Sharif Digital Repository

Low back pain is one the most prevalent disease and major economic issue facing modern countries. Epidemiological studies suggest that maximum trunk flexion, the angular velocity of trunk and the rate of repetitive movements (such as flexion-extension), are associated with low-back disorders. From biomechanical point of view, lack of stability during dynamic repetitive movements, increases the risk of injuries. On the other hand, some researchers suggest increasing motor variability could be an intrinsic factor to intervene muscuskeletal disorders during repetitive movements. Pace of repetitive occupational tasks could affect both, motor variability and dynamic stability. The goal of this... 

Low back pain is one of the musculoskeletal diseases which is an important issue for general health of society in both quality of life and costs. Most of the clinical instructions employ exercise as a clinical treatment in order to cure chronic low back pain. General and core stability exercises are of common prevalence, however, there are disputes about the effectiveness of these exercises in the literature. The aim of this study is to answer the question whether stabilizer exercise can significantly alter the stability of vertebral column in comparison with general exercises. Hence, experiments have been designed and conducted. The participants have been divided to two group. Within six... 

Low back pain is the most prevalence musculoskeletal pain that people experience in their life. Some cases of low back pain are called non-specific. These are cases for which the reason of pain is not well defined. The aim of this study is to propose a simple approach to diagnose and cluster low back pain patients which helps clinicians to evaluate patients by an affordable and simple tool. In this study, data are collected in two steps using Inertial Sensors. Inertial Sensors consist of a 3-axis gyroscope and a 3-axis accelerometer which represent the kinematic parameters of lumbar movement. In the first step, we examine 24 healthy and 28 patients with low back pain and in the second, 84... 

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess the risk of injury to the spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses the AnyBody modeling software to verify whether the RWL generates L5-S1 within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in the literature). Twenty-four symmetric and asymmetric lifting activities were simulated to evaluate the RWL by the NLE and the L5-S1 loads by AnyBody. In two activities, involving large trunk flexion and 30 and 60 degrees of load asymmetry, the estimated RWL generated L5-S1 spine loads exceeding the recommended limits. The NIOSH... 

Obesity is a worldwide growing health challenge affecting ~30% of the world's population. Increased rate of disc degeneration and herniation, low back pain and surgery has been reported in obese individuals. Although obesity-related low back diseases have multifactorial etiology, presumably greater mechanical loads on the spine of heavier individuals during their daily activities may be considered as a risk factor. Likely larger trunk muscle sizes, disc sizes and thus passive stiffness in heavier individuals may however partly or fully offset the effect of their additional body weight on the spinal loads. In absence of in vivo approaches, the present study aims to construct subject-specific... 

Obesity is a worldwide growing health challenge affecting ~30% of the world's population. Increased rate of disc degeneration and herniation, low back pain and surgery has been reported in obese individuals. Although obesity-related low back diseases have multifactorial etiology, presumably greater mechanical loads on the spine of heavier individuals during their daily activities may be considered as a risk factor. Likely larger trunk muscle sizes, disc sizes and thus passive stiffness in heavier individuals may however partly or fully offset the effect of their additional body weight on the spinal loads. In absence of in vivo approaches, the present study aims to construct subject-specific... 

Low Back Pain is one of the most problems in health domain which has a high treatment costs, also has high recurrence rates. Postural stability has been introduced as a health characteristic for musculoskeletal systems. Body stability is maintained with sensory feedback data such as Eyes, Vestibular and proprioception data which are sent to brain. Prior investigations have shown that proprioception data have many disorders in lumbar area of Low Back Pain patient and this data are not sent to brain encounters so many problems for muscle activation and stability of body. Researches have been indicated that Low Back Pain patients rely on Ankle proprioception more than healthy people and less... 

Low back disorders (LBD) is one of the most musculo-skeletal disorders in industrial environments in which it can impose to the society.Therefore, it is very important to reaserch the causes of LBDs, prevention methods and evaluation risk factor in lifting tasks in order to avoid the prevalence of LBDs in society. There is no doubt heavy lifting has a significant role in emerging of LBDs. Hence, many safety risk assessment tools have been made by researchers.Using assessment tools, we need to know the input parameters corrospending to the assessment tools. Input parameters in assessment tools have been measured in a way of traditional method or by expensive equipment in laboratories. On... 

Low back pain is one of the most prevalent musculoskeletal injuries in occupational activities. In order to reduce or prevent it, it is necessary to estimate the mechanical loads of body joints. Direct measurement of spinal loads is invasive and costly. Therefore, musculoskeletal modeling is a convenient tool in estimation of joints and muscles loads that often uses kinematics information as input.Marker-based motion capture systems are one of the most common ways for the estimation of body kinematics. Unfortunately, they are time consuming and expensive. Thus being marker-free and low-cost, Microsoft Kinect is a suitable alternative. Recent studies often have investigated accuracy of... 

According to epidemiological studies, low back pain is the most prevalent musculoskeletal disease thus indicating the important role of biomechanical engineers to manage risk of injury. Different quantitative (i.e., biomechanical models) and qualitative (empirical) assessment tools are used to evaluate risk of musculoskeletal injuries. The present study uses various quantitative and qualitative risk assessment tools to investigate the risk of injury among workers in Iran Khodro Automaker company (IKCO) assembly hall No. 3 (Pars Peugeot car assembly). Moreover, different engineering and administrative interventions are suggested to manage risk of musculoskeletal injuries when needed. The... 

80% of people in all over the world, experience Low Back Pain (LBP) once in their lives. LBP leads to dysfunction of spine. About 25% of LBP relates to the intervertebral disks which in the critical cases, a Posterior Lumbar Surgery (PLS) on the one or more lumbar disks should be done. Due to the some procedure such as retracting, cutting or denervation of muscles, PLS can hurt trunk muscles and spine. Thus, investigation of LBP and postoperative complications of PLS can help us in recognition of causes of LBP and PLS complications and modification of PLS approaches. The objective of this research was investigation of effects of LBP and PLS on the biomechanical function of spine. Pattern of... 

Investigating the influence of shoes on variables of human biomechanics is of a high importance. The purpose of this study was to examine the effect of auxetic Nike Free RN shoe on kinematics and kinetics of human body. It was asked from 11 healthy male to perform drop vertical jump in three conditions: with auxetic Nike Free RN, with conventional shoe and barefoot. 3D Cartesian positions of the markers, which were stuck to the subjects’ bodies, were recoeded using Vicon camera system. Ground reaction force and its center of pressure of each foot captured using two force plates. Moreover, activation of rectus abdominis, longissimus, iliocostalis lomburom and multifidus were recorded using...