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muscle--skeletal
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Trunk biomechanical models based on equilibrium at a single-level violate equilibrium at other levels
, Article European Spine Journal ; Volume 16, Issue 5 , 2007 , Pages 701-709 ; 09406719 (ISSN) ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
2007
Abstract
Accurate estimation of muscle forces in various occupational tasks is critical for a reliable evaluation of spinal loads and subsequent assessment of risk of injury and management of back disorders. The majority of biomechanical models of multi-segmental spine estimate muscle forces and spinal loads based on the balance of net moments at a single level with no consideration for the equilibrium at remaining levels. This work aimed to quantify the extent of equilibrium violation and alterations in estimations when such models are performed at different levels. Results are compared with those of kinematics-driven model that satisfies equilibrium at all levels and EMG data. Regardless of the...
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) ; Mousavi, S. J ; Olyaei, G. R ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
2010
Abstract
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...
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) ; Hoviattalab, M ; Azghani, M. R ; Ramezanzadehkoldeh, M ; Parnianpour, M ; Sharif University of Technology
2013
Abstract
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) ; Aminian, K ; Asghari, M ; Parnianpour, M ; Sharif University of Technology
2013
Abstract
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...
Trunk muscles strength and endurance in chronic low back pain patients with and without clinical instability
, Article Journal of Back and Musculoskeletal Rehabilitation ; Volume 25, Issue 2 , 2012 , Pages 123-129 ; 10538127 (ISSN) ; Maroufi, N ; Ebrahimi, I ; Farahmand, F ; Parnianpour, M ; Sharif University of Technology
2012
Abstract
Objectives: Previous research has shown inconsistent findings regarding muscle endurance in chronic low back pain (CLBP). Questions also remain about muscle endurance in patients with clinical instability. The aim of this study was to investigate trunk muscles strength and endurance in CLBP patients with and without clinical instability. Methods: 32 CLBP patients (15 with and 17 without clinical instability) and 39 matched healthy subjects participated in this study. The standing extension test was performed to assess the strength and endurance of the lumbar extensors while recording their electromyographic activity. The patients' disability was evaluated using the Oswestry and Roland-Morris...
Trapezius muscle activity in using ordinary and ergonomically designed dentistry chairs
, Article International Journal of Occupational and Environmental Medicine ; Volume 3, Issue 2 , Apr , 2012 , Pages 76-83 ; 20086520 (ISSN) ; Sanjari, M. A ; Amirfazli, A ; Narimani, R ; Parnianpour, M ; Sharif University of Technology
Abstract
Background: Most dentists complain of musculoskeletal disorders which can be caused by prolonged static posture lack of suitable rest and other physical and psychological problems. Objective: We evaluated a chair with a new ergonomic design which incorporated forward leaning chest and arm supports. Methods: The chair was evaluated in the laboratory during task simulation and EMG analysis on 12 students and subjectively assessed by 30 professional dentists using an 18-item questionnaire. EMG activity of right and left trapezius muscles for 12 male students with no musculoskeletal disorders was measured while simulating common tasks like working on the teeth of the lower jaw. Results:...
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) ; Farahmand, F ; Arazpour, M ; Zohoor, H ; Sharif University of Technology
Elsevier B.V
2018
Abstract
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...
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) ; Olyaei, G. R ; Talebian, S ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
2009
Abstract
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...
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) ; Parnianpour, M ; Nordin, M ; Sharif University of Technology
2008
Abstract
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°,...
Dynamic stability of spine using stability-based optimization and muscle spindle reflex
, Article IEEE Transactions on Neural Systems and Rehabilitation Engineering ; Volume 16, Issue 1 , 2008 , Pages 106-118 ; 15344320 (ISSN) ; Hemami, H ; Barin, K ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
2008
Abstract
A computational method for simulation of 3-D movement of the trunk under the control of 48 anatomically oriented muscle actions was developed. Neural excitation of muscles was set 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. The method was used to simulate the trunk movement from the upright standing to 60° of flexion. Incorporation of the stability condition as an additional constraint in the optimization resulted in an increase in antagonistic activities demonstrating that the antagonistic co-activation acts to increase...
Spinal muscle forces, internal loads and stability in standing under various postures and loads - Application of kinematics-based algorithm
, Article European Spine Journal ; Volume 14, Issue 4 , 2005 , Pages 381-392 ; 09406719 (ISSN) ; El-Rich, M ; Pop, D. G ; Parnianpour, M ; Sharif University of Technology
2005
Abstract
This work aimed to evaluate trunk muscle forces, internal loads and stability margin under some simulated standing postures, with and without external loads, using a nonlinear finite element model of the T1-S1 spine with realistic nonlinear load-displacement properties. A novel kinematics-based algorithm was applied that exploited a set of spinal sagittal rotations, initially calculated to minimize balancing moments, to solve the redundant active-passive system. The loads consisted of upper body gravity distributed along the spine with or without 200 N held in the hands, either in the front of the body or on the sides. Nonlinear and linear stability/perturbation analyses at deformed,...
Noninvasive estimation of tissue temperature via high-resolution spectral analysis techniques
, Article IEEE Transactions on Biomedical Engineering ; Volume 52, Issue 2 , 2005 , Pages 221-228 ; 00189294 (ISSN) ; Ebbini, E. S ; Georgiou, T. T ; Sharif University of Technology
2005
Abstract
We address the noninvasive temperature estimation from pulse-echo radio frequency signals from standard diagnostic ultrasound imaging equipment. In particular, we investigate the use of a high-resolution spectral estimation method for tracking frequency shifts at two or more harmonic frequencies associated with temperature change. The new approach, employing generalized second-order statistics, is shown to produce superior frequency shift estimates when compared to conventional high-resolution spectral estimation methods Seip and Ebbini (1995). Furthermore, temperature estimates from the new algorithm are compared with results from the more commonly used echo shift method described in Simon...
A comprehensive evaluation of spine kinematics, kinetics, and trunk muscle activities during fatigue-induced repetitive lifting
, Article Human Factors ; Volume 64, Issue 6 , 2022 , Pages 997-1012 ; 00187208 (ISSN) ; Mazloumi, A ; Arjmand, N ; Keihani, A ; Karimi, Z ; Ghasemi, M. S ; Kordi, R ; Sharif University of Technology
SAGE Publications Inc
2022
Abstract
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...
Submaximal electromyography-driven musculoskeletal modeling of the human trunk during static tasks: Equilibrium and stability analyses
, Article Journal of Electromyography and Kinesiology ; Volume 65 , 2022 ; 10506411 (ISSN) ; Shirazi Adl, A ; Gagnon, D ; Shahvarpour, A ; Arjmand, N ; Eskandari, A. H ; Larivière, C ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Conventional electromyography-driven (EMG) musculoskeletal models are calibrated during maximum voluntary contraction (MVC) tasks, but individuals with low back pain cannot perform unbiased MVCs. To address this issue, EMG-driven models can be calibrated in submaximal tasks. However, the effects of maximal (when data points include the maximum contraction) and submaximal calibration techniques on model outputs (e.g., muscle forces, spinal loads) remain yet unknown. We calibrated a subject-specific EMG-driven model, using maximal/submaximal isometric contractions, and simulated different independent tasks. Both approaches satisfactorily predicted external moments (Pearson's correlation ∼...
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) ; Mahmoudifard, M ; Mohamadyar Toupkanlou, F ; Dodel, M ; Hajarizadeh, A ; Adabi, M ; Soleimani, M ; Sharif University of Technology
Springer Verlag
Abstract
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...
Subject-specific 2D/3D image registration and kinematics-driven musculoskeletal model of the spine
, Article Journal of Biomechanics ; Volume 57 , 2017 , Pages 18-26 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Farahmand, F ; Sharif University of Technology
Abstract
An essential input to the musculoskeletal (MS) trunk models that estimate muscle and spine forces is kinematics of the thorax, pelvis, and lumbar vertebrae. While thorax and pelvis kinematics are usually measured via skin motion capture devices (with inherent errors on the proper identification of the underlying bony landmarks and the relative skin-sensor-bone movements), those of the intervening lumbar vertebrae are commonly approximated at fixed proportions based on the thorax-pelvis kinematics. This study proposes an image-based kinematics measurement approach to drive subject-specific (musculature, geometry, mass, and center of masses) MS models. Kinematics of the thorax, pelvis, and...
Modular neuromuscular control of human locomotion by central pattern generator
, Article Journal of Biomechanics ; Volume 53 , 2017 , Pages 154-162 ; 00219290 (ISSN) ; Farahmand, F ; Zohoor, H ; Sharif University of Technology
Abstract
The central pattern generators (CPG) in the spinal cord are thought to be responsible for producing the rhythmic motor patterns during rhythmic activities. For locomotor tasks, this involves much complexity, due to a redundant system of muscle actuators with a large number of highly nonlinear muscles. This study proposes a reduced neural control strategy for the CPG, based on modular organization of the co-active muscles, i.e., muscle synergies. Four synergies were extracted from the EMG data of the major leg muscles of two subjects, during two gait trials each, using non-negative matrix factorization algorithm. A Matsuoka׳s four-neuron CPG model with mutual inhibition, was utilized to...
Role and significance of trunk and upper extremity muscles in walker-assisted paraplegic gait: a case study
, Article Topics in Spinal Cord Injury Rehabilitation ; Volume 24, Issue 1 , 2018 , Pages 18-27 ; 10820744 (ISSN) ; Farahmand, F ; Arazpour, M ; Zohoor, H ; Sharif University of Technology
Thomas Land Publishers Inc
2018
Abstract
Background and Purpose: Understanding the role and significance of trunk and upper extremity muscles in paraplegic gait can help in designing more effective assistive devices for these patients and also provides valuable information for improving muscle strengthening programs. Methods: In a patient with a spinal cord injury (SCI) who could walk independently (rating scale of ambulatory capacity, 9) with the aid of bilateral ankle-foot orthosis and a walker, the kinematics, kinetics and electromyographic (EMG) activities of 16 muscles from the trunk and upper and lower extremities were recorded during gait. The onset, cessation, and duration of the EMG signal were associated with the 4 phases...
Trunk musculoskeletal response in maximum voluntary exertions: a combined measurement-modeling investigation
, Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 124-133 ; 00219290 (ISSN) ; El Ouaaid, Z ; Shirazi Adl, A ; Plamondon, A ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Maximum voluntary exertion (MVE) tasks quantify trunk strength and maximal muscle electromyography (EMG) activities with both clinical and biomechanical implications. The aims here are to evaluate the performance of an existing trunk musculoskeletal model, estimate maximum muscle stresses and spinal forces, and explore likely differences between males and females in maximum voluntary exertions. We, therefore, measured trunk strength and EMG activities of 19 healthy right-handed subjects (9 females and 10 males) in flexion, extension, lateral and axial directions. MVEs for all subjects were then simulated in a subject-specific trunk musculoskeletal model, and estimated muscle activities were...
Transient analysis of trunk response in sudden release loading using kinematics-driven finite element model
, Article Clinical Biomechanics ; Volume 24, Issue 4 , 2009 , Pages 341-347 ; 02680033 (ISSN) ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
2009
Abstract
Background: Sudden trunk perturbations occur in various occupational and sport activities. Despite numerous measurement studies, no comprehensive modeling simulations have yet been attempted to investigate trunk biodynamics under sudden loading/unloading. Methods: Dynamic kinematics-driven approach was used to evaluate the temporal variation of trunk muscle forces, internal loads and stability before and after a sudden release of a posterior horizontal load. Measured post-disturbance trunk kinematics, as input, and muscle electromyography (EMG) activities, for qualitative validation, were considered. Findings: Computed agonist and antagonist muscle forces before and after release agreed well...