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    Postural sway in low back pain: Effects of dual tasks

    , Article Gait and Posture ; Volume 31, Issue 1 , 2010 , Pages 116-121 ; 09666362 (ISSN) Mazaheri, M ; Salavati, M ; Negahban, H ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
    2010
    Abstract
    Recurrence quantification analysis (RQA), a nonlinear method of postural analysis, was used to explore the effects of dual-tasking on postural performance in people with nonspecific low back pain (LBP) compared with healthy participants. Postural performance was quantified by RQA % recurrence, % determinism, entropy and trend. People with nonspecific LBP (n = 22) and unimpaired individuals (n = 22) randomly performed quiet standing tasks with three levels of difficulty (rigid-surface eyes open, rigid-surface eyes closed and foam-surface eyes closed). These tasks were performed in isolation or concurrently with an easy or difficult cognitive task. Increasing postural difficulty was associated... 

    The effects of dual-tasking on postural control in people with unilateral anterior cruciate ligament injury

    , Article Gait and Posture ; Volume 30, Issue 4 , 2009 , Pages 477-481 ; 09666362 (ISSN) Negahban, H ; Hadian, M. R ; Salavati, M ; Mazaheri, M ; Talebian, S ; Jafari, A. H ; Parnianpour, M ; Sharif University of Technology
    2009
    Abstract
    Several studies have investigated postural control in anterior cruciate ligament (ACL) deficient patients; yet the contribution of cognitive processing (attention) in the postural control of these patients is still unclear. A dual-task design was used to determine the effects of a concurrent digit span memory task on standing balance in a group of ACL patients (n = 27) compared with a group of matched, healthy participants (n = 27). In double limb stance, three levels of postural difficulty were studies on a force platform (rigid surface with eyes open, rigid surface with eyes closed, and foam surface with eyes closed). There were three cognitive conditions (no cognitive task, easy cognitive... 

    Effect of dual-tasking on postural control in subjects with nonspecific low back pain

    , Article Spine ; Volume 34, Issue 13 , 2009 , Pages 1415-1421 ; 03622436 (ISSN) Salavati, M ; Mazaheri, M ; Negahban, H ; Ebrahimi, I ; Jafari, A. H ; Kazemnejad, A ; Parnianpour, M ; Sharif University of Technology
    2009
    Abstract
    STUDY DESIGN. Three factors mixed-design with 1 between-subject and 2 within-subject factors. OBJECTIVE. To compare the main effects and interactions of postural and cognitive difficulty on quiet stance between subjects with and without nonspecific low back pain (LBP). SUMMARY OF BACKGROUND DATA. The interference between postural control and cognitive tasks depends on factors such as sensorimotor/cognitive integrity. Changes in peripheral sensory and muscular systems as well as cognitive processes have been observed in LBP patients. It was hypothesized that the effect of cognitive task on postural performance might be different in subjects with nonspecific LBP as compared with healthy... 

    Calibration of hexaglide parallel manipulators using only input joint variables

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 861-867 ; 9780791848722 (ISBN) Abtahi, M ; Pendar, H ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
    2009
    Abstract
    In the application of parallel robots, it is necessary to calibrate the geometric parameters and improve the positioning accuracy for accurate task performance. Traditionally, to perform system calibration, one needs to measure a number of robot poses using an external measuring device. However, this process is often time-consuming, expensive and difficult for robot on-line calibration. In this paper, a methodical way of self-calibrating of Hexaglide parallel robot is introduced. This method is performable only by measuring input joint variables in some sets of configurations where in each set center of the end-effector is fixed, but orientations are different. Simulations give us an idea... 

    Kinematic calibration of the hexaglide parallel robot using a simple measurement system

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 853-859 ; 9780791848722 (ISBN) Abtahi, M ; Pendar, H ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
    2009
    Abstract
    Because of errors in the geometric parameters of the parallel robots, it is necessary to calibrate them to improve the positioning accuracy for accurate task performance. Traditionally, to perform system calibration, one needs to measure a number of robot poses using an external measuring device. However, this process is often time-consuming, expensive and difficult for robot on-line calibration. In this paper, a methodical way of self-calibrating of Hexaglide parallel robot is introduced. This method is performable only by measuring input joint variables and errors of positioning relative to the desired position in some sets of configurations where in each set the desired position is fixed,... 

    Metabolic load comparison between the quarters of a game in elite male basketball players using sport metabolomics

    , Article European Journal of Sport Science ; Volume 21, Issue 7 , 2021 , Pages 1022-1034 ; 17461391 (ISSN) Khoramipour, K ; Gaeini, A. A ; Shirzad, E ; Gilany, K ; Chashniam, S ; Sandbakk, Ø ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    Abstract
    Purpose: A basketball match is characterized by intermittent high-intensity activities, thereby relying extensively on both aerobic and anaerobic metabolic pathways. Here, we aimed to compare the metabolic fluctuations between the four 10-min quarters of high-level basketball games using metabolomics analyses. Methods: 70 male basketball players with at least 3 years of experience in the Iran national top-league participated. Before and after each quarter, saliva samples were taken for subsequent untargeted metabolomics analyses, where Principal component analysis (PCA) and Partial least squares-discriminant analysis (PLS-DA) were employed for statistical analysis. Results: Quarters 1 and 3... 

    Assessment of preprocessing on classifiers used in the P300 speller paradigm

    , Article 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'06, New York, NY, 30 August 2006 through 3 September 2006 ; 2006 , Pages 1319-1322 ; 05891019 (ISSN); 1424400325 (ISBN); 9781424400324 (ISBN) Mirghasemi, H ; Shamsollahi, M. B ; Fazel Rezai, R ; Sharif University of Technology
    2006
    Abstract
    Artifact removal is an essential part in electroencephalogram (EEG) recording and the raw EEG signals require preprocessing before feature extraction. In this work, we implemented three filtering methods and demonstrated their effects on the performance of different classifiers. Bandpass digital filtering, median filtering and facet method are three preprocessing approaches investigated in this paper. We used data set lib from the BCI competition 2003 for training and testing phase. Our accuracy varied between 80% and 96%. In our work, we demonstrated that the problems of choosing the classifier and preprocessing methods are not independent of each other. Two of our approaches could achieve... 

    Experimental kinematic calibration of parallel manipulators using a relative position error measurement system

    , Article Robotics and Computer-Integrated Manufacturing ; Vol. 26, Issue 6 , 2010 , pp. 799-804 ; ISSN: 07365845 Abtahi, M ; Pendar, H ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    Abstract
    Because of errors in the geometric parameters of parallel robots, it is necessary to calibrate them to improve the positioning accuracy for accurate task performance. Traditionally, to perform system calibration, one needs to measure a number of robot poses using an external measuring device. However, this process is often time-consuming, expensive and difficult for robot on-line calibration. In this paper, a methodical way of calibration of parallel robots is introduced. This method is performable only by measuring joint variable vector and positioning differences relative to a constant position in some sets of configurations that the desired positions in each set are fixed, but the moving... 

    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
    Abstract
    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... 

    Nonlinear dynamical structure of sway path during standing in patients with multiple sclerosis and in healthy controls is affected by changes in sensory input and cognitive load

    , Article Neuroscience Letters ; Volume 553 , 2013 , Pages 126-131 ; 03043940 (ISSN) Negahban, H ; Sanjari, M. A ; Mofateh, R ; Parnianpour, M ; Sharif University of Technology
    2013
    Abstract
    Although several studies have applied traditional linear measures to evaluate postural control of patients with multiple sclerosis (MS), little is known about the nonlinear dynamics of this patient group. In this study, recurrence quantification analysis (RQA), a well documented nonlinear method, was used to compare the nonlinear dynamical structure of postural sway in two groups consisting of MS patients (. n=. 23) and healthy matched controls (. n=. 23). The study focuses on three levels of postural difficulty consisting of (1) standing on a rigid surface (force platform) with eyes open, (2) standing on a rigid surface with eyes closed, and (3) standing on a foam surface with eyes closed.... 

    Multijoint coordination during sit-to-stand task in people with non-specific chronic low back pain

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 25, Issue 1 , 2013 ; 10162372 (ISSN) Tajali, S ; Negahban, H ; Shaterzadeh, M. J ; Mehravar, M ; Salehi, R ; Narimani, R ; Parnianpour, M ; Sharif University of Technology
    2013
    Abstract
    Sit-to-stand (STS) is an important functional task affected by low back pain (LBP). It requires fundamental coordination among all segments of the body to control important performance variables such as body's center of mass (CM) and head positions. This study was conducted to determine whether LBPs could coordinate their multiple joints to achieve the task stability to the same extent as healthy controls. About 11 non-specific chronic LBP and 12 healthy control subjects performed STS task at three postural difficulty levels: rigid surface - open eyes (RO), rigid surface - closed eyes (RC) and narrow surface - closed eyes (NC). Motion variability of seven body segments, CM and head positions... 

    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) Haddad, O ; 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:... 

    Controllability and maintenance of human trunk response surface for isometric extension strength

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 1 , July , 2010 , Pages 733-738 ; 9780791849156 (ISBN) Azghani, M. R ; Farahmand, F ; Meghdari, A ; Hakkak, F ; Parnianpour, M ; ASME Turkey Section; Loughborough University ; Sharif University of Technology
    2010
    Abstract
    From an ergonomic point of view, quantitative assessment of the feasibility of the task performance is an intricate process, which combines the multidimensional task demand profile with the individual's multidimensional performance capacity profile. Trunk muscle strength is affected by the trunk posture but it is not clear how the variability of trunk muscle is affected by the trunk posture or exertion level. A validated triaxial dynamometer, Sharif-LIST, was used for to model the surface response of trunk muscle extension strength variability as a function of trunk posture in the sagittal, coronal and transverse planes in standing position. Fifteen healthy males with no history of low back... 

    Non-linear dynamical features of center of pressure extracted by recurrence quantification analysis in people with unilateral anterior cruciate ligament injury

    , Article Gait and Posture ; Volume 31, Issue 4 , 2010 , Pages 450-455 ; 09666362 (ISSN) Negahban, H ; Salavati, M ; Mazaheri, M ; Sanjari, M. A ; Hadian, M. R ; Parnianpour, M ; Sharif University of Technology
    2010
    Abstract
    Knowledge about the non-linear dynamical pattern of postural sway may provide important insights into the adaptability (flexibility) of human postural control in response to everyday stresses imposed on the body. A commonly used non-linear tool, i.e. recurrence quantification analysis, was chosen to investigate the effect of prior anterior cruciate ligament injury on the deterministic pattern of postural sway under different conditions of postural and cognitive difficulty. In double leg stance, as postural difficulty increased from open-eyes to closed-eyes and rigid-surface to foam-surface, the centre of pressure regularity (%determinism) increased as well. In comparison to healthy... 

    Trunk coordination in healthy and chronic nonspecific low back pain subjects during repetitive flexion-extension tasks: Effects of movement asymmetry, velocity and load

    , Article Human Movement Science ; Volume 45 , 2016 , Pages 182-192 ; 01679457 (ISSN) Mokhtarinia, H. R ; Sanjari, M. A ; Chehrehrazi, M ; Kahrizi, S ; Parnianpour, M ; Sharif University of Technology
    Elsevier 
    Abstract
    Multiple joint interactions are critical to produce stable coordinated movements and can be influenced by low back pain and task conditions. Inter-segmental coordination pattern and variability were assessed in subjects with and without chronic nonspecific low back pain (CNSLBP). Kinematic data were collected from 22 CNSLBP and 22 healthy volunteers during repeated trunk flexion-extension in various conditions of symmetry, velocity, and loading; each at two levels. Sagittal plane angular data were time normalized and used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify lumbar-pelvis and... 

    Comparison of spinal stability following motor control and general exercises in nonspecific chronic low back pain patients

    , Article Clinical Biomechanics ; Volume 48 , 2017 , Pages 42-48 ; 02680033 (ISSN) Shamsi, M ; Sarrafzadeh, J ; Jamshidi, A ; Arjmand, N ; Ghezelbash, F ; Sharif University of Technology
    Abstract
    Background Motor control exercise was claimed to improve spinal stability in patients with chronic non-specific back pain, but to investigate the effectiveness of this exercise, other outcome measures have been used rather than spinal stability itself. The aim of our study is to assess motor control exercise effects on spinal stability using a biomechanical model. Methods Fifty-one patients were assigned to either motor control or general exercises. Before and after trainings, participants were tested for spinal stability at seven isometric tasks. Electromyography signals were recorded from ten superficial muscles, and a hybrid EMG-driven musculoskeletal model estimated spinal stability... 

    Effects of lumbosacral orthosis on dynamical structure of center of pressure fluctuations in patients with non-specific chronic low back pain: A randomized controlled trial

    , Article Journal of Bodywork and Movement Therapies ; Volume 23, Issue 4 , 2019 , Pages 930-936 ; 13608592 (ISSN) Azadinia, F ; Ebrahimi Takamjani, I ; Kamyab, M ; Asgari, M ; Parnianpour, M ; Sharif University of Technology
    Churchill Livingstone  2019
    Abstract
    Background: A few clinical trials have examined the effect of treatment interventions on postural control in patients with chronic low back pain, all of which have exclusively evaluated postural stability using traditional linear measures of postural sway. However, postural control improvement cannot be determined by exclusively relying on linear measurements, because these parameters provide no information on underlying motor control mechanisms. Objective: This study aimed to compare the effect of using lumbosacral orthoses (LSO) together with routine physical therapy, compared to routine physical therapy alone on postural control, using nonlinear analysis techniques. Methods: Forty-four... 

    The amount and temporal structure of center of pressure fluctuations during quiet standing in patients with chronic low back pain

    , Article Motor Control ; Volume 24, Issue 1 , 2020 , Pages 91-112 Azadinia, F ; Ebrahimi Takamjani, I ; Kamyab, M ; Asgari, M ; Parnianpour, M ; Sharif University of Technology
    Human Kinetics Publishers Inc  2020
    Abstract
    The characteristics of postural sway were assessed in quiet standing under three different postural task conditions in 14 patients with nonspecific chronic low back pain and 12 healthy subjects using linear and nonlinear center of pressure parameters. The linear parameters consisted of area, the mean total velocity, sway amplitude, the SD of velocity, and the phase plane portrait. The nonlinear parameters included the Lyapunov exponent, sample entropy, and the correlation dimension. The results showed that the amount of postural sway was higher in the patients with low back pain compared with the healthy subjects. Assessing the nonlinear parameters of the center of pressure showed a lower... 

    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
    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°,... 

    Biomechanical analysis of the pelvis angular excursion in sagittal plane in response to asymmetric leg loading tasks in females with and without nonspecific chronic low back pain

    , Article Journal of Biomedical Physics and Engineering ; Volume 11, Issue 3 , 2021 , Pages 367-376 ; 22517200 (ISSN) Meftahi, N ; Kamali, F ; Parni Anpour, M ; Davoudi, M ; Sharif University of Technology
    Shriaz University of Medical Sciences  2021
    Abstract
    Background: Controlling pelvic excursions is the focus of stabilization exercises such as legs loading tasks in rehabilitation of non-specific chronic low back pain (NSCLBP) patients. Progression of these exercises is based on the ability to perform tasks with minimal sagittal pelvic excursions. In spite of emphasis on minimizing pelvic motions, no previous studies have investigated kinematic analysis of the pelvic excursions during leg loading exercises in NSCLBP patients. Objective: This study aims to investigate the sagittal pelvis excursion during performing asymmetric leg loading tasks in individuals with and without NSCLBP. Material and Methods: In this cross-sectional study, kinematic...