The role of short latency reflexes in the motor control of quadriceps in humans

A total of 34 volunteer subjects participated in a series of experiments. These experiments were designed to investigate the characteristics and functional role of an excitatory reflex pathway linking the pretibial muscles to quadriceps (CPQ reflex). The CPQ reflex was evoked by low intensity electrical stimulation of common peroneal nerve (CPN) at the level of caput fibulae. The reflex was observed in averaged EMG of rectus femoris (RF) and vastus medialis (VM). Voluntary contraction of Q was needed to reveal the reflex and no responses were detected in the recordings from relaxed muscle. The peak to peak amplitude and area of the responses were measured in non-rectified and rectified averaged EMG. The stability of the CPQ reflex was investigated in the first series of experiments. Nine trials were distributed across three sessions with the perceptive caution to keep the stimulating and recording conditions similar. A constant contraction (20% of maximum voluntary contraction) in quadriceps was maintained by the subjects during the tests. Constant stimulus intensity to evoke maximum reflex was applied in all trials. The result suggested that the peak- peak amplitude and the threshold of the CPQ reflex was extremely consistent with-in session and between sessions of the experiment. Graded stimulus intensities between 0.9 and 1.5xmotor threshold (MT) in tibialis anterior (TA) were applied to CPN in the second series of experiments while the quadriceps (Q) was contracted at a level of 20% of maximum voluntary contraction (MVC). The electrical stimulation of the CPN evoked excitatory responses in all the subjects with a latency of about 30+/-2.1ms (mean +/- ISD). The responses were regarded significant with amplitude beyond 2 standard deviation (SD) of the mean. The mean was calculated from 30ms pre-stimulus averaged EMG. In three subjects making contractions at 20% of MVC significant CPQ reflexes were recorded with stimulation at an intensity of 0.9xMT. The extrapolation of the pooled data also suggests an electrical threshold of around O.8xMT. This low threshold and the short latency strongly suggest the participation of group I afferent types in this reflex pathway. Maximum response was evoked by stimulus intensity of about 1.3XMT. The changes in the reflex magnitude in different knee and hip joint positions were also investigated in another series of experiments. The knee positioning was shown to affect the reflex amplitude in all subjects. The reflex became smaller towards more flexed position of the knee joint. Two patterns of reaction were recognised among the subjects. One group showed a very significant and abrupt reduction in the magnitude of the reflex after 1

The effect of Hand Positions on the Vibration Platform on Shoulder Muscle: Strength and Proprioception

Introduction: To compare the short-term effect of one session of Whole Body Vibration (WBV) in two positions of hand on the vibration platform on isokinetic strength of Rotator cuff and shoulder proprioception. Method and Materials: A total of 60 young healthy students participated in the present study completing three positions of control (no vibration), push up with straight elbow, and push up with semi flexed elbow (two vibration positions) running for two minutes with 30-minute rest between the positions. After control position, vibration positions were tested randomly on the Power Plate device (F: 30Hz and low amp). The isokinetic strength of Rotator Cuff and the absolute angular error in joint repositioning test in 3 target angles of 0°, 45°, and 90° were measured using Kin-Com dynamometer before and after each position. Then, the results of the three positions were compared together. Results: Despite decrease in dynamic strength of medial rotators after three positions, this decrease was observed to be significantly less in push up with straight elbow compared with that in control position (P=0.03). Also, there was a significant difference in Concentric MPT of Lateral Rotators between the three positions with control position revealing the greatest decline in lateral rotators strength (P=0.01) and push up with straight elbow was found to be more effective than semi flexed elbow (P=0.03). Moreover, There was a significant improvement in angle repositioning for the three positions; however, it was considerably more only in zero degree in the push up with semi flexed elbow position as compared with that in the control position (P=0.03). No significant changes were found between push up with straight elbow and semi flexed elbow positions, either. Conclusions: The two different hand positions did not alter the effect of vibration on neuromuscular system in young and healthy individuals. Although a single session of WBV had a positive effect on the neuromuscular system of the young healthy participants, the two positioning did not make a significant difference.Key words: Whole body vibration training, shoulder muscle strength, proprioceptio

Comparison of Vertical Ground Reaction Force during Walking in Patients with Sacroiliac Joint Pain and Healthy People

Introduction: Vast majority of the muscular disorders are known to be related to Sacroiliac joint. Due to the main role played by Sacroiliac joint, the current study was conducted to examine the effect of the pain among the people suffering from Sacroiliac joint pain on the vertical ground reaction force parameter. Materials and Methods: This case control study was carried out on 19 participants with Sacroiliac joint pain, VAS 3-5 and average age of 27±5.7, and 19 subjects with normal health conditions and average age of 29±7.6. The relevant data were collected while the participants were asked to walk at their desired speed over the force plate located on their way. Later on, all the parameters of vertical ground reaction force in the stance phase were recorded. At the end, data collected were compared by independent T-test in SPSS. Results: The results of the study revealed that participants distributed in control (healthy individuals) and experimental (individuals with Sacroiliac joint pain) groups were significantly different regarding the parameters of time and speed required to reach the stage of weight transition to the heel. Discussion: Considering the findings, it can be concluded that some compensatory strategies were adopted by the individuals with Sacroiliac joint- related problems in order to decrease the force that body experienced during walking.Key words: Force Plate, Sacroiliac Joint, Vertical Ground Reaction Forc

Pedobarography of the coper and non-coper ACL-deficient knee subjects during single and double leg stance

Introduction: Biomechanical studies have frequently shown a close relationship between the knee and ankle joint movements. ACL-deficiency may change the foot pressure pattern of the ACL-deficient knee subjects. The current study aimed to investigate the pattern of the foot pressure in coper and non-coper ACL-deficient knee subjects during standing on one and both feet. Methods and Materials: This case-control study was conducted on 12 coper and 12 non-coper ACL-deficient knee subjects and 25 age-sex matched healthy subjects. The subjects were tested barefoot during single and bilateral standing on the platform of a Zebris pedobarograph tool. The outcome measures included the measurements of the pressures of each part of the foot during the tests. Results: The results showed a significantly decreased total pressure only between the non-coper and control groups during double leg stance test. In terms of the forefoot pressure, a significant increased pressure was shown only in the non-coper ACL-deficient knee subjects during both single and double leg stance tests (P<0.05). In both test conditions, the coper ACL-deficient knee subjects showed forefoot and hind foot pressures very close to the control group (P>0.05). Conclusion: This study revealed marked changes following ACL-deficiency mainlyin non-coper ACL-deficient knee subjects. The increased forefoot pressure in non-coper ACL-deficient knee subjects was probably due to the forwarded line of gravity in these patients aligned with their base of support to keep their knees more stable. Further studies are needed to verify the differences between the male and female ACL-deficient knee subjects.Keywords: Coper/non-coper ACL-deficient knee subjects; Stability; Pedobarograph; Foot pressure system; Postural contro

The Evaluation of Electromyography Biofeedback on Proprioception and Balance in Healthy Young Athletes

Introduction: We evaluated the effect of electromyography biofeedback on proprioception and functional balance in healthy young athletes. Materials and Methods: In this clinical trial, 24 athletes were randomly divided into two study (n=12) and control (n=12) groups. The study group received rehabilitation exercises, including one-foot standing, squatted standing, and isometric contraction of quadriceps muscle at different knee angles, including 30, 45, and 90 degrees of knee flexion along with electromyography biofeedback. The control group received only rehabilitation exercises without electromyography biofeedback. Exercises were performed by both groups for a 4-week period in three sessions per week. Functional balance and proprioception before and after exercises were measured using the star excursion balance test and a system consisting of digital photography non-reflective markers, respectively. The data of the center of pressure and time of vertical ground reaction force using a force plate was also collected to evaluate static balance and dynamic balance, respectively. Results: The absolute error in knee joint reconstruction for 30° (P=0.005), 45° (P=0.001), and 90° (P=0.033) angles significantly decreased after the intervention in the study group compared to the control group. Star excursion balance test scores in all directions did not show any significant differences between the two groups (P>0.05), except for the anterior-lateral direction (P=0.03). Moreover, all variables related to static and dynamic balance did not show a significant difference between two the groups after the interventions (P>0.05). Conclusion: The electromyography biofeedback intervention can probably be used as a rehabilitation protocol in recovering and healing proprioception injuries resulting from sports injuries

Measurement of superficial and deep abdominal muscle thickness: an ultrasonography study

BACKGROUND: Real-time ultrasound imaging is a valid method in the field of rehabilitation. The ultrasound imaging allows direct visualization for real-time study of the muscles as they contract over the time. Measuring of the size of each abdominal muscle in relation to the others provides useful information about the differences in structure, as well as data on trunk muscle activation patterns. The purpose of this study was to assess the size and symmetry of the abdominal muscles at rest in healthy adults and to provide a reference range of absolute abdominal muscle size in a relatively large population. METHOD: A total 156 healthy subjects with the age range of 18–44 years were randomly recruited. The thickness of internal oblique, external oblique, transverse abdominis, and rectus abdominis muscles was measured at rest on both right and left sides using ultrasound. Independent t test was used to compare the mean thickness of each abdominal muscle between males and females. Differences on side-to-side thicknesses were assessed using paired t test. The association between abdominal muscle thicknesses with gender and anthropometric variables was examined using the Pearson correlation coefficient. RESULTS: A normal pattern of increasing order of mean abdominal muscle thickness was found in both genders at both right and left sides: transverse abdominis < external oblique < internal oblique < rectus abdominis. There was a significant difference on the size of transverse abdominis, internal oblique, and external oblique muscles between right and left sides in both genders. Males had significantly thicker abdominal muscles than females. Age was significantly correlated with the thickness of internal oblique, external oblique, and rectus abdominis muscles. Body mass index was also positively correlated with muscle thickness of rectus abdominis and external oblique. CONCLUSIONS: The results provide a normal reference range for the abdominal muscles in healthy subjects and may be used as an index to find out abnormalities and also to evaluate the effectiveness of different interventions

Cupping: a reasonable choice for attenuating morphine withdrawal symptoms in Wistar rats

Background: Nowadays, the sedative drugs are the main treatments to attenuate the opioid withdrawal symptoms. However, physical therapies are found a safe alternative treatment without any serious adverse effects. This study aimed to evaluate the effects of cupping treatment on the morphine withdrawal symptoms in rats.Methods: Eighty rats were divided into two main groups; treated with morphine or saline, and each group was also divided to cupping and sham cupping subgroups (with single or daily treatment). Injection of morphine and saline were done in the morphine and saline groups twice a day for nine days. On the ninth day, the naloxone was administered and the withdrawal symptoms including jumping, rearing, body grooming, abdominal writing, and wet-dog shaking were recorded for 60 minutes. Cupping or sham cupping was applied on the GV14 once before or daily after withdrawal induction in each group.Results: The results revealed that a single cupping before the withdrawal induction significantly attenuated the withdrawal symptoms in the morphine group (p<0.01).But, the daily cupping failed to decrease the withdrawal symptoms in this group. The results also indicated that the daily cupping in the saline group increased the naloxone-induced withdrawal symptoms significantly (p<0.01).Conclusions: Single session cupping before the withdrawal induction could decreased the withdrawal symptoms. This finding might be related to the modulation of GABAergic system

The Relationship between Neural Properties, Mechanical Properties,Functional Outcomes, and Clinical Parameters in Spastic Chronic Stroke Patients: An Observational Study

Background: Subsequent to spasticity, which is a positive impairment of stroke,neural and mechanical changes often occur in paretic muscles, affecting muscle function. The aim of this study was to find more accurate indices, which could affect decisions about spasticity treatment by investigating the relationships among neural, mechanical, functional outcomes, and clinical parameters in spastic chronic stroke patients.Methods: This cross-sectional study investigated 45 spastic chronic stroke patients. Clinical assessments were conducted using the Modified Modified Ashworth Scale (MMAS). Neural properties including H-reflex latency and Hmax/Mmax ratio were acquired. Mechanical properties including fascicle length,pennation angle, and thickness of spastic medial gastrocnemius muscle were evaluated. Functional outcomes were evaluated by the Timed Up and Go (TUG) test and Timed 10-Meter Walk Test (10-m WTT). Spearman’s rank correlation analysis in SPSS version 22.0 was used to find correlations between parameters.Results:A low negative correlation was determined between MMAS and H-reflex latency (r=-0.320, P=0.032). MMAS score had a low significant relationship with pennation angle (r=0.296, P=0.049) and thickness of muscles (r=0.389,P=0.008). However, no significant correlation was found between MMAS and functional outcomes.Conclusion:Based on these findings, it is clear MMAS can partly identify changes in neural and mechanical properties of spastic muscles

A Survey Over The Effect Of Imaginary Exercises On Activation Of Shoulder Muscles

Background and Aim: The present study was conducted to identify the effect of imaginary exercises on electrical activity of the shoulder muscles.Materials and Method: Twenty three healthy subjects (17 females and 6 males) with no history of shoulder injury participated in this quasi experimental study. Surface EMG was recorded by bipolar electrodes that were applied over the supraspinatus, infraspinatus, posterior deltoid, middle deltoid, anterior deltoid and pectoralis major. Subjects performed 6 imaginary exercises including imagination of flexion, extension, abduction, adduction, external rotation and internal rotation. The amount of RMS obtained in EMG while exercising was compared with the one obtained at rest.Results: Performing the imaginary exercises resulted in significant activation (P < 0.01) of the shoulder muscles. In the case of the supraspinatus muscle, a significant difference (P < 0.05) was found between exercise type and intensity of activation but no significant value was seen for infraspinatus muscle. In flexion, abduction, adduction & internal rotation imaginary exercises, correlation between muscles activation was also statistically significant (P<0.01).Conclusions: Imaginary exercises can be used as alternative means and the first step for shoulder muscles rehabilitation specialty when the movement of the joint is contradicted