Plantar Cutaneous Sensitivity With and Without Cognitive Loading in People With Chronic Ankle Instability, Copers, and Uninjured Controls

Neuromuscular fatigue and cognitive constraints independently modify lower extremity landing biomechanics in healthy and chronic ankle instability individuals

The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain.

Gait and muscle activity measures after biomechanical device therapy in subjects with ankle instability: A systematic review

INTRODUCTION

Health specialists suggest a conservative approach comprising non-pharmacological interventions as the initial course of action for individuals with repetitive ankle sprain due to ankle instability. This systematic review aimed to assess the effectiveness of biomechanical devices (Foot Orthoses, Ankle Orthoses, and Taping) on gait and muscle activity in individuals with ankle instability.

METHODS

A systematic search was performed on electronic databases, including PubMed, EMBASE, Clinical Trials.gov, Web of Science, and Scopus. The PEDro scoring system was used to evaluate the quality of the included studies. We extracted data from population, intervention, and outcome measures.

RESULTS

In the initial search, we found 247 articles. After following the steps of the PRISMA flowchart, only 22 reports met the inclusion criteria of this study. The results show that biomechanical device therapy may increase swing time, stance time, and step. Additionally, studies suggest that these devices can reduce plantar flexion, inversion, and motion variability during gait. Biomechanical devices have the potential to optimize the subtalar valgus moment, push-off, and braking forces exerted during walking, as well as enhance the activity of specific muscles including the peroneus longus, peroneus brevis, tibialis anterior, gluteus medius, lateral gastrocnemius, rectus femoris, and soleus.

CONCLUSION

Biomechanical devices affect gait (spatiotemporal, kinetic, and kinematic variables) and lower limb muscle activity (root mean square, reaction time, amplitude, reflex, and wave) in subjects with ankle instability.

Deficits in neurocognitive performance in patients with chronic ankle instability during a neurocognitive balance task - A retrospective case-control study

OBJECTIVES

To assess the neurocognitive performance while maintaining balance of patients experiencing CAI compared to healthy controls. In patients with CAI, the affected limb was also compared to the contralateral limb.

DESIGN

A retrospective case-control study.

SETTING

Laboratory study.

PARTICIPANTS

We included 27 patients with CAI and 21 healthy controls.

METHODS

The study consisted of two sessions, namely familiarisation and experimentation, which were scheduled with a gap of at least one week between them. During the experimental trial, both groups performed the Y-Balance Test and Reactive Balance Test once on each limb.

MAIN OUTCOME MEASURES

The main outcome measures are accuracy and visuomotor response time (VMRT) calculated via video-analysis and with the Fitlight™-hardware and software respectively during the Reactive Balance Test (RBT).

RESULTS

No data was excluded from the final analysis. Patients with CAI exhibited significantly lower accuracy than healthy controls, with a mean difference of 8.7% (±3.0)%. There were no differences for VMRT between groups. Additionally, no significant differences were observed between the affected and contralateral limb of the patient group for both accuracy and VMRT.

CONCLUSIONS

Patients with CAI showed lower accuracy, but similar VMRT compared to healthy controls during a neurocognitive balance task, indicating impaired neurocognitive function. Patients exhibit comparable speed to healthy individuals when completing neurocognitive balance tasks, yet they display a higher frequency of accuracy errors in accurately perceiving their environment and making decisions under time constraints. Future research should gain more insights in which other cognitive domains are affected in patients with CAI for a better grasp of this condition's underlying mechanism.

Concentrating to avoid falling: interaction between peripheral sensory and central attentional demands during a postural stability limit task in sedentary seniors

Evidence suggests falls and postural instabilities among seniors are attributed to a decline in both the processing of afferent signals (e.g., proprioceptive, vestibular) and attentional resources. We investigated the interaction between the non-visual and attentional demands of postural control in sedentary seniors. Old and young adults performed a postural stability limit task involving a maximal voluntary leaning movement with and without vision as well as a cognitive-attentional subtraction task. These tasks were performed alone (single-task) or simultaneously (dual-task) to vary the sensory-attentional demands. The functional limits of stability were quantified as the maximum center of pressure excursion during voluntary leaning. Seniors showed significantly smaller limits of postural stability compared to young adults in all sensory-attentional conditions. However, surprisingly, both groups of subjects reduced their stability limits by a similar amount when vision was removed. Furthermore, they similarly decreased their anterior-posterior stability limits when concurrently performing the postural and the cognitive-attentional tasks with vision. The overall average cognitive performance of young adults was higher than seniors and was only slightly affected during dual-tasking. In contrast, older adults markedly degraded their cognitive performance from the single- to the dual-task situations, especially when vision was unavailable. Thus, their dual-task costs were higher than those of young adults and increased in the eyes-closed condition, when postural control relied more heavily on non-visual sensory signals. Our findings provide the first evidence that as posture approaches its stability limits, sedentary seniors allot increasingly large cognitive attentional resources to process critical sensory inputs.

Test-retest reliability of quantitative sensory testing, active joint position sense, and functional hop testing in amateur adult athletes with unilateral anterior cruciate ligament reconstruction

OBJECTIVES

The somatosensory system fulfils a critical role in functional knee joint stability (FKJS) by providing afferent feedback necessary for neuromuscular control. Individuals with anterior cruciate ligament reconstruction (ACLr) have altered somatosensory function. Somatosensory characteristics are assessed by proprioception and quantitative sensory testing. The purpose of the study was to examine intra-rater and inter-rater reliability of methods used to assess somatosensory characteristics and FKJS in amateur adult athletes with unilateral ACLr.

DESIGN

Repeated measures.

SETTING

University.

PARTICIPANTS

8 female, 4 male with unilateral autogenous ACLr.

MAIN OUTCOME MEASURES

Bilateral measurements at 5 lower extremity locations and the anterior forearm: light touch (LT), vibration sense (VS), pressure pain threshold (PPT); knee active joint position sense (AJPS); adapted crossover hop for distance (ACHD). Intraclass correlation coefficients (ICC) determined reliability, defined as: poor (<0.50), moderate (0.50-0.75), good (0.75-0.90).

RESULTS

ACLr-side intra-rater/inter-rater ICCs ranged: LT, -0.27-0.80/-0.01-0.84; VS, 0.12-0.90/0.25-0.90; PPT, 0.49-0.98/0.86-0.99; AJPS, 0.15-0.79/0.55-0.87; ACHD, 0.98/0.99. Uninjured-side intra-rater/inter-rater ICCs ranged: LT, 0.12-0.66/-0.09-0.64; VS, 0.35-0.89/0.05-0.81; PPT, 0.65-0.99/0.45-0.95; AJPS, 0.07-0.81/0.37-0.99; ACHD, 0.99/0.98.

CONCLUSIONS

Intra-rater and inter-rater reliability was poor to good for both limbs. Overall, PPT and the ACHD demonstrated the highest ICCs. Some somatosensory assessments can be employed with confidence, while others should be used with caution.

Lower Extremity Somatosensory Function Throughout Concussion Recovery: A Prospective Cohort Study

OBJECTIVE

Balance impairments may suggest somatosensory disruption beyond concussion clinical recovery, but somatosensory subsystems have never been directly assessed. Our objective was to examine somatosensory function between individuals with a concussion and healthy matched-controls at acute (<7 days) and asymptomatic (<72 hours of being symptom-free) time points.

SETTING

Laboratory.

PARTICIPANTS

Participants with a concussion and matched controls ( n = 24; 58% male, age: 19.3 ± 1.1 years, mass: 70.3 ± 16.4 kg, height: 177.3 ± 12.7 cm).

DESIGN

Prospective cohort.

MAIN MEASURES

Somatosensory assessments on the dominant limb at both time points included: (1) plantar touch sensation threshold via Semmes-Weinstein monofilaments, (2) plantar pressure pain threshold via algometry, and (3) knee absolute passive joint repositioning (PJR) error via Biodex across 3 arcs (105°-75°, 30°-60°, 90°-45° knee-flexion). We used mixed-model analyses of variance, post hoc Tukey honestly significant difference t tests with mean difference, 95% CI, and Hedges' g effect sizes to examine outcomes.

RESULTS

Touch sensation had a group effect with the concussion cohort needing 0.95 grams of force (gf) more relative to controls (95% CI: 0.03 to 1.87; P = .043). No touch sensation interaction was present, but medium and large effects were observed for greater gf needed among the concussed cohort at the acute (1.11 gf; 95% CI: 0.17 to 2.05; g = 0.96) and asymptomatic time points (0.79 gf; 95% CI: -0.15 to 1.73; g = 0.73). No plantar pressure pain threshold effects were observed ( P ≥ .311), with negligible pressure difference magnitudes at the acute (0.26 pound force [lbf]/cm 2 ; 95% CI: -1.54 to 2.06; g = 0.13) and medium magnitudes at the asymptomatic time points (0.99 lbf/cm 2 ; 95% CI: -0.81 to 2.80; g = 0.42) for the concussed cohort needing more pressure to detect pain. The 30° to 60° PJR had a time effect, with asymptomatic time point having 3.12° better accuracy (95% CI: 1.23° to 5.02; P = .002). The concussed cohort had small-to-medium magnitude differences relative to controls at the acute time point for PJR during 105° to 75° (0.89°; g = 0.30) and 90° to 45° (0.62°; g = 0.17), but not 30° to 60° (-1.75°; g = -0.40).

CONCLUSIONS

Individuals with a concussion exhibited large effects for diminished plantar touch sensation and small to medium effects for inhibited plantar pressure pain sensation compared with controls, which may indicate altered somatosensory function. Negligible PJR differences suggest knee joint position sense is not altered post-concussion. Pre- and postconcussion examination is warranted to understand causal somatosensory mechanisms.

Effects of the direction of Kinesio taping on sensation and postural control before and after muscle fatigue in healthy athletes

In this study, Kinesio tape (KT) was applied in two different directions to the gastrocnemius muscle, the most important muscle in stance stability, to investigate the effect of different taping directions on overall balance and sensation systems before versus after muscle fatigue. The participants, comprising 45 healthy athletes, were randomly divided into three groups: the placebo taping group (PTG), the facilitation KT group (FKTG), and the inhibition KT group (IKTG). The tests involved in this study were a balance test, a superficial sensory function test, and a combined cortical sensation test. The data from these tests were collected before taping, after taping and a 10-min rest, and immediately after continuous heel raises were performed to fatigue. The results of the balance tests showed no significant group × time interaction, whether subjects stood barefoot on one foot or stood on a soft mat with eyes open or closed (p > 0.05). Only the sway distance and sway velocity of the center of pressure (COP) when subjects stood barefoot on one foot with eyes open were significantly higher in the inhibition taping group than in the placebo taping group (p < 0.05). In addition, significant differences were noted in the sway area and sway distance of the COP before taping, after taping, and after exercise to fatigue when the participants stood on the soft mat with their eyes open (p < 0.05). When the participants stood on the soft mat on one foot with their eyes closed, no significant differences were noted among the groups. When subjects stood on a soft mat on one foot with eyes open, significant improvements were noted after fatiguing exercise versus before taping for all three groups (p < 0.05). The results of the superficial sensory test showed no significant group × time interaction and no difference among the three taping conditions or before/after taping and after fatiguing exercise. Only in the two-point discrimination test was a sensory difference observed, with the facilitation taping group having a significantly shorter discrimination distance than the placebo taping and inhibition taping groups (p < 0.05). The present study showed that KT application for a simple balance task (e.g., barefoot on a hard floor with eyes open) may slightly influence postural control, especially when the inhibition method is used. However, more difficult balance tasks (e.g., barefoot on a soft mat with eyes closed) show no effect of KT application-either the facilitation method or the inhibition method-on posture control.

Misencoding of ankle joint angle control system via cutaneous afferents reflex pathway in chronic ankle instability

This study aimed to investigate how the cutaneous reflexes in the peroneus longus (PL) muscle are affected by changing the ankle joint position in patients with chronic ankle instability (CAI). We also investigated the correlation between the degree of reflex modulation and angle position sense of the ankle joint. The participants were 19 patients with CAI and 20 age-matched controls. Cutaneous reflexes were elicited by applying non-noxious electrical stimulation to the sural nerve at the ankle joint in the neutral standing and eversion/inversion standing positions. The suppressive middle latency cutaneous reflex (MLR; ~ 70-120 ms) and angle position sense of the ankle joint were assessed. During neutral standing, the gain of the suppressive MLR was more prominent in the CAI patients than in controls, although no significant difference was seen during 30° inversion standing. In addition, the ratios of the suppressive MLR and background electromyography in a neutral position were significantly larger than those at the 15°, 25°, and 30° inversion positions in CAI patients. No such difference was seen in control individuals. Furthermore, the correlations between reflex modulation degree and position sense error were quite different in CAI patients compared to controls. These findings suggest that the sensory-motor system was deteriorated in CAI patients due to changes in the PL cutaneous reflex pathway excitability and position sense of the ankle joint.

The Immediate Carryover Effects of Peroneal Functional Electrical Stimulation Differ between People with and without Chronic Ankle Instability

Chronic ankle instability (CAI) is a common condition that may develop after an ankle sprain. Compared with healthy individuals, those with CAI demonstrate excessive ankle inversion and increased peroneal electromyography (EMG) activity throughout the stance phase of gait, which may put them at greater risk for re-injury. Functional electrical stimulation (FES) of targeted muscles may provide benefits as a treatment modality to stimulate immediate adaptation of the neuromuscular system. The present study investigated the effect of a single, 10 min peroneal FES session on ankle kinematics and peroneal EMG activity in individuals with (n = 24) or without (n = 24) CAI. There were no significant differences in ankle kinematics between the groups before the intervention. However, after the intervention, healthy controls demonstrated significantly less ankle inversion between 0-9% (p = 0.009) and 82-87% (p = 0.011) of the stance phase. Furthermore, a significant within-group difference was observed only in the control group, demonstrating increased ankle eversion between 0-7% (p = 0.011) and 67-81% (p = 0.006) of the stance phase after the intervention. Peroneal EMG activity did not differ between groups or measurements. These findings, which demonstrate that peroneal FES can induce ankle kinematics adaptations during gait, can help to develop future interventions for people with CAI.

Disrupted somatosensory input alters postural control strategies during the Star Excursion Balance Test (SEBT) in healthy people

BACKGROUND

Chronic adaptations, including persistent sensorimotor deficits, remain in individuals with a history of ankle instability, resulting in altered postural control strategies during functional tasks such as gait, running, or landing. However, we do not know the contribution of the altered somatosensory input on postural control strategies during a dynamic balance task such as the Star Excursion Balance Test (SEBT).

RESEARCH QUESTION

The purpose of this study was to characterize postural control strategies with and without disrupted somatosensory input during a dynamic balance task in people without chronic ankle sprain.

METHODS

This study was a crossover study design. Twenty healthy young adults (10 men, 10 women; age = 23.9 ± 3.0 years, height = 174.2 ± 7.4 cm, mass = 71.2 ± 16.7 kg) performed the posteromedial reach test during the SEBT while standing on the ground and on foam. We measured the maximum reach distance (MRD); joint angles of the ankle, knee, hip, and trunk in the sagittal, frontal, and transverse planes; and position and displacement of the center of mass (COM) and center of pressure (COP) during the posteromedial reach task.

RESULTS

The MRD was shorter when standing on the foam than on the ground (p < 0.001). There was a condition by phase interaction for ankle dorsiflexion; tibia internal rotation; and trunk flexion (p < 0.001; p = 0.03; p = 0.01, respectively). The COM and COP were positioned more laterally on the foam (p < 0.001). The COM and COP anterior-posterior displacements were more anterior during the foam condition (p = 0.017).

SIGNIFICANCE

By using a foam pad to disrupt somatosensory information, participants demonstrated altered strategies to control the joint kinematics, COM, and COP, as a function of posteromedial distance. Ankle and trunk movement strategies may influence the posteromedial reach distance. This model may simulate changes that occur with chronic ankle instability.

Plausible mechanisms of and techniques to assess ankle joint degeneration following lateral ankle sprains: a narrative review

Lateral ankle sprain (LAS) is the most common lower extremity musculoskeletal injury sustained during daily life and sport. The cascade of events that starts with ligamentous trauma leads to clinical manifestations such as recurrent sprains and giving way episodes, hallmark characteristics of chronic ankle instability (CAI). The sequelae of lateral ankle sprains and CAI appear to contribute to aberrant biomechanics. Combined, joint trauma and aberrant biomechanics appear to directly and/or indirectly play a role in talar cartilage degeneration. Up to 80% of all cases of ankle osteoarthritis (OA) are post-traumatic in nature and common etiologies for ankle post-traumatic osteoarthritis (PTOA) are histories of a single and recurrent ankle sprains. Despite known links between LAS, CAI, and PTOA and evidence demonstrating the burden of LAS and its sequelae, early pathoetiological changes of ankle PTOA and how they can be assessed are poorly understood. Therefore, the purpose of this paper is to review the plausible mechanistic links among LAS and its sequelae of CAI and PTOA as well as review non-surgical techniques that can quantify talar cartilage health. Understanding the pathway from ligamentous ankle injury to ankle PTOA is vital to developing theoretically sound therapeutic interventions aimed at slowing ankle PTOA progression. Further, directly assessing talar cartilage health non-surgically provides opportunities to quantify if current and novel intervention strategies are able to slow the progression of ankle PTOA.

The Ankle-Joint Complex: A Kinesiologic Approach to Lateral Ankle Sprains

Copious research exists regarding ankle instability, yet lateral ankle sprains (LASs) persist in being among the most common recurrent musculoskeletal injuries. Key anatomical structures of the ankle include a triform articulating structure that includes the inferior tibiofibular, talocrural, and subtalar joints. Functionally, force absorption and propulsion through the ankle complex are necessary for any task that occurs in weight bearing. For optimal ankle performance and avoidance of injury, an intricate balance between stability and mobility is necessary to ensure that appropriate force transfer occurs during sports and activities of daily living. Consideration for the many structures that may be directly or indirectly involved in LASs will likely translate into advancements in clinical care. In this clinical review, we present the structure, function, and relevant pathologic states of the ankle complex to stimulate a better understanding of the prevention, evaluation, and treatment of LASs.

Altered Movement Biomechanics in Chronic Ankle Instability, Coper, and Control Groups: Energy Absorption and Distribution Implications

CONTEXT

Patients with chronic ankle instability (CAI) exhibit deficits in neuromuscular control, resulting in altered movement strategies. However, no researchers have examined neuromuscular adaptations to dynamic movement strategies during multiplanar landing and cutting among patients with CAI, individuals who are ankle-sprain copers, and control participants.

OBJECTIVE

To investigate lower extremity joint power, stiffness, and ground reaction force (GRF) during a jump-landing and cutting task among CAI, coper, and control groups.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 22 patients with CAI (age = 22.7 ± 2.0 years, height = 174.6 ± 10.4 cm, mass = 73.4 ± 12.1 kg), 22 ankle-sprain copers (age = 22.1 ± 2.1 years, height = 173.8 ± 8.2 cm, mass = 72.6 ± 12.3 kg), and 22 healthy control participants (age = 22.5 ± 3.3 years, height = 172.4 ± 13.3 cm, mass = 72.6 ± 18.7 kg).

INTERVENTION(S)

Participants performed 5 successful trials of a jump-landing and cutting task.

MAIN OUTCOME MEASURE(S)

Using motion-capture cameras and a force plate, we collected lower extremity ankle-, knee-, and hip-joint power and stiffness and GRFs during the jump-landing and cutting task. Functional analyses of variance were used to evaluate between-groups differences in these dependent variables throughout the contact phase of the task.

RESULTS

Compared with the coper and control groups, the CAI group displayed (1) up to 7% of body weight more posterior and 52% of body weight more vertical GRF during initial landing followed by decreased GRF during the remaining stance and 22% of body weight less medial GRF across most of stance; (2) 8.8 W/kg less eccentric and 3.2 W/kg less concentric ankle power, 6.4 W/kg more eccentric knee and 4.8 W/kg more eccentric hip power during initial landing, and 5.0 W/kg less eccentric knee and 3.9 W/kg less eccentric hip power; and (3) less ankle- and knee-joint stiffness during the landing phase. Concentric power patterns were similar to eccentric power patterns.

CONCLUSIONS

The CAI group demonstrated altered neuromechanics, redistributing energy absorption from the distal (ankle) to the proximal (knee and hip) joints, which coincided with decreased ankle and knee stiffness during landing. Our data suggested that although the coper and control groups showed similar landing and cutting strategies, the CAI group used altered strategies to modulate impact forces during the task.

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.

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

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.

The importance of cutaneous feedback on neural activation during maximal voluntary contraction

PURPOSE

The purpose of this study was to investigate the importance of cutaneous feedback on neural activation during maximal voluntary contraction (MVC) of the ankle plantar flexors.

METHODS

The effects of cutaneous plantar anaesthesia were assessed in 15 subjects and compared to 15 controls, using a one-day pre/post-repeated measures design. Cutaneous plantar anaesthesia was induced by lidocaine injection at the centre of forefoot, lateral midfoot, and heel. Each subject performed isometric MVCs of the ankle plantar flexors. During each isometric ramp contraction, the following variables were assessed: maximal isometric torque; surface electromyography (EMG) activity of the medial gastrocnemius (MG) and tibialis anterior (TA) muscles; and co-contraction index (CCI) between the MG and TA.

RESULTS

For ankle torque, two-way ANOVA showed no significant interaction between the pre/post-measurements × group (p = 0.166). However, MG activity presented significant interactions between the pre/post-measurements × group (p = 0.014). Post hoc comparisons indicated a decrease of MG activity in the experimental group, from 85.9 ± 11.9 to 62.7 ± 30.8% (p = 0.016). Additionally, the post-anaesthesia MG activity of the experimental group differed statistically with pre- and post-MG activity of the control group (p = 0.027 and p = 0.008, respectively). For TA activity and CCI, two-way ANOVA detected no significant interactions between the pre/post-measurements × group (p = 0.605 and p = 0.332, respectively).

CONCLUSION

Our results indicate that during MVC, cutaneous feedback modulates neural activity to MG muscle, without changing the extent of MG-TA co-contraction.

High lateral plantar pressure is related to an increased tibialis anterior/fibularis longus activity ratio in patients with recurrent lateral ankle sprain

Introduction

Center of pressure (COP) is a sudden displacement at the time of a lateral ankle sprain (LAS). It has been suggested that the distribution of plantar pressure and the quantity of COP displacement are important for assessing the risk of LAS. Therefore, we evaluated the plantar pressure during a single-leg balance test with eyes closed (SLB-C) to identify the factors and characteristics of plantar pressure in people with repeated cases of LAS.

Methods

We recruited 22 collegiate athletes and divided them into an instability group (IG; n=11) and a control group (CG; n=11). We measured the distribution of plantar pressure and lower extremity muscle activity during a SLB-C along with static alignment and isometric ankle strength.

Results

The fibularis longus (FL) activity was significantly lower in the IG than in the CG. The lateral plantar pressure (LPP)/medial plantar pressure (MPP) ratio was also higher in the IG than in the CG. In addition, the LPP/MPP ratio was correlated with the tibialis anterior (TA)/FL ratio.

Conclusion

These results suggest that increased lateral plantar pressure is related to decreased FL activity and increased TA/FL ratio.

Therapeutic interventions for improving self-reported function in patients with chronic ankle instability: a systematic review

OBJECTIVE

To identify which therapeutic intervention may be most effective for improving self-reported function in patients with chronic ankle instability (CAI).

DESIGN

Systematic literature review. Articles were appraised using the Downs and Black Checklist by 3 reviewers.

DATA SOURCES

PubMed along with CINAHL, MEDLINE and SPORTDiscus within EBSCOhost for pertinent articles from their inception through August 2016.

ELIGIBILITY CRITERIA FOR SELECTED STUDIES

Articles included were required to (1) be written in English, (2) report adequate data to calculate effect sizes, (3) identify patients with CAI, (4) use some form of therapeutic intervention and (5) use a self-reported questionnaire as a main outcome measurement.

RESULTS

A broad spectrum of therapeutic interventions were identified related to balance training, multimodal rehabilitation, joint mobilisation, resistive training, soft-tissue mobilisation, passive calf stretching and orthotics. All of the articles included in the balance training category had moderate-to-strong Hedges g with none of the 95% CIs crossing 0. Hedges g effect sizes ranged from -0.67 to -2.31 and -0.51 to -1.43 for activities of daily living and physical activity, respectively. The multimodal rehabilitation category also produced moderate-to-strong Hedges g effect sizes but with large CIs crossing 0. Hedges g effect sizes ranged from -0.47 to -9.29 and -0.62 to -24.29 for activities of daily living and physical activity, respectively.

CONCLUSIONS

The main findings from this systematic review were balance training provided the most consistent improvements in self-reported function for patients with CAI.

Effects of a stocking on plantar sensation in individuals with and without ankle instability

INTRODUCTION

It is unknown whether footwear has a beneficial or deleterious effect on cutaneous sensitivity. We aimed to test a preliminary model of footwear and its effect on tactile perception among groups of controls, copers, and chronic ankle instability participants.

METHODS

Light-touch thresholds were obtained for 45 participants (age: 20.2 ± 2.8 years; height: 167.6 ± 9.8 cm; mass: 66.3 ± 14.7 kg) using Semmes-Weinstein monofilaments at the head of the first metatarsal (1MT), base of the fifth metatarsal (5MT), and calcaneus (CAL). Baseline measurements were compared with those taken after wearing a nylon stocking for 5 min.

RESULTS

Thresholds were increased at all 3 sites when the stocking was worn (P < 0.05). Controls had an increase at 1MT, copers had an increase at 5MT and CAL, and chronic ankle instability had an increase at CAL.

CONCLUSIONS

Cutaneous thresholds increase when subjects wear a nylon stocking, a model for the sensory effects of footwear. A history of ankle injury appears to influence which sites have altered sensibility. Muscle Nerve, 2016. Muscle Nerve 55: 513-519, 2017.