Showing 8 results for Muscle
Mohamad Hosein Ghasemi, Abed Salimi, Mehrdad Anbarian, Maasome Fadaee, Sara Moghadasi, Hamed Esmaeeli,
Volume 3, Issue 1 (6-2015)
Abstract
Introduction:
Today, computers are widely used in many homes and workplaces. The relationship
between computer use and musculoskeletal disorders in the neck and upper
extremities has been well documented. Muscle fatigue in the shoulder and arm
regions is one of the most frequently reported problems in computer users.
Supporting the upper extremities has been suggested as a way to reduce the
static load on upper body muscles while using a keyboard. The purpose of this
study was to determine the effect of elbow and forearm support on upper
trapezius muscle fatigue while typing.
Materials and Methods: Eight
students of Bu-Ali Sina University (Hamadan, Iran) participated in this quasi-experimental study. The
surface electromyography activity of the upper trapezius muscle of the dominant
side was recorded in three positions, namely without elbow support, elbow
support with the table, and elbow support with a pad while typing. The muscle fatigue index for the three
typing positions was
calculated based on the median frequency slope of the raw electromyography
signals. Repeated measures analysis of variance (ANOVA) was employed for
statistical analyses.
Results: Median
frequency slope decreased significantly in elbow support with the table in
comparison with non-support position (p = 0.04). There were no significant
differences between elbow support with a pad and other two positions.
Conclusion: These
results suggested elbow support as a mechanism to delay trapezius muscle
fatigue and thus increase task efficiency. More research is required to
determine the advantages or disadvantages of using different pads.
Farideh Dehghan Manshadi, Gholamreza Haj-Valie, Rashid Heydari Moghadam, Khosrou Khademi Kalantar, Alireza Yavari Kia, Manoochehr Karami,
Volume 3, Issue 1 (6-2015)
Abstract
Introduction: Concurrent pain in
the knee joint and its-related muscles is expectable in patients with
sacroiliac dysfunction. However, the association between the severity of knee
pain and the level of sacroiliac dysfunction is still unclear. The present
study aimed to determine the association between the severity of sacroiliac
dysfunction and the severity of pain due to involvement of knee compartment.
Materials and Methods: One hundred
consecutive patients who visited an orthopedic clinic with the primary
complaint of knee pain were recruited. According to specific diagnostic tests, 50
had sacroiliac dysfunction and 50 had no history of sacroiliac dysfunction. The
severity of knee pain was determined using the Anterior Knee Pain Scale (AKPS).
T-tests were then performed to compare the two groups in terms of AKPS scores.
Results: The mean AKPS score
was 33.2 ± 12.1 in patients with sacroiliac dysfunction and 62.6 ± 18.6 in
those without sacroiliac dysfunction (p < 0.001). Moreover, anterior knee
pain was more frequent in the first group (56% vs. 10% p < 0.001).
Conclusion: There is a
significant association between the severity of anterior knee pain and severity
of sacroiliac dysfunction. This association may be due to involvement of knee
extensor muscles following the progression of sacroiliac dysfunction.
Majid Motamedzade, Asghar Payoon, Rashid Heydari Moghaddam3, Javad Fradmal, Mohammad Babamiri, Payam Heydari,
Volume 5, Issue 1 (6-2017)
Abstract
Introduction: Muscle-skeletal disorders are one of the most common job-related disorders in industrial workplaces due to different reasons. The current study performed an ergonomic assessment using the key indicator index (KIM) in order to reduce injuries in the bottle-making salon of one of the detergent-producing industries of Qazvin province.
Methods: This study was an interventional study and consisted of 25 workers and was done in a bottle-making salon of one of the detergent-producing industries, during year 2016. For data collection, the Cornell questionnaire and key indicator index assessment method were used before and after the ergonomic interventions. Data was analyzed by descriptive analytical tests using the SPSS 16 software.
Results: According to the results, in the bottle production task (risk score: 4), the risk score decreased significantly by redesign (risk score: 2). Also, regarding the bottle's material, supply task that workers used to do it by manual material handling (risk score: 3), by redesign, risk score decreased significantly (risk score: 1).
Conclusions: In this study, musculoskeletal disorders decreased meaningfully by workstation ergonomic redesign after 5 months from the intervention.
Mehrdad Anbarian, Fatemeh Rajabian, Mohammad Hossein Ghasemi, Rashid Heidari Moghaddam,
Volume 5, Issue 3 (11-2017)
Abstract
Background: The aim of this study was to investigate the effect of the heel wedges on the electromyography activities of the selected left and right lower back muscles during load lifting.
Methods: A total of 17 male subjects voluntarily participated in this quasi-experimental study. The selected subjects lifted a box, weighing 10% of their body weight, above the height of their hip joint, descending as far as the thigh, parallel to the ground, and then ascending to the starting position. The above task was performed nine times in two conditions, including with and without the heel wedges. Using the ME6000 electromyography system, the activity level variables were normalized and the median frequencies of the erector spinae (ES) and the multifidus (MU) muscles were recorded. The subjects also held the box for 30 s in the standing position with stretched hands. The paired t-test was used for the data analysis.
Results: The results showed that during static load lifting using the heel wedge, the median frequency of the right ES muscle changed significantly (P<0.05). Also during dynamic load lifting using the heel wedge, the activities of the left and the right ES muscles as well as the left MU muscle decreased significantly (P<0.05). However, no significant differences between the two conditions were observed for the other variables (P>0.05).
Conclusion: During such occupational tasks, a decrease in the activities of the selected lower back muscles with the heel wedge might result in a delay in the onset of muscle fatigue. The above findings might be used in the design of shoes, suitable for the work environments. However, further investigations are needed in this area in order to provide more accurate results.
Reza Tahmasebi, Majid Motamedzade, Sadaf Torkashvand, Mehrdad Anbarian, Maryam Farhadian,
Volume 5, Issue 4 (3-2018)
Abstract
Background: Many workers, especially welders, have awkward postures during their working hours. Evaluating such kind of postures is done with the aim of corrective actions. Therefore, the present study was conducted to evaluate the activity of welder's muscles in common welding postures working on gas transmission pipelines.
Methods: This cross-sectional descriptive-analytical study was performed on 15 welders of the Iranian Gas Transmission Co. After the required analysis, three postures that were most used working on the gas transmission pipelines were identified to evaluate muscle activity. The surface electromyography (EMG) activity of the erector spinae, biceps femoris, vastus medialis, gastrocnemius medialis, gastrocnemius lateralis, tibialis anterior, rectus abdominis, abdominal internal oblique, abdominal external oblique, and semitendinosus muscles are evaluated in three postures. They are analyzed based on the maximum voluntary contraction (MVC).
Results: The results indicated that the mean of muscle activity in the kneeling posture is significantly lower than two other postures (P<0.001). The mean activity of each muscle in different postures were compared and evaluated. The highest activity was related to the tibialis anterior, vastus medialis and biceps femoris. Abdominal muscles have the lowest activity.
Conclusion: The muscle activity of the welders in the evaluated postures was very high. Based on the findings of this study, the muscle activity was strongly affected by the type of posture and angle of the joints, so the muscles’ activity in the kneeling posture was lower than the two other postures due to the suitable angle of joints and the direct transmission of body weight.
Sedigheh Karimi Avargani, Ali Maleki, Shahin Besharati, Reza Ebrahimi,
Volume 8, Issue 3 (10-2020)
Abstract
Background and Aim: Carriage of backpack sprayers is an inevitable part of agricultural operations that increases the risk of injury along with undesirable changes in walking mechanics. The purpose of this study is to formulate the muscle moment changes in the hip, knee and ankle for the backpack sprayer operator body.
Methods: In this study, a seven-link sprayer operator model is designed and the moment changes in the hip, knee and ankle joints are evaluated. Data are obtained using Plot-digitizer software. Excel software is used to fit the third degree curve on the data.
Results: In the hip joint, the moment is reduced by changing the angle from zero to 15°. At the end of the swing phase, the moment applied to the hip joint increases with increasing the angle up to 30°. In the beginning of the swing phase, the knee joint starts to open at -55°. At the end of the swing phase, the knee joint releases up to -5 ° and the moment applied to the knee joint increases slowly. The moment applied to the ankle joint increases by changing the ankle angle from -7.5° to 7.5°.
Conclusion: According to the results of this study, amount of moment changes of hip, knee and ankle joint affect the force applied to the backpack sprayer operator body. With the knowledge of the moment changes of joints, practical solutions can be provided to reduce amount of damage to these joints.
Abdollah Vahedi, Iman Dianat,
Volume 12, Issue 1 (4-2024)
Abstract
Objectives: Despite the increasing trend of automation and mechanization in the industry, many workers are exposed to high physical workloads, repetitive motions, and unusual body postures. In this regard, assistive technology (AT) is a relatively new and practical solution. This study was conducted to design an assistive arm according to ergonomic principles and investigate its effect on the electrical activity of shoulder muscles.
Methods: This research was fundamental in its approach, using an experimental intervention method. The investigated samples included students studying in the Tabriz University of Medical Sciences, Faculty of Health in 2021, of which 12 participated in the study, half of whom were female and half were male. A prototype of a passive assistive arm was first designed. The electrical activity of muscles was then evaluated at two work heights and two tasks in a simulated workstation with and without the use of an assist arm. The data were analyzed at a significance level of 0.05 using SPSS26 software.
Results: The designed assistive arm reduced the electrical activity of the muscles in the tested heights and tasks, and among the six investigated muscles, the activity of the trapezius and anterior deltoid muscles decreased the most.
Conclusion: According to the results, the designed assistive arm reduces the electrical activity of the shoulder muscles and differentially affects different tasks and work heights. The results generally indicate that the use of an assistive arm can be an effective intervention for overhead tasks.
Saeed Ilbeigi, Masoumeh Al-Eghabi, Mohammad Yousefi, Mohammad Hamed Hosseini,
Volume 12, Issue 3 (12-2024)
Abstract
Objectives: Designing one-handed carrying tasks based on biomechanical findings has a significant impact on preventing musculoskeletal injuries. The present study was conducted to investigate the muscle synergy of the trunk and pelvis in the manual carrying of loads with different weights in healthy young people.
Methods: In this experimental study, 20 male volunteers performed the walking protocol without load, carrying different weights of 5%, 10%, and 15% of their own weight during unilateral manual load carrying. The electrical activity of the trunk and pelvis muscles while carrying loads of different weights was recorded using an electromyography device (Biovision). To evaluate the differences between different load-carrying conditions, a repeated measures test was used at a significance level of P≤0.05.
Results: The results showed that in the performance of manual load carrying, there was a significant difference between muscle synergy (synergy size) in all walking protocols, including 5% and 10% of body weight and 5% and 15% of body weight and between 15% and 10% (P≤05). While in the performance of manual load carrying, a significant difference was found between muscle synergy (synergy direction) in 5% of body weight and 10% of body weight, this difference was not seen in manual load carrying with 5% of body weight and 15% of body weight and also between synergy of 15% and 10% (P≥0.05).
Conclusion: It seems that the difference in muscle synergy in terms of size in unilateral manual load carrying can, with increasing load, create more tension in the back and pelvic muscles; however, the direction or angle does not change compared to the no-load state.
