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Background and Objective: Critical illness diaphragmatic neuromyopathy are significant  causes of weakness, morbidity and prolong mechanical ventilation among critically ill patients under mechanical ventilation. It is important determine the true initial time of neuromyopathic changes associated with critically ventilated patients. Based on new electrodiagnostic studies, electrophysiological studies of diaphragm and phrenic nerve, as an important muscle and nerve in ventilation, compared with other evaluating methods, have specific importance. This study was done to evaluate of the diaphragmatic myopathy onset time among mechanically ventilated patients using electrophysiological method.

Materials and Methods: This descripvtive study was performed on 56 mechanically ventilated patients in intensive care unit without primary neuromuscular disease in Tabriz Imam Khomeini hospital in West of Iran between 2004-06 years. Electromyography (EMG) and nerve conduction velocity test were performed in the 4^th and then in 4 days intervals.

Results: In 56 patients EMG and NCV performed at 4 and 8 days after mechanical ventilation, none of them had any evidence in favor of diaphragmatic myopathy. During the course of study, EMG were done on 24 patients in 12^th days , that in three of them (12.5%), mild myopathy were reported. From 18 patients, considered in 16^th days, only five (31.25%) of them showed mild myopathy. From 10 (100%) reminder patients, in 20^th day, all of them had mild to moderate myopathy.

Conclusion: According to these results, minimum duration of the diaphragmatic weakness onset time in mechanically ventilated patients with diverse causes in general critical care ward were 12 days and increased with prolonged time of mechanical ventilation.

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Background and Objective: The reduction of shoe heel height can increase abdominal muscles activity. This study was conducted to evaluate the effect of low shoe heel height on the trunk muscle activity in young healthy females. Materials and Methods: In this quasi- experimental (Pre-post ) study, 48 healthy females were evaluated at University of social welfare and rehabilitation at 2009-2010. Females were selected in a non probability sampling manner and divided randomly into two groups. Subjects in the first group (12 females) were used low heel height shoes(less than 3.4 cm) for six months. The second group (12 female) was used standard heel shoes height (3.5-5 cm) for six months. After the end of the first step of study, females in first group were used standard heel shoes height (3.5-5 cm) for six months. The Kinsiologic Electromyography instrument was used to test the Electromyography magnitude of rectus abdominal and external oblique activity. Data was analyzed with Paired and independent T student and Kolmogorrov-Smirnov tests. Results: Muscle activity in first and second groups at external oblique was 9.72±3.15 μν and 7.87±2.47 μν and at rectus abdominal was 11.60±3.58 μν and 9.81±3.46 μν respectively. Muscle activity before and after using standard shoe heel height was significant (p<0.05). Conclusion: It seems that using lower heel shoes height increase the trunk muscle activity.

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Background and Objective: Patellofemoral is a pain syndrome, common among athletes and the theraputic regiment based on the improvement of muscle involved in this disorder. This study was done to compare electromyography activity of the vastus medialis obliques and vastus lateralis longus during squat with isometric hip adduction in athletes with patellofemoral pain syndrome and healthy athletes.

Materials and Methods: This case – control study was carried out on 16 national team male athletes (volleyball, handball and taekwondo) aged 30-18 years with patellofemoral pain syndrome and 16 healthy male athletes. Subjects were matched based on weight, height, age, dominant of lower extremity and voluntarily participated. Electromyography activity of vastus medialis obliques and vastus lateralis longus muscles recorded by surface electrodes at 15, 30 and 45 knee flexion degrees. Paired t test was used to compare electromyography activities in each group and One-way ANOVA and Tukey post hoc test was used to compare each muscle in different angles.

Results: There was significant differences in the activity of vastus medialis obliques and vastus lateralis longus muscles in athletes with patellofemoral pain syndrome at 45 knee flexion degree (P<0.05). There were no significant differences between the muscle activities in healthy athletes at none of the knee flexion degrees. There were significant differences in the activity of vastus medialis obliques (P<0.05) and vastus lateralis longus (P<0.05) muscles at 45 degrees in comparison with muscle activities in each group in knee flexion degrees.

Conclusion: Electromyography activity of the vastus medialis obliques in healthy athletes during squat with isometric hip adduction at 45 knee flextion is greater than other degrees and in athletes with patellofemoral pain syndrome is greater than healthy athletes.

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Background and Objective: Anterior cruciate ligament (ACL) injury is one of the most serious knee injuries and it happens frequently during sports activities. Appropriate muscle activity is essential to provide joint stability and prevention of ACL injury. This study was performed to determine the effect of external focus instructions and functional training on basketball knee stabilization muscle activity timing.
Methods: This clinical trial study was performed on 48 healthy male basketball players of the Iranian Provincial League in the age range of 19-25 years. The basketball players were randomly divided into 3 groups of 16 people including control group, functional training group with feedback and group without feedback. The timing of the onset of electrical activity in the quadriceps, hamstrings, and Gluteus medius muscles of individuals before and after eight weeks in the single-leg landing task was examined by electromyography.
Results: There was a significant difference between the groups at the onset of Biceps Femoris, Gluteus Maximus, Gluteus Medius, Vastus Medialis, Vastus Lateralis, Rectus Femoris and Medial Hamstring muscles. There was a significant decrease in muscle activity onset between functional groups with and without feedback in compared to control group (P<0.05). There was no significant difference between the training groups at the beginning of the activity of the mentioned muscles.
Conclusion: Functional basketball training with and without feedback can optimize the activity time of the knee stabilizing muscles, during exercises such as jump-landing, increase the stability of the knee joint and possibly reduce ACL injury in athletes.

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Background and Objective: Proprioceptors of the plantar surfaces of the foot have less efficiency and the stimulation and reinforcement of them may be lead to reduction of falling risk. One of the methods to reinforce proprioceptor receptors in these individuals is using textured foot orthoses. The aim of this study was to evaluate the effect of textured foot orthoses on frequency spectrum of lower extremity muscles, stance time and comfort in individuals over age of 55 years during walking.
Methods: This quasi-experimental study was done on the 14 females and 14 males age ranged of 56-70 years with the ability to walk independently and with physical and mental health status. Subjects were compared during five conditions including without foot orthoses and using four foot orthoses (including small and large foot orthoses with two types of flexible and rigid), flexible and rigid large textured foot orthoses. The 8 electrodes were located on tibialis anterior, medial gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, semitendinisus, gluteus, and erector spinae in 3 lumbar vertebrae region muscles.
Results: Frequency content of tibialis anterior and vastus medialis was significantly increased in males than female (P<0.05). Vastus medialis frequency during walking with large foot orthoses was more than walking without foot orthoses (P<0.05). The comfort level was different during flexible large textured foot orthoses condition compared with flexible small textured foot orthoses condition (P<0.05). The stance time was not significant between all conditions.
Conclusion: Increased frequency content of the vastus medialis muscle can increase the absorption and decrease the vertical loading rate imposed on the foot, which in turn reduces the risk of injury of the lower limb in older adults.

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Background and Objective: Multiple sclerosis (MS) is one of the most common diseases of the central nervous system. MS is more common among women. Gait pattern dysfunction is a relevant symptom in these patients. This study was conducted to compare the electromyography activity of selected lower extremity muscles and the ellipse area of center of pressure during unplanned gait termination in female patients with multiple sclerosis and healthy individuals.
Methods: This case-control study was performed on 10 female patients with MS (classified based on the EDSS scale) and 10 healthy subjects matched for height, age and weight. Electromyography activity of rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), semitendinosus (SM), gastrocnemius medius (GM) and tibialis anterior (TA) and center of pressure (CoP) recorded using foot pressure system during unplanned gait termination. Subjects were instructed to stop, as soon as possible, in response to an auditory cue delivered when the heel strike phase accidentally.
Results: Vastus Lateralis muscle activity was significantly higher in able-bodied group than patients (P<0.05), whereas in the patient group gastrocnemius medius muscle activity increased significantly (P<0.05). Also, the ellipse area of center of pressure significantly reduced in MS group in compered to able-bodied group (P<0.05).
Conclusion: Increased gastrocnemius medius muscle activity in MS patients may be due to their attempt to slow down the displacement of the center of mass to limit the tibia forward translation consequently, attempting to control balance as a strategy to limit the ellipse area of center of pressure to prevent fall.

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Background and Objective: Genu varus is a deformity in frontal plane that in weight bearing position whiles the medial malleolus’s touch each other, the medial knee epicondyles far from each other. Genu varus is very prevalent in soccer players. This study was done to evaluate the effect of using knee brace and lateral wedge on muscular activity amplitude in male soccer players with genu varus during running.
Methods: This quasi-experimental study was done on 15 right-footed male soccer players with genu varus and 15 healthy soccer players. A wireless electromyography system with eight pairs of bipolar Ag/AgCl surface electrodes (20 mm center-to-center distance; input impedance of 100 MΩ; and common-mode rejection ratio of >110 dB) was used to record the activity of the tibialis anterior, gastrocnemius medialis, biceps femoris, semitendinosus, vastus lateralis, vastus medialis, and rectus femoris, and gluteus medius muscles of the right leg. Electromyography data were recorded by sampling rate of 1000 Hz in selected muscles during running at five conditions including: control, 10 degrees lateral wedge, 15 degrees lateral wedge, simultaneous using 30 degrees brace and 10 degrees lateral wedge, and simultaneous using 30 degree brace and 15 degrees lateral wedge.
Results: Treatment intervention had reduction effect on muscular amplitude of biceps femoris and vastus lateralis during push-off phase (P<0.05). Muscular amplitude of biceps femoris and vastus lateralis during loading phase was reduced due to Treatment intervention (P<0.05).
Conclusion: Simultaneous using of lateral wedge and knee brace reduce the electromyography activity of vastus lateralis and biceps femoris muscles. This reduction may be associated with passive support of knee brace that in result could decrease the external knee adductor mowment.

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Background and Objective: The use of lumbar braces affects kinetics and kinematics. This study evaluated the effects of two types of simple and sensor thoracolumbosacral braces on electromyography activity of selected muscles in patients with kyphosis during running.
Methods: This quasi-experimental study was performed on 15 males with kyphosis. The subjects performed a running task in three conditions: without braces, with simple braces, and with sensor braces. An 8-channel wireless electromyography system was used to record the activity of the muscles of the lower back and lower limbs during running.
Results: There was no significant difference between the tested conditions in response to loading, middle support and swing; however, during push-off, the median frequency of the gastrocnemius muscle was greater when running with a simple brace compared with running without brace (P<0.05). In addition, the median frequency of the semitendinosus muscle was significantly higher while running with sensor brace compared with simple brace (P<0.05).
Conclusion: Using brace, especially sensor brace, can improve muscle activities in patients with kyphosis.

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Background and Objective: Genu varum is a lower limb deformity. This study was done to evaluate the effects of shoe aging on the general and directional contraction of ankle muscles during running in females with genu varum.
Methods: This case-control study was done on 30 female students (15 individuals with genu varum degree 2 and 15 healthy individuals) using new and old sneakers for 6 months in the sports biomechanics laboratory of the University of Mohaghegh Ardabili, Iran. Each subject was given a new pair of sneakers, and after the initial data collection, the subjects were asked to use them in their daily activities for at least an hour a day for 6 months. Electrical muscle activity was recorded using surface electromyography.
Results: There was no significant difference in the general and directional contractions if ankle muscles during the running phases.
Conclusion: Shoe aging has no effect on ankle joint co-contractions.
 

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Background and Objective: Long-standing groin pain (LSGP) is a common injury in ball games. This study aimed to compare the electrical activity of selected lumbopelvic-hip muscles during a single leg jump-cut maneuver in football players with LSGP and healthy players.
Methods: In this case-control study, 32 football players were divided into two groups: LSGP (n=16) and healthy (n=16). A force plate was used to determine the heel-contact and heel-off moment. The ground reaction forces and the average of three trials of the electrical activity of selected lumbopelvic-hip muscles during a single leg jump-cut maneuver were recorded bilaterally.
Results: At the heel-contact moment, the rectus abdominis and adductor longus muscles on the dominant side and the multifidus muscle on the opposite side showed significantly higher activity in the LSGP group compared to the healthy group (P<0.05). Similarly, at the peak of the vertical reaction force, the rectus abdominis and adductor longus muscles on the dominant side and the multifidus and gluteus medius muscles on the opposite side were significantly more active in the LSGP group (P<0.05). At the toe-off moment, the internal oblique, adductor longus, and gluteus medius muscles on the dominant side and the internal oblique, multifidus, and gluteus medius muscles on the opposite side were also more active in the LSGP group compared to the control group (P<0.05).
Conclusion: Long-standing groin pain causes changes in the electrical activity of muscle groups during different phases of the single-leg jump-cut maneuver, leading to increased dynamic stability and possibly an increased risk of overuse injuries, chronic injuries, economic consequences, and exclusion from sports activities.
 

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Background and Objective: Fatigue is considered one of the factors effective in changing the electrical activity of muscles so that it is directly linked to increasing the potential of muscular injuries and functional decline in various stages of sports. The present study was conducted to evaluate the frequency of electrical activity of lower limb muscles before and after fatigue during running in individuals with a history of coronavirus disease 2019 (COVID-19) compared to healthy individuals.
Methods: This quasi-experimental research was conducted on 14 women with a history of COVID-19 over the past two months (the experimental group) and 14 women without a history of COVID-19 (the control group) with an age range of 18-30 years using the convenience sampling method in the city of Ardabil. The fatigue protocol started using a sophisticated treadmill at a speed of 6 km/h, and the treadmill speed was accelerated by 1 km/h every 2 minutes. The Borg’s Rating of Perceived Exertion (RPE) 6-20 Scale was used to determine the participants’ final moment of fatigue. A steady-state running fatigue protocol ended at a score higher than 17 on the Borg’s RPE 6-20 scale or 80% of maximum heart rate. Electromyography data were analyzed using the data LITE biometrics software before and after the fatigue protocol.
Results: There was a statistically significant increase in the frequency of the electrical activity of the vastus lateralis (VL) muscle between the post-test of the control group and the experimental group (d=0.410, P=0.035). The pretest-posttest difference of the frequency of electrical activity of the VL muscle after fatigue compared to before fatigue during the loading response phase during running had a statistically significant increase in the experimental group than in the control group (d=0.602, P=0.016). The frequency of the activity of the semitendinosus muscle increased after fatigue compared to before fatigue during the mid-stance phase of running (d=0.261, P=0.005). The impact of fatigue on the frequency of the activity of the VL muscle during the push-off phase of running was statistically significant (d=0.140, P=0.049). The frequency of the activity of the VL muscle increased after fatigue compared to before fatigue during the push-off phase of running in the experimental group.
Conclusion: The increased electrical activity of the lower limb muscles in various phases of running after fatigue in individuals with a history of COVID-19 can be attributed to decreased neuromuscular coordination.

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Background and Objective: Ankle instability is one of the most prevalent injuries among athletes. Biomechanical changes, sensory-motor impairments, and neuromuscular disorders have been reported in individuals with chronic ankle instability. The present study was conducted to compare the electrical activity of selected leg and thigh muscles during performing functional movements in female athletes with and without chronic ankle instability.
Methods: This case-control research was conducted on 40 female athletes in the age range of 18-30 years in two groups, including the case (with ankle instability, n=20) and healthy control (without ankle instability, n=20) groups. The electrical activity of selected leg and thigh muscles was recorded during three functional patterns, i.e., the overhead squat, overhead squat with heel lift, and single-legged squat, by electromyography apparatus. The investigated muscles consisted of the gastrocnemius medialis (GM) muscle, the gastrocnemius lateralis (GL) muscle, the tibialis anterior (TA) muscle, the fibularis longus (FL) muscle, the soleus (SO) muscle, the vastus lateralis (VL) muscle, the vastus mediali (VM) muscle, and the biceps femoris (BF) muscle.
Results: The activity of the VM, VL, BF, and TA muscles in the single-legged squat and the activity of the VM, VL, BF, SO, and TA muscles in the overhead squat showed a statistically significant increase in the case group compared to the control group (P<0.05). The highest difference in the muscle activity of the two groups was observed in the overhead squat with heel lift movement, which in this movement, except for the GL muscle, there was a statistically significant increase among all other muscles (P<0.05).
Conclusion: Functional movements culminate in increasing the electrical activity level of leg and thigh muscles in female athletes with ankle instability.