Search for: electromyography
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    Effect of fatigue on torque output and electromyographic measures of trunk muscles during isometric axial rotation

    , Article Archives of Physical Medicine and Rehabilitation ; Volume 84, Issue 3 SUPPL. 1 , 2003 , Pages 374-381 ; 00039993 (ISSN) Ng, J. K. F ; Parnianpour, M ; Richardson, C. A ; Kippers, V ; Sharif University of Technology
    W.B. Saunders  2003
    Objectives: To examine the changes in torque output resulting from fatigue, as well as changes in electromyographic measures of trunk muscles during isometric axial rotation and to compare these changes between directions of axial rotation. Design: Subjects performed fatiguing right and left isometric axial rotation of the trunk at 80% of maximum voluntary contraction while standing upright. Setting: A rehabilitation center. Participants: Twenty-three men with no history of back pain. Interventions: Not applicable. Main Outcome Measures: Surface electromyographic signals were recorded from 6 trunk muscles bilaterally. The primary torque in the transverse plane and the coupling torques in... 

    Reliability of electromyographic and torque measures during isometric axial rotation exertions of the trunk

    , Article Clinical Neurophysiology ; Volume 114, Issue 12 , 2003 , Pages 2355-2361 ; 13882457 (ISSN) Ng, J. K.-F ; Parnianpour, M ; Kippers, V ; Richardson, C. A ; Sharif University of Technology
    Elsevier Ireland Ltd  2003
    Objective: The aim of the present study was to investigate the between-days reliability of electromyographic (EMG) measurement of 6 bilateral trunk muscles and also the torque output in 3 planes during isometric right and left axial rotation at different exertion levels. Methods: Ten healthy subjects performed isometric right and left axial rotation at 100, 70, 50 and 30% maximum voluntary contractions in two testing sessions at least 7 days apart. EMG amplitude and frequency analyses of the recorded surface EMG signals were performed for rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus bilaterally. The primary torque in the... 

    Modeling of Human Quadriceps Muscles and Design of a Magnetorheological Fluid-based Muscle Strengthening Device

    , M.Sc. Thesis Sharif University of Technology Seifi, Mohammad Mahdi (Author) ; Farahmand, Farzam (Supervisor) ; Behzadi Poor, Saeed (Supervisor)
    The Quadriceps Muscle as one of the major muscles of the human body plays a key role in knee function. Strengthening of this muscle is recommanded to prevent knee pain and even cure some diseases. Many believe that by strengthening the medial part with respect to the lateral part of the quadriceps muscles, patellofemoral pain syndrome can be prevented or treated. In this regard, a muscle strengthening system, based on magneticorheological brake is designed which provides isometric, isotonic and isokinetic exercise of knee joint and also enables the selective muscle strengthening. Beforehand a musculoskeletal model of lower extremity is developed in OpenSim software, capable to estimate force... 

    A comprehensive evaluation of spine kinematics, kinetics, and trunk muscle activities during fatigue-induced repetitive lifting

    , Article Human Factors ; 2021 ; 00187208 (ISSN) Kazemi, Z ; Mazloumi, A ; Arjmand, N ; Keihani, A ; Karimi, Z ; Ghasemi, M. S ; Kordi, R ; Sharif University of Technology
    SAGE Publications Inc  2021
    Objective: Spine kinematics, kinetics, and trunk muscle activities were evaluated during different stages of a fatigue-induced symmetric lifting task over time. Background: Due to neuromuscular adaptations, postural behaviors of workers during lifting tasks are affected by fatigue. Comprehensive aspects of these adaptations remain to be investigated. Method: Eighteen volunteers repeatedly lifted a box until perceived exhaustion. Body center of mass (CoM), trunk and box kinematics, and feet center of pressure (CoP) were estimated by a motion capture system and force-plate. Electromyographic (EMG) signals of trunk/abdominal muscles were assessed using linear and nonlinear approaches. The L5-S1... 

    EMG activity normalization for trunk muscles in subjects with and without back pain

    , Article Medicine and Science in Sports and Exercise ; Volume 34, Issue 7 , 2002 , Pages 1082-1086 ; 01959131 (ISSN) Ng, J.K.-F ; Kippers, V ; Parnianpour, M ; Richardson, C. A ; Sharif University of Technology
    American College of Sports Medicine  2002
    Purpose: The aims of the present study were to examine electromyographic (EMG) activity of six bilateral trunk muscles during maximal contraction in three cardinal planes and to determine the direction of contraction that gives maximal activation for each muscle, both for healthy subjects and back-pain patients. Methods: Twenty-eight healthy subjects and 15 back-pain patients performed maximum voluntary contractions in three cardinal planes. Surface EMG signals were recorded from rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum, and multifidus bilaterally. Root mean square values of the EMG data were calculated to quantify the amplitude of EMG... 

    A novel stability-based EMG-assisted optimization method for the spine

    , Article Medical Engineering and Physics ; Volume 58 , 2018 , Pages 13-22 ; 13504533 (ISSN) Samadi, S ; Arjmand, N ; Sharif University of Technology
    Elsevier Ltd  2018
    Traditional electromyography-assisted optimization (TEMG) models are commonly employed to compute trunk muscle forces and spinal loads for the design of clinical/treatment and ergonomics/prevention programs. These models calculate muscle forces solely based on moment equilibrium requirements at spinal joints. Due to simplifications/assumptions in the measurement/processing of surface EMG activities and in the presumed muscle EMG-force relationship, these models fail to satisfy stability requirements. Hence, the present study aimed to develop a novel stability-based EMG-assisted optimization (SEMG) method applied to a musculoskeletal spine model in which trunk muscle forces were estimated by... 

    Generalizability of trunk muscle EMG and spinal forces

    , Article IEEE Engineering in Medicine and Biology Magazine ; Volume 20, Issue 6 , 2001 , Pages 72-81 ; 07395175 (ISSN) Sparto, P. J ; Parnianpour, M ; Sharif University of Technology
    The generalizability of trunk muscle EMG and spinal loading estimates obtained from an EMG-assisted biomechanical model was assessed over three occasions and three repetitions. The greatest sources of variability consisted of the intersubject differences and the interaction between subject and occasion. The ID (reliability coefficient) was less for trunk muscle activity compared with estimates of anteroposterior shear force, compression force, and gain computed from the biomechanical model. In order to obtain an ID of 0.8, we recommend five testing occasions for submaximal EMG measurements and three testing occasions for biomechanical estimates. Reproducible estimates of maximal trunk... 

    A Novel Stability-based EMG-assisted Model of the Lumbar Spine to Estimate Trunk Muscle Forces and Spinal Loads in Various Static Activities

    , M.Sc. Thesis Sharif University of Technology Samadi, Soheil (Author) ; Arjmand, Navid (Supervisor)
    The spine like every other mechanical pillar, is exposed to buckling and loss of stability. While existing biomechanical models emphasize the pressure force on the disk as the main cause of injury, there is also a possibility of local buckling phenomenon in vertebral discs. Because of the prevalence and high cost of lower back pain, it is essential to evaluate the forces carried by disks and lumbar muscles during occupational activities more accurately. In this regard, hybrid EMG-assisted optimization (EMGAO) approaches are most common methods for estimation of spinal loads. These models, not only use EMG data to be physiologically creditable, but also satisfy equilibrium requirements at all... 

    A Hyrid EMG-optimization Based Model of the Lumbar Spine to Estimate Muscle Forces in Different Tasks

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Yousef (Author) ; Arjmand, Navid (Supervisor)
    Low back pains (LBP) are prevalent and costly. One of the important factors causing LBP is excessive axial compression and shear forces that are applied on the intervertebral discs during different activities. Due to lack of direct in vivo measurement methods for estimating these loads, musculoskeletal biomechanical models have been emerged as indispensable tools under various activities. Different biomechanical models have been suggested to estimate muscle forces and spinal loads base on optimization, EMG and hybrid (EMG assisted optimization, EMGAO) methods. Although there have been a number of studies on the differences between various optimization and EMG-based methods, there has been no... 

    Control of Exoskeletal System in Coordination with Upper Extremity System

    , M.Sc. Thesis Sharif University of Technology Ghassemi, Mohammad (Author) ; Jahed, Mehran (Supervisor)
    With technological advances in fabrication and control of prosthesis and assistive devices the importance of such systems has increased drastically. On the other hand the appropriate coupling of these devices, especially the exoskeletal systems with the upper or lower extremities is of immense importance as it is an integral part of the control system. In particular, the control strategy and its ability to adapt the exoskeletal system with the existing and physiological functionality of the user, is an integral part of the system requirement. In the controller implementation, a number of methods are proposed including using the excitation signal, similar to the existing neuromuscular system.... 

    Musculoskeletal Modeling and Analysis of Gait Pattern of Paraplegic Patients

    , Ph.D. Dissertation Sharif University of Technology Arab Baniasad, Mina (Author) ; Farahmand, Farzam (Supervisor) ; Zohoor, Hassan (Supervisor)
    Spinal cord injury (SCI) is one of the most important causes of disability in the youth and costs enormous expenses for the government. Most SCI subjects use wheelchair as their main way of locomotion while standing and walking can benefit them in various aspects. The role of lower extremity muscles has been investigated in paraplegic gait with active orthoses or in partial weight support condition. However, due to the large expenses of active orthoses, their application have been limited to clinical trials and yet most SCI individuals use traditional AFO and KAFO for walking. The role and significance of trunk and upper extremity muscles (TUEM) has been investigated only in balance... 

    Design and Implementations of an Intelligent Control System for a Lower Limb Extremity Robot Based on Human-Robot Interaction and Muscular Activity to Reduce Human Energy Consumption

    , M.Sc. Thesis Sharif University of Technology Talatian, Hamid Reza (Author) ; Vosoughi, Gholamreza (Supervisor) ; Jahed, Mehran (Co-Supervisor)
    With advancements in control and robotics technology, wearable robots have gained multiple applications in rehabilitation and power augmentation. In robots developed for power augmentation purposes, human decisions are combined with robot power to enhance the human ability to perform various activities, such as carrying heavy loads and walking for a long time. In cases where robots are designed to help humans to carry heavy loads, the robot control strategy should minimize the human-robot interaction forces. In this case, heavy loads influence the robot and the user no longer need to use more energy than normal walking, and the robot works following human intentions. Where the robot works to... 

    Investigation on a developed wearable assistive device (WAD) in reduction lumbar muscles activity

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 25, Issue 3 , 2013 ; 10162372 (ISSN) Heydari, H ; Hoviattalab, M ; Azghani, M. R ; Ramezanzadehkoldeh, M ; Parnianpour, M ; Sharif University of Technology
    A new wearable assistive device (WAD) was developed to decrease required force on the lumbar spine in static holding tasks. In order to obtain moments on lumbar spine in two conditions, with and without WAD, a biomechanical static model was used for estimation of external moments on lumbar spine. The results of biomechanical models indicated that there was a reduction in the lumbar moment ranging from 20% to 43% using WAD depending on the load and flexion angle. A total of 15 male healthy subjects were tested to experimentally verify the predicted reduction of external moments on the spine by wearing WAD. Normalized electromyography (EMG) of the right and left lumbar and thoracic erector... 

    Differences in muscle synergies between healthy subjects and transfemoral amputees during normal transient-state walking speed

    , Article Gait and Posture ; Volume 76 , February , 2020 , Pages 98-103 Mehryar, P ; Shourijeh, M. S ; Rezaeian, T ; Khandan, A. R ; Messenger, N ; O'Connor, R ; Farahmand, F ; Dehghani Sanij, A ; Sharif University of Technology
    Elsevier B. V  2020
    Background: Lower limb amputation is a major public health issue globally, and its prevalence is increasing significantly around the world. Previous studies on lower limb amputees showed analogous complexity implemented by the neurological system which does not depend on the level of amputation. Research question: What are the differences in muscle synergies between healthy subjects (HS) and transfemoral amputees (TFA) during self-selected normal transient-state walking speed? Methods: thirteen male HS and eleven male TFA participated in this study. Surface electromyography (sEMG) data were collected from HS dominant leg and TFA intact limb. Concatenated non-negative matrix factorization... 

    Introducing a new multi-wavelet function suitable for sEMG signal to identify hand motion commands

    , Article 29th Annual International Conference of IEEE-EMBS, Engineering in Medicine and Biology Society, EMBC'07, Lyon, 23 August 2007 through 26 August 2007 ; 2007 , Pages 1924-1927 ; 05891019 (ISSN) ; 1424407885 (ISBN); 9781424407880 (ISBN) Khezri, M ; Jahed, M ; Sharif University of Technology
    In recent years, electromyogram signal (EMG) feature selection, based on wavelet transform, has received considerable attention. This study introduces a new multiwavelet function for surface EMG (sEMG) signal intended for tasks that involve hand movement recognition. To create the new wavelet function, several types of well known mother wavelet were exploited and through their integration the proposed mother wavelet was generated. The proposed wavelet function closely reproduced the characteristics of the EMG signal, while increasing the recognition accuracy of hand movements. We used eight unique classes of hand motions and considered the ability of various mother wavelets and the proposed... 

    Improvement and Manufacture of The Wearable Assistive Device to Support Spine in Static Holding Tasks

    , M.Sc. Thesis Sharif University of Technology Heydari, Hadi (Author) ; Parnianpour, Mohammad (Supervisor) ; Hoviattalab, Maryam (Supervisor)
    One of the most common diseases associated with musculo-skeletal ailment is low back pain which is epidemic among general public so that billions of dollars is spent annually to treat this disease. There are back pain prevention strategies include training on correct lifting, ergonomic tool design, and industrial automation amongst others. In recent years, assistive devices have also been used to prevent back pain. There are assistive devices that can be installed on the body and significantly have reduced forces required for Erector Spinae muscle and Lumbar moments. In this research, at first the anatomy of the spine and muscles and method of processing Electromyography (EMG) of muscles... 

    Comparison of Stabilization Exercise and General Exercise on the Spinal Stability of Non-specific Low Back Pain Patients Using an EMG-based Biomechanical Model

    , M.Sc. Thesis Sharif University of Technology Ghezelbash, Farshid (Author) ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohamad (Supervisor)
    Low back pain is one of the musculoskeletal diseases which is an important issue for general health of society in both quality of life and costs. Most of the clinical instructions employ exercise as a clinical treatment in order to cure chronic low back pain. General and core stability exercises are of common prevalence, however, there are disputes about the effectiveness of these exercises in the literature. The aim of this study is to answer the question whether stabilizer exercise can significantly alter the stability of vertebral column in comparison with general exercises. Hence, experiments have been designed and conducted. The participants have been divided to two group. Within six... 

    Studying the Effect of Motor Learning on Muscle Synergies During Balance

    , M.Sc. Thesis Sharif University of Technology Karami, Hojat (Author) ; Farahmand, Farzam (Supervisor) ; Baniasad, Mina (Co-Supervisor)
    Our body makes use of many degrees of freedom in muscle space. As a result, there are many solutions for activating muscles when performing a specific task. “how our central nervous system (CNS) controls abundant degrees of freedom?” has been a popular question for researchers in the field of motor control since Bernstein. The existence of muscle synergies is one of the proposed hypothesis, and there is experimental evidence that they are encoded in our CNS as building blocks. The aim of this study is to study the effect of training on the number, structures, and activation profiles of muscle synergies that are used for maintaining balance. For this purpose, electromyography data from 28... 

    Short Time Effect of Auxetic Shoe on Kinematics and Kinetics of Vertebral Column During Drop Vertical Jump

    , M.Sc. Thesis Sharif University of Technology Rahmani Dahaghani, Mostafa (Author) ; Nourani, Amir (Supervisor) ; Arjmand, Navid (Supervisor)
    Investigating the influence of shoes on variables of human biomechanics is of a high importance. The purpose of this study was to examine the effect of auxetic Nike Free RN shoe on kinematics and kinetics of human body. It was asked from 11 healthy male to perform drop vertical jump in three conditions: with auxetic Nike Free RN, with conventional shoe and barefoot. 3D Cartesian positions of the markers, which were stuck to the subjects’ bodies, were recoeded using Vicon camera system. Ground reaction force and its center of pressure of each foot captured using two force plates. Moreover, activation of rectus abdominis, longissimus, iliocostalis lomburom and multifidus were recorded using... 

    The effect of exertion level on activation patterns and variability of trunk muscles during multidirectional isometric activities in upright posture

    , Article Spine ; Volume 35, Issue 11 , May , 2010 , Pages E443-E451 ; 03622436 (ISSN) Talebian, S ; Mousavi, S. J ; Olyaei, G. R ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
    STUDY DESIGN.: An experimental design to investigate activation patterns of trunk muscles during multidirectional exertions. OBJECTIVES.: To evaluate trunk muscle activation patterns in varying directions and moment magnitudes during an isometric task, and to investigate the effects of angle and level of isometric exertion on the electromyography (EMG) variability of trunk muscles in upright posture. SUMMARY OF BACKGROUND DATA.: Few studies have investigated trunk muscle activation patterns in multidirectional exertions with different moment magnitudes. METHODS.: A total of 12 asymptomatic male subjects were participated in the study. The EMG activity of 10 selected trunk muscles was...