(s):  
Lilly H. VanDeMark ◽  
Christina B. Vander Vegt ◽  
Cassie B. Ford ◽  
Jason P. Mihalik ◽  
Erik A. Wikstrom
Keyword(s):  
Postural Control ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Heterogeneous Sample ◽  
Eyes Closed ◽  
Visual Occlusion ◽  
Sensory Organization ◽  
Eyes Open ◽  
History Of ◽  
Partially Occluded

Context: Prophylactic and rehabilitative balance training is needed to maximize postural control and develop appropriate sensory organization strategies. Partially occluding vision during functional exercise may promote appropriate sensory organization strategies, but little is known about the influence of partially occluded vision on postural control in those with and without a history of musculoskeletal injury. Objective: To determine the effect of increasing levels of visual occlusion on postural control in a heterogeneous sample of those with and without chronic ankle instability (CAI). The secondary objective was to explore postural control responses to increasing levels of visual occlusion among those with unilateral and bilateral CAI relative to uninjured controls. Design: Cross-sectional. Setting: Sports medicine research laboratory. Patients or Other Participants: Twenty-five participants with unilateral CAI, 10 with bilateral CAI, and 16 participants with no history of lower extremity injury. Main Outcome Measures: All participants completed four 3-minute postural control assessments in double-limb stance under the following 4 visual conditions: (1) eyes open, (2) low occlusion, (3) high occlusion, and (4) eyes closed. Low- and high-occlusion conditions were produced using stroboscopic eyewear. Postural control outcomes included time-to-boundary minima means in the anteroposterior (TTB-AP) and mediolateral directions (TTB-ML). Repeated-measures analysis of variances tested the effects of visual condition on TTB-AP and TTB-ML. Results: Postural control under the eyes-open condition was significantly better (ie, higher) than the limited visual occlusion and eyes-closed conditions (P < .001) for TTB-AP and TTB-ML. For TTB-AP only, partially occluded vision resulted in better postural control than the eyes-closed condition (P ≤ .003). Conclusions: Partial and complete visual occlusion impaired postural control during dual-limb stance in a heterogeneous sample of those with and without CAI. Stroboscopic eyewear appears to induce postural control impairments to the same extent as complete visual occlusion in the mediolateral direction.

The Effect of 2 Forms of Talocrural Joint Traction on Dorsiflexion Range of Motion and Postural Control in Those With Chronic Ankle Instability

2017 ◽  
Vol 26 (3) ◽  
pp. 239-244 ◽  
Author(s):  
Cameron J. Powden ◽  
Kathleen K. Hogan ◽  
Erik A. Wikstrom ◽  
Matthew C. Hoch
Keyword(s):  
Postural Control ◽  
Range Of Motion ◽  
Outcome Measures ◽  
Ankle Instability ◽  
Weight Bearing ◽  
Chronic Ankle Instability ◽  
Physical Contact ◽  
Future Research ◽  
Talocrural Joint ◽  
Sham Condition

Context:Talocrural joint mobilizations are commonly used to address deficits associated with chronic ankle instability (CAI).Objective:Examine the immediate effects of talocrural joint traction in those with CAI.Design:Blinded, crossover.Setting:Laboratory.Participants:Twenty adults (14 females; age = 23.80 ± 4.02 y; height = 169.55 ± 12.38 cm; weight = 78.34 ± 16.32 kg) with self-reported CAI participated. Inclusion criteria consisted of a history of ≥1 ankle sprain, ≥2 episodes of giving way in the previous 3 mo, answering “yes” to ≥4 questions on the Ankle Instability Instrument, and ≤24 on the Cumberland Ankle Instability Tool.Intervention:Subjects participated in 3 sessions in which they received a single treatment session of sustained traction (ST), oscillatory traction (OT), or a sham condition in a randomized order. Interventions consisted of four 30-s sets of traction with 1 min of rest between sets. During ST and OT, the talus was distracted distally from the ankle mortise to the end-range of accessory motion. ST consisted of continuous distraction and OT involved 1-s oscillations between the mid and end-range of accessory motion. The sham condition consisted of physical contact without force application. Preintervention and postintervention measurements of weight-bearing dorsiflexion, dynamic balance, and static single-limb balance were collected.Main Outcome Measures:The independent variable was treatment (ST, OT, sham). The dependent variables included pre-to-posttreatment change scores for the WBLT (cm), normalized SEBTAR (%), and time-to-boundary (TTB) variables(s). Separate 1-way ANOVAs examined differences between treatments for each dependent variable. Alpha was set a priori at P < .05.Results:No significant treatment effects were identified for any variables.Conclusion:A single intervention of ST or OT did not produce significant changes in weight-bearing dorsiflexion range of motion or postural control in individuals with CAI. Future research should investigate the effects of repeated talocrural traction treatments and the effects of this technique when combined with other manual therapies.

Static Postural Stability in Chronic Ankle Instability, an Ankle Sprain and Healthy Ankles

2018 ◽  
Vol 39 (08) ◽  
pp. 625-629 ◽  
Author(s):  
Yong Kwon
Keyword(s):  
Postural Stability ◽  
Ankle Instability ◽  
Mean Amplitude ◽  
Chronic Ankle Instability ◽  
Medial Gastrocnemius ◽  
Muscle Type ◽  
Eyes Closed ◽  
Ankle Muscles ◽  
Eyes Open ◽  
Balance Error

AbstractTo identify the single leg balance (SLB) test that discriminates among healthy, coper, and chronic ankle instability (CAI) groups and to determine effects of ankle muscles on the balance error scoring system (BESS) among the three populations. 60 subjects (20 per group) performed the SLB test with eyes open (EO) and eyes closed (EC). Normalized mean amplitude (NMA) of the tibia anterior (TA), fibularis longus (FL), and medial gastrocnemius (MG) muscles and BESS were measured while performing the SLB test. The coper group had a lower error score than the CAI group in the EC. NMA was greater in the CAI group compared to in the healthy and coper groups regardless of muscle type. NMA of the TA was less than the PL and MG regardless of the group in the EO. The CAI group demonstrated greater NMAs of the PL and MG than the healthy and coper groups in the EC. The CAI group demonstrated greater NMA of the PL and MG by compensating their ankle muscles in the EO and EC. BESS suggests that the coper group may have coping mechanisms to stabilize static postural control compared to the CAI group. The EC may be better to detect static postural instability in the CAI or coper group.

The Immediate Effects of an Anterior-To-Posterior Talar Mobilization on Neural Excitability, Dorsiflexion Range of Motion, and Dynamic Balance in Patients With Chronic Ankle Instability

2014 ◽  
Vol 23 (4) ◽  
pp. 351-359 ◽  
Author(s):  
Matthew Harkey ◽  
Michelle McLeod ◽  
Ashley Van Scoit ◽  
Masafumi Terada ◽  
Michael Tevald ◽  
...  
Keyword(s):  
Postural Control ◽  
Range Of Motion ◽  
Outcome Measures ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Corticospinal Excitability ◽  
Spinal Reflex ◽  
Control Group ◽  
Joint Mobilization ◽  
Grade Iii

Context:Altered neuromuscular function and decreased dorsiflexion range of motion (DFROM) have been observed in patients with chronic ankle instability (CAI). Joint mobilizations are indicated for restoring DFROM and dynamic postural control, yet it remains unknown if a mobilization can alter neuromuscular excitability in muscles surrounding the ankle.Objective:To determine the immediate effects of a Maitland grade III anterior-to-posterior joint mobilization on spinal-reflex and corticospinal excitability in the fibularis longus (FL) and soleus (SOL), DFROM, and dynamic postural control.Design:Single-blinded randomized control trial.Setting:Research laboratory.Patients:30 patients with CAI randomized into a mobilization (n = 15) or control (n = 15) group.Intervention:Maitland grade III anterior-to-posterior joint mobilization.Main Outcome Measures:Spinal-reflex excitability was measured with the Hoffmann reflex, while corticospinal excitability was evaluated with transcranial magnetic stimulation. DFROM was measured seated with the knee extended, and dynamic postural control was quantified with the Star Excursion Balance Test. Separate 2 × 2 repeated-measures ANOVAs were performed for each outcome measure. Dependent t tests were used to evaluate individual differences within groups in the presence of significance.Results:Spinal-reflex and corticospinal excitability of the SOL and FL were not altered in the mobilization or control group (P > .05). DFROM increased immediately after the mobilization (P = .05) but not in the control group, while dynamic postural control was unchanged in both groups (P > .05).Conclusion:A single joint-mobilization treatment was efficacious at restoring DFROM in participants with CAI; however, excitability of spinal reflex and corticospinal pathways at the ankle and dynamic postural control were unaffected.

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 Acute Effects of Increased Joint Mobilization Treatment Duration on Ankle Function and Dynamic Postural Control in Female Athletes With Chronic Ankle Instability

2020 ◽  
Vol 8 (6) ◽  
pp. 232596712092737 ◽  
Author(s):  
Christopher J. Holland ◽  
Jonathan D. Hughes ◽  
Mark B.A. De Ste Croix
Keyword(s):  
Postural Control ◽  
Outcome Measures ◽  
Mixed Model ◽  
Female Athletes ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Effect Sizes ◽  
Treatment Groups ◽  
Joint Mobilization ◽  
All Treatment

Background: Chronic ankle instability (CAI) is linked to mechanical and functional insufficiencies. Joint mobilization is purported to be effective at treating these deficits. Purpose: To examine the effect of different treatment durations of a grade IV anterior-to-posterior ankle joint mobilization on weightbearing dorsiflexion range of motion (WB-DFROM), posterior talar glide (PG), and dynamic postural control in individuals with CAI. Study Design: Controlled laboratory study. Methods: A total of 48 female athletes (mean age, 22.8 ± 4.8 years) with unilateral CAI participated in this study. Participants were randomly assigned to 1 of 3 treatment conditions: 30 seconds, 60 seconds, and 120 seconds. Treatment was provided to the injured limb on 3 separate occasions 48 hours apart and consisted of a Maitland grade IV anterior-to-posterior talar joint mobilization based on the participant’s initial group assignment. WB-DFROM; PG; and the anterior (ANT), posteromedial (PM), and posterolateral (PL) reach directions of the Star Excursion Balance Test were measured bilaterally before and after each treatment. The uninjured limb acted as a control. Data were analyzed using 2-way mixed-model analyses of variance, and effect sizes were calculated through use of Hedges g. Results: Significant differences were detected after all treatment sessions for all outcome measures ( P ≤ .001) and between treatment groups after sessions 1, 2, and 3 for all outcome measures ( P ≤ .001). Effect sizes were very large or huge for all treatment groups for WB-DFROM, PG, and ANT reach direction. Substantial variation was found in effect sizes for PM and PL measures. Conclusion: Accessory mobilization is an effective treatment to induce acute changes in ankle motion and dynamic postural control in patients with CAI, with longer treatment durations conferring greater improvements. Clinical Relevance: This study adds clarity to the use of joint mobilization treatments and will add to the current clinical practice strategy for patients with CAI.

scholarly journals Effect of ultrasound-guided percutaneous neuromodulation in ankle instability: a case study

2019 ◽  
Vol 02 (02) ◽  
pp. 100-101
Author(s):  
Rodríguez Rosal M. ◽  
Sánchez Sixto A. ◽  
Álvarez Barbosa F. ◽  
Yáñez Álvarez A.
Keyword(s):  
Effect Size ◽  
Center Of Pressure ◽  
Tibial Nerve ◽  
Ankle Instability ◽  
Center Of Mass ◽  
Force Plate ◽  
Chronic Ankle Instability ◽  
Balance Test ◽  
Eyes Closed ◽  
Eyes Open

Abstract Background and Aims Ankle proprioception can be tested in many ways. Some studies have found improvements in individuals with chronic ankle instability after receiving treatment and training proprioceptive acuity and speed. Currently, there is a scarcity of evidence concerning percutaneous neuromodulation. The first findings were reported in the post-surgical stage after total knee arthroplasty and in neural improvements and symptoms in patients with hyperactive bladder. Aim To evaluate the effectiveness of percutaneous neuromodulation on the tibial nerve for the improvement of various proprioception parameters in patients with chronic ankle instability. Material and Methods Five men (age: 24.8 ± 4.9 years; height: 1.78 ± 0.08 m; weight: 86 ± 9.8 kg) with chronic ankle instability, who regularly practiced sports activities participated in the present study. People who had undergone an injury in the previous three months were excluded from the speed. Currently, there is a scarcity of evidence concerning test before and immediately after percutaneous neuromodulation. A single leg balance test was performed with eyes open and closed, maintaining the single-legged position on a force plate during 30 seconds (Accupower; AMTI, Watertown, MA) registering 1000 Hz. The displacement of the center of pressure (DOT) was determined based on the distances of its antero-posterior axes (DOT_AP) and medio-lateral (DOT_ML). Furthermore, the amplitudes of anteroposterior and mediolateral displacement were evaluated (ACPap and ACPml). The posterior tibial nerve was stimulated under ultrasound guidance using a 100 Vpp current, with a pulse width of 250 μs and a repetition frequency of 2 to 10 Hz. The process was performed on three occasions during 30 seconds, with an intensity that was acknowledged by the patient but which did not go beyond a score of 3 in the visual analog scale (VAS). The means and standard deviations were calculated for all variables. The effect size was calculated establishing the confidence interval at 90% and the probability of the change being significant was qualitatively calculated. Results A decrease was found in the ACPap (Pre-test eyes open: 5.42 ± 0.62 and eyes closed: 15.99 ± 0.60; Post-test eyes open 4.05 ± 0.36 and eyes closed 10.33 ± 0.49) after the neuromodulation intervention on the tibial nerve. This was a significant change and a “possible” effect size was found in the closed eyes condition (-0.54; ± 0.72), according to Hopkins. For the remaining variables, no significant differences were observed. Conclusions A decreased displacement of the center of mass was found in the antero-posterior axis after performing the neuromodulation technique on the tibial nerve in patients with chronic ankle instability.

scholarly journals Modulation of the Fibularis Longus Hoffmann Reflex and Postural Instability Associated With Chronic Ankle Instability

2016 ◽  
Vol 51 (8) ◽  
pp. 637-643 ◽  
Author(s):  
Kyung-Min Kim ◽  
Joseph M. Hart ◽  
Susan A. Saliba ◽  
Jay Hertel
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Postural Instability ◽  
H Reflex ◽  
Reflex Modulation ◽  
Hoffmann Reflex ◽  
Eyes Closed ◽  
The Relationship

Context: Individuals with chronic ankle instability (CAI) present with decreased modulation of the Hoffmann reflex (H-reflex) from a simple to a more challenging task. The neural alteration is associated with impaired postural control, but the relationship has not been investigated in individuals with CAI. Objective: To determine differences in H-reflex modulation and postural control between individuals with or without CAI and to identify if they are correlated in individuals with CAI. Design: Descriptive laboratory study. Setting: Laboratory. Patients or Other Participants: A total of 15 volunteers with CAI (9 males, 6 females; age = 22.6 ± 5.8 years, height = 174.7 ± 8.1 cm, mass = 74.9 ± 12.8 kg) and 15 healthy sex-matched volunteers serving as controls (9 males, 6 females; age = 23.8 ± 5.8 years, height = 171.9 ± 9.9 cm, mass = 68.9 ± 15.5 kg) participated. Intervention(s): Maximum H-reflex (Hmax) and motor wave (Mmax) from the soleus and fibularis longus were recorded while participants lay prone and then stood in unipedal stance. We assessed postural tasks of unipedal stance with participants' eyes closed for 10 seconds using a forceplate. Main Outcome Measure(s): We normalized Hmax to Mmax to obtain Hmax : Mmax ratios for the 2 positions. For each muscle, H-reflex modulation was quantified using the percentage change scores in Hmax : Mmax ratios calculated from prone position to unipedal stance. Center-of-pressure data were used to compute 4 time-to-boundary variables. Separate independent-samples t tests were performed to determine group differences. Pearson product moment correlation coefficients were calculated between the modulation and balance measures in the CAI group. Results: The CAI group presented less H-reflex modulation in the soleus (t26 = −3.77, P = .001) and fibularis longus (t25 = −2.59, P = .02). The mean of the time-to-boundary minima in the anteroposterior direction was lower in the CAI group (t28 = −2.06, P = .048). We observed a correlation (r = 0.578, P = .049) between the fibular longus modulation and mean of time-to-boundary minima in the anteroposterior direction. Conclusions: The strong relationship indicated that, as H-reflex amplitude in unipedal stance was less down modulated, unipedal postural control was more impaired. Given the deficits in H-reflex modulation and postural control in the CAI group, the relationship may provide insights into the neurophysiologic mechanism of postural instability.

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