Lift performance and lumbar loading in standing and seated lifts |
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Authors: | Kane J Middleton Daniel J Ham |
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Affiliation: | 1. Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, Australia;2. Land Division, Defence Science and Technology Group, Melbourne, Australia |
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Abstract: | This study investigated the effect of posture on lifting performance. Twenty-three male soldiers lifted a loaded box onto a platform in standing and seated postures to determine their maximum lift capacity and maximum acceptable lift. Lift performance, trunk kinematics, lumbar loads, anthropometric and strength data were recorded. There was a significant main effect for lift effort but not for posture or the interaction. Effect sizes showed that lumbar compression forces did not differ between postures at lift initiation (Standing 5566.2?±?627.8 N; Seated 5584.0?±?16.0) but were higher in the standing posture (4045.7?±?408.3 N) when compared with the seated posture (3655.8?±?225.7 N) at lift completion. Anterior shear forces were higher in the standing posture at both lift initiation (Standing 519.4?±?104.4 N; Seated 224.2?±?9.4 N) and completion (Standing 183.3?±?62.5 N; Seated 71.0?±?24.2 N) and may have been a result of increased trunk flexion and a larger horizontal distance of the mass from the L5-S1 joint. Practitioner Summary: Differences between lift performance and lumbar forces in standing and seated lifts are unclear. Using a with-in subjects repeated measures design, we found no difference in lifted mass or lumbar compression force at lift initiation between standing and seated lifts. |
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Keywords: | Biomechanics physical work capacity military ergonomics manual handling injury risks |
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