Dynamic Postural Stability Deficits in Subjects with Self-Reported Ankle Instability

The impact of fatigue on dynamic balance in coopers athletes with chronic ankle instability

Athletes who have successfully regained high sports performance despite prior inversion injuries, and who do not have persistent symptoms, are referred to as "copers" in the literature. The aim of the study was to assess dynamic stability under fatigue in patients with chronic ankle instability in comparison to healthy controls. We conducted a case - controlled study on a group of 60 young, physically active individuals aged 29.8 ± 4.6. They were divided into 3 groups: I - unilateral ankle instability n = 14, II - bilateral ankle instability n = 15, III - no ankle instability, n = 31. All participants filled out questionnaires on the health, the FADI and FADI-S. The study protocol consisted of a dynamic stability measurements by Biodex Balance System, followed by a fatigue test, followed by the series of the same measurements. General stability index value before and value after fatigue test did not differ significantly. The differences between groups in measurements taken before fatigue test (F (2.49) = 1.59; p = 0.214; ηp2 = 0.06) and after fatigue test also proved insignificant (F (2.49) = 1.28; p = 0.286; ηp2 = 0.05). The incidence of structural ankle instability did not affect functional stability. "Copers" had efficient neural-muscular control in dynamic stabilography tests.

The influence of jump-landing direction on dynamic postural stability following anterior cruciate ligament reconstruction

BACKGROUND

Traditional testing prior to return to sport following anterior cruciate ligament reconstruction typically involves jump-landing tasks in the forward direction. As injury is most likely the result of multiplanar neuromuscular control deficits, assessment of dynamic postural stability using landing tasks that require multiplanar stabilization may be more appropriate. The purpose of this study was to examine how dynamic postural stability is affected when performing jump-landing tasks in three different directions.

METHODS

Fifteen athletes [11 females (18.0 ± 3.0 years) and 4 males (18.5 ± 3.1 years)] following anterior cruciate ligament reconstruction performed a series of single-limb jump-landing tasks in 3 directions. Individual directional stability indices and a composite dynamic postural stability index were calculated using ground reaction force data and were compared using separate one-way repeated measures ANOVAs.

FINDINGS

All directional stability indices demonstrated a significant main effect for jump-landing direction (medial-lateral P < 0.001, η2p = 0.95; anterior-posterior P < 0.001, η2p = 0.97; vertical P = 0.021, η2p = 0.24). The diagonal jump-landing direction produced increased medial-lateral stability and vertical stability scores, while the forward and diagonal jump-landing directions produced increased anterior-posterior stability scores. There was no significant effect for the composite dynamic stability index score.

INTERPRETATION

Jump-landing direction affects dynamic postural stability in all 3 planes of movement in athletes following anterior cruciate ligament reconstruction. Results indicate the potential need to incorporate multiple jump-landing directions to better assess dynamic postural stability prior to return to sport.

Chronic Ankle Instability and Neuromuscular Performance in Prerecruitment Infantry Soldiers

CONTEXT

Ankle instability can describe various impairments, including perceived instability (PI), mechanical instability (MI), and recurrent sprains (RSs), alone or combined.

OBJECTIVE

To examine the prevalence of 8 ankle impairment subgroups and their effect on neuromuscular performance in prerecruitment combat soldiers.

DESIGN

Cross-sectional study.

SETTING

Military infantry basic training base.

PATIENTS OR OTHER PARTICIPANTS

A total of 364 infantry male combat soldiers entering basic training (aged 18-21 years).

MAIN OUTCOME MEASURE(S)

Participants were assessed for PI (via the Cumberland Ankle Instability Tool), MI (using the Anterior Drawer Test and Medial Talar Tilt Test), and RSs (based on history) of their dominant and nondominant legs. Injuries were categorized in 8 subgroups: PI, RSs, PI + RSs, MI, PI + MI, MI + RSs, PI + MI + RSs, and none. Participants were screened for neuromuscular performance (dynamic postural balance, proprioceptive ability, hopping agility, and triceps surae muscle strength) during the first week of military basic training.

RESULTS

For the dominant and nondominant legs, RSs were reported by 18.4% (n = 67) and 20.3% (n = 74) of the participants, respectively; PI was reported by 27.1% (n = 99) and 28.5% (n = 104) of the participants, respectively; and MI was seen in 9.9% (n = 36) and 8.5% (n = 31) of the participants, respectively. A 1-way analysis of variance showed differences in the mean proprioceptive ability scores (assessed using the Active Movement Extent Discrimination Apparatus) of all subgroups with impairments in both the dominant and nondominant legs (F = 6.943, η2 = 0.081, P < .001 and F = 7.871, η2 = 0.091, P < .001, respectively). Finally, differences were found in the mean muscle strength of subgroups with impairment in the nondominant leg (F = 4.884, η2 = 0.056, P = .001).

CONCLUSIONS

A high prevalence of ankle impairments was identified among participants who exhibited reduced abilities in most neuromuscular assessments compared with those who did not have impairments. Moreover, participants with 1 impairment (PI, MI, or RSs) exhibited different neuromuscular performance deficits than those with >1 impairment.

Dynamic postural control in injured collegiate cross-country runners is not associated with running-related injury

BACKGROUND

Biomechanical factors have been associated with running-related injury, but associations are unclear. Dynamic postural stability may be a factor related to injury that has not been studied extensively.

RESEARCH QUESTION

Does dynamic postural control differ in those with a history of running-related injury or those who go on to sustain a running-related injury?

METHODS

Sixty-five (45 injured; 20 uninjured) and fifty-eight (13 injured; 45 uninjured) collegiate cross-country runners were available for our retrospective and prospective analyses. Time to stabilization and dynamic postural stability index were collected during two separate jump landing tasks (forward and lateral direction) for each leg. Retrospective injury was tabulated by a running history survey. Prospective injuries were recorded by a licensed athletic trainer during the competitive season. Differences in postural stability were compared between injured and uninjured groups and between limbs using two-way ANOVA's. An overall group by leg comparison was completed for each task.

RESULTS

The non-dominant limb demonstrated better postural stability indices regardless of injury history. An interaction was observed between limbs and history of injury for the anterior-posterior time to stabilization for the lateral task. The non-dominant limb demonstrated better medio-lateral postural stability indices and time to stabilization during the lateral task, regardless of prospective injury.

SIGNIFICANCE

Dynamic postural stability was reduced in the dominant limb, but no clear differences were seen between injured and uninjured runners. This suggests dynamic postural stability may be altered in individuals with a history of a running-related injury, but no relationship to subsequent injury was substantiated. Further work is needed to understand how dynamic postural stability may be related to running-related injury.

The effects of neuromuscular electrical stimulation to the ankle pronators on neural excitability & functional status in patients with chronic ankle instability

OBJECTIVES

Chronic ankle instability (CAI) is associated with decreased neural excitability that negatively impacts function. This study assessed a 2-week neuromuscular electrical stimulation (NMES) or transcutaneous electrical nerve stimulation (TENS) intervention over the ankle pronators on neural excitability, performance, and patient-reported function in patients with CAI.

STUDY DESIGN

Randomized controlled trial.

PARTICIPANTS

Twenty participants with CAI completed the study.

MAIN OUTCOME MEASURES

Participants were assessed for reflexive and corticospinal excitability to the ankle muscles, dynamic balance, side-hop test performance and patient-reported outcomes at baseline, post-intervention (2-weeks), and retention (4-weeks). Between baseline and post-intervention, participants reported for 5 sessions where they received either sub-noxious NMES (n = 11) or sensory-level TENS (n = 9) over the ankle pronators.

RESULTS

Improved reflexive excitability to the ankle pronators was observed in TENS at post-intervention (p = 0.030) and retention (p = 0.029). Cortical excitability to the dorsiflexors increased in TENS at post-intervention (p = 0.017), but not at retention (p = 0.511). No significant changes were found for other neural measures, balance ability, hopping, or patient-reported function (p > 0.050).

CONCLUSIONS

Our results suggest TENS modified neural excitability; however, these changes were not enough to impact clinical function. While TENS may be capable of neuromodulation, it may require rehabilitative exercise to generate lasting changes. NCT04322409.

LEVEL OF EVIDENCE

Level 2.

Less impact absorption at the ankle joint is related to the single-leg landing stability deficit in patients with chronic ankle instability

Single-leg landing (SLL) stability deficits are common dysfunctions after lateral ankle sprain (LAS), and are associated with reinjury and needs to be addressed. SLL stability deficits could be associated with impact absorption ability. Thus, we evaluated these relationships. We recruited 46 patients with chronic ankle instability (CAI) and 64 control patients and measured their kinematics, SLL stability, and impact absorption ability. The SLL stability was evaluated by calculating the anterior-posterior stability index (APSI) and medial-lateral stability index (MLSI). The impact absorption ability was evaluated by calculating the energy absorption (EA). The large negative value of the EA indicated the absorption of a large amount of energy. The Japanese version of identification of functional ankle instability (IdFAI-J) score (P < 0.001), MLSI value (P = 0.004), and sagittal plane ankle EA value (less EA at ankle joint) (P < 0.001) were significantly high in CAI, and sagittal plane knee EA value (more EA at knee joint) (P < 0.041) was significantly low in CAI than in the control group. Multiple regression analysis showed that the APSI was associated with sagittal plane ankle EA (β = 0.275, P = 0.004). The MLSI was associated with sagittal plane ankle EA (β = 0.204, P = 0.034) and the idFAI score (β = 0.234, P = 0.015). The SLL stability impairment after LAS was related to decreased impact absorption ability at the ankle joint.

Effects of Conservative Interventions on Static and Dynamic Balance in Individuals With Chronic Ankle Instability: A Systematic Review and Meta-analysis

OBJECTIVE

To determine which conservative interventions are effective for static and dynamic balance in patients with chronic ankle instability (CAI).

DATA SOURCES

PubMed, Cochrane Library, Web of Sciences, and CINAHL databases were searched up to March 20, 2022.

STUDY SELECTION

Randomized controlled trials investigating the effects of conservative interventions on static and/or dynamic balance in patients with CAI compared with those of different conservative interventions or controls were included.

DATA EXTRACTION

Two independent reviewers extracted the data. Certainty of the evidence was assessed using the GRADE approach.

DATA SYNTHESIS

Forty-eight studies (1906 participants) were included. Whole-body vibration training (WBVT) was significantly more effective than controls for both static (standardized mean difference, 1.13; 95% confidence interval [CI], 0.58-1.68; moderate-certainty evidence) and dynamic balance (0.56; CI, 0.24-0.88; low-certainty evidence). Balance training (BT) and joint mobilization were significantly more effective than controls for dynamic balance (0.77; CI, 0.41-1.14; and 0.75; CI, 0.35-1.14, respectively), but not for static balance (very low to low-certainty evidence). Adding other interventions to BT had no significant effect on either type of balance compared with that of BT alone (moderate to low-certainty evidence). Strength training (ST) and taping had no significant effect on either type of balance (very low- to low-certainty evidence). Multimodal interventions were significantly effective in improving dynamic balance (0.76; CI, 0.32-1.20; low-certainty evidence). Adding transcranial direct current stimulation to ST was significantly more effective for dynamic balance than ST (0.81; CI, 0.08-1.53; moderate-certainty evidence). The effects on balance were not significantly different among BT, ST, and WBVT (very low- to low-certainty evidence).

CONCLUSIONS

The significantly effective interventions reviewed may be treatment options for balance impairments associated with CAI. However, interventions should be chosen carefully, as much of the certainty of evidence is very low to low.

Quantification of Gait Stability During Incline and Decline Walking: The Responses of Required Coefficient of Friction and Dynamic Postural Index

This study aims to investigate the gait stability response during incline and decline walking for various surface inclination angles in terms of the required coefficient of friction (RCOF), postural stability index (PSI), and center of pressure (COP)-center of mass (COM) distance. A customized platform with different surface inclinations (0°, 5°, 7.5°, and 10°) was designed. Twenty-three male volunteers participated by walking on an inclined platform for each inclination. The process was then repeated for declined platform as well. Qualysis motion capture system was used to capture and collect the trajectories motion of ten reflective markers that attached to the subjects before being exported to a visual three-dimensional (3D) software and executed in Matlab to obtain the RCOF, PSI, as well as dynamic PSI (DPSI) and COP-COM distance parameters. According to the result for incline walking, during initial contact, the RCOF was not affected to inclination. However, it was affected during peak ground reaction force (GRF) starting at 7.5° towards 10° for both walking conditions. The most affected PSI was found at anterior-posterior PSI (APSI) even as low as 5° inclination during both incline and decline walking. On the other hand, DPSI was not affected during both walking conditions. Furthermore, COP-COM distance was most affected during decline walking in anterior-posterior direction. The findings of this research indicate that in order to decrease the risk of falling and manage the inclination demand, a suitable walking strategy and improved safety measures should be applied during slope walking, particularly for decline and anterior-posterior orientations. This study also provides additional understanding on the best incline walking technique for secure and practical incline locomotion.

Validity of the frame subtraction method in dynamic postural stability

Background

The movement of targeted subjects can be calculated using the frame subtraction method. However, the validity of this evaluation method of dynamic postural stability has not been clarified yet. This study aimed to verify the validity of the evaluation method for jump landing using the frame subtraction score based on the ground reaction force (GRF).

Methods

Twenty subjects performed single-leg jump landing, and their dynamic postural stability index (DPSI), medial‒lateral stability index (MLSI), anterior‒posterior stability index, and vertical stability index (VSI) were calculated from the GRF. Simultaneously, motion images were captured using digital video cameras in the sagittal and frontal planes. After the motion images were analyzed using the frame subtraction method, the frame subtraction scores in the frontal, sagittal, and combined planes were calculated. To confirm its validity, the relationship between the frame subtraction scores and GRF parameters was investigated using Pearson's correlation analysis.

Results

The frame subtraction scores in the frontal and combined planes were significantly correlated with the DPSI, MLSI, and VSI (r = 0.46–0.75, P < 0.05).

Conclusions

Therefore, the frame subtraction method could be applied to the evaluation of dynamic postural stability. Markerless systems are deemed useful in clinical practice.

Effects of Transcranial Direct Current Stimulation over the Primary Motor Cortex in Improving Postural Stability in Healthy Young Adults

Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) is of increasing interest to improve motor performance in healthy adults and patients with respective deficits. This study aimed to examine whether tDCS over M1 can improve static and dynamic postural stability in young healthy adults. Seventeen healthy participants (mean age = 25.14 ± 2.50 (standard deviation, SD) years) received sham and anodal tDCS (2 mA) over the vertex at the Cz electrode position for 15 min. Static and dynamic postural stability were evaluated before and immediately after tDCS. The center of pressure (COP) sway area (COPSA) and COP maximum displacements to medio-lateral (COPML) and antero-posterior directions (COPAP) were used to evaluate static postural stability. The anterior−posterior stability index (APSI), medial−lateral stability index (MLSI), vertical stability index (VSI), dynamic postural stability index (DPSI), and time to stabilization (TTS) in forward (FL), 45° anterior lateral (LL), and 45° anterior medial (ML) direction landing, as well as the Y-balance composite score (YBTCS) were used to assess dynamic postural stability. The results showed that the LL-TTS (p = 0.044), non-dominant leg COPSA (p = 0.015), and YBTCS (p < 0.0001) were significantly improved in the real stimulation as compared with the sham stimulation session, and anodal tDCS significantly changed dominant leg COPAP (p = 0.021), FL-APSI (p < 0.0001), FL-TTS (p = 0.008), ML-TTS (p = 0.002), non-dominant leg YBTCS (p < 0.0001), and dominant leg YBTCS (p = 0.014). There were no significant differences in all obtained balance values in the sham stimulation session, except for non-dominant leg YBTCS (p = 0.049). We conclude that anodal tDCS over M1 has an immediate improving effect on static postural stability and dynamic performance in young healthy adults. This makes tDCS a promising adjuvant rehabilitation treatment to enhance postural stability deficits in the future.

Effects of balance training with stroboscopic glasses on postural control in chronic ankle instability patients

Individuals with chronic ankle instability (CAI) are believed to rely more on visual information during postural control due to impaired proprioceptive function, which may increase the risk of injury when their vision is limited during sports activities.

OBJECTIVES

To compare (1) the effects of balance training with and without stroboscopic glasses on postural control and (2) the effects of the training on visual reliance in patients with CAI.

DESIGN

A randomized controlled clinical trial.

METHODS

Twenty-eight CAI patients were equally assigned to one of 2 groups: strobe or control group. The strobe group wore stroboscopic glasses during a 4-week balance training. Static postural control, a single-leg hop balance test calculated by Dynamic Postural Stability Index (DPSI), and the Y-Balance test (YBT) were measured. During the tests, there were different visual conditions: eyes-open (EO), eyes-closed (EC), and strobe vision (SV). Romberg ratios were then calculated as SV/EO, and EC/EO and used for statistical analysis.

RESULTS

The strobe group showed a higher pretest-posttest difference in velocity in the medial-lateral direction and vertical stability index under SV compared with the control group (p < .05). The strobe group showed higher differences in EC/EO for velocity in the medial-lateral and anterior-posterior directions, and 95% confidence ellipse area (p < .05), and in SV/EO for velocity in the medial-lateral, 95% confidence ellipse area, and YBT-anterior direction (p < .05).

CONCLUSION

The 4-week balance training with stroboscopic glasses appeared to be effective in improving postural control and altering visual reliance in patients with CAI.

Identification of Neuromuscular Performance Parameters as Risk Factors of Non-contact Injuries in Male Elite Youth Soccer Players: A Preliminary Study on 62 Players With 25 Non-contact Injuries

Introduction: Elite youth soccer players suffer increasing numbers of injuries owing to constantly increasing physical demands. Deficits in neuromuscular performance may increase the risk of injury. Injury risk factors need to be identified and practical cut-off scores defined. Therefore, the purpose of the study was to assess neuromuscular performance parameters within a laboratory-based injury risk screening, to investigate their association with the risk of non-contact lower extremity injuries in elite youth soccer players, and to provide practice-relevant cut-off scores. Methods: Sixty-two elite youth soccer players (age: 17.2 ± 1.1 years) performed unilateral postural control exercises in different conditions, isokinetic tests of concentric and eccentric knee extension and knee flexion (60°/s), isometric tests of hip adduction and abduction, and isometric tests of trunk flexion, extension, lateral flexion and transversal rotation during the preseason period. Non-contact lower extremities injuries were documented throughout 10 months. Risk profiling was assessed using a multivariate approach utilizing a Decision Tree model [Classification and Regression Tree (CART) method]. Results: Twenty-five non-contact injuries were registered. The Decision Tree model selected the COP sway, the peak torque for knee flexion concentric, the functional knee ratio and the path of the platform in that hierarchical order as important neuromuscular performance parameters to discriminate between injured and non-injured players. The classification showed a sensitivity of 0.73 and a specificity of 0.91. The relative risk was calculated at 4.2, meaning that the risk of suffering an injury is four times greater for a player, who has been classified as injured by the Decision Tree model. Conclusion: Measuring static postural control, postural control under unstable condition and the strength of the thigh seem to enable a good indication of injury risk in elite youth soccer players. However, this finding has to be taken with caution due to a small number of injury cases. Nonetheless, these preliminary results may have practical implications for future directions in injury risk screening and in planning and developing customized training programs to counteract intrinsic injury risk factors in elite youth soccer players.

Differences in the locomotion biomechanics and dynamic postural control between individuals with chronic ankle instability and copers: a systematic review

An empirical consensus of differences between chronic ankle instability (CAI) individuals and copers (individuals who sprained ankle once and without recurrent symptoms or injury) has not been reported. This study aimed to review the locomotion biomechanics and dynamic postural control between these two populations. Database of ScienceDirect, PubMed and Web of Science was used to search ('chronic ankle instability' OR 'ankle instability') AND ('ankle sprain' OR 'coper*') until 30 November 2020. Articles that made a comparison about changes in biomechanical parameters between Copers and CAI individuals during locomotor or functional tasks were included in this review. Twenty-three articles met the inclusion criteria. CAI individuals exhibited an increased hip flexion to maintain stability, suggesting the adopted hip strategy compared to copers during landing. Dorsiflexion angle and ankle frontal displacement increased considerably compared to copers, which might increase risks of lateral ankle sprain injury. CAI individuals reduced the ankle displacements in the sagittal plane and indicated worse performance of Star Excursion Balance Test in the posterior-lateral direction compared to copers. Identified motion deficits or altered motion strategies provide opportunities for targeted intervention and scheme after index sprain or in CAI individuals.

The effects of visual feedback disruption on postural control with chronic ankle instability

OBJECTIVES

The purpose of this study was to identify the effects of reduced visual feedback via stroboscopic glasses on dynamic postural control among chronic ankle instability (CAI), lateral ankle sprain (LAS) coper and uninjured control participants.

DESIGN

Controlled trial in a laboratory setting.

METHODS

Twenty CAI patients, 20 copers, and 20 controls participated in this study. Each participant performed a single-leg hop stabilization test with eyes open (EO) and stroboscopic vision (SV). Two-way ANOVAs (group × condition) were used to examine the differences between group (CAI, coper, and control) and condition (EO and SV).

RESULTS

There was a significant group by condition interaction for DPSI scores. CAI patients displayed increased DPSI scores with SV compared to EO (p < 0.01), and CAI patients had increased DPSI scores only with SV when compared with controls. All participants displayed decreased dynamic postural control under the SV condition compared to the EO condition (p < 0.01) regardless of ankle group.

CONCLUSIONS

CAI patients rely more on visual feedback during dynamic postural control than copers and controls. However, they may not be as able to compensate for the disrupted visual feedback during a dynamic task. Regardless of ankle injury history, stroboscopic glasses could be cost-effective visual disruption devices during a dynamic balance task.

Postural Control and Functional Ankle Stability in Professional and Amateur Skateboarders

Basic maneuvers in skateboarding, such as the ollie, put the player at high risk for ankle injuries because of the position of the feet required to perform the maneuvers. This study investigated ankle stability and reaction time for the tibialis anterior, fibularis longus, and fibularis brevis in professional and amateur skateboarders. In total, 16 professional and 16 amateur skateboarders were recruited as participants and underwent range of motion assessments, balance testing, and muscle reaction time measurements. The results revealed that professional skateboarders had a significantly smaller inversion angle compared to amateur players, which suggested better joint control and hence greater safety in the former. Balance testing results indicated better balance in professional skateboarders, and healthy skateboarders had better balance than did injured professional and amateur skateboarders. No significant difference in muscle reaction time was observed between amateur and professional skateboarders.

Effects of Plyometric and Balance Training on Neuromuscular Control of Recreational Athletes with Functional Ankle Instability: A Randomized Controlled Laboratory Study

Plyometric exercise has been suggested for knee injury prevention in sports participation, but studies on ankle plyometric training are limited. This study aims to investigate the change of joint position sense and neuromuscular activity of the unstable ankle after six-week integrated balance/plyometric training and six-week plyometric training. Thirty recreational athletes with functional ankle instability were allocated into three groups: plyometric group (P) vs. plyometric integrated with balance training group (BP) vs. control group (C). Ankle joint position sense, integrated electromyography (EMG), and balance adjusting time during medial single-leg drop-landing tasks were measured before and after the training period. Following the six-week period, both training groups exhibited a lower absolute error in plantar flexion (P group: pre: 3.79° ± 1.98°, post: 2.20° ± 1.31°, p = 0.016; BP group: pre: 4.10° ± 1.87°, post: 2.94° ± 1.01°, p = 0.045), and the integrated group showed a lower absolute error in inversion angles (pre 2.24° ± 1.44° and post 1.48° ± 0.93°, p = 0.022), and an increased integrated EMG of ankle plantar flexors before landing. The plyometric group exhibited a higher integrated EMG of the tibialis anterior before and after landing (pre: 102.88 ± 20.93, post: 119.29 ± 38.33, p = 0.009 in post-landing) and a shorter adjusting time of the plantar flexor following landing as compared to the pre-training condition (pre: 2.85 ± 1.15 s, post: 1.87 ± 0.97 s, p = 0.006). In conclusion, both programs improved ankle joint position sense and muscle activation of the ankle plantar flexors during single-leg drop landing. The plyometric group showed a reduced adjusting time of the ankle plantar flexor following the impact from drop landing.

The Effects of Transcranial Direct Current Stimulation on Chronic Ankle Instability

PURPOSE

Given maladaptive neuroplasticity after musculoskeletal injury, interventions capable of restoring corticospinal excitability should be considered. We therefore aimed to determine if a 4-wk intervention of anodal transcranial direct current stimulation (aTDCS) with eccentric exercise would improve neural excitability, functional performance, and patient-reported function in individuals with chronic ankle instability (CAI).

METHODS

Twenty-six individuals with CAI were recruited to undergo 4 wk of eccentric evertor strengthening. Subjects were randomized into aTDCS (n = 13) and sham (n = 13) groups, where the aTDCS group received 18 min of aTDCS (1.5 mA) over the primary motor cortex. Participants were assessed for cortical excitability, dynamic balance, muscle activation, functional performance, strength, and patient-reported function at baseline, week 2, week 4, and week 6.

RESULTS

Twenty-two subjects completed the training and test sessions. Cortical excitability (resting motor threshold) to peroneus longus in aTDCS increased from baseline (36.92 ± 11.53) to week 6 (32.91 ± 12.33, P = 0.024), whereas sham increased excitability from baseline (36.67 ± 12.74) to week 2 (27.86 ± 14.69, P = 0.007), but decreased at week 4 (35.63 ± 13.10, P = 0.022) and week 6 (35.99 ± 13.52, P = 0.006). Dynamic balance and muscle activation also improved in the aTDCS group from baseline to week 6 (P = 0.034). Functional performance on a side-hop test increased in all participants from baseline to week 2 (P = 0.003). The aTDCS group had decreased perceived disablement from week 2 (18.09 ± 6.41) to week 4 (15.55 ± 4.82, P = 0.046), whereas the sham group reported increased disablement from baseline (17.91 ± 4.59) to week 2 (21.00 ± 8.52, P = 0.047).

CONCLUSIONS

Our results provide preliminary evidence that 4 wk of eccentric training with aTDCS improves cortical excitability, functional performance, and patient-reported function in individuals with CAI. These data are the first to show the efficacy of noninvasive brain stimulation therapies in patients with musculoskeletal injury, and demonstrate the link between improved neural excitability and functional outcomes.

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

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.

THE EFFECTS OF MULTIPLE MODALITIES OF COGNITIVE LOADING ON DYNAMIC POSTURAL CONTROL IN INDIVIDUALS WITH CHRONIC ANKLE INSTABILITY

BACKGROUND

Evidence of neuroplasticity after joint injury has suggested that individuals with chronic ankle instability (CAI) may have degraded movement when facing cognitive demand. To date, research into these effects have been limited to static balance models, and typically only incorporate a single type of cognitive demands.

RESEARCH QUESTION

We aimed to determine the effects of multiple modalities of cognitive load (quantitative, verbal-memory, visuospatial) on dynamic postural control strategies in a sample of patients with CAI compared to uninjured controls.

METHODS

Thirty-two participants (16 CAI, 16 healthy) performed a series of 20 hops-to-stabilization while either under no cognitive load (CON), or while performing Benton's judgment of line orientation (JLO), the symbol digit modalities test (SDM), or a serial seven task (SVN). Dynamic postural stability indices and mean muscle activation from the lower leg muscles were extracted and assessed via analysis of variance.

RESULTS

Healthy subjects demonstrated better vertical and dynamic postural stability indices under JLO (P ≤ 0.017) and SVN (P ≤ 0.010) conditions compared to CON. Postural stability was unaffected in CAI (P > 0.050). Peroneus longus and lateral gastrocnemius activation was lowest in SVN across all subjects (P ≤ 0.033). Lateral gastrocnemius activation was greatest in SDM (P ≤ 0.033).

SIGNIFICANCE

These results suggest improvements in postural stability under cognitive demand in healthy individuals that did not occur in CAI, suggesting less movement optimization. Quantitative tasks appear to impede stabilizing muscle activation in the leg, while verbal-memory tasks result in a more protective landing strategy.

Effects of Different Ankle Supports on the Single-Leg Lateral Drop Landing Following Muscle Fatigue in Athletes with Functional Ankle Instability

Background: Ankle support has been utilized for athletes with functional ankle instability (FAI), however, its effect on the landing performance during muscle fatigue is not well understood. This study aimed to examine the effects of ankle supports (ankle brace vs. Kinesio tape) on athletes with FAI following fatigued single-leg landing. Methods: Thirty-three young FAI athletes (CAIT scores < 24) were randomly allocated to control (Cn), ankle brace (AB) and Kinesio tape (KT) groups. All athletes performed single-leg lateral drop landings following ankle fatigue protocol. The fatigue-induced changes in kinetic parameters were measured among three groups. Results: A significant increase in peak vertical ground reaction force (vGRF) was found in the AB group (0.12% body weight (BW)) compared to that of the KT (0.02% BW) and Cn (median = 0.01% BW) groups. Significant decrease in both COP medial-lateral (ML) and anterior-posterior (AP) ranges were also found in the KT group (median = −0.15% foot width (FW) & median = −0.28% foot length (FL)) than those of the Cn group (median = 0.67% FW& median = 0.88% FL). Conclusions: Ankle braces might hamper the ability to absorb the impact force during landing. On the other hand, Kinesio tape might be beneficial for the postural control during landing.

Ability of Functional Performance Tests to Identify Individuals With Chronic Ankle Instability: A Systematic Review With Meta-Analysis

OBJECTIVE

The purpose of this systematic review with meta-analysis was to determine the effectiveness of functional performance tests (FPTs) in differentiating between individuals with chronic ankle instability (CAI) and healthy controls.

DATA SOURCES

The National Library of Medicine Catalog (PubMed), the Cumulative Index for Nursing and Allied Health Literature (CINAHL), and the SPORTDiscus, from inception to June 2017 were searched. Search terms consisted of: "Functional Performance Test*" OR "Dynamic Balance Test*" OR "Postural Stability Test*" OR "Star Excursion Balance Test*" OR "Hop Test*" AND "Ankle Instability" OR "Ankle Sprain." Included articles assessed differences in FPTs in patients with CAI compared with a control group.

MAIN RESULTS

Included studies were assessed for methodological quality and level of evidence. Individual and mean effect sizes were also calculated for FPTs from the included articles. Twenty-nine studies met the criteria and were analyzed. The most common FPTs were timed-hop tests, side-hop, multiple-hop test, single-hop for distance, foot-lift test, and the Star Excursion Balance Tests (SEBTs). The side-hop (g = -1.056, P = 0.009, n = 7), timed-hop tests (g = -0.958, P = 0.002, n = 9), multiple-hop test (g = 1.399, P < 0.001, n = 3), and foot-lift tests (g = -0.761, P = 0.020, n = 3) demonstrated the best utility with large mean effect sizes, whereas the SEBT anteromedial (g = 0.326, P = 0.022, n = 7), medial (g = 0.369, P = 0.006, n = 7), and posteromedial (g = 0.374, P < 0.001, n = 13) directions had moderate effects.

CONCLUSIONS

The side-hop, timed-hopping, multiple-hop, and foot-lift seem the best FPTs to evaluate individuals with CAI. There was a large degree of heterogeneity and inconsistent reporting, potentially limiting the clinical implementation of these FPTs. These tests are cheap, effective, alternatives compared with instrumented measures.

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 effectiveness of rearfoot medial wedge intervention on balance for athletes with chronic ankle instability

BACKGROUND

Athletes with chronic ankle instability (CAI) often develop complications such as pain, instability, and reduced postural control and balance stability, all of which affect athletic performance. This study investigated the effects of a 4° medal wedge intervention on static and dynamic balance in athletes with CAI.

METHODS

The participants were 24 healthy and 25 CAI athletes. Participants received a 4° medial wedge applied at the rear foot insole and completed the experiment measurements before and after the wedge intervention. The main outcome measures included the area and path length of the center of pressure when participants performed single-leg standing balance in the closed eye condition and the dynamic balance scores of a multiple single-leg hop stabilization test.

RESULTS

The single-leg standing balance significantly improved in CAI (P = .027) and control groups (P = .005) after the medial wedge intervention. The dynamic balance scores significantly decreased from 53.00 ± 25.22 to 41.24 ± 21 48 (P = .015) in CAI group after medial wedge intervention.

CONCLUSION

Wearing a 4° medial wedge applied at the rear foot insole improved static and dynamic balance immediately in athletes with CAI. We suggest that clinicians may provide the foot insole to improve balance deficit in athletes having CAI.

Anterior cruciate ligament reconstruction and dynamic stability at time of release for return to sport

OBJECTIVE

Examine dynamic stability using Dynamic Postural Stability Index (DPSI) in athletes following anterior cruciate ligament reconstruction (ACLR) at time of release for return-to-sport (RTS), compared to matched controls.

DESIGN

Cross-sectional case-control study.

SETTING

Sports medicine clinic.

SUBJECTS

Fifteen ACLR athletes who had completed post-operative rehabilitation and were within 6 weeks following release to RTS were age-, gender-, and activity-matched to 15 healthy controls.

MAIN OUTCOME MEASURES

Ground reaction forces (GRFs) were collected using a portable force plate during stabilization from three different single-leg landing tasks. A composite DPSI was calculated using GRFs.

RESULTS

Compared to matched controls, ACLR athletes within 6 weeks of release for RTS did not significantly differ in dynamic postural stability and there were no significant differences between the involved and uninvolved limbs in the ACLR group.

CONCLUSION

Current findings indicate that dynamic postural stability, as measured using the DPSI, is not significantly different in ACLR subjects at time of release for RTS compared to matched controls. In addition, the DPSI was not significantly different between the involved and uninvolved limbs in the ACLR subjects. The results suggest that the post-ACLR rehabilitation program utilized may have adequately restored postural stability in this particular sample.

Effects of Peroneal Muscles Fatigue on Dynamic Stability Following Lateral Hop Landing: Time to Stabilization Versus Dynamic Postural Stability Index

CONTEXT

Dynamic stability is a necessary requirement in many sports competitions. Muscle fatigue, which can impair stability, may be occurred in many sports competitions in which lateral movements and landing repeated frequently.

OBJECTIVE

To assess the effects of peroneal muscles fatigue on dynamic stability following lateral hop landing through measuring time to stabilization (TTS) and dynamic postural stability index (DPSI).

DESIGN

Quasi-experimental.

SETTING

Laboratory study.

PARTICIPANTS

A total of 20 recreationally active, healthy males with no lower-extremity injury during the previous 6 months participated in this study.

INTERVENTION

Participants performed a lateral hop on a force plate before and immediately after a fatigue intervention using a Biodex dynamometer. For inducing fatigue, the participant made a prolonged eversion effort with 40% of the maximal voluntary contraction. Fatigue was met when the eversion torque declined by 50% of the initial value. TTS and DPSI were calculated using sequential averaging method and relevant formulas, respectively.

MAIN OUTCOME MEASURES

Premeasures and postmeasures of TTS in the anteroposterior, mediolateral and vertical directions, resultant vector of TTS, stability indices in the anteroposterior, mediolateral and vertical directions, and DPSI.

RESULTS

Means of the DPSI or its components did not change significantly due to fatigue (P > .05). Means of the TTS in the anteroposterior and mediolateral directions, and the mean of the resultant vector of the TTS increased significantly after fatigue (P < .05).

CONCLUSIONS

The question that the dynamic stability is affected or not affected by fatigue depends on which of the TTS or DPSI is used for analysis. The TTS may be a sensitive measure to detect subtle changes in postural stability due to fatigue. But, the DPSI which may be changed after a more strenuous fatigue may be related to actual fatiguing situations.

Dynamic postural stability, is associated with competitive level, in youth league soccer players

OBJECTIVES

To assess the effect of competitive level on dynamic postural stability in young elite and sub-elite soccer players.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Fifty-four male soccer players of Under 16 and Under 17 categories (mean age 15.9 ± 0.6), divided into two groups who regularly compete at national (n = 28) and regional (n = 26) levels.

MAIN OUTCOME MEASURES

Dynamic Postural Stability Index (DPSI) and vertical Time to Stabilization (vTTS) for a forward-jump landing. Static postural sway was calculated on the basis of center-of-pressure trajectories for a 20 s one-legged stance.

RESULTS

Players at national level exhibit better dynamic postural control than those at regional level, as indicated by the significantly lower DPSI (0.327 vs. 0.373, p < 0.001) and vTTS (0.887 vs. 1.158 s, p = 0.003). In contrast, no differences between groups were found in any of the postural sway parameters for the static test.

CONCLUSIONS

Young soccer players at national level are characterized by better balance performance in terms of faster and more efficient stabilization after a forward jump, while one-leg static standing tests appear not challenging enough to reveal differences in balance abilities associated with the combination of superior technical and physical features.

Individuals with chronic ankle instability exhibit dynamic postural stability deficits and altered unilateral landing biomechanics: A systematic review

OBJECTIVE

To evaluate the literature regarding unilateral landing biomechanics and dynamic postural stability in individuals with and without chronic ankle instability (CAI).

METHODS

Four online databases (PubMed, ScienceDirect, Scopus, and SportDiscus) were searched from the earliest records to 31 January 2018, as well as reference sections of related journal articles, to complete the systematic search. Studies investigating the influence of CAI on unilateral landing biomechanics and dynamic postural stability were systematically reviewed and evaluated.

RESULTS

Twenty articles met the criteria and were included in the systematic review. Individuals with CAI were found to have deficits in dynamic postural stability on the affected limb with medium to large effect sizes and altered lower extremity kinematics, most notably in the ankle and knee, with medium to large effect sizes. Additionally, greater loading rates and peak ground reaction forces, in addition to reductions in ankle muscle activity were also found in individuals with CAI during unilateral jump-landing tasks.

CONCLUSIONS

Individuals with CAI demonstrate dynamic postural stability deficits, lower extremity kinematic alterations, and reduced neuromuscular control during unilateral jump-landings. These are likely factors that contribute recurrent lateral ankle sprain injuries during dynamic activity in individuals with CAI.

Military personnel with self-reported ankle injuries do not demonstrate deficits in dynamic postural stability or landing kinematics

BACKGROUND

The odds of sustaining non-contact musculoskeletal injuries are higher in Special Operations Forces operators than in infantry soldiers. The ankle is one of the most commonly injured joints, and once injured can put individuals at risk for reinjury. The purpose of this study was to determine if any differences in postural stability and landing kinematics exist between operators with a self-reported ankle injury in the past one year and uninjured controls.

METHODS

A total of 55 Special Operations Forces operators were included in this analysis. Comparisons were made between operators with a self-reported ankle injury within one-year of their test date (n=11) and healthy matched controls (n=44). Comparisons were also made between injured and uninjured limbs within the injured group. Dynamic postural stability and landing kinematics at the ankle, knee, and hip were assessed during a single-leg jump-landing task. Comparisons were made between groups with independent t-tests and within the injured group between limbs using paired t-tests.

FINDINGS

There were no significant differences in dynamic postural stability index or landing kinematics between the injured and uninjured groups. Anterior-posterior stability index was significantly higher on the uninjured limb compared to the injured limb within the injured group (P=0.02).

INTERPRETATION

Single ankle injuries sustained by operators may not lead to deficits in dynamic postural stability. Dynamic postural stability index and landing kinematics within one year after injury were either not affected by the injuries reported, or injured operators were trained back to baseline measures through rehabilitation and daily activity.

Single-limb landing biomechanics are altered and patellar tendinopathy related pain is reduced with acute infrapatellar strap application

BACKGROUND

Patellar tendinopathy, a common condition of the knee, is often treated with patellar tendon straps to control pain during dynamic activity. Little is known regarding their effect on pain, landing kinematics and kinetics with their application. The purpose of this study was to determine if patellar tendon straps influenced pain, kinematics at landing and ground reaction forces in individuals with patellar tendinopathy versus healthy controls.

METHODS

Thirty participants with patellar tendinopathy and 30 controls participated. They completed single-limb landings with and without patellar tendon straps while pain, three-dimensional kinematics and vertical ground reaction forces were measured. A multivariate analysis of variance was completed to determine the differences in strapping condition and group for the dependent variables.

RESULTS

Individuals with patellar tendinopathy demonstrated a significant decrease in pain (no strap=37.1±22.1mm (mean±SD), strap=28.0±18.5mm (mean±SD)). With the strap at landing all participants displayed less hip rotation (F=7.16, p=.01), knee adduction (F=10.20, p=.002), ankle inversion (F=4.60, p=.04), and peak vertical ground reaction force (F=7.30, p=.009).

CONCLUSIONS

Patellar tendon straps reduced pain in those with patellar tendinopathy. Additionally, with the strap, individuals landed in a more neutral alignment and decreased landing forces which could provide a benefit to those with patellar tendinopathy.

Comparison Between Single and Combined Clinical Postural Stability Tests in Individuals With and Without Chronic Ankle Instability

OBJECTIVE

To determine if a single or/and combined clinical tests match group membership based on self-reported ankle function.

DESIGN

Cross-sectional.

SETTING

Biomechanics Laboratory.

PARTICIPANTS

From participants, 58 meeting inclusion/exclusion criteria were divided into a chronic ankle instability (CAI) group (n = 25) who reported ≤25 on the Cumberland Ankle Instability Tool (CAIT) and a history of moderate-severe ankle sprain(s) and a control group (n = 33) who reported ≥29 on the CAIT and no history of ankle sprain(s).

INTERVENTIONS

Participants completed the following clinical tests: Foot Lift Test (FLT), the Star Excursion Balance Test (SEBT), the Single-Leg Hop Test (SLHT), and the Time in Balance Test (TIB) in a randomized order. A linear regression model was applied to determine measures that matched ankle group membership.

MAIN OUTCOME MEASURES

The mean of SEBT reach distance was normalized to percentage leg length. The mean of number of errors in the FLT was recorded. The SLHT and TIB were reported as time in seconds, and the means were calculated.

RESULTS

The most parsimonious combination of tests (SLHT and SEBT) resulted in correctly matching 70.69% (41/58) of participants into groups, which was significantly better than chance. The multiple correlation coefficients (R value) for combining the SLHT and SEBT was 0.39.

CONCLUSIONS

Using SLHT and SEBT resulted in improved recognition of participants designated into the CAI or control groups. Self-report perception of ankle function provides limited information for clinicians and researchers. Using multiple clinical function tests may be more helpful in determining deficits and intervention effectiveness.

Comparison of dynamic postural stability scores between athletes with and without chronic ankle instability during lateral jump landing

BACKGROUNDS

Many ankle injuries occur while participating in sports that require jumping and landing such as basketball, volleyball and soccer. Most recent studies have investigated dynamic postural stability of patients with chronic ankle instability after landing from a forward jump. The present study aimed to investigate the dynamic postural stability of the athletes who suffer from chronic ankle sprain while landing from a lateral jump.

METHODS

Twelve athletes with self-reported unilateral chronic ankle instability (4 females and 8 males) and 12 matched controls (3 females and 9 males) voluntarily participated in the study. Dynamic postural stability index and its directional indices were measured while performing lateral jump landing test.

RESULTS

No differences were found between athletes with and without chronic ankle instability during our landing protocol by means of the dynamic postural stability index and its directional indices. Findings showed that in each group, medial/lateral stability index is significantly higher than anterior/posterior and vertical stability indexes.

CONCLUSION

Findings showed that dynamic postural stability was not significantly different between the two groups. Future studies should examine chronic ankle instability patients with more severe disabilities and expose them to more challenging dynamic balance conditions to further explore postural stability.

LEVEL OF EVIDENCE

IIIa.

Effects of the application of ankle functional rehabilitation exercise on the ankle joint functional movement screen and isokinetic muscular function in patients with chronic ankle sprain

[Purpose] This study was conducted to investigate the effects of ankle functional rehabilitation exercise on ankle joint functional movement screen results and isokinetic muscular function in patients with chronic ankle sprain patients. [Subjects and Methods] In this study, 16 patients with chronic ankle sprain were randomized to an ankle functional rehabilitation exercise group (n=8) and a control group (n=8). The ankle functional rehabilitation exercise centered on a proprioceptive sense exercise program, which was applied 12 times for 2 weeks. To verify changes after the application, ankle joint functional movement screen scores and isokinetic muscular function were measured and analyzed. [Results] The ankle functional rehabilitation exercise group showed significant improvements in all items of the ankle joint functional movement screen and in isokinetic muscular function after the exercise, whereas the control group showed no difference after the application. [Conclusion] The ankle functional rehabilitation exercise program can be effectively applied in patients with chronic ankle sprain for the improvement of ankle joint functional movement screen score and isokinetic muscular function.

H-reflex excitability is inhibited in soleus, but not gastrocnemius, at the short-latency response of a horizontal jump-landing task

Impaired spinal-level neuromuscular control is suggested to contribute to instability and injury during dynamic landing tasks. Despite this suggestion, spinal-level neuromuscular control is yet to be examined during a horizontal jump-landing task. The aim of the current study was to assess changes in H-reflexes and its reliability at the short-latency response of landings from short and long distances. Eight healthy individuals (five male, three female; age, 22±1.2yrs; height, 178±8.1cm; weight, 72±15.7kg) participated in the study. H-reflexes were evoked at the SLR in the soleus and medial gastrocnemius muscles, during two landing conditions: 25% and 50% of maximal broad jump distance. H-reflexes were expressed relative to the background electromyography (EMG) and maximal M-wave responses (M-max). Soleus H-reflexes were inhibited when landing from shorter distance (25%, 13.9±7.6%; 50%, 8.3±6.5%; p<0.01). No change in H-reflex excitability was observed in medial gastrocnemius. Background EMG was unaltered across landing conditions. Inhibition of soleus H-reflex excitability from 25% to 50% landing condition indicates a reduced contribution of Ia-afferent feedback to the alpha-motor neuron during landings from greater distances, which may contribute to stiffness regulation at the ankle joint. Unaltered H-reflex excitability of medial gastrocnemius is most likely attributed to its functional role during the landing task.

Altered Kinematics and Time to Stabilization During Drop-Jump Landings in Individuals With or Without Functional Ankle Instability

CONTEXT

It has been proposed that altered dynamic-control strategies during functional activity such as jump landings may partially explain recurrent instability in individuals with functional ankle instability (FAI).

OBJECTIVE

To capture jump-landing time to stabilization (TTS) and ankle motion using a multisegment foot model among FAI, coper, and healthy control individuals.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Participants were 23 individuals with a history of at least 1 ankle sprain and at least 2 episodes of giving way in the past year (FAI), 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (copers), and 23 individuals with no history of ankle sprain or instability in their lifetime (controls). Participants were matched for age, height, and weight (age = 23.3 ± 3.8 years, height = 1.71 ± 0.09 m, weight = 69.0 ± 13.7 kg).

INTERVENTION(S)

Ten single-legged drop jumps were recorded using a 12-camera Vicon MX motion-capture system and a strain-gauge force plate.

MAIN OUTCOME MEASURES

Mediolateral (ML) and anteroposterior (AP) TTS in seconds, as well as forefoot and hindfoot sagittal- and frontal-plane angles at jump-landing initial contact and at the point of maximum vertical ground reaction force were calculated.

RESULTS

For the forefoot and hindfoot in the sagittal plane, group differences were present at initial contact (forefoot: P = .043, hindfoot: P = .004). At the hindfoot, individuals with FAI displayed more dorsiflexion than the control and coper groups. Time to stabilization differed among groups (AP TTS: P < .001; ML TTS: P = .040). Anteroposterior TTS was longer in the coper group than in the FAI or control groups, and ML TTS was longer in the FAI group than in the control group.

CONCLUSIONS

During jump landings, copers showed differences in sagittal-plane control, including less plantar flexion at initial contact and increased AP sway during stabilization, which may contribute to increased dynamic stability.

Individuals with both perceived ankle instability and mechanical laxity demonstrate dynamic postural stability deficits

BACKGROUND

Chronic ankle instability is a frequent and serious consequence of lateral ankle sprains. The contribution of perceived instability and potential for mechanical laxity to contribute to the overall deficit in dynamic postural stability is unclear. The purpose was to determine if those with mechanical laxity demonstrated significant differences in dynamic postural stability compared to controls, copers and those with perceived instability.

METHODS

Of 93 participants, 83 recreationally active individuals were divided into 4 groups: controls, copers, those with perceived instability, and those with both perceived instability and mechanical laxity. Injury history and the Cumberland Ankle Instability Tool were collected, and an instrumented arthrometer was applied. Participants completed a single limb jump landing, balancing upon completion. Ground reaction force data were collected, scaled to body mass, and the Dynamic Postural Stability Indices were calculated for anterior-posterior, medial-lateral, vertical and composite. One-way ANOVAs with Tukey post-hoc tests (α<0.05) were conducted on each of the stability indices among the four groups.

FINDINGS

The mechanically lax group had significantly greater mean (standard deviation) medial-lateral stability index scores 0.57 (0.62) than the coper group 0.24 (0.20; P=0.02) and significantly greater composite index scores 0.73 (0.57) than the perceived instability 0.49 (0.09) and coper groups 0.47 (0.12 P=0.05). No other indices were significantly different among groups.

INTERPRETATION

Individuals with perceived instability and mechanical laxity exhibited dynamic postural deficits compared to copers and those with perceived instability alone. Mechanical laxity may contribute to the deficits in dynamic postural stability.

Chronic Ankle Instability and Neural Excitability of the Lower Extremity

CONTEXT

Neuromuscular dysfunction of the leg and thigh musculature, including decreased strength and postural control, is common in patients with chronic ankle instability (CAI). Understanding how CAI affects specific neural pathways may provide valuable information for targeted therapies.

OBJECTIVE

To investigate differences in spinal reflexive and corticospinal excitability of the fibularis longus and vastus medialis between limbs in patients with unilateral CAI and between CAI patients and participants serving as healthy controls.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 56 participants volunteered, and complete data for 21 CAI patients (9 men, 12 women; age = 20.81 ± 1.63 years, height = 171.57 ± 11.44 cm, mass = 68.84 ± 11.93 kg) and 24 healthy participants serving as controls (7 men, 17 women; age = 22.54 ± 2.92 years, height = 172.35 ± 10.85 cm, mass = 69.15 ± 12.30 kg) were included in the final analyses. Control participants were matched to CAI patients on sex, age, and limb dominance. We assigned "involved" limbs, which corresponded with the involved limbs of the CAI patients, to control participants.

MAIN OUTCOME MEASURE(S)

Spinal reflexive excitability was assessed via the Hoffmann reflex and normalized to a maximal muscle response. Corticospinal excitability was assessed using transcranial magnetic stimulation. Active motor threshold (AMT) was defined as the lowest transcranial magnetic stimulation intensity required to elicit motor-evoked potentials equal to or greater than 100 μV in 5 of 10 consecutive stimuli. We obtained motor-evoked potentials (MEPs) at percentages ranging from 100% to 140% of AMT.

RESULTS

Fibularis longus MEP amplitudes were greater in control participants than in CAI patients bilaterally at 100% AMT (control involved limb: 0.023 ± 0.031; CAI involved limb: 0.014 ± 0.008; control uninvolved limb: 0.021 ± 0.022; CAI uninvolved limb: 0.015 ± 0.007; F1,41 = 4.551, P = .04) and 105% AMT (control involved limb: 0.029 ± 0.026; CAI involved limb: 0.021 ± 0.009; control uninvolved limb: 0.034 ± 0.037; CAI uninvolved limb: 0.023 ± 0.013; F1,35 = 4.782, P = .04). We observed no differences in fibularis longus MEP amplitudes greater than 110% AMT and no differences in vastus medialis corticospinal excitability (P > .05). We noted no differences in the Hoffmann reflex between groups for the vastus medialis (F1,37 = 0.103, P = .75) or the fibularis longus (F1,41 = 1.139, P = .29).

CONCLUSIONS

Fibularis longus corticospinal excitability was greater in control participants than in CAI patients.

The correlation between postural control and upper limb position sense in people with chronic ankle instability

Background

Chronic ankle instability (CAI) is attributed to functional instability driven by insufficient proprioception. However, it is not clear whether the deficits are related to global impaired performance or to specific decrease in ankle motor-control. The aim of this study was to assess the correlation between lower limb postural control and upper limb position sense among people with CAI, in order to further explore the function of the central neural control in people with CAI.

Methods

Fourteen participants (10 males, 4 females) with self-reported CAI and 14 age- and gender-matched, healthy controls participated in this study. Each participant completed single-limb stance postural control tests and shoulder position sense tests. The Overall Stability Index (OSI) was used as a measure of postural stability. The average of the absolute error score (AES) was calculated as a measure of shoulder position sense. Pearson correlations between the scores of the four body sites –lower limb postural stability (preferred/non-preferred), shoulder (preferred/non-preferred) were determined separately for each group.

Results

In the control group, significant correlations were found between the OSI score of the right and left ankles (r = 0.887, p < 0.001), between the AES of the right and left shoulders (r = 0.656, p = 0.011), as well as between the OSI score and the AES of the non-preferred side (r = 0.649, p = 0.012). In the CAI group, significant correlation was found only between the OSI score at both ankles (r = 0.6, p = 0.002).

Conclusions

Individuals with CAI demonstrated lower limb postural control and upper limb position sense similar to those shown in healthy controls. However, correlations between the lower and upper limbs were observed only in the healthy controls. Clinicians can use this information and employ activities that focus on coordinating the upper and lower extremities when designing neuromuscular control training programs for people with CAI.

Altered visual focus on sensorimotor control in people with chronic ankle instability

The purpose of this investigation was to examine the effects of the combination of chronic ankle instability (CAI) and altered visual focus on strategies for dynamic stability during a drop-jump task. Nineteen participants with self-reported CAI and 19 healthy participants performed a drop-jump task in looking-up and looking-down conditions. For the looking-up condition, participants looked up and read a random number that flashed on a computer monitor. For the looking-down condition, participants focused their vision on the force plate. Sagittal- and frontal-plane kinematics in the hip, knee and ankle were calculated at the time points of 100 ms pre-initial foot contact to ground and at IC. The resultant vector time to stabilisation was calculated with ground reaction force data. The CAI group demonstrated less hip flexion at the point of 100 ms pre-initial contact (P < 0.01), and less hip flexion (P = 0.03) and knee flexion at initial contact (P = 0.047) compared to controls. No differences in kinematics or dynamic stability were observed in either looking-up or looking-down conditions (P > 0.05). Altered visual focus did not influence movement patterns during the drop-jump task, but the presence of CAI did. The current data suggests that centrally mediated changes associated with CAI may lead to global alterations in the sensorimotor control.

Gender difference in distance of tibiofibular syndesmosis to joint dynamics of lower extremities during squat

The incidence of lower extremity injury is greater in women than men, indicating gender difference in lower extremity function. Here we investigate the role of the ankle during squatting in young men and women by measuring the tibiofibular syndesmosis (TFS) distance and the angles of hip, ankle and knee joints. TFS distance was positively correlated to body mass in men, but not in women, suggesting some factor(s) affecting TSF distance in women. When divided into two groups with wide and narrow TFS distances, men apparently used ankle and hip joints evenly during squatting, but women, specifically those with a narrow TFS distance, used the hip joint more effectively than ankle. Estimated knee moment was positively correlated to TFS distance in women, but not in men. These results suggest that the women possessing a wider TFS distance use ankle function rather than hip junction when performing lower-extremity exercises (i.e. squatting), presumably accounting for the higher incidence of ankle injury in women during such activities.

Physical and cognitive consequences of fatigue: A review

Fatigue is a common worrying complaint among people performing physical activities on the basis of training or rehabilitation. An enormous amount of research articles have been published on the topic of fatigue and its effect on physical and physiological functions. The goal of this review was to focus on the effect of fatigue on muscle activity, proprioception, and cognitive functions and to summarize the results to understand the influence of fatigue on these functions. Attaining this goal provides evidence and guidance when dealing with patients and/or healthy individuals in performing maximal or submaximal exercises.

The acute effects of vibration training on balance and stability amongst soccer players

Acute whole body vibration training (WBVT) is a tool used amongst coaches to improve performance prior to activity. Its effects on other fitness components, such as balance and stability, along with how different populations respond are less well understood. The aim of the current research is to determine the effect of acute WBVT on balance and stability amongst elite and amateur soccer players. Forty-four healthy male soccer players (22 elite and 22 amateur) were assigned to a treatment or control group. The intervention group then performed 3 × 60 seconds static squat on vibration platform at 40 Hz (±4 mm) with Y balance test (YBT) scores and dynamic postural stability index (DPSI) measured pre and post. DPSI was significantly lower in the elite players in the acute WBVT compared to amateur players (F1, 40= 6.80; P = 0.013). YBT anterior reach distance showed a significant improvement in both amateur and elite players in the acute WBVT group (F1, 40= 32.36; P < 0.001). The improvement in DPSI amongst the elite players indicates a difference in responses to acute high frequency vibration between elite and amateur players during a landing stability task. The results indicate that acute WBVT improves anterior YBT reach distances through a possible improvement in flexibility amongst both elite and amateur players. In conclusion, acute WBVT training appears to improve stability amongst elite soccer players in comparison to amateur players, the exact reasoning behind this difference requires further investigation.

Lateral Ankle Sprain and Chronic Ankle Instability: A Critical Review

Many studies investigated the contributing factors of chronic ankle instability, but a consensus has not yet been obtained. The objective of this critical review is to provide recent scientific evidence on chronic ankle instability, including the epidemiology and pathology of lateral ankle sprain as well as the causative factors of chronic ankle instability. We searched MEDLINE from 1964 to December 2013 using the terms ankle, sprain, ligament, injury, chronic, functional, mechanical, and instability. Lateral ankle sprain shows a very high recurrence rate and causes considerable economic loss due to medical care, prevention, and secondary disability. During the acute phase, patients with ankle sprain demonstrate symptoms such as pain, range of motion deficit, postural control deficit, and muscle weakness, and these symptoms may persist, leading to chronic ankle instability. Although some agreement regarding the effects of chronic ankle instability with deficits in postural control and/or concentric eversion strength exists, the cause of chronic ankle instability remains controversial.

LEVELS OF EVIDENCE

Therapeutic Level IV: Review of Level IV studies.

The effect of kinesio tape on force sense in people with functional ankle instability

OBJECTIVE

To evaluate the effect of kinesio tape (KT) on proprioception of the ankle.

DESIGN

Case-control study.

SETTING

Controlled laboratory.

PARTICIPANTS

Twenty-eight subjects participated in this study: 14 subjects were in the control group (no history of ankle injuries) and 14 subjects were in the functional ankle instability (FAI) group (history of ankle injuries and a recent history of giving way).

INTERVENTIONS

Subjects in the FAI group received lateral ankle sprain KT application, whereas those in the control group received no tape application.

MAIN OUTCOME MEASURES

Proprioception was measured using eversion force sense. This task was performed at 30% of the eversion maximum voluntary isometric contraction. Force sense was tested at baseline, immediately after KT application, and 72 hours after KT application.

RESULTS

Results revealed a significant time by group interaction (P = 0.03). At baseline and immediately after KT, subjects in the FAI group had significantly more force sense errors than those in the control group. However, after wearing the tape for 72 hours, no significant differences were identified between the groups.

CONCLUSIONS

We found that after wearing KT for an extended amount of time, proprioceptive deficits were improved. After the tape application, the improvements resulted in similar conscious proprioceptive awareness in both the subjects with and without ankle instability.

Single-leg drop landing motor control strategies following acute ankle sprain injury

No research currently exists investigating the effect of acute injury on single-limb landing strategies. The aim of the current study was to analyze the coordination strategies of participants in the acute phase of lateral ankle sprain (LAS) injury. Thirty-seven participants with acute, first-time LAS and 19 uninjured participants completed a single-leg drop landing task on both limbs. Three-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment-of-force) data were acquired for the joints of the lower extremity from 200 ms pre-initial contact (IC) to 200 ms post-IC. The peak magnitude of the vertical component of the ground reaction force (GRF) was also computed. Injured participants displayed a bilateral increase in hip flexion, with altered transverse plane kinematic profiles at the knee and ankle for both limbs (P < 0.05). This coincided with a reduction in the net-supporting flexor moment of the lower extremity (P < 0.05) and magnitude of the peak vertical GRF for the injured limb (21.82 ± 2.44 N/kg vs 24.09 ± 2.77 N/kg; P = 0.013) in injured participants compared to control participants. These results demonstrate that compensatory movement strategies are utilized by participants with acute LAS to successfully reduce the impact forces of landing.