Spinal loading when lifting from industrial storage bins

Abstract

The study documented three-dimensional spinal loading during lifting from an industrial bin. Two lifting styles and two bin design factors were examined in Phase I. The lifting style measures in Phase I were one hand versus two hand and standing on one foot versus two feet. The bin design variables were region of load in the bin and bin height. The Phase II study examined one-handed lifting styles with and without supporting body weight with the free hand on the bin as well as region and the number of feet. Twelve male and 12 female subjects lifted an 11.3 kg box from the bin. Spinal compression, lateral shear and anterior - posterior shear forces were estimated using a validated EMG-assisted biomechanical model. Phase I results indicated that the bin design factor of region had the greatest impact on spinal loading. The upper front region minimized spinal loading for all lifting styles. Furthermore, the lifting style of two hands and two feet minimized spinal loading. However, comparing Phase I two-handed lifting with Phase II one-handed supported lifting, the one-handed supported lifting techniques had lower compressive and anterior - posterior shear loads in the lower regions as well as the upper back region of the bin. A bin design that facilitates lifting from the upper front region of the bin reduces spinal loading more effectively than specific lifting styles. Furthermore, a bin design with a hand hold may facilitate workers using a supported lifting style that reduces spinal loading.

Foot positioning instruction, initial vertical load position and lifting technique: effects on low back loading

“…With a muscle force of 5000 N this would be equivalent to a change in shear force of over 1400 N. Since the orientation difference between L5/S1 and L4/L5 also causes the reaction force component of the forward shear force to be larger in L5/S1 than in L4/L5, quite large forward shear forces at the L5/S1 joint are not unexpected. The order of magnitude of shear forces in the L5/S1 joint was quite comparable with previous studies using EMG assisted (not single equivalent) trunk muscle models (Kingma and van Dieen 2004, Granata et al 1999, Ferguson et al 2002.…”

“…Knowledge about the effect of those determinants on low back loading could be used to develop effective preventive measures. For some determinants, like object weight (Davis and Marras 2000), lifting speed (Gagnon and Gagnon 1992, de Looze et al 1994, Kingma et al 2001, horizontal (Dolan et al 1994, Ferguson et al 2002 and vertical (Davis et al 1998, Ferguson et al 2002 position of the object relative to the worker, as well as several interactions between these factors (Lavender et al 2003), substantial evidence has been presented showing their influence on lumbar loading (de Looze et al 1994, Dolan et al 1994, Kingma et al 2001, Lavender et al 2003.…”

The effect of a lower extremity kinematic constraint on lifting biomechanics

“…The constraint that this barrier places on the kinematics of the lower extremities has a direct impact on the postures of the torso and it is believed that this will influence lifting biomechanics and lumbar stress. A review of the literature revealed that prior studies on this topic have focused on an alternative strategy wherein lifters used their off hand to support the weight of the upper body on the barrier while the dominant hand lifts the load (Ferguson et al, 2002;Kingma and van Dieën, 2004). Both studies illustrated the superiority of this strategy in terms of reduced trunk moment, reduced spine compression and reduced anterior-posterior shear force on low back.…”

Supporting the upper body with the hand on the thigh reduces back loading during lifting

“…Compared to two-handed lifting, lifting with one hand showed a minor (5-10%) reduction in lumbar moments or compression forces Marras and Davis, 1998), whereas more substantial (15-30%) reductions were found when the free hand was used to support the upper body by leaning on an external object (Ferguson et al, 2002;.…”