Background and Aim: Postural control is the ability of maintaining of the body posture in space. Peripheral and central factors have important role in muscle fatigue. Repetitive muscle contraction leads to muscle fatigue. If strength is educed up to 30% of maximum contraction can be disturbed stance control of subjects. The objective of the present study was to compare the effect of lumbar muscle fatigue on postural control in athlete and non-athlete subjects.

Materials and Methods: Fifteen men as athlete subjects and other fifteen matched men as non- athlete subjects participated in this study. Trunk extensor muscle fatigue was produced by dynamometer. Stance postural sways were evaluated by force platform device in bipedal stance with open eye.

Results: In pre-fatigue state there is no significant difference between two groups. Fatigue had significantly effect on postural sways in both group after Lumbar muscle fatigue specially in non-athlete group (P ≥ 0.05) .

Conclusion: The postural control of athletes after muscle fatigue was better than non athlete subjects probably due to better proprioception in athlete subjects.

Keywords: Muscle fatigue, Postural control, Force plattform.

Backgrouna and Aim : Children with cerebral palsy have often movement and postural disorders. The purpose of this study is to evaluate the effect of new neoprene dynamic orthosis on balance in children with cerebral palsy.

Materials and Methods : This study is quazi experimental. Five children with cerebral palsy (spastic diplegia) with mean age of 9/6± 3.78 years old participated in this study. The degree of knee extension was measured using electrogoniometer. Center of Pressure(COP) displacement in anterior/posterior and medial/lateral planes and functional balance were also measured using kistler forceplate (BA, Kistler- Switzerland 9286) and berg test in two occasions, before and after wearing neoprene orthosis in a period of six weeks. Wilcoxon test was used for comparing data before and after 6 weeks.

Results : There was statistically significant difference in right knee extension before and after wearing orthosis (p<0/05). The result of this study show no statistically significant in COP parameters. However, functional balance of children with CP shows significant improvement using neoprene orthosis.

Conclusion : New neoprene orthosis can be effective in knee biomechanical alignment as well as functional balance

Keywords : Cerebral palsy, Lycra dynamic orthosis, Postural control

Background and Aim: Patellofemoral pain syndrome (PFPS) is the most common overuse injury occurring at the knee. Reduction of proprioception, pain, changes in muscle activity patterns are seen in PFPS. Therefore these patients may demonstrate less balance. Thus the main objective of this study was to determine the postural control in patients with patellofemoral syndrome and compare it with healthy subjects.

Materials and Methods: Ten subjects (age 31.1 ± 5.31, weight 59.6 ± 8.95, height 1.62 ± 0.05) presenting with PFPS were compared with 10 matched control subjects (age 27.2 ± 1.81, weight 60.6 ± 2.36, height 1.67 ± 0.01).

Pain was measured with VAS scale and patella position was assessed using the method first described by McConnell. Force Plate was used to measures COP paths in sagittal and frontal plane with open and close eyes.

Results: The data showed that COP paths were different between PFPS and healthy subjects with open eyes in sagittal and frontal plane (P< 0.05). Means of COP paths increase in patients with PFPS. No differences were detected between PFPS and healthy subjects with closed eyes in sagittal and frontal plane.

Conclusion: Body sways increase in patients with PFPS with open eyes due to pain, lateral tracking patella and reduction of proprioception in knee.

Keyword:  Postural control, Patellofemoral syndrome, Open & close eye

Background and Aim: Different aspects of the motor control parameters of dominant and non-dominant legs are investigated but the effect of dominancy on motor control strategy is still unclear. The aim of the present study is to compare the pre- motor time, motor time and reaction time in dominant and non- dominant leg muscles of the non- professional healthy athletes in response to visual stimulus during forward jumping.

Methods and Materials: Eleven non- professional healthy athletes participated in this cross-sectional study determined by convenience non probability sampling. Surface electromyography were performed in the dominant and non-dominant leg muscles including  gastrosoleous , peroneus longus, peroneus brevis, and tibialis anterior in response to visual stimulus during forward jumping.

Results: There was no significant difference (P > 0.05) between the dominant and no-dominant legs with respect to the pre-motor time, motor time and reaction time of the gastrosoleus, peroneus longus, peroneus brevis and tibialis anterior.

Conclusion: Our findings suggest that limb dominancy is not an important parameter in the motor control studies.

Keywords: Motor control strategy, Visual stimulus, Forward jumping

Background and Aim: ACL injury is one of the most common sport injuries which undergo reconstructive surgery. Electromyography or recording of muscles’ electrical activity is a suitable means to assess changes in motor control system output. The goal of this study is to compare the lower limb muscles EMG activity during drop landing in individuals after ACL reconstruction and healthy subjects.

Materials and Methods: Eleven men who had undergone ACL reconstruction 6 to 24 months ago (Age 29±6 years old) and 11 healthy men (Age 28±2 years old) participated in the study. Amount of electrical activity for tibialis anterior, vastus medialis, vastus lateralis, semitendinosus and biceps femoris muscles was recorded using surface electrodes during drop landing and calculated for two time intervals. The amount of activity was measured in -150 to +50 and +50 to +180 intervals in relation to the landing moment. Subjective IKDC questionnaire and cross-over hop functional test were used to determine the subjective and objective functional level.  Independent t test was used to determine between-group statistical differences.

Results: Feed forward activity of semitendinosus (P=.041) and biceps femoris (P=.008) muscles were significantly higher in ACLR group and feedback activity of vastus medialis (P=.03) muscles was significantly lower in ACLR group. Healthy individuals showed higher score on both the functional test and IKDC questionnaire. (P<.0005)

Conclusion: Individuals who had undergone reconstructive surgery of ACL showed different muscular activity compared to healthy subjects and closer to ACL deficient individuals 6 months after surgery and routine rehabilitation.

Keywords: Anterior cruciate ligament reconstruction, Electromyography, Neuromuscular control

Background and Aim: The structure and function of the hamstring and quadriceps can contribute to the development and process of patellofemoral pain syndrome. As open and closed kinetic chain exercises have different effects on the knee joint, the aim of the current study was to investigate motor control of knee joint in both kinetic chains according to voluntary response index aspect.

Materials and Methods: 12 healthy knees and 12 injured knees (6 females in each group) were examined. Surface electromyography were performed in knee muscles including vastus medialis oblique, rectus femoris, vastus lateralis and biceps femoris while the subjects were doing flexion-extension of knee joint by isokinetic dynamometer system and one leg semi-squat movement. Then voluntary response index was calculated.

Results: There were no significant difference between the patients and healthy groups (p>0.05). In the patient group, correlation between similarity index and magnitude was seen.

Conclusion: Probably in the low intensity patellofemoral syndromes, voluntary response index could not differentiate between healthy and the patient groups. In the patients with patellofemoral syndrome group, correlation between similarity index and magnitude may represent co-contraction in their muscles.

Keywords: Patellofemoral pain syndrome, Motor control, Voluntary response index, Surface electromyography

Background and Aim: This study was conducted dueto the limited results of past studies in relation to postural control in children with developmental coordination disorders and the importance of postural control with the ability to integrate the vestibular, visual and somatosensory inputs. In this study the postural control of the children with Developmental Coordination Disorder (DCD) and their normal peers was compared under the reduced or the conflicted sensory input conditions.

Materials and Methods: Twenty two children with Developmental Coordination Disorder (16 males, 6 females with mean age of 7 years old and 9 months, SD 1 year and 5 months) and 19 children with normal motor development (13 males, 6 females, with mean age of 6 years and 11 months, SD 1 year and 1 month) were evaluated. Standing balance, sensory organization and motor control strategy were evaluated using the sensory organization test (SOT).

Result: The results showed that the children with DCD had poorer function than the normal children in the composite equilibrium (p&le; 0.001), visual ratios (p=0.005) and vestibular ration (p=0.002). There were no meaningful differences between groups in their average somatosensory ratio. Additionally, children with Developmental Coordination Disorder had lower motor strategy scores than the normal children when they were forced to depend on vestibular cues alone (p < 0.05). The children with Developmental Coordination Disorder had deficits in standing balance control in conditions that included reduced or conflicting sensory signals. The visual and vestibular systems tended to be more involved in contributing to the balance deficits than the somatosensory system. Moreover, children with Developmental Coordination Disorder were tended to use hip strategy excessively when forced to rely primarily on vestibular signals to maintain postural stability.

Conclusion: In order to improve the postural control in the patients, the rehabilitation protocols should focus on the sensory-motor deficits.

Keywords: Postural control, Postural stability, Developmental Coordination Disorder

Background and Aim: The concept of locus of control refers to the degree in which a person perceives daily occurrences to be a consequence of his or her own behavior. Some people accept responsibility of their own continued well-being and maintained improvement, but the others, particularly those who do not accept this responsibility, may be at risk of relapse. It recommends a kind of measurement in order to identify such persons so that further steps can be taken to inhibit the relapse before occurs. One of this measurement is Locus of Control of Behavior. The purpose of the present study is to translate the Locus of Control of Behavior (LCB) into Persian and investigation of validity and reliability of the scale.

Materials and Methods: In this research, 35 adults with stuttering and 35 non-stuttering were evaluated. After the translation of the test according to Protocol IQOLA and its equalization to Persian Language, content validity and face validity of it were determined by the opinions of experts. Then, for concurrent validity determination 35 adults with stuttering were examined by LCB and Rotters locus of control .In order to test reliability, test –retest and Cronbach,s alpha were used.

Results: Entirely relevant items had simple translation. The translation items had content and face validity. Correlation between the marks of LCB and Rotters locus of control was (p=0.000, r= %53). LCB has high Test-retest (p=0.000, ICC= %87) and internal reliability (p=0.000, &alpha;=%85).

Conclusion: The present research showed that the Persian version of the LCB is a reliable and valid tool for locus of control from the perspective of a person who is stutter.

Key Words: Stuttering, Reliability, Validity, Locus of Control of Behavior