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Background and aim:The knee joint is one of the most important joints of human body, witch tolerates many forces while the subject is standing up or walking especially during close chain and squat positions.

Muscle fatigue may causes some modifications on effects of forces and accordingly some changes on strategy of movement, therefore the concentration in thigh muscles impression on continuous movements is a guidance that makes the investigation on these changes so important.

Materials and Methods: Fifteen healthy women in the range of 20-30 years were contributed in this study. Muscle fatigue were applied in separate sessions by maximal voluntary contraction (MVC) in both open and close chains.

Subjects were done five dynamic repetitions of flexion / extension motion of knee before and after fatigue tests. Surface electromyography (sEMG) recorded from vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) muscles during all conditions of tests. Normalized electromyography (NEMG) of muscles activities in two conditions of concentric (Con) and eccentric (Ecc), also median frequency (MF) were calculated for fatigue index. Muscle timing or recruitment pattern indicated by onset of muscle activities for both dynamics chains.

Results:  There are significant different of fatigue indexes between before and after fatigue tests (p<0.05).  After fatigue muscle timing delayed in open chain (p<0.05) and recruitment patterns changed from VL- VM- RF to VL-RF-VM. Fatigue test in close chain caused increment of muscle timing (p<0.05), but it did not change recruitment patterns.

Conclusion: After fatigue tests MF reduced little than NEMG. Significant difference occurred in muscle timing. These variations were increase and delay of timing with change of recruitment in open chain. These findings suggest that motor control strategy is will change at different condirions of with and without load situations.

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Background and aim: Chronic ankle instability (CAI) is a current disability that can affect on activity daily living of the patients. Many studies have indicated postural control deficits in these patients but the effect of a dual task on postural control has not been examined yet.

Materials and methods: Postural stability in CAI patients and healthy subjects was measured using the Force Plate. Eight positions concluded two different stances (double & single) with closed or opened eyes. All positions concurrently were done with a cognitive task. Anterior/posterior (Rfa) and medial/lateral (Rsw) mean sway quantified static postural stability.

Results: Mean sway significantly increased in patients in the anterior/posterior (single and double leg stance) and medial/lateral (single leg stance) directions (P<0.05). While performing a dual task anterior/posterior mean sway decreases within the patients group on the impaired leg stance (P<0.05). No difference is seen in the healthy subjects.

Conclusion: Postural control deficits were identified in participants with chronic ankle instability. In view of the fact that a cognitive task resulted in decreasing displacement of center of pressure in patients, this method may identify as an examination and a plan of treatment for affecting on ankle stabilizing factors.

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Background and aim: Asymmetric motions of trunk, external forces and other occupational factors such as frequent bending and twisting, lifting and forceful movement contribute to low back disorders. However, the dynamic and three-Dimensional motions of trunk at varying exertion levels were not addressed in literature. Hence, the aim of this study was to investigate the movement pattern and motor output during resisted trunk three-dimensional motion. 

Materials and Methods: Thirty healthy male subjects randomly performed dynamic asymmetric trunk motion at four resistance levels (nominal resistance, 25%, 50%, and 75% maximal voluntary contraction (MVC) torque) while positioned in standing with the L5-S1 interspinous space aligned with the flexion / extension axis of isostation B200. Under each resistance condition, movement patterns (range of motion), motor output (maximum torque) of the trunk were measured.

Results: In general, with increasing resistance from nominal to 75% MVC torque, the maximum torque of trunk in different directions of motion (flexion, extension, right & left lateral flexion, right & left rotation) increased significantly (p= 0.000). With increasing resistance from nominal to 50%  MVC torque, the range of motion of the trunk decreased significant (p<0.0083), but no significant change was found in this variable between resistance conditions of 50% and 75% MVC torque (p>0.0083).

Conclusion: When the resistance level is increased , the created external forces  must be balanced by internal forces generated by trunk muscles. Because the muscles have short lever arms compared with the external forces, they must generate large amounts of forces, placing compressive and shear loads on the structures of the spine. Under these conditions, spine injuries may be enhanced.

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Background and aim: Belts and back supports are frequently used to prevent low back pain. Despite many studies, there are not sufficient evidence and conclusive consensus about the effects of these supports. The purpose of the present study was to determine the effect of lumbosacral supports on motor control pattern during combined trunk motion.

Materials and Methods: 30 healthy young men were selected for the study. Temporal parameters of motor control and activity level of three pairs of trunk muscles were measured during combined trunk motion against minimum resistance and resistance equal to 50% of maximal isometric strength, under with and without back support conditions.

Results: By application of a lumbosacral support, movement response time was significantly decreased under minimum resistance (P=0/004). Application of support decreased reaction time and motor time under two resistance conditions significantly (P<0/05). No significant changes were found in trunk muscle activity levels following wearing a back support (P>0/05).

 Conclusion: By application of a lumbosacral support, individual reaction time was decreased. Although back support did not change the trunk muscle activity level, but the erector spinae muscle efficiency was increased to initiate desired movement.

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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: 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: Few studies have assessed the reliability of postural balance measures during dynamic balance performance that introduce additional challenging to postural control system. In addition sometimes in the static conditions some deficiencies of the postural control system may not be revealed obviously therefore the aim of this study was to assess the reliability of postural control parameters during functional performance on force plate in healthy subjects.
Materials and Methods:  Ten healthy male subjects (mean age: 25.4 years, weight: 68.2 kg height:176.9cm) participated  in this study. None of the subjects were involved in sport activities. Every subject performed three 15seconds trials of eyes open single leg stance on a force plate during dynamic balance task. Participants grasped object with hand at their waist level and release it at above shoulder level.  The reproducibility of the center of pressure (COP) deviations (average speed &length of path) was assessed. All participants were tested on 2 sessions with an inter-measurement interval of 7 days. COP data was collected for each trial. The intraclass correlation coefficient (ICC) was used as parameter of intra-session and inter-session (Test-Retest) reliability.
Results: The ICCs for intra-session reliability of average speed and length of COP path were  0.89 and 0.91  respectively. The ICCs for inter-session reliability were 0.95 and 0.96 respectively.
Conclusion: The study showed high and very high reliability for center of pressure measures during dynamic balance task. Therefore this dynamic performance can be used as a balance pattern in postural control assessment. These can be used as reliable parameters in dynamic postural control assessment due to high reliability of average speed and length of COP path

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Background and aim: The importance of cognitive resources was shown in dual task studies of postural control. However, there was no definite evidence on how verbal instructions influence the allocation of attention to postural control. Therefore, the objective of this study is to explore the effect of verbal instructions on postural performance.
Materials and Methods: this Cross-sectional study was performed in 20 young adults (23.95 ± 3.31). Parallel standing/ hard surface, parallel standing/ foam surface, tandem standing/ hard surface were used as postural tasks and the choice reaction time task were conducted as cognitive task. Dual- task performance was measured under three different instructions including to pay attention to cognitive task, to postural task, and equal attention to both tasks.
Results: Comparing the performance of postural tasks under three different instructions were conducted by One-way ANOVA and showed in parallel standing on hard surface (p=0.831), parallel standing on foam (p=0.433), tandem standing on hard surface (p=0.912) for path length of COP and instructions in parallel standing on hard surface (p=0.308), parallel standing on foam (p=0.414), tandem standing on hard surface (p=0.867) for mean velocity were not significant. Postural performance in single and dual task conditions was significant only in parallel standing/ foam surface (p=0.046).
Conclusion: various instructions could not influence the amount of attention allocated to automatic postural tasks.

 

 

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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: 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: 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.

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Background and Aim: Accurate control of movement is one of the multiple components in skillful motor performance that can be impaired by disease. Trackingtests quantify the effects oftreatments designed toimprovecontrol of movement and they are considered as anideal protocol forimproving motor control. The purpose of the present study was to examine reliability of the control error during target tracking tasks in trunk region in sagittal transverse torque plane in healthy subjects.

Materials and Methods: Nine healthy subjects (4 females and 5 males) randomly performed target tracking tasks at levels of 0% to 80% Maximum Voluntary Exertions (MVE) and twelve different directions (0 ̊, 30 ̊, 60 ̊, …, 330 ̊) twice in upright standing posture. In this study, the tracking system included a moving target circle, which moved on a straight line in specific direction from 0 to 80% of individual MVE with speed of 6% MVE/S.The direction of isometric trunk exertion was presented to participants in the online visual feedback by a computer monitor positioned in front of them. Trunk controllability was determined by computing the control errors (Absolute Value Error from the Target [AVET], Error from the Target Path [ETP] and Error from the Target in the Target Path [ETTP]) during each performance. Relative reliability (Intra-class Correlation Coefficient [ICC]) of the control error in each direction was determined. Also absolute reliability (Standard Error of Measurement [SEM]) and Minimal Detected Change (MDC95) were computed.

Results:The results have shown that ICC for AVET, ETP and ETTP ranged from 0.81 to 0.99, 0.71 to 0.98 and 0.7 to 0.99, respectively. Also SEM for these variables ranged between 0.003- 0.013, 0.001- 0.009 and 0.003- 0.011, respectively and finally MDC95 ranged between 0.008 to 0.036 for AVET, 0.003 to 0.025 for ETP and 0.008 to 0.03 for ETTP.

Conclusion: The study showed high and very high reliability for control error measures during target tracking tasks in sagittal transverse torque plane in asymptomatic subjects. Therefore this performance may be used as a test in trunk controllability assessment.

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Abstract

 Background and Aim: Regard with the importance of balance in daily activities especially in sport activities and understanding the important factor affecting it, the purpose of this study was to compare the role of vision system on dynamic postural stability of young women with men elite athletes.

Materials and Methods: Twenty six young women and men elite swimmer were chosen from the available society. They were divided in two groups according to body mass index. Each subject performed postural stability tests for 6 trials with open and close eyes (3 trials with open and 3 trial with close eyes) that each trial was taken for 30 seconds and with 10 seconds rest between each of them. Balance index in anterior- posterior and medial- lateral directions were calculated and independent t test was used to compare between groups.

Result: Results show that men swimmer are more depended to vision than women swimmer in maintaining retrieval postural stability (p= 0.001), while most impairment in maintaining postural stability in both groups occur in lack of vision status in anterior- posterior direction (p= 0.001).

 Conclusion: The findings of this study can be used to design training programs to prepare athletes.

Key words: balance, vision, athlete, control

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Background and Aim: The target tracking tests is a known method to quantify the performance of the neuromuscular system. It has been used in several studies for evaluation of neuromuscular control strategies. The purpose of the present study was to examine the effect of direction and speed of isometric trunk exertion on the trunk controllability during the target tracking tests in sagittal versus axial rotation torque plane.

  

Materials and Methods: Twenty- two healthy subjects (13 female and 9 male) randomly performed target tracking tasks at levels of 0% to 80% Maximum Voluntary Exertions (MVE) and seven different directions (0 ̊ , 30 ̊ , 60 ̊ , …, 180 ̊ ) in upright standing posture. In this study, the tracking system included a moving target circle, which moved on a straight line in specific direction from 0 to 80% of individual MVE with speed of 5, 6 and 7% MVE/s . The d irection of isometric trunk exertion was presented to participants in the real time visual feedback by a computer monitor positioned in front of them. Trunk controllability was determined by computing the control errors (Absolute Value Error from the Target [AVET], Error from the Target Path [ETP] and Error from the Target in the Target Path [ETTP]) during each performance. Analysis of variance was used to test the effect of speed and direction of isometric trunk exertion on trunk controllability.

  

Results: The results have shown that the direction of isometric trunk exertion had significant effect on the AVET and ETTP (p= 0.000) while the effect of speed and interaction between direction and speed were not significant. The error decomposition in to two independent parts showed that the only direction of exertion on ETTP was significant (p= 0.000) and speed of exertion on any of them ( ETP and ETTP ) was not significant. On the other hand, Borg scale (a simple method of rating perceived exertion) significantly affected by direction (p= 0.000) and speed (p= 0.000) of exertion during the target tracking tests.

  

Conclusion: According to the findings of the current study, the effect of d irection of isometric trunk exertion on the controllability was significant. Trunk controllability was significantly decreased during rotational exertions which may impair trunk neuromuscular coordination, increasing the risk of developing low back pain.

  

Keywords: Target t racking t ests , T runk controllability , Speed and d irectio n of isometric trunk exertion