functional ankle instability

Ankle injury is one of the most common sports and daily life injuries. Usually, in 15%–60% of cases, Functional Ankle Instability (FAI) occurs after the initial sprain of the ankle. People with FAI have different muscle recruitment patterns and neuromuscular firing rates than healthy people. The human body relies on three sensory systems to maintain balance: vision, somatosensory, and vestibular. Information obtained from weight can be united by all three systems in the central nervous system, and balance can be established. Virtual reality technology is a new way to create more visual impairment and instability. By providing unreal visual cues, virtual reality makes the central nervous system rely on somatosensory and vestibular to maintain balance. This study aims to investigate the electromyographic activity of selected lower limb muscles in feedback and feedforward phases with and without using virtual reality in male badminton players with and without FAI.

The current research method was quasi–experimental. The statistical population of this research comprised Badminton athletes aged 15 to 18 who were playing at the professional level. Thirty Badminton players were divided into two groups with and without ankle instability, and each group included 15 subjects. The Cumberland Ankle Instability Tool (Hiller et al., 2006) was used to diagnose FAI. The group with FAI received a Cumberland questionnaire score of 0 to 27, and the control group received a score of 27 to 30. The Anterior Drawer of the Ankle Test was performed to ensure the absence of mechanical instability, and if the participants showed mechanical instability, they were excluded from the research. Motion Lab System MA400 (DTU) device was used to measure the electrical activity of muscles, and the F–RG model electrode was made by Skintact. The electromyographic activity of the tibialis anterior, peroneus longus, and lateral gastrocnemius muscles in the feedforward and feedback phases was studied using virtual reality. After checking the normality of the data, the independent t test and Man–Whitney U test were used to analyze the data at a significance level of 0.05 using SPSS 27.

The independent t test and Man–Whitney U test results showed a significant difference in the feedforward and feedback phases between the groups with FAI and without FAI regarding the tibialis anterior, peroneus longus muscles activities (p<0.05). When using Virtual Reality in the feedforward phase, there is a significant difference between the tibialis anterior (p=0.003) and lateral gastrocnemius muscles (p<0.001) in the group with and without FAI when using virtual reality. It should be noted that the activity of the tibialis anterior and lateral gastrocnemius muscle in the group without functional instability of the ankle in the feedforward phase was higher than the group with FAI. Also, a significant difference was observed in the feedback phase in the tibialis anterior (p=0.006) and the lateral gastrocnemius muscle (p<0.001) between the group with and without ankle functional instability. It should be noted that the activity of the tibialis anterior and lateral gastrocnemius muscle in the group without ankle functional instability in the feedback phase was higher than in the group with ankle functional instability. Also, there is no significant difference between the FAI and non–FAI groups regarding peroneus longus. 

According to the results, virtual reality can change the electromyography activity of the ankle muscles. There are changes in the electromyographic activity of the tibialis anterior and lateral gastrocnemius muscle when using virtual reality between athletes with and without FAI, indicating the effect of virtual reality on the electromyographic activity of ankle muscles in these people.

Several studies have investigated gait biomechanics in people with functional ankle instability (FAI). However, the potential role of information processing (attention) in the gait control of these patients is still unknown. Therefore, this study aimed to investigate the effect of cognitive load on the range of motion (ROM) of lower limb joints during walking in men with and without FAI.

The study was a non-randomized controlled clinical trial. Eighteen male subjects with FAI and 19 healthy subjects participated in this study and completed three randomized conditions (three trials per condition): normal walking on a treadmill (single task), normal walking while performing a cognitive task (dual task), and (3) performing cognitive task while sitting. Three-dimensional information of hip, knee, and ankle joint ROM in the sagittal, frontal, and transverse planes were measured as gait kinematic components, and the error ratio and average reaction time were measured as cognitive task indicators. The intraclass correlation coefficient (ICC) was used to determine the intrasession reliability of kinematic and cognitive measures.

The ICC of kinematic variables, including the hip, knee, and ankle joint ROM, with and without applying cognitive tasks in three planes was more than 0.70. During the single task, the group with FAI showed a significantly decreased knee ROM in the transverse plane and a decreased hip ROM in the sagittal plane compared to the healthy group. During the dual task, the group with FAI showed a significantly increased hip ROM in the sagittal plane compared to the healthy group. The results of the cognitive task showed that the group with FAI had a longer reaction time in the auditory Stroop test during dual-task walking than in the sitting position.

FAI can be an important factor in motor-cognitive interactions. Using a cognitive task may be an effective strategy in the rehabilitation program of men with FAI.

 Ankle joint injuries and lateral sprains are the most common sports injuries. Understanding this injury through functional tests can reduce the risk of recurrence, and athlete's medical expenses reduce keeping athletes away from sports fields and smooth out the way of rehabilitation and return to exercise. This study aimed to collect functional tests that identify the ankle instability and the overall summary of these tests.

In this study, comprehensive search to identify articles and studies conducted on functional tests for ankle instability PEDRO, PubMed, MEDLINE, Web of Science, Science Direct, Cochrane Central Register of Controlled Clinical Trials, Google Scholar, and Scopus based in the period 1994 to 2020 took place. In addition, a manual search and comprehensive review of article sources were conducted.

Out of 49 different tests that studied the functional tests for ankle instability, 23 articles were selected, and their results were reported. 25 performance-related tests, 7 postural control system tests, 10 self-report tests, and 7 scoring system tests were identified for ankle function evaluation.

An analysis of studies showed that 4 different testing tools had been used in the literature to evaluate functional ankle instability in athletes. The present study identifies and explains how these tests are applied. Therefore, it performs an elaborated analysis of the 4 existing tests to see which one offers a more accurate analysis of functional ankle instability in athletes.

Ankle sprain is one of the most common sports injuries. While the effects of static constraints in stabilizing the ankle joint are relatively well understood, those of dynamic constraints are less clear and require further investigation. The purpose of this study was to compare kinematic variables of ankle joint in athletes with functional ankle instability, Coper and healthy during running.

75 athletes were randomly divided into 3 groups of functional ankle instability (age: 24.04±4.42 years, height: 182.20±6.63 cm, weight: 73.96±7.06 kg), Coper (age: 25.56±4.96 years, height: 185.44±6.97 cm, weight: 77.44±7.03 kg) and healthy (age: 26.40±4.71 years, height: 183.72±6.52 cm, weight: 74.26±6.56 kg). Subjects were asked to run on a treadmill at a speed of 10 km / h for 30 seconds. Kinematic data were recorded using a 3D optic track camera and then used with MATLAB to construct a dynamic model and analyze the data. To compare three groups, one-way analysis of variance test with a significance level of 0.05 was used.

The present study showed that there was a significant difference in dorsiflexion and ankle inversion between the three groups at the moment of initial contact (P≤0/05). Also, the results of the Toki follow-up test showed that there was no significant difference between the Coper and healthy groups in the dorsiflexion and inversion (P≥0/05).

The results showed that functional ankle instability group had less dorsiflexion and more inversion than Coper and healthy group at the moment of initial contact. There was also no significant difference between Coper and healthy groups in dorsiflexion and inversion. Therefore, athletes' strategy of functional ankle instability has altered and the focus of rehabilitation protocols should be on the kinematics of ankle joint in functional activities to prevent recurrent sprain.

Functional ankle instability is one of the most common residual and debilitating symptoms of acute ankle sprain which usually makes the athlete to be out of training program for a while. This study aimed to investigate the effect of four weeks core stability training on some lower extremity kinematics variables in athletes with functional ankle instability during a single-leg drop landing taskIn this semi-experimental research, study population included 24 athletes with functional ankle which were divided into two experimental (n=12), and control (n=12) groups. To assess the drop-landing task with functional instability foot,240 Hz frequency motion analysis system was used. The recorded movements were analyzed by Nexus 2.6 version. The hip, knee, and ankle angles were extracted on the sagittal plane, and finally, repeated measure ANOVA and Bonferroni posthoc were used to compare two groups (p≤0.05).There was no significant difference in the angle of the ankle after four weeks training (p≥0.05). However, in the angle of the hip and knee were found a significant difference from pretest to post-test (p≤0.05)The results indicated that four weeks core stability training improves kinematics of landing in athletes with functional ankle instability, and it seems that these exercises can be a method of preventing re-injury of the ankle.

The effect and persistence of neuromuscular activities on the timing of lower extremity proximal muscles are questionable. So the purpose of this study was to investigate the persistence effect of neuromuscular exercise on activity timing of lower extremity distal and proximal muscles in athletes with functional ankle instability.

26 athletes with functional ankle instability were randomly divided into two groups of neuromuscular exercises and control. Subjects were selected based on inclusion and exclusion criteria. In the pretest phase, the activity timing of muscles was evaluated with surface electromyography. The next step was to exercise group performing their own exercises for 6 weeks. Exercises were performed 3 sessions per week and each exercise session lasted 15 to 20 minutes. Then all pre-test measurements were performed in the post-test and persistence test. Repeated analysis using ANOVA and Bonferroni post hoc tests were used for statistical analysis. The significance level was considered less than 0.05.

Results of Mixed-ANOVA showed the interactive effect of time(pretest-posttest-persistence) on the group(neuromuscular-control) significantly changes the activity timing of distal muscles in the neuromuscular group(P≤0/05). But there was no difference in the activity timing of proximal muscles in either of two groups in post-test and persistence compared to pre-test(P≥0/05).

Although neuromuscular exercises improves the activity timing of distal muscles and persistence, this improvement does not apply to proximal muscles that play an important role in the lower extremity chain. Therefore, it is suggested that in the rehabilitation of functional ankle instability, use exercises that, in addition to affecting the distal segments, also focus on the proximal muscles to reduce the risk of re-injury.

Functional dysfunction has been reported as one of the most important consequences of functional ankle instability injury. One of the newest tools used to rehabilitate musculoskeletal injuries is suspension training with TRX )Total Body Resistance Exercise(. However, so far, its effect on the various functional factors in athletes with functional ankle instability has not been determined.  Therefore, the purpose of this study was to investigate the effect of 6 weeks of suspension training with TRX on the performance scores of athletes with functional ankle instability.

30 male athletes with functional ankle instability were selected and then randomly assigned into the control and training groups. The subjects were selected by inclusion and exclusion criteria. Subjects' performance was assessed by side hop test, figure 8 test, and three single-leg hop test. The training group performed 18 training sessions of 45 minutes during 6 weeks. During 6 weeks, control group were asked to not perform any special exercise. Then, the post-test was performed in both groups. In order to compare the scores of functional tests between two groups, paired t-test and covariance analysis were used. Significant level was considered as p≤0.05 in all statistical analyzes.

The results of statistical tests showed that there is a significant difference between the mean scores of each of the three side hop test (p=0.001) figure 8 test (p=0.001), and three single-leg hop tests (p=0.001) between the two groups in the post-test. Therefore, that subjects of the TRX training group had better performance in all three tests than those in the control group.

Since the results of this study showed that performing TRX suspension training can improve the performance of athletes in side-hop test, figure 8 test and triple hop test, therefore it recommended that all sport trainers use the exercises used in this study to improve the performance of athletes with functional ankle instability.

Despite of prevalence of ankle sprain, there is not have been enough study about sensory mechanism and change in force pattern of external support, that acting on sensory- motor system (process) and postural control in functional ankle instability (FAI). The aim of this study was to evaluate the immediate effect of lateral heel wedge and soft brace on postural control in FAI and uninjured controls. Subject and

30 individuals with FAI in 2 groups examined with lateral heel wedge and soft brace, and 15 healthy controls participated in this study. Dynamic postural stability with and without external support, was assessed by biodex balance system in level 5.

In FAI individuals, after using lateral heel wedge, significant increase in overall limit of stability (LOS) (p=0.03), and wright LOS (p=0.04) was observed. however there was no significant increase in left LOS after using lateral heel wedge and in LOS indexes after using soft brace.

The results showed that changing in force pattern and decrease of stress on injured tissue after using lateral heel wedge can improve dynamic postural control in subjects with FAI.

The aim of the current study was to investigate the effect of six weeks of hopping training on the dynamic balance of volleyball players with Functional Ankle Instability(FAI). To do so, 30 volleyball players with FAI were selected using Cumberland ankle instability tool (CAIT) questionnaire and then divided into experimental and control groups. Pre-test was performed using drop-landing test on force plate and after six weeks of training on experimental group, the post-test was given.Participants' dynamic stability was evaluated using Time to Stabilization (TTS) index during drop-landing task, as one of the deleterious athletic movements. The participants' TTS were calculated in three directions (Vertical, Medio-lateral, and Antero-posterior) and ANCOVA was used to analyze data (α ‹ 0.05). The results showed that six weeks of hopping training had no significant effects on time to stabilization mean in the vertical (P = 0.513), the medio-lateral (P = 0.369), and the antero-posterior directions (P = 0.999) in both experiment and control groups. The results of the present study may not be compatible with those of the previous studies because of the limitations of the previous tests and methods. Also, given that the participants in our study were elite volleyball players, they may have been kept within a certain range by making compensatory changes in their joints. Therefore, it is suggested that further researches, with regard to the effect of exercises on the joints and muscles, be conducted separately and also in conjunction with each other until the possibility of observing changes in each joint separately is provided and also consideration of compensatory changes in the movements of joints involved in motion is possible

Some individuals, copers, despite of an acute lateral ankle sprain could return to high-level physical activities, without development of functional ankle instability (FAI). Study about differences between copers and FAI groups results in identify factors that cause FAI. The aim of this study was to compare the effect of cognitive demands on dynami postural control in FAI, copers and uninjured controls. 42 individuals in three groups with FAI, copers and uninjured controls participated in this study. Dynamic postural stability with and without cognitive demands, was assessed. Repeated measure ANOVAs was used to determine possible significant interactions for the 2 factors. Interaction of group by cognitive difficulty was significant for Overal stability index (OSI) (P<0.001) and mediolateral stability index (MLSI) (P=0.005). A significant increase in OSI and MLSI observed in FAI group during dual task compared to the single task performance (p<0.05). However, a significant decrease in OSI was demonstrated in copers during dual task condition (p=0.004). The results showed that concurrent performance of cognitive task could effect on postural control after first lateral ankle sprain. responses to cognitive perturbations can consider as an important factor to identify adaptation mechanisms in copers and distinguish between copers and FAI groups.

  It is essential to consider balance as a modifiable risk factor to consequently prevent injury. The aim of the present study was to investigate the effect of six weeks of core stability and hopping exercises on balance among girls with ankle instability. A total of 36 female university students (age 22.08±7.1 year, height 1.61±0.05 m, and weight 58.77±9.89 kg) from among 90 individuals with an ankle instability were objectively selected from Shahid Bahonar University of Kerman and were randomly divided into three groups of 12: the core stability group, the hopping group, and the control group. The CIAT questionnaire was used to select people with ankle instability and the balance was measured using Biodex Balance System before and after six weeks of intervention program (3 times per week with 30 minutes duration per session) in the similar times and condition. The control group did not have any sport activities during this period. The results of mix repeated measure ANOVA test showed that there was a significant difference between core stability and hopping exercises groups in balance (p=0.001). The results also showed that balance was significantly different between pre-test and post-test in core stability group (P=0.000) and in the hopping group (P=0.001). The result of the current study showed that core stability and hopping exercises can be useful training programs for improving balance among girls with ankle instability.

People with functional ankle instability face various complications which entail quick actions via multifaceted and combined exercises. Therefore, the main objective of this semi-experimental research was to determine the effectiveness of the comprehensive combined programs on functional strength of ankle in active men with functional ankle instability.
The subjects of this research were active university men with functional ankle instability (with a mean age and standard deviation of 20.00 ± 3.72 year and mean height of 185.85 ± 8.55 cm), of whom 30 were selected and randomly assigned to experimental and control groups (15 in the control group and 15 in the experimental group ). The experimental group performed eight weeks of combined exercises, mostly neuro-muscular and strength training exercises (using red Tera band), for eight weeks and three sessions per week for one hour. The research variable was the functional strength of the ankle muscles. The instruments for collecting research data were isokinetic biodex system3, and foot ankle inability index questionnaire. To figure out the normality of inputs, Kolmogorov-Smirnov test was used and to compare groups, Covariance test was run and to attain differences within groups, paired t-test was used.
Results showed significant differences before and after the exercise program in the experimental group. However, in the control group these changes were not statistically significant.
The results of the current research showed that combined program can be effective and reliable in improving functional strength of agonist and antagonist muscles.

It is known that one of the most important findings in people with functional ankle instability is change of joint kinematic before ankle's contact during walking, thus it is acceptable that change in joint kinematic can be considered as one of the probable reasons of sprained ankle relapse. Although the mechanic of foot and ankle play a significant role in the occurrence of this injury, it fails to completely expose mechanisms hidden in functional ankle instability. For this reason, today, researchers have suggested that improper variation in neuromuscular control plays a more important role in the occurrence of ankle functional instability. The present article was carried out to review the literature on variation of ankle joint movement pattern and neuromuscular control strategies in individuals with functional ankle instability.
The survey was performed on articles in credible databases such as ProQuest, ScienceDirect, and Pubmed Medline, searching for the terms functional ankle instability, variability, walking gait, neuromuscular control, during 1960 to 2016. A total of 65 articles with direct relevance were selected for the analysis.
Results reported in the studies conducted regarding identification of mechanisms hidden in functional ankle instability suggest disparity between dynamic nonlinear view and linear view. These studies showed that kinematic consideration of this phenomenon cannot, per se, be practical in the occurrence of functional ankle instability due to complexity of neuromuscular control phenomenon and combinatory role of open and close mechanisms. Thus, further investigation is required to study neuromuscular control strategies in people with functional ankle instability.

Appropriate muscle recruitment has a significant role in the stabilization of joints. The aim of this study is to investigate the effects of six weeks Plyometric training on performance and the feed-forward activation of calf muscles in active females with functional ankle instability in single leg drop landing.
Thirty active females with functional ankle instability participated in this quasi-experimental study. The experimental group underwent six weeks of Pi-Yin Hung Plyometric training protocol during the period of 18 sessions. In order to assess the performance, functional tests (lateral hop and multiple hop tests) and ankle joint function assessment tool were used. Electrical activation assessments of peroneus longus, tibialis anterior and gastrocnemius muscles (in single leg drop landing task) were completed in the pre-test and post-test (after six weeks). SPSS Software version 20 was used in order to analyze the data (pFinding: Results revealed that after the implementation of six weeks Plyometric training, multiple hops testing time dropped significantly and lateral hop testing distance had a significant increase.
A significant increase in the feed-forward activation of peroneus longus and medial gastrocnemius was seen (p≤0.05), but there were no significant changes at the feed-forward activation of tibialis anterior (pDiscussion & Plyometric training by changing the feed-forward activation of peroneus longus and medial gastrocnemius muscles, improved lower extremity performance in patients with functional ankle instability and should be incorporated into rehabilitation programs for those with functional ankle instability.

Considering the high prevalence of sprain and ankle instability and subsequent adverse outcomes such as decreased balance and increased postural sway, implementation of preventive measures of injury is necessary. Therefore, the aim of this study was to investigate the effect of eight weeks of resistance training on balance and postural sway of basketball men athletes with functional ankle instability.
This study is quasi-experimental. 24 male basketball players with functional ankle instability participated in this study. After primary screening and identification of eligible athletes with ankle joint functional assessment tool (AJFAT), subjects were divided into the experimental (n = 12) and control group (n = 12). Assessment of postural sway by the force plate and dynamic balance by Y test was conducted. The experimental group did resistance training for eight weeks.
Statistical tests showed that resistance training affected on dynamic balance and postural sway in basketball male athletes with functional ankle instability and significantly reduced their postural sway and increased dynamic balance (p˂0/05).
Add resistance training with weights to rehabilitation programs on men's basketball programs with FAI to ease restrictions caused by this injury such as impairment of balance and postural sway, is recommended.

Functional ankle instability (FAI) as giving away after recurrent sprains is the most common disabling complications of ankle sprain among athletes. The purpose of this study was to compare the effects of core stability exercises and neuro-muscular exercises on dynamic balance and lower limb function of athletes with functional ankle instability.
Material and Hence, 36 athlete women with FAI selected purposively by functional ankle tool questionnaire were assigned randomly to a control group (n=12), core stability group (n=12) and neuromuscular group (n=12). Exercise groups performed 6 weeks of supervised core and neuromuscular training programs for 3 days per week. Before and after performing 6 weeks of core and neuromuscular exercises, dynamic balance, subjective and objective function of participants were assessed respectively by y-balance test, foot and ankle ability measure and 8 hopping test. Gathered data was analyzed by descriptive statistics and MANCOVA test at significant level of p≤0.05.
Research findings showed significant improvement in reach distance in three different directions of the y-balance test in the experimental groups compared with control group (P Six weeks progressive supervised core stability and neuromuscular training programs significantly improved measured dynamic balance and lower limb function of athletes with FAI, but these two different exercise protocols had the same effects in improvement of these mentioned factors in athletes with functional ankle instability.

The purpose of the present study was to evaluate the reliability of persian version of the “Cumberland Ankle Instability Tool (CAIT)” in Iranian athletes with lateral ankle sprain.
Matterials & The present study is a methodological and non-experimental study. After forward and backward translation of CAIT, 46 athletes were selected with convenient nonprobably sampling from Physical Education Faculty of Tehran university and Taekwondo Club. Questionnaire was given to participants who experienced at least one lateral ankle sprain based on doctor’s diagnosis. In the second phase (one week later) the questionnaire was distributed among the participants again to test the reliability of the measured between the two tests. After collecting the data, the test-retest reliability of Persian version of the questionnaire was evaluated by calculating the intraclass correlation coefficient, standard error of measurement, smallest detectable change and Cronbach’s alpha coefficients were calculated to assess the internal consistency of the questionnaire’s items.
Cronbach’s alpha was 0.64, which is close to acceptable level of internal consistency (0.7-0.95). Factor analysis showed that questionnaires’ items can be classified in 4 categories with maximum of 72% variance cover. The test-retest correlation coefficient ICC for the total score of CAIT was 0.95 (P>100.0), indicating excellent reproducibility of the Persian version of the questionnaire. The standard error of measurement (SEM) was 1 and the smallest acceptable change (SDC) was 2.76 with 95% confidence.
The results show that the Persian version of the CAIT can be used in athletes with functional ankle instability as a reliable tool to detect instability and assess changes caused by therapeutic interventions.

Functional ankle instability has described as a “feeling of giving way”. Balance control deficit is one of the sensorimotor impairments observed in people with functional ankle instability that has been described to damage to the afferent receptors within the ligaments and joint capsule that affected during sprain. Foot orthosis can improve balance control via enhanced sensory afferent feedback of plantar surface of the feet and prevent inappropriate moment around the ankle joint. The purpose of this study was to examine the of effect lateral wedge and textured lateral wedge insole on static balance in people with functional ankle instability.
Materials and 20 athletes(mean age: 25.57±4.77 years)with clinically diagnosed unilateral functional ankle instability were recruited. Measurments performed in three conditions by using a kistler force plate(Kistler instrument corp, Amherst, New York USA,version.5060). The mean center-of-pressure excursion and mean velocity in medial-lateral and anterior-posterior directions, area of 95% confidence circle and sway area were assessed as measures of standing balance. The results were statistically analyzed using the nonparametric Friedman test followed by Wilcoxon Signed Rank.
Foot orthoses resulted in decrease mean total and anterior-posterior COP excursion, %95 confidence circle area and increase mean medial-lateral COP excursion, mean COP velocity in medial-lateral direction and area sway, but these changes were not statistically significant.
Foot orthoses had no significant effect on postural stability in patients with functional ankle instability.