Showing papers by "Mohamad Parnianpour published in 2012"

Trapezius muscle activity in using ordinary and ergonomically designed dentistry chairs.

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: Normalized EMG data showed significant reduction (p<0.05) in all EMG recordings of the trapezius muscle. Dentists also unanimously preferred the ergonomically designed chair. Conclusion: Such ergonomically designed chairs should be introduced as early as possible in student training before bad postural habits are acquired.

Design and prototyping of wearable measuring system for trunk movement using textile sensors

Abstract: Wearable system is a proper solution for rehabilitation and instrumentation applications for human daily activities. Recently, several researches are concentrated on this technology significantly because of new progress in sensors and fusion sensors. In the near future, wearable and ambulatory devices will be used considerably in biomedical applications. In this study, we reviewed some methods about wearable measuring system then introduced and designed innovative wearable clothing for this purpose. Some specifications and advantages of our system in comparison with relevant researches are; using painted sensors that are manufactured through nano electro active polymer technology, low weight, low price, applicable for daily activity, three dimensional detection of human body movements and noninvasive. We utilized textile sensor to measure the trunk movements in three dimensions. Twenty textile sensors were attached on the clothing in this version of system. In addition to wearable system, clothing was prepared in order to determine the positions of textile sensors on the body. Furthermore, an electronic board is developed for data acquisition and transfer data to computer real-time. Finally, the wearable clothing for ambulatory purposes was manufactured and also different methods for the system calibration have been presented.

The effects of intra-abdominal pressure on the stability and unloading of the spine

Abstract: In spite of earlier experimental and modeling studies, the relative role of the intra-abdominal pressure (IAP) in spine mechanics has remained controversial. This study employs simple analytical and finite element (FE) models of the spine and its surrounding structures to investigate the contribution of IAP to spinal loading and stability. The analytical model includes the abdominal cavity surrounded by muscles, lumbar spine, rib cage and pelvic ring. The intra-abdominal cavity and its surrounding muscles are represented by a thin deformable cylindrical membrane. Muscle activation levels are simulated by changing the Young's modulus of the membrane in the direction of muscle fibers, yielding IAP values recorded under the partial Valsalva maneuver. In the FE model, the abdominal cavity is cylindrical and filled with a nearly incompressible fluid. The surrounding muscles are modeled as membrane elements with transverse isotropic material properties simulating their fiber orientation. Results indicate a good...

Sharif-human movement instrumentation system (SHARIF-HMIS) for daily activities

Abstract: Wearable measuring system has major effects on biomechanics of human movements especially in daily activities in order to monitor and analyze the human movements to achieve the most important kinematics parameters. In the recent decade, inertial sensors were utilized by researchers in order to developing wearable system for instrumentation of human movements. In this study, Sharif-Human Movement Instrumentation System (SHARIF-HMIS) was designed and manufactured. The system consists of inertial measurement units (IMUs), stretchable clothing and data logger. The IMU sensors are installed on the human body. The system can be used at home and also industrial environments. The main features of this system are: low cost, low weight, saving data for ten hours and being wearable. Furthermore, the software was designed for data acquisition of the IMUs.

Principal component analysis of kinematic patterns variability during sit to stand in people with non-specific chronic low back pain

Abstract: Sit to stand (STS) task requires variability of all body segments to achieve the stability of the important control variables (i.e., center of mass (CM) and head positions). In this study, the possible differences in the variability patterns of various body segments were investigated between 11 chronic low back pain (LBP) and 12 control subjects during STS task through two types of variability analyses; first by calculating the variability of seven limb angles, CM and head positions across 15 trials and second by principal component analysis (PCA) of seven limb angles. Participants performed the task at 3 postural difficulty levels: rigid surface, open eyes (RO), rigid surface, close eyes (RC) and narrow surface, close eyes (NC). The results revealed that LBPs could stabilize the CM and head positions same as controls. Also there was more than 1 synergic combination of whole body segments in both LBP and healthy groups. But the number of PCs accounting for the major part of variance was reduced in the LBPs in the most unstable phase of movement (50%–80% trajectory) in the RO and RC conditions. This may indicate that LBPs have reduced flexibility in the most unstable phase of task.

Are tibiofemoral compressive loads transferred only via contact mechanisms

Abstract: The tibiofemoral joint is known to bear compressive loads of several body-weights during daily activities. These forces are known to be transferred through the joint via compression of the tibial and femoral surfaces against one another. The menisci are also known to enhance this process by increasing the contact area and decreasing contact stress. However, calculations presented in this paper suggest that the load-bearing capacity of contact mechanisms is seemingly several times smaller than tibiofemoral joint loads. This suggests that probably one or more non-contact load-bearing mechanism(s) exist, and share the load with the already known contact mechanisms.

On low back pain: Identification of structural changes in system parameters for fatigue loaded intervertebral disc using PCA

Abstract: This paper presents the background of low back problem caused by repetitive fatigue loading. We emphasize on mechanism of Intervertebral Disc (IVD) and conditions for which the disc does not recover its original status under repetitive work and cause low back pain. The objective of this study is to identify structural changes in system parameters for fatigue loaded intervertebral disc. Principal component analysis (PCA) is used for studying the behavioral change of spine against cyclic loading as a function of time. Percentage difference and similarity factor was calculated for the analysis. Specimens were applied with impulse testing to measure the stiffness and acceleration after fracture, augmentation and fatigue loading. The fatigue loading were 650N, 950N and 1150N at 5Hz for 1, 2, 3, 4 and 5 hours. 12 hours rest was given between different loadings. Based on PCA analysis, it is observed that IVD does not restore to original condition after 50 minutes of fatigue loading. In addition, if people set load at range between 30 to 50 minutes, vertebra discs cannot fully return to the normal position anymore depending on total load. Vertebra can support load as much as 0.5kN limited to 30 to 50 minutes. It implies that fracture may occur. Rest is very important in order to prevent the deformity and abnormalities of backbone discs. We found that in spine vertebral acceleration and displacement are dependent on the applied force.

An Ultrasonic Investigation of Stability of Pelvic Floor in Women with and without Urinary Stress Incontinence

Abstract: Introduction: Bladder base movement (BBM) reflects the level of pelvic floor (PF) stability and responds with mechanical load induced changes of PF or body position. Adoption of proper body position during pelvic floor muscle (PFM) training for management of Stress Urinary Incontinence (SUI) is very important. This study was performed aimed on investigating BBM while performing different postural interventions in women with and without SUI using Trans Abdominal Ultrasonography (TAUS). Methods: This clinical trial was conducted on 41 women referred to Vali Asr hospital of Imam Khomeini Hospital in Tehran during 2008-2009. After collecting demographic information, Trans Abdominal Ultrasonography was done at rest, during Crook lying and Straight Leg Raising (SLR), cough and Valsalva maneuvers, during PFM and Transversus Abdominis (TrA) contractions and BBM was assessed. Data were analyzed using SPSS software (version 16), Kolmogorov-Smirnov test, independent T-test, repeated measures ANOVA test, Bonferroni post hoc test and Pearson’s correlation test. P less than 0.05 was considered statistically significant. Results: Regarding ultrasonic assessment, only the main effect of intervention was significant (p=0.0001). Adopting crook lying position affected BBM more positively in continent women compared with incontinent women (mean 6.3 vs. 2.5 mm; P 0.05). Conclusion: Changing patient position from straight leg raising to crook lying causes upward movement of bladder base. Comparing the two groups was shown that the effect of crook lying on elevation of bladder base in control group was significantly more than patients.