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    Simulation of mechanical force in skeletal muscle according to the intracellular Ca2+ concentration level

    , Article 2017 24th Iranian Conference on Biomedical Engineering and 2017 2nd International Iranian Conference on Biomedical Engineering, ICBME 2017, 30 November 2017 through 1 December 2017 ; 2018 ; 9781538636091 (ISBN) Karami, M ; Grasa, J ; Calvo, B ; Zohoor, H ; Firoozbakhsh, K ; Sharif University of Technology
    Active behavior in skeletal muscle soft tissue is affected by electrical, chemical and mechanical parameters. More realistic model of skeletal muscle demands detailed formulation which is able to involve other parameters in addition to mechanical ones. In this paper a new formulation for considering Ca2+ level (as the most important chemical factor) along with mechanical parameters in force producing process of skeletal muscle is introduced and validated comparing simulated results with some experimental data. Prepared skeletal muscle behavior is able to predict the maximum generated force in muscle according to the concentration of intracellular Ca2+ level and muscle contraction velocity... 

    Dynamic iso-resistive trunk extension simulation: Contributions of the intrinsic and reflexive mechanisms to spinal stability

    , Article Technology and Health Care ; Volume 15, Issue 6 , 2007 , Pages 415-431 ; 09287329 (ISSN) Davarani, S. Z ; Shirazi Adl, A ; Hemami, H ; Mousavi, S. J ; Parnianpour, M ; Sharif University of Technology
    IOS Press  2007
    The effects of external resistance on the recruitment of trunk muscles and the role of intrinsic and reflexive mechanisms to ensure the spinal stability are significant issues in spinal biomechanics. A computational model of spine under the control of 48 anatomically oriented muscle actions was used to simulate iso-resistive trunk movements. Neural excitation of muscles was attained based on inverse dynamics approach along with the stability-based optimization. The effect of muscle spindle reflex response on the trunk movement stability was evaluated upon the application of a perturbation moment. In this study, the trunk extension movement at various resistance levels while extending from... 

    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... 

    The nanofibrous PAN-PANi scaffold as an efficient substrate for skeletal muscle differentiation using satellite cells

    , Article Bioprocess and Biosystems Engineering ; Volume 39, Issue 7 , 2016 , Pages 1163-1172 ; 16157591 (ISSN) Hosseinzadeh, S ; Mahmoudifard, M ; Mohamadyar Toupkanlou, F ; Dodel, M ; Hajarizadeh, A ; Adabi, M ; Soleimani, M ; Sharif University of Technology
    Springer Verlag 
    Among polymers, polyaniline (PANi) has been introduced as a good candidate for muscle regeneration due to high conductivity and also biocompatibility. Herein, for the first time, we report the use of electrospun nanofibrous membrane of PAN-PANi as efficient scaffold for muscle regeneration. The prepared PAN-PANi electrospun nanofibrous membrane was characterized by scanning electron microscopy (SEM), Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) and tensile examination. The softer scaffolds of non-composite electrospun nanofibrous PAN govern a higher rate of cell growth in spite of lower differentiation value. On the other hand, PAN-PANi electrospun... 

    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... 

    Lumbopelvic muscle activation patterns in three stances under graded loading conditions: Proposing a tensegrity model for load transfer through the sacroiliac joints

    , Article Journal of Bodywork and Movement Therapies ; Vol. 18, Issue. 4 , October , 2014 , pp. 633-642 ; ISSN: 13608592 Pardehshenas, H ; Maroufi, N ; Sanjari, M. A ; Parnianpour, M ; Levin, S. M ; Sharif University of Technology
    Purpose: According to the conventional arch model of the pelvis, stability of the sacroiliac joints may require a predominance of form and force closure mechanisms: the greater the vertical shear force at the sacroiliac joints, the greater the reliance on self-bracing by horizontally or obliquely oriented muscles (such as the internal oblique). But what happens to the arch model when a person stands on one leg? In such cases, the pelvis no longer has imposts, leaving both the arch, and the arch model theory, without support. Do lumbopelvic muscle activation patterns in one-legged stances under load suggest compatibility with a different model? This study compares lumbopelvic muscle... 

    Elevation and orientation of external loads influence trunk neuromuscular response and spinal forces despite identical moments at the L5-S1 level

    , Article Journal of Biomechanics ; Vol. 47, issue. 12 , September , 2014 , p. 3035-3042 Ouaaid, Z. E ; Shirazi-Adl, A ; Plamondon, A ; Arjmand, N ; Sharif University of Technology
    A wide range of loading conditions involving external forces with varying magnitudes, orientations and locations are encountered in daily activities. Here we computed the effect on trunk biomechanics of changes in force location (two levels) and orientation (5 values) in 4 subjects in upright standing while maintaining identical external moment of 15. Nm, 30. N. m or 45. Nm at the L5-S1. Driven by measured kinematics and gravity/external loads, the finite element models yielded substantially different trunk neuromuscular response with moderate alterations (up to 24% under 45 Nm moment) in spinal loads as the load orientation varied. Under identical moments, compression and shear forces at... 

    Normal postural responses preceding shoulder flexion: Co-activation or asymmetric activation of transverse abdominis?

    , Article Journal of Back and Musculoskeletal Rehabilitation ; Vol. 27, issue. 4 , 2014 , p. 545-551 Davarian, S ; Maroufi, N ; Ebrahimi, E ; Parnianpour, M ; Farahmand, F ; Sharif University of Technology
    BACKGROUND AND OBJECTIVES: It is suggested that activation of the transverse abdominis muscle has a stabilizing effect on the lumbar spine by raising intra-abdominal pressure without added disc compression. However, its feedforward activity has remained a controversial issue. In addition, research regarding bilateral activation of trunk muscles during a unilateral arm movement is limited. The aim of this study was to evaluate bilateral anticipatory activity of trunk muscles during unilateral arm flexion.MATERIALS AND METHODS: Eighteen healthy subjects (aged 25 ± 3.96 years) participated in this study and performed 10 trials of rapid arm flexion in response to a visual stimulus. The... 

    A novel stability and kinematics-driven trunk biomechanical model to estimate muscle and spinal forces

    , Article Medical Engineering and Physics ; Vol. 36, issue. 10 , 2014 , p. 1296-1304 Hajihosseinali, M ; Arjmand, N ; Shirazi-Adl, A ; Farahmand, F ; Ghiasi, M. S ; Sharif University of Technology
    An anatomically detailed eighteen-rotational-degrees-of-freedom model of the human spine using optimization constrained to equilibrium and stability requirements is developed and used to simulate several symmetric tasks in upright and flexed standing postures. Predictions of this stability and kinematics-driven (S. +. KD) model for trunk muscle forces and spine compressive/shear loads are compared to those of our existing kinematics-driven (KD) model where both translational and rotational degrees-of-freedom are included but redundancy is resolved using equilibrium conditions alone. Unlike the KD model, the S. +. KD model predicted abdominal co-contractions that, in agreement with... 

    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... 

    How well do the muscular synergies extracted via non-negative matrix factorisation explain the variation of torque at shoulder joint?

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 16, Issue 3 , 2013 , Pages 291-301 ; 10255842 (ISSN) Moghadam, M. N ; Aminian, K ; Asghari, M ; Parnianpour, M ; Sharif University of Technology
    The way central nervous system manages the excess degrees of freedom to solve kinetic redundancy of musculoskeletal system remains an open question. In this study, we utilise the concept of synergy formation as a simplifying control strategy to find the muscle recruitment based on summation of identified muscle synergies to balance the biomechanical demands (biaxial external torque) during an isometric shoulder task. A numerical optimisation-based shoulder model was used to obtain muscle activation levels when a biaxial external isometric torque is imposed at the shoulder glenohumeral joint. In the numerical simulations, 12 different shoulder torque vectors in the transverse plane are... 

    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... 

    Coordinated activities of trunk and upper extremity muscles during walker-assisted paraplegic gait: A synergy study

    , Article Human Movement Science ; Volume 62 , 2018 , Pages 184-193 ; 01679457 (ISSN) Baniasad, M ; Farahmand, F ; Arazpour, M ; Zohoor, H ; Sharif University of Technology
    Elsevier B.V  2018
    Individuals with spinal cord injury (SCI) at lower thoracic levels might walk independently with the aid of mechanical orthoses and walker by using their unimpaired trunk and upper extremity muscles (TUEM). The required motor skills and the associated subtasks of the paraplegic locomotion, however, have not been well understood yet. The purpose of this study was to investigate the coordination of the TUEM activities throughout the paraplegic gait cycle using synergy analysis. For eight paraplegic individuals (30.6 ± 11.6 years; SCI level: T12), the kinematics data and the surface electromyography (EMG) signals of TUEM were recorded during 15 gait cycles. Non-negative matrix factorization... 

    A model-based approach for estimation of changes in lumbar segmental kinematics associated with alterations in trunk muscle forces

    , Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 82-87 ; 00219290 (ISSN) Shojaei, I ; Arjmand, N ; Meakin, J ; Bazrgari, B ; Sharif University of Technology
    Elsevier Ltd  2018
    The kinematics information from imaging, if combined with optimization-based biomechanical models, may provide a unique platform for personalized assessment of trunk muscle forces (TMFs). Such a method, however, is feasible only if differences in lumbar spine kinematics due to differences in TMFs can be captured by the current imaging techniques. A finite element model of the spine within an optimization procedure was used to estimate segmental kinematics of lumbar spine associated with five different sets of TMFs. Each set of TMFs was associated with a hypothetical trunk neuromuscular strategy that optimized one aspect of lower back biomechanics. For each set of TMFs, the segmental... 

    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... 

    Effect of changes in the lumbar posture in lifting on trunk muscle and spinal loads: A combined in vivo, musculoskeletal, and finite element model study

    , Article Journal of Biomechanics ; Volume 104 , February , 2020 Khoddam Khorasani, P ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Irrespective of the lifting technique (squat or stoop), the lumbar spine posture (more kyphotic versus more lordotic) adopted during lifting activities is an important parameter affecting the active-passive spinal load distribution. The advantages in either posture while lifting remains, however, a matter of debate. To comprehensively investigate the role on the trunk biomechanics of changes in the lumbar posture (lordotic, free or kyphotic) during forward trunk flexion, validated musculoskeletal and finite element models, driven by in vivo kinematics data, were used to estimate detailed internal tissue stresses-forces in and load-sharing among various joint active-passive tissues. Findings... 

    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... 

    Simulation of movement in three-dimensional musculoskeletal human lumbar spine using directional encoding-based neurocontrollers

    , Article Journal of Biomechanical Engineering ; Vol. 136, issue. 9 , 2014 Nasseroleslami, B ; Vossoughi, G ; Boroushaki, M ; Parnianpour, M ; Sharif University of Technology
    Despite development of accurate musculoskeletal models for human lumbar spine, the methods for prediction of muscle activity patterns in movements lack proper association with corresponding sensorimotor integrations. This paper uses the directional information of the Jacobian of the musculoskeletal system to orchestrate adaptive critic-based fuzzy neural controller modules for controlling a complex nonlinear redundant musculoskeletal system. The proposed controller is used to control a 3D 3-degree of freedom (DOF) musculoskeletal model of trunk, actuated by 18 muscles. The controller is capable of learning to control from sensory information, without relying on pre-assumed model parameters.... 

    Trunk muscle fatigue and its implications in EMG-assisted biomechanical modeling

    , Article International Journal of Industrial Ergonomics ; Volume 43, Issue 5 , 2013 , Pages 425-429 ; 01698141 (ISSN) Haddad, O ; Mirka, G.A ; Sharif University of Technology
    Muscle fatigue affects the underlying EMG-force relationship on which EMG-assisted biomechanical models rely. The aim of this study was to evaluate the impact of short duration muscle fatigue on the muscle gain value. Participants performed controlled, isometric trunk extension exertions at 10, 20, and 30 degrees of trunk flexion and controlled isokinetic trunk extension exertions at 5 and 15°/sec on five separate days. Fatigue of the lumbar extensors was generated by moderate-intensity, trunk extension exertions. Participants performed controlled test contractions at defined intervals throughout the fatiguing bout and the EMG activities of trunk muscles were collected. These EMG data were... 

    Comparison of trunk muscle forces, spinal loads and stability estimated by one stability- and three EMG-assisted optimization approaches

    , Article Medical Engineering and Physics ; Volume 37, Issue 8 , 2015 , Pages 792-800 ; 13504533 (ISSN) Mohammadi, Y ; Arjmand, N ; Shirazi-Adl, A ; Sharif University of Technology
    Elsevier Ltd  2015
    Various hybrid EMG-assisted optimization (EMGAO) approaches are commonly used to estimate muscle forces and joint loads of human musculoskeletal systems. Use of EMG data and optimization enables the EMGAO models to account for inter- and intra-individual variations in muscle recruitments while satisfying equilibrium requirements. Due to implications in ergonomics/prevention and rehabilitation/treatment managements of low-back disorders, there is a need to evaluate existing approaches. The present study aimed to compare predictions of three different EMGAO and one stability-based optimization (OPT) approaches for trunk muscle forces, spinal loads, and stability. Identical measured...