Dolan P, Earley M, Adams M A
University of Bristol, U.K.
J Biomech. 1994 Oct;27(10):1237-48. doi: 10.1016/0021-9290(94)90277-1.
Cadaveric studies have shown that intervertebral discs and ligaments are most vulnerable to injury when loaded simultaneously in bending and compression. The purpose of the present experiment was to measure bending and compressive stresses acting on the lumbar spine during forward bending and lifting activities, and to identify those aspects of lifting which increase the risk of injury. Twenty-one men and eighteen women lifted objects from the ground while the following parameters were varied: the angle of the knees ('squat' lift or 'stoop' lift), the mass of the object, its bulk, its distance in front of the feet, its distance away from the sagittal plane, and the speed of movement. Spinal compression was assessed by measuring the peak extensor moment generated by the back muscles and fascia during the lift. Extensor moment was calculated from the EMG activity of the erector spinae muscles, using corrections for muscle length, contraction velocity and electro-mechanical delay. The bending moment ('bending torque') acting on the intervertebral discs and ligaments was quantified by comparing dynamic measurements of lumbar flexion, obtained with the '3-Space Isotrak', with the normalised bending properties of cadaveric lumbar spines. Results showed that stoop lifting reduced the peak extensor moment by about 10% compared to squat lifting, but increased the bending torque by about 75%. Extensor moment and bending torque both increased substantially with increasing mass, bulk and distance from the feet. Non-sagittal plane lifts increased the bending torque by about 30%. The fastest lifts increased peak extensor moment by 60% but did not increase bending torque. We conclude that complex spinal loading during lifting tasks depends as much on the speed of movement, and the size and position of the object lifted, as on its mass. Analyses of spinal loading which consider only compressive forces do not give a full indication of the risk of injury to the intervertebral discs and ligaments.
尸体研究表明，椎间盘和韧带在同时承受弯曲和压缩负荷时最易受伤。本实验的目的是测量前屈和提举活动期间作用于腰椎的弯曲应力和压缩应力，并确定提举过程中增加受伤风险的那些因素。21名男性和18名女性从地面提起物体，同时改变以下参数：膝盖角度（“深蹲”提举或“弯腰”提举）、物体质量、体积、物体在脚前方的距离、物体与矢状面的距离以及移动速度。通过测量提举过程中背部肌肉和筋膜产生的伸肌峰值力矩来评估脊柱压缩情况。伸肌力矩根据竖脊肌的肌电图活动计算得出，并对肌肉长度、收缩速度和机电延迟进行了校正。通过将使用“3-Space Isotrak”获得的腰椎前屈动态测量结果与尸体腰椎的标准化弯曲特性进行比较，来量化作用于椎间盘和韧带的弯矩（“弯曲扭矩”）。结果表明，与深蹲提举相比，弯腰提举使伸肌峰值力矩降低了约10%，但使弯曲扭矩增加了约75%。随着物体质量、体积和离脚距离的增加，伸肌力矩和弯曲扭矩均大幅增加。非矢状面提举使弯曲扭矩增加了约30%。最快的提举使伸肌峰值力矩增加了60%，但未增加弯曲扭矩。我们得出结论，提举任务期间复杂的脊柱负荷同样取决于移动速度、所提物体的大小和位置以及物体质量。仅考虑压缩力的脊柱负荷分析并不能全面表明椎间盘和韧带受伤的风险。
