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Background and aim: Muscles are involved in complex and three dimensional activities. Timing and response to onset of external trigger need to perception and processing of data in central nervous system. The propose of this study is to determine reaction time, pre motor time and motor time with and without external load in healthy subjects. 

Material and methods: Twenty healthy subjects contributed in this study. Isoinertial dynamometer was used to assess complicated motions in sagital, frontal and transverse planes from full flexion, rotation and lateral flexion to right side to opposite direction inclusive full extension, rotation and lateral flexion to left side without and with 25 and 50% MVE. Reaction time, pre motor time, motor time, and maximum torque were also measured.

Results: Following combined motions,  reaction time and pre motor time were increased by external load (25 and 50% MVE). Lateral flexion showed more changes than extension (P<0.001). By increasing load, particularly in extension time and maximum torque were changed (P<0.001).

 Conclusion: Reaction time and pre motor time in combined motions are affected under extension and lateral flexion motions. Rotation has less effect on combined motions. Motions occur in sagital and frontal plane more than transverse plane. 

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Background and aim: Swallowing disorder is one of the most important complaints of patients with upper motor neuron lesions.The rate of disphagia increases due to elderly subjects and brain injuries in our society Majority of these patients have hidden aspiration. Electromyographic assessment of swallowing can produce indicators of recovery and treatment effectiveness. This study tries to indicate pattern and recruitment of muscle activity in swallowing by surface electromyography.
Methods and Materials: Twenty healthy subjects (20-50) and ten subjects with swallowing dysfunction contribute at this study. Activities of bilateral orbicularis oris, buccinator, sternocleidomastoid and anterior region of throat muscles recorded during three stage of liquid swallowing include water, juice and honey by surface electrodes. Value of activity (RMS), duration of activity (Dur) , median (Mdf) and band (Banf) frequency of above muscles were measured.
Results: Healthy subjects indicated increase of RMS, Dur, Mdf and Banf of muscles, following increase of sweeten and viscose of liquid (P<0.05). Patients had more increase of this findings at oral muscles markedly, whereas Dur of throat muscle showed more increase in time (P<0.05). Comparison of between two groups indicated patients have more Dur time especially at throat muscles (P<0.05) and in contras reduce of activities and frequency parameters than healthy subjects (P<0.05).
Conclusion: Patients lean to keep liquid in oral phase and during throat swallow have more limitation. Patients may catch early fatigue and dysfunction for maintenance and keep of liquid particularly in throat region and it redound to change of trajectory of liquid to the respiratory tube. Therefore, rehabilitation protocols must enforce on coordination of oropharengeal muscles and recovery by movement therapy patterns.

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Background and Aim: in hemiplegic children Postural tone of the two sides of body is different. Once, asymmetric stance is a typical state in individuals' with unilateral pain and/or paresis and standing is with weight bearing on the stronger side. Obviously, an asymmetric stance with majority of weight bearing on the affected side can counter faces individual with the falling risk and causes instability. It seems coordinating of the two sides of body is the most vitally important therapeutic exercises in hemiplegic patients. Although stable stance is a simple postural task but it's controlled semi-automatically by cortical and spinal centers. It is established that stable standing, also demands cognition resources. So, postural control demands the interaction between musculoskeletal and nervous systems.
Material and method: In this clinical trial (before-after) 17 children 5-12 years old with spastic hemiplegia were participated. The subjects stayed in the center of force plate with the most stable standing position while using /not-using lateral wedge and in each state with/without doing cognition task. Short- memory test of digit span used as dual task condition. The mean range of fore-after and mediolateral sway and velocity and area as postural control independent variables and error measures in recalling of randomized digit chain as cognition task independent variables were registered.
Results: The wedge affected Rsw (P=0.015), Area (P=0.007) and Vm (P=0.005) significantly. Dual task also had significant effect on Rfa (P=0.014), Rsw (P=0.014), Area (P=0.002) and Vm (P=0.002). But the wedge declines its effect properly.
Conclusion: The results represent that a 5º lateral wedge applied to the unaffected limb, can improve factors of postural control even in Dual tasking thus The wedge can be used with a good effect on the posture of hemiplegic children.

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Background and Aim: Neck pain is one of the common diseases (66.7%), which contains different age's groups such as youn. Results of researches indicate prevalence of women neck pain is higher than men, so experiment in neck disease in female is more necessary. The aim of this study is to evaluate changes of postural stability in patient with muscular neck pain. 

Materials & Methods: Twenty patients and fifteen healthy subjects contribute in this study.  Postural sway in quiet standing was assessed in both limb stance (BLS), one limb stance (OLS) of dominant side, on a force platform with open eyes (rigid-open) and standing on a force platform with closed eyes (rigid-closed) and standing on the foam (10.5 cm-thick) with open eyes (foam-open) without shoes. All of above conditions were done with dual task. Mean changes of logarithmic displacement in medial-lateral and for- aft directions were calculated.

 Results: There are significant differences between two groups, especially following dual task, and difficult conditions of OLS and standing on the foam.

 Conclusion: Patients with neck pain have difficultly in postural control that need to attending in treatment and prevention of following damages.

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Background and aim: Knee osteoarthritis is one of the most common musculoskeletal problems, can affect on patient's daily activity and produce dependency in their daily activity and functional disability The aim of present study is to compare static balance in patients with knee osteoarthritis and healthy subjects using force plate. 

Materials & Methods: Postural stability in knee OA patients and healthy subjects (each group 20 subjects) were measured by force plate. Two positions were selected double stance with closed or opened eyes. Range of fore/aft (Rfa) and Range of side ways (Rsw), were measured as static postural stability.

Results: Rsw increased significantly in the double stance position in patients group (P<0.05). Also in both groups, Rsw and Rfa in the double stance with closed eyes were more than of open eyes position (P<0.05).

Conclusion: Postural control deficits and increase of center of pressure's sway were identified in participants with knee osteoarthritis. Therefore, one of the most important goals of rehabilitation is to improve balance control in knee OA patients.

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Background and Aim: Biomechanical conditions of limbs can affect on motor unit recruitment (MUR) markedly. Surface Electromyography (SEMG) is an approach for evaluation of muscle activities and onset time during different functions. The purpose of this study is to use SEMG for detection of central motor control in different functions of knee extensor muscles.

Materials and Methods: Ten healthy subjects contributed in this study. They were done five repetitions of knee flexion/extension in open and close chain separately during recording of SEMG simultaneously. Integrated EMG (iEMG) of three middle repeated cycles were detected according to chain (open- close) and kind of contraction (concentric- eccentric).then the Average of three slope of iEMG compared to each other. 

Results: There were not significant differences in MUR of three extensor muscles for concentric and eccentric contractions in open chain but vastus medialis and lateralis muscles showed significant changes in close chain (P<0.05). Result showed that there were significant differences of MUR for two kind of muscle contractions between open and close chains (P<0.05).  

Conclusion: Recruitment of motor units has not shown difference in open chain between concentric and eccentric contractions. This process indicates representative similarity of control pattern in two kind of contraction in open chain. Concentric contraction at close chain cycle has more MUR in comparison with eccentric contraction. It is equal to more interference of contractible compartment in concentric to eccentric contraction. This happens due to the nature of two kind of contraction particularly in close chain cycle. Comparison between two chains indicated that more motor units contribute in close chain (concentric and eccentric). It means that motor unit recruitment increased due to effect of increase of load in close chain. 

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Background and aim: Spinal injury especially during occupational lifting is one of the most common neuromuscular disorders in the general population of the world. Asymmetric motions of trunk frequent bending and twisting, lifting and forceful activities contribute to spine disorders. Sport as a comprehensive activity might be able to cause less force to the spine and decrease spinal injuries. The purpose of present study was to determine the effect of lifting on motor control pattern during combined symmetric and asymmetric trunk motions on athlete and non-athlete subjects.
Materials and Methods: Seventeen non-athlete female subjects and seventeen athlete female subjects performed to lift four loads ( 5,7,9 ,12 kilogram ) at symmetric and asymmetric conditions. Under each condition temporal parameters of motor control were measured on flexor and extensor of trunk muscles.
Result: In two groups of athletes and non-athletes with increasing load , muscles begin their activity faster ( P<0.05 ). No significant change was found at asymmetric condition. Also, in athletes premotor time of muscles during lifting was less than non-athletes.
Conclusion: With increasing load, according to the feed forward control mechanism and awareness of subjects from amount of loads, muscles quickly prepared to contract for starting the movement. It seems that the response of movement on the neuromotor system of athletes is preprogrammed and automatic due to sport experience. Actually muscles have anticipation activity.

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Background and aim: Cognition of fatigue effects on motion response can improve treatment approaches. Determination of mechanism (maximal voluntary contraction and repetition of movement) that cause change of central responses and neuromuscular transmission have specific emphasis in evaluation and treatment of patients. Following fatigue it is arguable which is more important, neural or osteo-ligamental components. Behavior of para spinal muscles due to their roles in control of posture and spinal alignments are more importance. Gesture and motion pattern of neck and lumbar column following fatigue is due to accession of disorder in neuromuscular junction (NMJ) or limitation in reflex response at this system. Reflex influence is not just for muscle fatigue but also it appeared in synergic muscles. It is clear that stimuli and inhibitory ways have important role in this process.
Materials and Methods: Twenty normal subjects (10 female and 10 male) contributed in this study. Tests were including: 1- Training and warm up 2- Placement of recording electrodes on neck extensor muscles at second and forth spinal vertebra of dominant side. 3- Five motion of neck flexion and extension in sitting position at full range without external load. 4- Fatigue test, contain A- Maximal isometric contraction at middle range about 3 minute, which were controlled by a dynamometer until onset of fatigue. B- Fifty dynamic and cyclic motions of neck flexion and extension in full range of it. 5- Perform five motions similar stage 3 immediately after muscle fatigue. Three middle cycles were chosen for evaluation. Degree of off activities in flexion, degree of onset of activities in extension, silent period and mean of muscles activities (RMS), before and after fatigue selected for analysis.
Results: Comparison of two type of fatigue indicated that there are significant differences between them. Range of motion and eccentric activity were similar for two conditions. Isometric fatigue showed more effect than cyclic condition.
Conclusion: In neck motions flexion relaxation occurred. Dynamic motion and isometric activities caused muscle fatigue and changed silent period. This period reduced and it means that onset of extensor muscle activities occurred very soon and moved to middle and outer ranges. In this manner, naught privilege mechanical of non contractile elements in neck region is cause of this reduction. On the other hand extensor muscles have more responsibility for control and preservation of posture. Comparison of two approaches indicated that isometric activity produce more fatigue and spectral indexes such as median and mean frequency reduced markedly.

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Background and Aim: Cerebral palsy (CP) is the most common motor impairment in childhood and affects 2 in 1000 live births, in which postural and motor control involved. In hemiplegic type, two sides of the body have differences in postural tone that cause weight shift to the intact side. In these children postural disorders appear as postural stability disorder. The aim of this study is to assess the effect of lateral wedge insole on postural control in cerebral palsy children.
Materials and Methods:  Sixteen hemiplegic children attended in this program and stood in two conditions on the force plate with and without lateral wedge on the hard plate. Center of pressure displacement measured for medio-lateral and antro-posterio directions. Every test took 20 seconds. It was repeated 3 times.
Results: Range of sideways decreased significantly with use of 5º wedge. Also a shoe wedge of 5º provided symmetrical weight distribution.
Conclusion: The results represent that a 5º lateral wedge applied to the unaffected limb, can improve factors of postural control and gain the symmetry in hemiplegic children

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Background and aim: Altered muscle activity in the scapulothoracic and glenohumeral muscles is commonly believed to be a factor contributing to shoulder impingement syndrome (SIS), then, the aim of the study was to determine and compare the activity pattern of the shoulder muscles in subjects with and without SIS.
Materials & Methods: In this case-control study, 9 female subjects with shoulder impingement syndrome and 13 matched healthy female subjects were participated voluntarily by simple random sampling. Surface electromyography of serratus anterior, pectoralis major, upper trapezium, lower trapezium, posterior deltoid, anterior deltoid muscles of dominant side were recorded during D1ext and D1flex movement. Muscle activities were processed and compared in subjects with and without SIS. Non parametric test (Mann-Whitney Test)) was used for data analysis
Results: In both movement patterns, all muscles of the patient showed a greater normalized RMS than healthy group but this increase was statistically significant in anterior deltoid (p=0/003, p=0/04), pectoralis major (p=0/01, p=0/02), serratus anterior (p=0/01) and posterior deltoid (p=0/01) during D1ext and in lower trapezium (p=0/005,p=0/006) and pectoralis major (p=0/01) during D1flex.
Conclusion: The results of this study indicate that patients with impingement symptoms show abnormal muscle activity. The findings support the theory that shoulders impingement may be related to altered muscle activity in the scapulothoracic and glenohumeral muscles.

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Background and aim: Knee joint has a major role in various lower extremity activities. Among different elements of knee joint complex more interest was seen to anterior cruciate ligament because of its alignment, structural complications, more nerve receptors and susceptibility to injury. After injury of this ligament, knee extensor torque decreases but it is believed that this decrease compensated for by muscles of hip and ankle joints. This suggestion has not investigated by isokinetic studies. Therefore, the aim of this research was that if quadriceps muscle torque decreases in spite of rehabilitation process and if this decrease compensated for by hip extensors and ankle plantar flexors?

Materials and methods: 10 healthy men (age: 22-35 years old) and 10 patients with ACL deficiency (age: 23-42 years old) participated in this study. Plantar flexor muscle strength, quadriceps muscle strength and hip extensor muscle strength were tested by Isokinetic Biodex System 3 at 60 and 180 degrees of angular velocities. Also functional vertical jump test was done for each lower extremity.
Results: Will coxson test and Spearman correlation coefficient were used. Results showed that there was no significant difference between mean strength of gastrosoleus, hip extensors and sum of mean strength of gastrosoleus, quadriceps and hip extensors of patient's injured and sound limbs (P>0.05). Results showed that there was significant difference between mean strength of quadriceps of injured and sound limbs (P> 0.01). There was no relationship between gastrosoleus, quadriceps and hip extensor summation and vertical jump functional test in the patients and normal subjects (P>0.05).
Conclusion: The results show that compensation occurs in the ankle plantar flexors and hip extensors of injured lower extremity. Thus in spite of significant decrease in quadriceps strength in the injured limb, sum of mean strength of gastrosoleus, quadriceps and hip extensor muscles between injured and sound limbs was not statistically significant. Also there was no relationship between functional test and isokinetic parameters. Thus functional vertical jump test can not be used instead of isokinetic test.

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Backgroung and aim: Neck pain is one of three common complains of neuromuscular system. There are three subsystem to maintain stability of spine: passive subsystem, active (muscles) subsystem and control subsystem. Detection of postural muscle response during postural perturbation like fast arm movement can be utilized to analyse of postural control. Wearing cervical collars is a way to prevent or cure cervical pain. The aim of the present study was to investigate the effect of soft cervical collar on movement response and duration of activity and recruitment pattern of cervical muscles. 

Materials and methods: Twenty healthy young women participated in this study. They flex right shoulder in response to sound stimulus with and without wearing soft cervical collar. Surface Electromyography (EMG) used to assess postural muscle activity in following muscles: Deltoid , Trapezius , Cervical Erector spinae and  Sternocleidomastoid. The effect of soft cervical collar on reaction time, onset and duration of activity of cervical muscles was calculated.

Results: Wearing soft cervical collar increased reaction time of arm flexion  (P< 0.05) and decreased duration of activity of cervical extensor, trapezius and erector spinae (P< 0.05). During shoulder flexion with additional load, onset activity of trapezius muscle was significantly earlier than other neck muscles but cervical erector spinae and sternocleidomastoid exhibit coactivation pattern in response to perturbation .

Conclusion: During fast arm movement that leads to postural perturbation, soft cervical collar alleviates the response and reduce activity of muscles. The strategy of motor control centers in response to perturbation in cervical spine is coactivation of flexor and extensor muscles to maintain stability. 

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Background and Aim: In spite of massive knowledge increase and ergonomic correction, lumbar disorders extremely prevail in working environments. Efforts have been made in order to decrease prevalence of musculoskeletal disorders caused by lifting, carrying and pulling down objects by using some belts. The purpose of this research is to determine the effect of lumbo-pelvic belt in symmetrical load lifting on one of motor control indexes.
Materials and Methods: In this research twenty men were asked to lift objects with different weights of 5.5, 7.5, 9.5 and 12.5 kg in position of complete trunk and hips flexion and knees extension using and not using belt and put them on the target desk. Surface Electromyography has been recorded from two pairs of back muscles and three of abdominal muscles. 
Results: Lifting different loads with belt showed significant increase in symmetrical index (p<0.05). 
Conclusion:  Using belt brings about more coordination in trunk agonist and antagonist muscles activity while lifting the loads.  

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Background and Aim: Muscle fatigue is a factor that caused muscle injuries. Ability to perform movement without error and controllability has important role in reduction of injuries. Reproduce ability of motion is reduced after muscle fatigue. Evaluation of motor control can produce suitable conditions for assessment of these changes and help us treatment guide lines for prevention of injuries. The aim of this study was to evaluate motor control changes following onset of fatigue in patients with anterior knee pain as a physiological aspect.
Materials and Methods: Fifteen voluntary female (10 healthy, 5 patients with bilateral syndromes) participated in this study. During dynamic fatigue test (open and closed chain movements), muscle activities were recorded from bilateral vastus medialis, vastus lateralis and rectus femoris (20 healthy and 10 patients quadriceps muscles) by surface electromyography (sEMG). Five dynamic cycles of motions were selected before and immediately after fatigue and then average of three middle cycles were compared for Symmetry Index (SI) as motor control assessment.  Also Median Frequency (MDF) were computed as an indicator for onset of fatigue. 
Results: MDF reduced significantly in both groups. This reduction was markedly showed in patients group. Reduction of SI was significant after fatigue test. Comparison of SI between groups indicated that before fatigue there was significant difference but after fatigue test was not significant.  
Conclusion: Dynamic motions can produce muscle fatigue and reduction of MDF. High central control system used different synergies following pain and functional impairment. Synergy patterns change after dynamic motions fatigue and cause reduction of SI. This change is dependent to pain and functional impairment and has not a stable pattern. 

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Background and Aim: Whole Body Vibration (WBV), as a new exercise modality, can improve neuromuscular performance but, there is no study to assess the effects of WBV on the reaction time as an indicator of muscular performance especially in upper extremity muscles. Therefore, the aim of the present study is to investigate the immediate effects of WBV on timing parameters of upper extremity muscles. 

Materials and Methods: Forty healthy young women were randomly assigned in two groups of intervention (with WBV) and control (without WBV). In the intervention group, timing parameters (Reaction time (RT), Premotor time (PMT), Motor time (MT)) were measured by using EMG before and after the vibration (5 sets of 30seconds at 5 mm amplitude and 30 Hz frequency) session. The same protocol but without vibration was used for control group.

Results: Whole body vibration did not alter the RT significantly (P=0.253). Premotor time was increased significantly only in the triceps muscle (P=0.006). There was also a significant difference (P=0.003) in MT of the serattus anterior muscle between two groups.

Conclusion: It seems that WBV can induce different effects on upper extremity muscles. Whole body vibration has not any significant effects on the total RT 

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Background and Aim: Forces which applied to ankle joint for control of stability can cause damage to joint if it does not have suitable control. Chronic ankle instability (CAI) is a current disability that can affect on activity daily living of the patients. The aim of this study is to evaluate forces which contribute to control of posture in difficult conditions.

Material and Methods: Postural control was measured by force plate in two groups of CAI and healthy subjects. Eight positions were selected , including of double stances with closed or opened eyes, and single stances with opened eyes (right/ left) with and without a cognitive task. Force changes in two direction medial/lateral and anterior/posterior were evaluated with fractal time series analysis.

Results: Fractal dimension of force in two groups, following dual task in all of conditions reduced significantly (P<0.05). There was not significant different between two groups in double stance with or without dual task. Single stance in patients indicated significant increase of fractal dimension in affected ankle joint (P<0.05) but comparison of two side in healthy subjects did not have difference. Also there was significant increase of fractal in affected ankle joint of patients in comparison with similar side of healthy subjects (P<0.05).

Conclusion: Patients with (CAI) have a problem in regulation of force for control of posture. This difficulty increased and clearly indicated by dual task condition, which can cause susceptible qualifications for recurrent injuries. Fractal dimension is a suitable factor for analysis of control of posture in difficult situations.

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Background and aim: Various studies indicate that background noise affects speech recognition ability of bilingual listeners (BL) more than monolingual ones (ML). However, no study has engaged in the speech recognition performance of Turkish-Persian bilinguals in the background noise. The purpose of the present study was to compare word recognition scores (WRSs) in the continuous and interrupted noises among ML Persian and BL Turkish-Persian young adults.

Material and methods: The cross- sectional analytical study was conducted by presenting speech stimuli in quiet and in the background continuous and interrupted noises at signal to noise ratios (SNRs) of -20, -10, 0, +10 dB. Two groups of 33 ML Persian and 36 BL Turkish- Persian subjects with age ranging from eighteen to twenty-five years old participated   

 Results: The degree of reduction in WRSs was significantly higher in the continuous noise relative to the interrupted one at four studied SNRs (p<0.0001) Moreover, the difference between WRSs of ML Persian and BL Turkish-Persian groups in the presence of both continuous (p≤0.001) and interrupted (p=0.002) noises was significant.

Conclusion: It seems that Persian-words recognition ability of Turkish-Persian BLs reduces more than Persian MLs in the background noises and continuous noise affects speech perception ability more than interrupted one. 

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Background and Aim: Anterior knee pain (AKP or AnKP) is one of the most common disorders of knee. Many studies have been implemented about anterior knee pain and effect of different treatments on this disorder. Todays, this general term has been divided and studied more closely. Knee extension syndrome is one of the common disorders in orthopedic and physical therapy that diagnosed with increased stiffness of quadriceps muscle and causes anterior knee pain. The purpose of this review article is to evaluate this disorder more closely.

Materials and Methods: A literature search was carried out using MEDLINE and SCIENCE DIRECT cite and JOSPT journal database to assess existing literature about anterior knee pain. Furthermore, literatures about the different standpoints of anterior knee pain and effectiveness of different treatments and interventions of anterior knee pain and knee extension syndrome have been identified.

 Results: Fifty articles have been surveyed: forty-two articles evaluated the effect of different treatments on anterior knee pain. Five articles evaluated the various aspects of anterior knee pain more closely and three ones related to knee extension syndrome.

Conclusion: According to these studies results, the causes of anterior knee pain can be classified in two categories: 1) anterior knee pain associated with patellofemoral disorders and 2) anterior knee pain non-associated with patellofemoral disorders. The knee extension syndrome is the cause for anterior knee pain but non-associated with patellofemoral disorders. In this disorder, the tilt angle of patella could be increased and this factor can increase the patients' pain. In contrast to general belief that focuses on tensor fascia lata- ilotiobial band complex (TFL-ITB complex), the rectus femoris muscle stretching should be focused more, because the ilotiobial band has a less effect on patellar tilt. 

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 Background and Aim: The translation, cultural adaptation and validation of the Persian version of the American shoulder and elbow surgeons (ASES) were carried out in accordance with published guidelines.

Materials and Methods: The study was conducted on 100 athletes (25.96±5.81 years), which suffered from different shoulder disorders. When the translation and cultural adaptation of the original questionnaire was carried out on the standardized method, the participants were asked to complete a questionnaire booklet including the DASH, the Short Form General Health Survey (SF-36) and ASES questionnaires. In addition, 30 randomly selected patients were asked to complete the ASES questionnaire 48 hours later for the second time. After data collection the Statistical analysis was performed by using SPSS software.

Results: The Cronbach's alpha was used to indicate internal consistency. Cronbach's alpha was 0.91 for ASES. Test-retest reliability was quantified by use of the intraclass correlation coefficient. It was 0.91 for ASES questionnaire. The Pearson Correlation Coefficient was used for the questionnaire validation study. The DASH questionnaire showed high correlation of ICC=0.78 with ASES. The ASES showed moderate correlation of 0.48 to 0.62 with those of the various scales of the SF-36.

Conclusion: The Iranian ASES showed good reliability and validity and can be used for shoulder-specific patient self-assessment.

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Background and Aim: Knee osteoarthritis is one of the most common musculoskeletal problems that can affect activity daily living of patients. Many studies have indicated postural control deficits in these patients but the effect of dual tasking on postural control has not been examined yet. The aim of this study is to investigat the effect of cognitive task on postural control in the female patients with knee osteoarthritis.
Materials and Methods: Postural stability in knee OA patients and healthy subjects (20 subjects in each group ) in four positions was measured using the Force plate. Positions included double leg stance with closed or opened eyes with and without cognitive task. Area of COP and mean velocity (Vm) were measured for as static postural stability.
Results: Area under the curve increased in the double leg stance position in the patients significantly (P<0.05). While mean velocity decreased by performing a dual task (P<0.05). The response to dual-tasking was not significant between the 2 groups(P>0.05).
Conclusion: Postural control deficits and increased of center of pressure’s sway were identified in participants with Knee osteoarthritis. Also performance of a cognitive task resulted in decrease of postural sway, but the dual- tasking did not change the postural performance of knee OA patients compared to healthy subjects.