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

CONTEXT: Dynamic stability is a necessary requirement in many sports competitions. Muscle fatigue, which can impair stability, may be occurred in many sports competitions in which lateral movements and landing repeated frequently. OBJECTIVE: To assess the effects of peroneal muscles fatigue on dynamic stability following lateral hop landing through measuring time to stabilization (TTS) and dynamic postural stability index (DPSI). DESIGN: Quasi-experimental. SETTING: Laboratory study. PARTICIPANTS: A total of 20 recreationally active, healthy males with no lower-extremity injury during the previous 6 months participated in this study. INTERVENTION: Participants performed a lateral hop on a force plate before and immediately after a fatigue intervention using a Biodex dynamometer. For inducing fatigue, the participant made a prolonged eversion effort with 40% of the maximal voluntary contraction. Fatigue was met when the eversion torque declined by 50% of the initial value. TTS and DPSI were calculated using sequential averaging method and relevant formulas, respectively. MAIN OUTCOME MEASURES: Premeasures and postmeasures of TTS in the anteroposterior, mediolateral and vertical directions, resultant vector of TTS, stability indices in the anteroposterior, mediolateral and vertical directions, and DPSI. RESULTS: Means of the DPSI or its components did not change significantly due to fatigue (P > .05). Means of the TTS in the anteroposterior and mediolateral directions, and the mean of the resultant vector of the TTS increased significantly after fatigue (P < .05). CONCLUSIONS: The question that the dynamic stability is affected or not affected by fatigue depends on which of the TTS or DPSI is used for analysis. The TTS may be a sensitive measure to detect subtle changes in postural stability due to fatigue. But, the DPSI which may be changed after a more strenuous fatigue may be related to actual fatiguing situations.

Effects of transcutaneous electrical stimulation on vocal folds adduction.

According to most previous studies, inducing movements in internal laryngeal muscles by transcutaneous electrical stimulation (TES) was impossible. However, the movements have been reported after using needle electrodes inserted into the internal superior laryngeal nerve (ISLN). Herein, we aimed to apply an innovative TES protocol to cause movements in vocal folds. A short duration and high frequency electrical current was applied by two surface electrodes just above the entrance of ISLN to larynx. The subjects were 32 normal participants (mean age = 23.87; SD = 3.43). During TES application, the vocal folds' movements were examined by flexible videonasolaryngoscopy. Statistical paired t test was used to analyze the differences of vocal folds opening angle, in degrees, during rest and TES periods. Furthermore, the movements were judged by seven experienced speech pathologists via a 9-point rate scale from -1 (any abduction) to 8 (complete adduction). The mean vocal folds adduction increased by 35.68° (t = 9.35, p > 0.001) due to TES application. The mean qualitative scores assigned by raters to each subject were between 6 and 7 points, which indicate an acceptable adduction in vocal folds through TES. Unlike previous studies, the applied TES protocol in this research induced significant vocal fold movements. This might be attributed to our different stimulation parameters, which were designed to penetrate deeply and stimulate ISLN specifically. It is worth noting that we introduced a novel TES protocol, which should be confirmed and then examined as a complementary therapy for neurologic voice disorders in future studies.

Role of the Internal Superior Laryngeal Nerve in the Motor Responses of Vocal Cords and the Related Voice Acoustic Changes.

BACKGROUND: Repeated efforts by researchers to impose voice changes by laryngeal surface electrical stimulation (SES) have come to no avail. This present pre-experimental study employed a novel method for SES application so as to evoke the motor potential of the internal superior laryngeal nerve (ISLN) and create voice changes. METHODS: Thirty-two normal individuals (22 females and 10 males) participated in this study. The subjects were selected from the students of Iran University of Medical Sciences in 2014. Two monopolar active electrodes were placed on the thyrohyoid space at the location of the ISLN entrance to the larynx and 1 dispersive electrode was positioned on the back of the neck. A current with special programmed parameters was applied to stimulate the ISLN via the active electrodes and simultaneously the resultant acoustic changes were evaluated. All the means of the acoustic parameters during SES and rest periods were compared using the paired t-test. RESULTS: The findings indicated significant changes (P=0.00) in most of the acoustic parameters during SES presentation compared to them at rest. The mean of fundamental frequency standard deviation (SD F0) at rest was 1.54 (SD=0.55) versus 4.15 (SD=3.00) for the SES period. The other investigated parameters comprised fundamental frequency (F0), minimum F0, jitter, shimmer, harmonic-to-noise ratio (HNR), mean intensity, and minimum intensity. CONCLUSION: These findings demonstrated significant changes in most of the important acoustic features, suggesting that the stimulation of the ISLN via SES could induce motor changes in the vocal folds. The clinical applicability of the method utilized in the current study in patients with vocal fold paralysis requires further research.

Comparing the Effects of Peroneal Muscle Fatigue and Cyclic Loading on Ankle Neuromuscular Control During Lateral-Hop Landing.

CONTEXT: Cyclic movements and muscle fatigue may result in musculoskeletal injuries by inducing changes in neuromuscular control. Ankle frontal-plane neuromuscular control has rarely been studied in spite of its importance. OBJECTIVE: To compare the effects of peroneal muscle fatigue and a cyclic passive-inversion (CPI) protocol on ankle neuromuscular control during a lateral hop. DESIGN: Quasi-experimental, repeated measures. SETTING: University laboratory. PARTICIPANTS: 22 recreationally active, healthy men with no history of ankle sprain or giving way. INTERVENTIONS: Participants performed a lateral hop before and after 2 interventions on a Biodex dynamometer. They were randomly assigned to intervention order and interventions were 1 wk apart. A passive intervention included 40 CPIs at 5°/s through 80% of maximum range of motion, and a fatigue intervention involved an isometric eversion at 40% of the maximal voluntary isometric contraction until the torque decreased to 50% of its initial value. MAIN OUTCOME MEASURES: Median frequency of the peroneus longus during the fatigue protocol, energy absorption by the viscoelastic tissues during the CPI protocol, and feedforward onset and reaction time of the peroneus longus during landing. RESULTS: A significant fall in median frequency (P < .05) and a significant decrease in energy absorption (P < .05) confirmed fatigue and a change in viscoelastic behavior, respectively. There was a significant main effect of condition on feedforward onset and reaction time (P < .05). No significant main effect of intervention or intervention × condition interaction was noted (P > .05). There was a significant difference between pre- and postintervention measures (P < .0125), but no significant difference was found between postintervention measures (P > .0125). CONCLUSIONS: Both fatigue and the CPI may similarly impair ankle neuromuscular control. Thus, in prolonged sports competitions and exercises, the ankle may be injured due to either fatigue or changes in the biomechanical properties of the viscoelastic tissues.

Effect of functional fatigue on vertical ground-reaction force in individuals with flat feet.

CONTEXT: Flat foot is one of the lower extremity deformities that might change kinetic variables of gait. Fatigue is one of the factors that can alter the vertical ground-reaction force (GRF). The effect of a fatiguing condition on vertical GRF has not been documented in individuals with flat feet. OBJECTIVE: To examine the fatigue effect on vertical GRF in individuals with flat feet compared with a normal group during barefoot walking. DESIGN: Repeated-measure ANOVA for the effects of fatigue on individuals with flat feet and normal feet. SETTING: Biomechanics laboratory. PARTICIPANTS: 17 subjects with flat feet and 17 normal subjects (recruited according to their arch-height ratio). MAIN OUTCOME MEASURES: Three vertical GRF measures (F1, the first peak force; F2, minimum force; and F3, the second peak force) were extracted before and after a functional fatigue protocol. RESULTS: No significant interaction between fatigue and group was observed for the 3 vertical GRF measures. For F2, fatigue and group effects were significant (P = .001 and P = .02, respectively). Furthermore, F2 was higher in the flat-feet group than in the normal group; F2 also increased after fatigue. For F3, only a significant fatigue effect was observed (P = .004). F3 decreased after fatigue in both groups. CONCLUSIONS: In the flat-feet group, a decrease in the variation of vertical GRF might be due to more flexible foot joints. After fatigue, muscles might lose their ability to control the foot joints and cause higher F2 in the flat-feet group.

Gait initiation and lateral wedge insole for individuals with early knee osteoarthritis.

BACKGROUND: People with knee osteoarthritis are at higher risk of postural deficits and locomotor adaptations which could be manifested in transient tasks like gait initiation. To better understand the effect of early knee osteoarthritis on gait initiation, we measured the gait initiation in two groups of early knee osteoarthritis and healthy age-matched controls and assessed the effect of lateral wedge insole in knee osteoarthritis group. METHODS: Twenty-one individuals with early knee osteoarthritis, mean (SD) age = 53.1 (7.4, years), and 19 age- and sex-matched asymptomatic healthy individuals, mean (SD) age = 47.5 (11.2, years), participated. Centre of pressure trajectories were used to quantify the two phases of gait initiation in barefoot condition: anticipatory postural adjustment, and locomotor phase. The immediate and four-week effect of lateral wedge insole and shod condition were also compared for individuals in knee osteoarthritis group. FINDINGS: Longer duration of anticipatory postural adjustment phase (P = 0.046), locomotor phase (P = 0.049), and total duration of gait initiation (P = 0.035) with lower length and velocity of the center of pressure trajectories in anticipatory postural adjustment phase (P = 0.002, and 0.008, respectively) were observed in knee osteoarthritis group compared to controls. Lateral wedge insole could increase the length and velocity of the centre of pressure in locomotor phase compared to barefoot condition (P = 0.001, and 0.002, respectively). INTERPRETATION: Our study outlined that people with early knee osteoarthritis adopt different gait initiation strategies mainly in postural preparation phase. The potential effect of lateral wedge insole was shown with better performance of the locomotor phase. CLINICAL TRIAL REGISTRY NUMBER: IRCT2016060628310N1.

Application of High-Frequency Transcutaneous Electrical Nerve Stimulation in Muscle Tension Dysphonia Patients With the Pain Complaint: The Immediate Effect.

INTRODUCTION: The aim of the present study was to investigate the immediate effect of the application of high-frequency Transcutaneous electrical nerve stimulation (TENS) in muscle tension dysphonia (MTD) patients with the pain complaint. MATERIALS AND METHODS: Thirty patients with MTD, 10 men and 20 women with a mean age of 36.40 ± 5.76 years, participated in the study. The patients were randomized into two groups: (1) Treatment group (TENS) (10 women and 5 men) and (2) Sham TENS group (10 women and 5 men). The treatment group (TENS) received a unique 20-minute session of high-frequency TENS. The sham TENS group was treated in the same condition as the treatment group and received a unique 20-minute session of high-frequency TENS, but no stimulation was given. Auditory-perceptual assessments, acoustic voice analysis, vocal tract discomfort (VTD), and musculoskeletal pain were used to compare the patients pre- and post-treatment. RESULTS: There was a significant improvement in the asthenia parameter of auditory-perceptual assessment in the TENS group. This improvement in asthenia was significant when comparing the TENS group with the sham TENS group. These differences in the asthenia were not significant after using Holm-Bonferroni correction. A comparison of the VTD before and after the TENS application showed there was a significant reduction in the severity of the symptoms (burning, tight, dry, pain, tickling, sore, irritable, and lump in the throat). When comparing the TENS group with the sham TENS group, improvements in burn, tight, dry, pain, and irritable items of VTD were observed. However, after applying the Holm-Bonferroni correction, only reductions in dry and pain items remain significantly different between the groups. After the TENS application, the pain intensity was significantly reduced in the anterior and posterior neck, larynx, submandibular, masseter, temporal region, and upper back. After applying the Holm-Bonferroni correction, pain intensity reduction was significant in the anterior neck and larynx. When comparing the TENS group with the sham TENS group, pain intensity was reduced significantly in the larynx of the TENS group. This difference between the two groups was not significant after using Holm-Bonferroni correction. The pain and VTD assessments in the present study were performed using valid and reliable self-reported scales (NMSQ-E and VTD). CONCLUSION: High-frequency TENS can be used in the voice treatment program of patients with MTD. MTD patients with pain complaint reported that their vocal tract discomfort and pain were decreased following the high-frequency TENS. Notably, these positive effects were obtained after a single session of high-frequency TENS application.

Transcutaneous Electrical Nerve Stimulation Combined With Voice Therapy in Women With Muscle Tension Dysphonia.

OBJECTIVES: The purpose of the present study was to investigate the effect of Voice Therapy (VT) with and without Transcutaneous Electrical Nerve Stimulation (TENS) in women with Muscle Tension Dysphonia (MTD). METHODS: A total of 20 women with MTD participated in the study. Participants underwent evaluation of auditory-perceptual assessment, acoustic voice analysis, Vocal Tract Discomfort (VTD), and musculoskeletal pain before and after the treatment. The participants were divided into two groups: (1) TENS + VT group (10 participants) and (2) VT group (10 participants). Both groups received 10 sessions of treatment, twice a week, each lasting 50 minutes. The statistical analysis was performed using Wilcoxon signed ranked and Mann-Whitney U tests (P < 0.05). RESULTS: After VT, significant improvements were observed in all auditory-perceptual parameters and all VTD items except for the tickling frequency and severity. The VT caused significant reduction in the frequency of pain in anterior neck, posterior neck, and the larynx. Also, VT resulted in a significant reduction in pain intensity only in the larynx. After VT + TENS, significant improvements were observed in all auditory-perceptual parameters, shimmer, and all VTD items. Moreover, the VT + TENS led to a significant decrease in the frequency and intensity of pain in anterior neck, posterior neck, the larynx, masseters, shoulders, and upper back. The findings of between-group comparison after treatment showed significantly more reduction in the frequency (dry and pain items) and severity (tight and pain items) of the VTD in VT + TENS group compared with VT group. Regarding the musculoskeletal pain, significantly more reduction in the frequency and intensity of pain in anterior neck and the larynx was observed in VT + TENS group compared with VT group. CONCLUSIONS: The VT and VT + TENS could lead to positive outcomes in auditory perceptual assessment, acoustic voice analysis, the VTD, and assessment of musculoskeletal pain. In some items of frequency and severity of VTD scale and assessment of musculoskeletal pain, VT + TENS also produced better results compared with VT. As a result, TENS was recommended as a complementary therapy for patients with MTD, especially when these patients had more complaints about VTD and musculoskeletal pain.

Effects of Voice Therapy on Vocal Tract Discomfort in Muscle Tension Dysphonia.

INTRODUCTION: Patients with muscle tension dysphonia (MTD) suffer from several physical discomforts in their vocal tract. However, few studies have examined the effects of voice therapy (VT) on the vocal tract discomfort (VTD) in patients with voice disorders. Therefore, the aim of the present study was to investigate the effects of VT on the VTD in patients with MTD. MATERIALS AND METHODS: This study was carried out on 25 subjects with MTD, including 5 men and 20 women, with the mean age of 37.20±5.70 years. The participants underwent 10 consecutive sessions of VT twice a week. The acoustic voice analysis, auditory-perceptual assessment, and the Persian version of the vocal tract discomfort (VTDp) scale were used to compare the pre- and post-treatment results. RESULTS: After VT, significant improvements were observed in the acoustic characteristics, including jitter, shimmer, and harmonics-to-noise ratio (P<0.05). Regarding the auditory-perceptual assessment, a significant reduction was noticed in the overall severity, roughness, and breathiness (P<0.05). Moreover, VT led to a significant reduction in all the items of the VTDp, including burn, tightness, dryness, pain, tickling, soreness, irritability, and lump in the throat, after VT in both frequency and severity sections of the VTDp scale (P<0.05). CONCLUSION: The results of the present study showed that VT can be effective in reducing the frequency and severity of the VTD in patients with MTD in addition to improving voice quality.

Comparison of Selective Local and Global Muscle Thicknesses in Females with and without Chronic Low Back Pain.

BACKGROUND: Chronic low back pain (LBP) leads to long-term physical and psychological problems and may result in acute deterioration of the pain. It is hypothesized that size changes in selected limb and pelvis muscles during contracting movements are different between healthy individuals and LBP patients. MATERIALS AND METHODS: A case-control study including two groups of 30 female participants with and without LBP symptoms was designed. Participants were 20-45 years old (36.7±6.7, healthy subjects; 34.6±6.2 LBP subjects). Ultrasonography was used to estimate the thicknesses of the quadratus lumborum (QL), gluteus medius (GMed), transversus abdominis (TrA) and lumbar multifidus (MF). Thickness changes of the muscles in a submaximal contracting position compared to the rest position were measured. Statistical analysis included an independent t-test to determine the significance of differences, and the Kolmogrov-Smirnov two-sample test to evaluate the normality and reliability. RESULTS: All muscles increased their thickness during contractions. The average increase in LBP subjects was lower than in the healthy subjects. The smaller increase in the muscle thickness of GMed in the LBP group may suggest a weakness because of imbalance in the GMed muscle of LBP patients. CONCLUSIONS: 1. Ultrasonography of local and global muscles is an appropriate device for clinical diagnosis of LBP. 2. Strengthening TrA, MF, and GMed muscles for pain prevention is effective in the prevention and treatment of LBP.

Upper trapezius fatigue in carpet weaving: the impact of a repetitive task cycle.

INTRODUCTION: Shoulder disorders are one of the most prevalent musculoskeletal disorders among carpet weavers. The most important cause of these disorders is muscle fatigue. The aim of the present study is to investigate the effect of carpet weaving characteristics on upper trapezius (UTr) muscle fatigue during a task cycle. METHOD: In this cross-sectional study, 9 women and 3 men participated. During an 80-min cycle of carpet weaving, a times-series model was applied to assess electromyography amplitude and frequency changes. RESULT: According to the joint analysis of electromyogram spectrum and amplitude method, the participants experienced 0% force decrease, 0.9% recovery, 18% force increase and 72% fatigue in the left UTr. Furthermore, the rates of force decrease, recovery, force increase and fatigue in the right UTr were 18%, 18%, 18% and 45%, respectively. Fatigue in the right and the left UTr was reported to be the dominant state during one carpet weaving task cycle. CONCLUSION: Task cycle appears to have a significant impact on UTr fatigue in participants, and UTr fatigue can be considered a serious risk factor in shoulder musculoskeletal disorders. Hence, further studies should focus on better workstations and work-rest periods during various subtasks.

Effect of ankle taping on postural control measures during grasp and release task in patients with chronic ankle instability.

OBJECTIVE: The aim of this study was to examine the effect of Mulligan ankle taping on center of pressure (COP) parameters during performance of a functional upper limb task in patients with chronic ankle instability (CAI). METHODS: A clinical controlled trial study designed between 4 ankle conditions: untaped and taped, CAI and healthy subjects. Fifteen subjects with CAI and 15 healthy controls were asked to grasp an object at their waist level and release it above shoulder level in an oblique pattern during performance of single-leg stance balance test. All the subjects performed 3 trials of single-leg stance with eyes opened before and after Mulligan taping on a force plate during performance of functional upper limb task. The mean displacement (mdCOP), range of COP excursion (rangeCOP) and average speed of COP (velCOP) in anteroposterior (AP) and mediolateral (ML) directions were analysed for differences between groups. RESULTS: mdCOP and rangeCOP in AP direction were significantly increased (P= 0.04 and 0.03, respectively) in the CAI group. Mulligan taping significantly reduced velCOP in AP and ML directions (P= 0.02). CONCLUSION: In CAI patients Mulligan ankle taping can improve postural control by decreasing velCOP, therefore Mulligan taping can have immediate positive effects on postural parameters and maintenance of dynamic postural control.

Postural Control in Deaf Children.

This cross-sectional study aimed to determine the reliability of static control evaluation with Synapsys Posturography System (SPS, Marseille, France) and to compare the static postural control of deaf children with typically developing children. This study was conducted in 2 phases on 81 children of 7 to 12 years old in Tehran schools. The first phase examined the reliability of static balance evaluation with SPS. In this phase, a total of 12 children with typical development were evaluated and then do a re-test 1 week later. In the second phase, 30 children with profound sensorineural hearing loss (SNHL) and high risk in their balance (selected from Baghcheban Schools for the Deaf) as the experimental group, and 37 children with typical development (selected randomly from 2 primary schools for girls and boys in District 12 of Tehran Department of Education) as control group were enrolled in the study. They were all placed under sensory organization test evaluation. Based on the results of intraclass correlation coefficient (ICC), the unilateral random effects model, test-retest reliability in different sensory conditions, the moderate to excellent results were obtained (ICC between 0.68 and 0.94). Also, the mean displacement of pressure center in all sensory conditions, the limits of stability (LOS) area, the overall balance scores, and scores for balance sensory ratio (except the somatosensory ratio) of children with typical development were better than the deaf peers (P˂0.05). The SPS has acceptable reliability to evaluate static posture in children between the ages of 7 and 12 years. Furthermore, deaf children as compared to children with typical development had a lower static postural control in all sensory conditions. This finding confirms the need to examine the postural control for identifying the extent of sensory deficit that has caused poor balance function, and also the need for early intervention to address the balance deficit in deaf children.

The Effect of Vestibular Rehabilitation Therapy Program on Sensory Organization of Deaf Children With Bilateral Vestibular Dysfunction.

The purpose of this study was to determine the effect of vestibular rehabilitation therapy program on the sensory organization of deaf children with bilateral vestibular dysfunction. This cross-sectional and analytic study was conducted on 24 students between the age of 7 and 12 years (6 girls and 18 boys) with the profound sensorineural hearing loss (PTA>90 dB). They were assessed through the balance subtest in Bruininks-Oseretsky test of motor proficiency (BOTMP). For children which the total score of the balance subtest was 3 standard deviation lower than their peers with typical development, vestibular function testing was completed pre-intervention. Posturography Sensory organization testing (SOT) was completed pre- and post-intervention with SPS (Synapsys, Marseille, France). Children with bilateral vestibular impairment were randomly assigned to either the exercise or control group. Exercise intervention consisted of compensatory training, emphasizing enhancement of visual and somatosensory function, and balance training. The exercise group entered in vestibular rehabilitation therapy program for 8 weeks. The children initially participating in the control group were provided the exercise intervention following the post-test. Based on the results there was significant difference in condition 5 and 6, areas of limits of stability (LOS), vestibular ratio and global score in posturography at the end of the intervention, but there was no significant difference in the control group in posturography (P<0.05). The results indicated that testing of vestibular, and postural control function, as well as intervention for deficiencies identified, should be included in deaf children rehabilitation program.

Goal equivalent manifold analysis of task performance in non-specific LBP and healthy subjects during repetitive trunk movement: Effect of load, velocity, symmetry.

Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading; each at two levels. A goal function for the task was defined as maintaining a constant movement time at each cycle. Given the GEM, flexibility index and performance index were calculated respectively as amounts of goal-equivalent variability and the ratio of goal-equivalent to non-goal-equivalent variability. CNSLBP group was as similar as healthy individuals in both flexibility index (p=0.41) and performance index (p=0.24). Performance index was higher in asymmetric (p<0.001), high velocity (p<0.001), and loaded (p=0.006) conditions. Performance and flexibility in using motor abundance were influenced by repeated trunk flexion/extension conditions. However, these measures were not significantly affected by CNSLBP.

Balance Performance of Deaf Children With and Without Cochlear Implants.

 The aim of this study was to compare the static and dynamic balance performance of deaf children with and without cochlear implants. This is a cross-sectional study of 145 school children, aged between 7 and 12 years comprising 85 children with congenital or early acquired bilateral profound sensorineural hearing loss (the hearing loss group) and 60 normal hearing aged-matched control counterparts were assessed using the balance subtest of Bruininks-Oseretsky test of Motor Proficiency (BOTMP). The hearing loss group, 50 without cochlear implants (the non-implant group) and 35 of them with unilateral cochlear implants (the implant group) were recruited from schools for the deaf and normal hearing children (the control group) randomly selected from two randomly selected elementary schools of Tehran city. The scores were analyzed using one-way ANOVA. The total score of deaf children especially the implant group were significantly lower than the control group )P<0.001). The balance performance of the control group was better than the implant group in all of the items as well as the non-implant group except the fourth tested item (walking forward on a line) (P<0.05). The balance score of the implant group was significantly lower than the non-implant group except for the third tested item (standing on the preferred leg on a balance beam with eyes closed). The findings suggested that deaf children, specifically those with cochlear implants are at risk for motor and balance deficits. Thus, vestibular and motor evaluations, as well as interventions to improve balance and motor skills, should be prioritized for this population.

Prevalence of Voice Disorders and Associated Risk Factors in Teachers and Nonteachers in Iran.

OBJECTIVES: Teachers are at increased risk for development of voice disorders. Because there is no published study on Iranian teachers, the aim of this study was to compare the prevalence of voice disorders among teachers and nonteachers in Iran and define the causing risk factors. METHODS: In the present study, 104 teachers and 41 nonteacher participants, whose jobs did not involve vocal effort, completed a questionnaire regarding to vocal complaint and four relevant risk factors. RESULTS: According to our gained data, 54.6% of teachers experienced vocal complaints during their work, although this value was 21.1% for the nonteacher group (P < 0.001). Moreover, investigating the prevalence of voice disorders during other periods of life was performed. Analyzing the questionnaire data indicated a significant higher vocal load risk factor for teachers (70.77%; standard deviation [SD], 29.48), in comparison with their nonteacher counterparts (27.44%; SD, 37.83; P < 0.001). In addition, our study revealed the significance of vocal load, as well as physical and environmental risk factors in the development of voice disorders in teachers with voice complaints. CONCLUSIONS: Present findings indicated a higher epidemiology of voice problems among teachers in comparison with nonteacher individuals and introduced vocal load as the most important risk factor in development of voice disorder in Iranian teachers. Accordingly, it is recommended to pay special attention to negative effects of vocal load, although environmental and physical factors are also of importance.

Effects of static stretching of knee musculature on patellar alignment and knee functional disability in male patients diagnosed with knee extension syndrome: A single-group, pretest-posttest trial.

BACKGROUND: Knee extension (Kext) syndrome is based on movement system impairments and is described as knee pain associated with quadriceps stiffness. OBJECTIVE: To investigate the effects of 3 times per week for 4 weeks static stretching of knee musculature on patellar alignment and knee functional disability in male Kext syndrome patients. DESIGN: A single-group, pretest-posttest clinical trial. SETTING: Hazrat-e-Rasoul Akram Hospital. PARTICIPANTS: Forty-six male Kext syndrome patients aged 18-35 years. METHODS: Knee functional disability was assessed by the Kujala questionnaire. Patellar tilt was assessed using the skyline view X-ray. In addition, patella alta was assessed by X-ray using the Insall-Salvati ratio. After intervention, changes in knee flexion-extension range of motion (ROM) and hip adduction were assessed by goniometer and inclinometer. Changes in patellar tilt and patella alta were evaluated. Correlations between muscles length, patellar tilt and knee functional disability were also evaluated. RESULTS: The mean of patellar tilt in male Kext syndrome patients was 15.19°. Only the correlation between rectus femoris shortness and patellar tilt (P = 0.002) and the correlation between rectus femoris shortness and knee functional disability (P = 0.037) were significant. Patella alta was not severe in male Kext syndrome patients (1.28 ± 0.10). Knee flexion-extension ROM and femoral adduction increased significantly after a 12-session stretching programme (P < 0.0001). CONCLUSION: The results demonstrated that rectus femoris shortness had higher correlation with patellar tilt and knee functional disability than iliotibial band and hamstring shortness. Stretching was effective in reducing patellar tilt, patella alta, knee functional disability, increasing knee ROM and hip adduction in these patients.

Influence of functional knee bracing on the isokinetic and functional tests of anterior cruciate ligament deficient patients.

Use of functional knee braces has been suggested to provide protection and to improve kinetic performance of the knee in Anterior cruciate ligament(ACL)-injured patients. However, many athletes might refrain from wearing the braces because of the fear of performance hindrance in the playing field. The aim of this study was to examine the effect of three functional knee brace/sleeves upon the isokinetic and functional performance of ACL-deficient and healthy subjects. Six anterior cruciate ligament deficient (29.0 ± 5.3 yrs., 175.2 ± 5.4 cm, and 73.0 ± 10.0 kg) and six healthy male subjects (27.2 ± 3.7 yrs., 176.4 ± 6.4 cm, and 70.3 ± 6.9 kg) were selected. The effect of a custom-made functional knee brace, and two neoprene knee sleeves, one with four metal supports and one without support were examined via the use of isokinetic and functional tests in four sets (non-braced,wearing functional knee brace,and wearing the sleeves). Cross-over hop and single leg vertical jump test were performed and jump height, and hop distance were recorded. Peak torque to body weight ratio and average power in two isokinetic velocities(60°.s(-1),180°.s(-1)) were recorded and the brace/sleeves effect was calculated as the changes in peak torque measured in the brace/sleeves conditions, expressed as a percentage of peak torque measured in non-braced condition. Frequency content of the isokinetic torque-time curves was also analyzed. Wilcoxon signed rank test was used to compare the measured values in four test conditions within each control and ACL-deficient group,and Mann-Whitney U test was used for the comparison between the two groups. No significant differences in peak torque, average power, torque-time curve frequency content, vertical-jump and hop measurements were found within the experimental and the non-braced conditions (p>0.05). Although the examined functional knee brace/sleeves had no significant effect on the knee muscle performance, there have been some enhancement regarding the extension peak torques and power generating capacity of the ACL-deficient subjects that could be helpful in reducing the bilateral asymmetry in these patients.

The effects of a prophylactic knee brace and two neoprene knee sleeves on the performance of healthy athletes: a crossover randomized controlled trial.

Knee injury is one of the major problems in sports medicine, and the use of prophylactic knee braces is an attempt to reduce the occurrence and/or severity of injuries to the knee joint ligament(s) without inhibiting knee mobility. The aim of the present study was to examine the effect of one recently designed prophylactic knee brace and two neoprene knee sleeves upon performance of healthy athletes. Thirty-one healthy male athletes (age = 21.2 ± 1.5) volunteered as participants to examine the effect of prophylactic knee brace/sleeves on performance using isokinetic and functional tests. All subjects were tested in four conditions in a random order: 1. nonbraced (control) 2. using a neoprene knee sleeve 3. using a knee sleeve with four bilateral metal supports and 4. using a prophylactic knee brace. The study design was a crossover, randomized, controlled trial. Subjects completed single leg vertical jump, cross-over hop, and the isokinetic knee flexion and extension (at 60, 180, 300°/sec). Data were collected from the above tests and analyzed for jump height, cross-over hop distance, peak torque to body weight ratio and average power, respectively. Comparisons of these variables in the four testing conditions revealed no statistically significant difference (p>0.05). The selected prophylactic brace/sleeves did not significantly inhibit athletic performance which might verify that their structure and design have caused no complication in the normal function of the knee joint. Moreover, it could be speculated that, if the brace or the sleeves had any limiting effect, our young healthy athletic subjects were well able to generate a mean peak torque large enough to overcome this possible restriction. Further studies are suggested to investigate the long term effect of these prophylactic knee brace and sleeves as well as their possible effect on the adjacent joints to the knee.