Abstract
(1) Background: Yearly, more than 40% of the European employees suffer from work-related musculoskeletal disorders. Still, ergonomic guidelines defining optimal lifting techniques to decrease work-related musculoskeletal disorders (WMSDs) has not been unambiguously defined. Therefore, this study investigates if recommended squat lifting imposes lower musculoskeletal loading than stoop lifting while using a complex full body musculoskeletal OpenSim model. (2) Methods: Ten healthy participants lifted two different weights using both lifting techniques. 3D marker trajectories and ground reaction forces were used as input to calculate joint angles, moments and power using a full body musculoskeletal model with articulated lumbar spine. In addition, the muscle activity of nine different muscles was measured to investigate muscle effort when lifting. (3) Results: Peak moments and peak joint power in L5S1 were not different between the squat and the stoop, but higher peak moments and peak power in the hip, knee, elbow and shoulder were found during squat lifting. Moment impulses in L5S1 were higher during stoop lifting. This is reflected in higher peak electromyography (EMG) but lower muscle effort in prior described muscles during the squat. (4) Conclusions: Squat lifting imposes higher peak full body musculoskeletal loading but similar low back loading compared to stoop lifting, as reflected in peak moments, peak power, and peak EMG.
Highlights
(3) Results: Peak moments and peak joint power in L5S1 were not different between the squat and the stoop, but higher peak moments and peak power in the hip, knee, elbow and shoulder were found during squat lifting
The 40% arm lifting strength test (ALST) condition is described because this weight is relative to the strength of the participant and did not influence the results between the male and female participants [31], as three women and seven men were included in this study
Joint power generation was highest at the hip for both techniques, with knee power generation being equal to hip power during squat lifting (Figure 3)
Summary
More than 40% of all employees in Europe suffer from work-related musculoskeletal disorders (WMSDs), such as low back, neck or shoulder pain, despite ongoing efforts to improve the working conditions [1]. These WMSDs result from excessive physical workloads due to repetitive movements (61%), non-neutral posture (44%) and heavy material handlings (31%) [1]. They are responsible for the absence of 3%–6% of the working time, causing an average cost of 2.5% of the gross domestic product across Europe [2].
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