Lift performance and lumbar loading in standing and seated lifts

摘要

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 5566.2627.8N; Seated 5584.0 +/- 16.0) but were higher in the standing posture (4045.7 +/- 408.3N) when compared with the seated posture (3655.8 +/- 225.7N) at lift completion. Anterior shear forces were higher in the standing posture at both lift initiation (Standing 519.4 +/- 104.4N; Seated 224.2 +/- 9.4N) and completion (Standing 183.3 +/- 62.5N; Seated 71.0 +/- 24.2N) 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.