Search for: abdomen
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    A novel approach to evaluate abdominal coactivities for optimal spinal stability and compression force in lifting

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 12, Issue 6 , 2009 , Pages 735-745 ; 10255842 (ISSN) Ouaaid, Z. E ; Arjmand, N ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
    A novel optimisation algorithm is developed to predict coactivity of abdominal muscles while accounting for both trunk stability via the lowest buckling load (Pcr) and tissue loading via the axial compression (Fc). A nonlinear multi-joint kinematics-driven model of the spine along with the response surface methodology are used to establish empirical expressions for Pcr and Fc as functions of abdominal muscle coactivities and external load magnitude during lifting in upright standing posture. A two-component objective function involving Fc and Pcr is defined. Due to opposite demands, abdominal coactivities that simultaneously maximise Pcr and minimise Fc cannot exist. Optimal solutions are... 

    Fetal R-wave detection from multichannel abdominal ECG recordings in low SNR

    , Article Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society: Engineering the Future of Biomedicine, EMBC 2009 ; 2009 , Pages 344-347 ; 1557170X (ISSN) Kharabian, S ; Shamsollahi, M. B ; Sameni, R ; Sharif University of Technology
    Abdominal recordings of fetal ECG (fECG) have lower signal-to-noise ratio (SNR) as compared with invasive procedures. In this paper we have combined two previously proposed methods, one for extracting fECG, called piCA and the other, a transformation based on Hilbert transform to enhance the R-peaks. The combination of these methods seems to work well in situations of noisy data and fetal repositioning. Also a comparison is done by using ICA in order to extract the fetal signals. Performance of both methods is studied separately. Results show that applying the transformation on the components extracted with the use of piCA (after maternal ECG cancellation), had a very good performance. Also,... 

    The effect of angle and level of exertion on trunk neuromuscular performance during multidirectional isometric activities

    , Article Spine ; Volume 34, Issue 5 , 2009 , Pages E170-E177 ; 03622436 (ISSN) Mousavi, J ; Olyaei, G. R ; Talebian, S ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
    STUDY DESIGN.: To quantify trunk muscle capability and controllability in different angles and levels of isometric exertion using a torque tracking system. OBJECTIVE.: To investigate the effect of biaxial isometric exertions on the maximum capability of trunk and to examine the effect of angle and level of isometric exertion on trunk controllability during the tracking task in upright posture. SUMMARY OF BACKGROUND DATA.: Combined motions of trunk at varying exertion levels occur in most daily and occupational activities and are important risk factors of low back pain. Few studies have investigated trunk capability and controllability during multidirectional activities with different... 

    Rigid-bar loading on pregnant uterus and development of pregnant abdominal response corridor based on finite element biomechanical model

    , Article International Journal for Numerical Methods in Biomedical Engineering ; Volume 36, Issue 1 , January , 2020 Irannejad Parizi, M ; Ahmadian, M. T ; Mohammadi, H ; Sharif University of Technology
    Wiley-Blackwell  2020
    During pregnancy, traumas can threaten maternal and fetal health. Various trauma effects on a pregnant uterus are little investigated. In the present study, a finite element model of a uterus along with a fetus, placenta, amniotic fluid, and two most effective ligament sets is developed. This model allows numerical evaluation of various loading on a pregnant uterus. The model geometry is developed based on CT-scan data and validated using anthropometric data. Applying Ogden hyper-elastic theory, material properties of uterine wall and placenta are developed. After simulating the “rigid-bar” abdominal loading, the impact force and abdominal penetration are investigated. Findings are compared... 

    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°,... 

    Trunk biomechanics during maximum isometric axial torque exertions in upright standing

    , Article Clinical Biomechanics ; Volume 23, Issue 8 , 2008 , Pages 969-978 ; 02680033 (ISSN) Arjmand, N ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
    Background: Activities involving axial trunk rotations/moments are common and are considered as risk factors for low back disorders. Previous biomechanical models have failed to accurately estimate the trunk maximal axial torque exertion. Moreover, the trunk stability under maximal torque exertions has not been investigated. Methods: A nonlinear thoracolumbar finite element model along with the Kinematics-driven approach is used to study biomechanics of maximal axial torque generation during upright standing posture. Detailed anatomy of trunk muscles with six distinct fascicles for each abdominal oblique muscle on each side is considered. While simulating an in vivo study of maximal axial...