title: Lift performance and lumbar loading in standing and seated lifts.
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.
authors.affiliation: a Centre for Human and Applied Physiology, School of Medicine , University of Wollongong , Wollongong , Australia.
authors.forename: Kane J
authors.initials: KJ
authors.lastname: Middleton
authors.affiliation: b Land Division, Defence Science and Technology Group , Melbourne , Australia.
authors.forename: Greg L
authors.initials: GL
authors.lastname: Carstairs
authors.affiliation: b Land Division, Defence Science and Technology Group , Melbourne , Australia.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Ham
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D017770:Lifting; D008159:Lumbar Vertebrae / Q000502:physiology*; D008161:Lumbosacral Region / Q000502:physiology*; D008297:Male; D008886:Military Hygiene / Q000379:methods*; D008889:Military Personnel; D011187:Posture / Q000502:physiology*; D013647:Task Performance and Analysis; D016474:Weight-Bearing / Q000502:physiology*; D000066477:Work Performance
keywords: Biomechanics; injury risks; manual handling; military ergonomics; physical work capacity