فهرست نشریات علمی دسترسی آزاد ایران

Bricklaying tasks are prone to causing Lower Back Pain (LBP) due to the nature of repetitive and awkward body movements. However, the effect of different working positions on the lumbar joints during bricklaying tasks yet remains unexplored. The aim of this study was to investigate the effect of four working positions (i.e., foot, knee, waist, and shoulder) on six lumbar joints ( i.e., L5_sacrum, L5_L4, L4_L3, L3_L2, L2_L1, and T12_L1) reaction forces during bricklaying tasks, especially mortar spreading and bricklaying. Twelve young male participants (age: 21.83±1.27 years) performed bricklaying tasks in a laboratory environment. The actual tasks movement data were collected by Inertial Measurement Unit (IMU) sensors. Joint reaction forces were determined through a 3D musculoskeletal model by running inverse dynamics simulations. Analysis of Variance (ANOVA) test was conducted to determine the effect of working positions on joint reaction forces, with the significant level at p-value<0.05. Results revealed that the L5_sacrum joint reaction force was significantly higher (1.9kN to 3.1kN, p<0.01) than in other joints for both tasks and all working positions, which may lead to develop the risk of LBP. The reaction forces in all joints were significantly higher (1.6kN to 3.1kN) at the foot position compared to other working positions. Joints reaction forces were significantly lower (1.2kN to 2.5kN, p<0.05, p<0.01) in the knee and waist positions than in the foot and shoulder positions, which indicate lower risk of LBP. Thus, bricklaying from the knee (47 cm) to waist (107 cm) positions showed the best compromise between joints reaction forces and LBP risk. Therefore, these findings help to set optimal working positions (47 cm to 107 cm) for bricklayers to prevent the risk of LBP. This study also contributes to improve the working layout for bricklaying and helps to provide guidelines to reduce lumbar joint loads.