Search for: abdominal-muscles
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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... 

    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... 

    Relative efficiency of abdominal muscles in spine stability

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 11, Issue 3 , 2008 , Pages 291-299 ; 10255842 (ISSN) Arjmand, N ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
    Using an iterative kinematics-driven nonlinear finite element model, relative efficiency of individual abdominal muscles in spinal stability in upright standing posture was investigated. Effect of load height on stability and muscle activities was also computed under different coactivity levels in abdominal muscles. The internal oblique was the most efficient muscle (compared with the external oblique and rectus abdominus) in providing stability while generating smaller spinal loads with lower fatigue rate of muscles. As the weight was held higher, stability deteriorated requiring additional flexor-extensor activities. The stabilising efficacy of abdominal muscles diminished at higher... 

    The effects of intra-abdominal pressure on the stability and unloading of the spine

    , Article Journal of Mechanics in Medicine and Biology ; Volume 12, Issue 1 , 2012 ; 02195194 (ISSN) Mokhtarzadeh, H ; Farahmand, F ; Shirazi Adl, A ; Arjmand, N ; Malekipour, F ; Parnianpour, M ; Sharif University of Technology
    In spite of earlier experimental and modeling studies, the relative role of the intra-abdominal pressure (IAP) in spine mechanics has remained controversial. This study employs simple analytical and finite element (FE) models of the spine and its surrounding structures to investigate the contribution of IAP to spinal loading and stability. The analytical model includes the abdominal cavity surrounded by muscles, lumbar spine, rib cage and pelvic ring. The intra-abdominal cavity and its surrounding muscles are represented by a thin deformable cylindrical membrane. Muscle activation levels are simulated by changing the Young's modulus of the membrane in the direction of muscle fibers, yielding... 

    Role of Intra-Abdominal Pressure and Abdominal Muscle Activities on Spinal Stability and Spinal Loads

    , M.Sc. Thesis Sharif University of Technology Farahmand, Masoud (Author) ; ParnianPour, Mohamad (Supervisor) ; Firoozbakhsh, Keikhosrow (Co-Advisor)
    Spine is one of the most important musculoskeletal systems of the human body. Any problem which is related to this part of human body causes pain and disability. Spinal compression forces are one of the main reasons of this disability and pain. It is assumed that intra-abdominal pressure causes spinal unloading in lifting. Studies usually don’t consider the role of intra-abdominal pressure and introduce it as an effective parameter which can increases spinal stability and influences spinal mechanics.Generation mechanism of intra-abdominal pressure remain enigmatic, studies that advocate the unloading effect of IAP usually consider a raise in IAP to be primarily due to the activity of... 

    Investigation of Excitation-contraction behavior in Skeletal Muscle by Means of Chemomechanical Modeling

    , Ph.D. Dissertation Sharif University of Technology Karami, Mina (Author) ; Zohoor, Hassan (Supervisor) ; Firoozbakhsh, Keikhosrow (Supervisor)
    Numerous studies have shown a direct relationship between skeletal muscle active force and intracellular calcium ion concentrations; In fact, no matter how the muscle is stimulated (neurological, electrical, chemical, and mechanical stimuli), the main cause of muscle activation and consequently force generation is calcium ions.According to this scientific finding, the purpose of this study is to present a new chemo-mechanical multiscale model of skeletal muscle based on the fundamental principles of continuum thermodynamics. In this model, unlike other similar studies, muscle active force is not considered as the conventional multiplication of isometric force in a set of corrective... 

    Abdominal hollowing and lateral abdominal wall muscles' activity in both healthy men & women: An ultrasonic assessment in supine and standing positions

    , Article Journal of Bodywork and Movement Therapies ; Volume 15, Issue 1 , Jan , 2011 , Pages 108-113 ; 13608592 (ISSN) Manshadi, F. D ; Parnianpour, M ; Sarrafzadeh, J ; Azghani, M. R ; Kazemnejad, A ; Sharif University of Technology
    The objective of this study was to investigate the effects of Abdominal Hollowing (AH) maneuver on External Oblique (EO), Internal Oblique (IO) and Transversus Abdominis (TrA) muscles in both healthy men and women during the two postures of supine and upright standing. The study was conducted on 43 asymptomatic volunteers (22 males and 21 females) aged 19-44 (27.8 ± 6.4) years. Rehabilitative Ultrasonic Imaging (RUSI) was simultaneously performed to measure muscle thickness in both rest and during AH maneuvers while activation of the TrA during AH was controlled by Pressure Biofeedback (PBF) device. Mixed-model ANOVA with repeated measures design, and Pearson correlation tests were used to... 

    Can lumbosacral orthoses cause trunk muscle weakness? A systematic review of literature

    , Article Spine Journal ; Volume 17, Issue 4 , 2017 , Pages 589-602 ; 15299430 (ISSN) Azadinia, F ; Ebrahimi Takamjani, E ; Kamyab, M ; Parnianpour, M ; Cholewicki, J ; Maroufi, N ; Sharif University of Technology
    Elsevier Inc  2017
    Background Wearing lumbosacral orthosis (LSO) is one of the most common treatments prescribed for conservative management of low back pain. Although the results of randomized controlled trials suggest effectiveness of LSO in reducing pain and disability in these patients, there is a concern that prolonged use of LSO may lead to trunk muscle weakness and atrophy. Purpose The present review aimed to evaluate available evidence in literature to determine whether LSO results in trunk muscle weakness or atrophy. Study Design This is a systematic review. Methods A systematic search of electronic databases including PubMed, Scopus, ScienceDirect, and Medline (via Ovid) followed by hand search of... 

    Capability and recruitment patterns of trunk during isometric uniaxial and biaxial upright exertion

    , Article Clinical Biomechanics ; Volume 23, Issue 5 , 2008 , Pages 527-535 ; 02680033 (ISSN) Sheikhzadeh, A ; Parnianpour, M ; Nordin, M ; Sharif University of Technology
    Background: Work-related risk factors of low back disorders have been identified to be external moments, awkward postures, and asymmetrical dynamic lifting amongst others. The distinct role of asymmetry of load versus posture is hard to discern from the literature. Hence, the aim of this study is to measure isometric trunk exertions at upright standing posture at different exertion level and degree of asymmetry to further delineate the effects of exertion level and asymmetry on neuromuscular capability response. Methods: Fifteen healthy volunteers randomly performed trunk exertions at three levels (30%, 60%, and 100% of maximum voluntary exertion and five different angles (0°, 45°, 90°,... 

    Is there a reliable and invariant set of muscle synergy during isometric biaxial trunk exertion in the sagittal and transverse planes by healthy subjects?

    , Article Journal of Biomechanics ; Volume 48, Issue 12 , Sep , 2015 , Pages 3234-3241 ; 00219290 (ISSN) Sedaghat Nejad, E ; Mousavi, S. J ; Hadizadeh, M ; Narimani, R ; Khalaf, K ; Campbell Kyureghyan, N ; Parnianpour, M ; Sharif University of Technology
    Elsevier Ltd  2015
    It has been suggested that the central nervous system simplifies muscle control through basic units, called synergies. In this study, we have developed a novel target-matching protocol and used non-negative matrix factorization (NMF) technique to extract trunk muscle synergies and corresponding torque synergies. Isometric torque data at the L5/S1 level and electromyographic patterns of twelve abdominal and back muscles from twelve healthy participants (five females) were simultaneously recorded. Each participant performed a total number of 24 isometric target-matching tasks using 12 different angular directions and 2 levels of uniaxial and biaxial exertions. Within- and between-subject...