The Effects of Lifting Techniques on the L5-S1 Joint: Lifting Different Loads from Ground Level

Abstract Manual material lifting is a common activity in daily life and industrial work conditions, significantly affecting the L5/S1 joint in the lower back. This study replaces lifting objects with handles on both sides, as found in literature, with lifting industrial cargo boxes from the bottom using both hands. Experiments involved 5 healthy male cargo workers lifting weights of 4, 8, 12, and 16 kg from ground level using squat and stoop lifting techniques. Body joint positions and ground reaction forces were captured without markers using the Microsoft Kinect v2 sensor. These data were transferred to a 3D human model in the Opensim biomechanical analysis program for inverse kinematic and dynamic analyses. The force and moment values at the L5/S1 joint for each subject, weight, and lifting technique were compared. In conclusion, it was determined that, depending on the load, the squat lifting technique increased the torque values at the L5-S1 joint by 7.1–9.9%, increased the compression force by 8.8–9.2%, and decreased the shear force by 24.5–25.3% compared to the stoop lifting technique.