Bioceramics / Bioglasses
Mehrdad Davoudi; S. Mohammad Reza Shokouhyan; Mahdi Bagheri Rouchi; Masoud Abdollahi; Soha Bervis; Maryam Hoviat Talab; Mohamad Parnianpour
Volume 14, Issue 2 , July 2020, , Pages 81-96
Abstract
An open research question is how the central nervous system (CNS) to find a solution for the problem of redundancy or degree of freedom in the human shoulder motion control. We used time-varying synergy theory in which assumed that the relative activation between muscles is time-varying, to investigate ...
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An open research question is how the central nervous system (CNS) to find a solution for the problem of redundancy or degree of freedom in the human shoulder motion control. We used time-varying synergy theory in which assumed that the relative activation between muscles is time-varying, to investigate the combination of activation patterns of muscles in twelve 3-D hand-held exercises by Flexi-Bar using Anybody Technology software (A/S, Aalborg, Denmark). Using activation of 12 muscles and the moment across the joint as an input matrix for the optimization procedure to extract functional time-varying synergies, time delays and amplitude coefficients, the achieved 5 tonic and phasic synergies explained 79% of the data variation. Matching pursuit procedure and non-negative least square used to find timing shifts and amplitude coefficients respectively. Considering a new exercise out of the primary database, 60% of the activation patterns reconstructed using time-varying synergies. Although the extracted synergies seem to be directionally tuned, the results show that due to the same velocity in all exercises and also because the torque which that was applied due to the weight of the bar and arm on the joint is not significant, both timing shifts and separation phasic-tonic parts of the activation patterns provide no further explanation on CNS behavior and finding them causes unnecessary computational cost. Future study can focus on the comparison of synergies between two or more groups of exercises by the Flexi-Bar such as holding the bar vertically or horizontally with swinging it up and down or back and forth.
Biomechanics / Biomechanical Engineering
Mahdi Bagheri Rouchi; Mehrdad Davoudi; Mohammad Parnianpour
Volume 13, Issue 2 , August 2019, , Pages 177-187
Abstract
According to the literature, changes in muscle activity patterns are considered as one of the causes of non-specific chronic low back pain. Recent studies have introduced muscle synergy as a valuable tool for analyzing how muscles work in body movements. In this way, a new study method is proposed for ...
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According to the literature, changes in muscle activity patterns are considered as one of the causes of non-specific chronic low back pain. Recent studies have introduced muscle synergy as a valuable tool for analyzing how muscles work in body movements. In this way, a new study method is proposed for modeling upper body and extracting time-varying muscle synergies in flexural motion of the waist. In this way, a new study method is proposed for modeling trunk and extracting time-varying muscle synergies in plane bending movements of lumbar flexion. Considering 18 effective muscles and function of the combined cost of the minimum jerk-energy, 24 different movements and their corresponding muscle patterns have been simulated. To evaluate the role of velocity, the pattern of muscle activity was divided into two parts: tonic, to overcome the gravity force, and phasic, proportional to the trunk movement velocity. In the following, three fast-reaching times of 0.75, 1, and 2 seconds were considered for each direction. The results showed that 77% of the lumbar muscle pattern of movement was achieved by four phasic synergies and four tonic synergies. The resulting synergies are quite influenced by the movement direction and velocity, so that each pair of phasic and tonic synergy is most effective in one of the main directions. On the other hand, the increase in velocity causes elevated amplitude coefficient and accelerated activation of phasic synergies compared to normal mode. Considering the 45° flexion combination with 30° left lateral bending, 77.2% of the muscle pattern of movement has been reconstructed using time-varying synergies. It can be argued that the use of muscle synergies expresses a good explanation for how muscles work in movement at different directions and velocities.
Human Movement Modeling
Hossein Ehsani; Mostafa Rostami; Mohammad Parnianpour
Volume 9, Issue 2 , July 2015, , Pages 191-203
Abstract
In the current study, a novel method for deriving the governing equations of the skeletal system of the human body has been presented. In this method, a novel approach for incorporating the kinematic characteristics of biological joints and also the effects of complex kinematic chains of the skeletal ...
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In the current study, a novel method for deriving the governing equations of the skeletal system of the human body has been presented. In this method, a novel approach for incorporating the kinematic characteristics of biological joints and also the effects of complex kinematic chains of the skeletal system has been proposed. The suggested method while utilizing the calculus of matrix-valued functions, derives the governing equations of the skeletal system in the form of ordinary differential equations. Moreover, since the formulations were presented in a recursive fashion, this paper suggests a computationally efficient algorithm to derive the differential equations of motion for the skeletal system. In order to examine the validity of the proposed formulations, a benchmark mechanism with three closed-loop kinematic constraints were considered. We compared the results obtained from our formulations with the outcomes presented in other studies and validated the proposed formulations. Besides, in order to investigate the application of the suggested method in simulation of the skeletal system of the human body, dynamical modeling of the shoulder rhythm was taken into consideration. Two models were employed for describing the shoulder rhythm: Original model and simplified model. The discrepancies observed between the outcomes of these two models delineate the necessity of using the original data for the shoulder rhythm. While the limitations of the available formulations have compelled the researchers to employ the simplified model for the shoulder rhythm, with the method we propose in this study this problem is obviated.
Gait Analysis
Samane Moeini Sedeh; Navid Arjmand; Mohammad Ali Sanjari; Hamid Reza Mokhtarinia; Morteza Asgari; Mohammad Parnianpour
Volume 7, Issue 4 , June 2013, , Pages 333-340
Abstract
Stability is important to prevent falling during occupational and daily living activities. Control parameters such as direction of motion and external load can affect stability pattern. The purpose of this paper was to evaluate the effect of the mentioned control parameters on stability. Time series ...
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Stability is important to prevent falling during occupational and daily living activities. Control parameters such as direction of motion and external load can affect stability pattern. The purpose of this paper was to evaluate the effect of the mentioned control parameters on stability. Time series of lumbar rotation angle in 19 healthy subjects were investigated. Each subject performed spine flexionextension in two different directions of symmetric (sagittal plane) and asymmetric (between sagittal and transverse planes), with two loading cases of 8 Kg weight and load free. To evaluate dynamic stability of repetitive movement, a nonlinear method of largest Lyapunov exponent has been used. After calculating maximum Lyapunov exponent from each of the experimental cases, results of analysis of variance showed a significant difference between symmetric and asymmetric directions (p=0.016). To interpret this result we can suggest higher recruitment of the internal and external oblique muscle groups and higher mechanical constraints in spine during asymmetric tasks. Mean comparison showed that movement in symmetric direction has more instability than the asymmetric case. Moreover, presence of load and interaction between direction and load did not significantly affect local dynamic stability.
Gait Analysis
Mohammad Iman Mokhlespour Esfahani; Omid Zobeiri; Ali Akbari; Behzad Moshiri; Mohammad Parnianpour
Volume 7, Issue 4 , June 2013, , Pages 361-369
Abstract
Wearable measuring system has major effects onbiomechanics of human movements especially in daily activitiesin order to monitor and analyze the human movements to achievethe most important kinematics parameters. In the recent decade,inertial sensors were utilized by researchers in order todeveloping ...
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Wearable measuring system has major effects onbiomechanics of human movements especially in daily activitiesin order to monitor and analyze the human movements to achievethe most important kinematics parameters. In the recent decade,inertial sensors were utilized by researchers in order todeveloping wearable system for instrumentation of humanmovements. In this study, Sharif-Human MovementInstrumentation System (SHARIF-HMIS) was designed andmanufactured. The system consists of inertial measurement units(IMUs), stretchable clothing and data logger. The IMU sensorsare installed on the human body. The system can be used at homeand also industrial environments. The main features of thissystem are: low cost, low weight, saving data for ten hours andbeing wearable. Furthermore, the software was designed for data acquisition of the IMUs.
Biomechanics of Bone / Bone Biomechanics
Mohammad Nikkhoo; Mohammad Haghpanahi; J. L. Wang; Mohammad Parnianpour
Volume 5, Issue 1 , June 2011, , Pages 21-32
Abstract
Prediction of the relationship between different types of mechanical loading and the failure of the intervertebral disc is so important to identify the risk factors which are difficult to study in vivo and in vitro. On the basis of finite element methods some of these issues may be overcome ...
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Prediction of the relationship between different types of mechanical loading and the failure of the intervertebral disc is so important to identify the risk factors which are difficult to study in vivo and in vitro. On the basis of finite element methods some of these issues may be overcome enabling more detailed assessment of the biomechanical behavior of the intervertebral disc. The objective of this paper is to develop a nonlinear axisymmetric poroelastic finite element model of lumbar motion segment and show its capability for studying the time-dependent response of disc. After comparison of the response of different models in quasi-static analysis, the poroelastic model of intervertebral disc is presented and the results of short-term, long-term creep tests and cyclic loading were investigated. The results of the poroelastic model are in agreement with experimental ones reported in the literature. Hence, this model can be used to study how different dynamic loading regimes are important as risk factors for initiation of intervertebral disc degeneration.
Neuro-Muscular Engineering
Amir Hosein Eskandari; Ehsan Sedaghat Nejad; Seyed Javad Mousavi; Mohsen Asghari; Mohammad Parnianpour
Volume 5, Issue 3 , June 2011, , Pages 257-273
Abstract
Selection of muscle activation pattern to reach a specific goal by considering the complexities of neuromuscular system and the way it overcomes these complications, is of researchersinterest in motor control. One proposed solutionfor resolving thesecomplexities is the concept of simple module (synergies) ...
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Selection of muscle activation pattern to reach a specific goal by considering the complexities of neuromuscular system and the way it overcomes these complications, is of researchersinterest in motor control. One proposed solutionfor resolving thesecomplexities is the concept of simple module (synergies) that the combination of them leads to more complex activities. In the present work, the existence and arrangement of synergies in the lumbar spine are proved. For this purpose, a model with 18-muscles in level L4-L5 is utilized in the static condition. In order to obtaina muscular and stability synergies, muscle activation, which are obtained by exerting moments in 2D and 3D spaces and angular stiffness to the model,are used. The results show that six muscular synergies suffice to be able to reach any point in the moment space. Also, three stability synergies can reconstruct a part of joint angular stiffness space. In addition, the obtained muscular synergies are robust against changes in the amplitude of exerted moment. In this study, it is shown that one can generates any task involves producing determined moment and angular stiffness in the joint, by combining muscular and stability synergies together.
Biomechanical Motor Control / Motor Control of Human Movement
Ehsan Rashedi; Mohammad Reza Nassajian; Bahman Nasseroleslami; Mohammad Parnianpour
Volume 2, Issue 2 , June 2008, , Pages 109-122
Abstract
Human motor system is organized for execution of various motor tasks in different and flexible ways. This is mainly achieved by the way that CNS uses the redundancy in musculoskeletal system. The kinetic redundancy in human musculoskeletal systems is a significant property by which CNS achieves many ...
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Human motor system is organized for execution of various motor tasks in different and flexible ways. This is mainly achieved by the way that CNS uses the redundancy in musculoskeletal system. The kinetic redundancy in human musculoskeletal systems is a significant property by which CNS achieves many complementary goals. Following the definition and role of uncontrolled manifold for movement kinematics, the kinetic redundancy concept is explored in mathematical terms. The null space of the kinetically redundant system when certain joint Moment and/or Stiffness are needed is derived and discussed. The mathematical methods have already been developed and applied to a simpler planar model. However in this paper, the aforementioned concepts were illustrated, using a 3-dimensional 3- degree of the freedom biomechanical model of spine with 18 anatomically oriented Hill-type-model muscle fascicles. The results can shed light to the interaction mechanisms in activation patterns of muscles, seen in various tasks and exertions and can provide a significant understanding for future studies and clinical practices related to low back disorders.
