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Showing 2 results for Muscle Activity
Muscular Activity Assessment of Common Welding Postures in Welders of Gas Transmission Pipelines
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.

Muscular synergy of trunk and hip segments in carrying hand loads with different weights in healthy young people
Saeed Ilbeigi, Masoumeh Aleghbi, Mohammad Yousefi, Mohammad Hamed Hosseini,
Volume 12, Issue 3 (12-2024)
Abstract

Background and Objective: 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 carrying manual loads of different weights .

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 , 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≤50). While in the performance of manual load carrying, although a significant difference was found between muscle synergy (synergy direction) in 5% of body weight and 10% of body weight, while 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; But the direction or angle does not change compared to the no-load state.


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