Gagnon Denis, Plamondon André, Larivière Christian
Faculté des sciences de l'activité physique, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Institut de recherche Robert Sauvé en santé et en sécurité du travail, Montréal, Québec, Canada.
J Biomech. 2018 Nov 16;81:76-85. doi: 10.1016/j.jbiomech.2018.09.017. Epub 2018 Sep 19.
There is a clear relationship between lumbar spine loading and back musculoskeletal disorders in manual materials handling. The incidence of back disorders is greater in women than men, and for similar work demands females are functioning closer to their physiological limit. It is crucial to study loading on the spine musculoskeletal system with actual handlers, including females, to better understand the risk of back disorders. Extrapolation from biomechanical studies conducted on unexperienced subjects (mainly males) might not be applicable to actual female workers. For male workers, expertise changes the lumbar spine flexion, passive spine resistance, and active/passive muscle forces. However, experienced females select similar postures to those of novices when spine loading is critical. This study proposes that the techniques adopted by male experts, male novices, and females (with considerable experience but not categorized as experts) impact their lumbar spine musculoskeletal systems differently. Spinal loads, muscle forces, and passive resistance (muscle and ligamentous spine) were predicted by a multi-joint EMG-assisted optimization musculoskeletal model of the lumbar spine. Expert males flexed their lumbar spine less (avg. 21.9° vs 30.3-31.7°) and showed decreased passive internal moments (muscle avg. 8.9% vs 15.9-16.0%; spine avg. 4.7% vs 7.1-7.8%) and increased active internal moments (avg. 72.9% vs 62.0-63.9%), thus producing a different impact on their lumbar spine musculoskeletal systems. Experienced females sustained the highest relative spine loads (compression avg. 7.3 N/BW vs 6.2-6.4 N/BW; shear avg. 2.3 N/BW vs 1.7-1.8 N/BW) in addition to passive muscle and ligamentous spine resistance similar to novices. Combined with smaller body size, less strength, and the sequential lifting technique used by females, this could potentially mean greater risk of back injury. Workers should be trained early to limit excessive and repetitive stretching of their lumbar spine passive tissues.
在人工搬运物料过程中，腰椎负荷与背部肌肉骨骼疾病之间存在明确的关联。背部疾病的发病率女性高于男性，并且在相似的工作要求下，女性更接近其生理极限。对于包括女性在内的实际操作人员，研究脊柱肌肉骨骼系统上的负荷对于更好地理解背部疾病风险至关重要。从不熟练受试者（主要为男性）身上进行的生物力学研究推断出的结果可能不适用于实际的女性工人。对于男性工人，专业技能会改变腰椎前屈、脊柱被动阻力以及主动/被动肌肉力量。然而，当脊柱负荷至关重要时，有经验的女性会选择与新手相似的姿势。本研究表明，男性专家、男性新手以及女性（有相当经验但未归类为专家）所采用的技术对其腰椎肌肉骨骼系统的影响有所不同。通过多关节肌电图辅助优化的腰椎肌肉骨骼模型预测脊柱负荷、肌肉力量和被动阻力（肌肉和脊柱韧带）。男性专家的腰椎前屈程度较小（平均21.9° 对比30.3 - 31.7°），被动内力矩降低（肌肉平均降低8.9% 对比15.9 - 16.0%；脊柱平均降低4.7% 对比7.1 - 7.8%），主动内力矩增加（平均增加72.9% 对比62.0 - 63.9%），从而对其腰椎肌肉骨骼系统产生不同的影响。有经验的女性除了与新手相似的被动肌肉和脊柱韧带阻力外，承受着最高的相对脊柱负荷（压缩平均7.3 N/BW 对比6.2 - 6.4 N/BW；剪切平均2.3 N/BW 对比1.7 - 1.8 N/BW）。再加上女性体型较小、力量较弱以及采用的连续提举技术，这可能意味着背部受伤的风险更大。应尽早对工人进行培训，以限制其腰椎被动组织过度和重复的拉伸。
