Gagnon D, Gagnon M
Faculté d'éducation physique et sportive, Université de Sherbrooke, Québec, Canada.
J Biomech. 1992 Aug;25(8):891-901. doi: 10.1016/0021-9290(92)90229-t.
Asymmetrical lifting and lowering are predominant activities in the workplace. Mechanical causes are suggested for many back injuries and the dynamic conditions within which spine loading occurs are related to spine loading increase. More data on tridimensional biomechanical lumbar spine loading during asymmetrical lifting and lowering are needed. A tridimensional dynamic multisegment model was developed to compute spinal loading for asymmetrical box-handling situations. The tridimensional positions of the anatomical markers were generated by a direct linear transformation algorithm adapted for the processing of data from two real and two virtual views (mirrors). Two force platforms measured the external forces. Five male subjects performed three variations (slow, fast and accelerated) of asymmetric lifting and two variations (slow and fast) of asymmetric lowering. The torsional, extension/flexion and lateral bending net muscular moments at the L5/S1 joint were computed and peak values selected for statistical analysis. For the lifting task, the fast and accelerated conditions showed significant increases over the slow condition for torsion, extension/flexion and lateral-bending moments. The accelerated condition also showed significant increases over the fast condition for extension. A comparison between lifting and lowering tasks showed equivalent loadings for torsion and extension. The moments were compared to average maximal values measured on equivalent male subject populations by isokinetic dynamometry. This showed torsional and extension values of 30 and 83% of the maximal possible subject capacity, respectively. These results demonstrated that dynamic factors do influence the load on the spine and highlighted the influence of both lifting and lowering on the loading of the spine. This suggested that for a more complete analysis of asymmetrical handling, the maximal velocity and acceleration produced during lifting should be included.
不对称的起升和下降是工作场所的主要活动。许多背部损伤被认为是由机械原因造成的，而脊柱负荷发生时的动态条件与脊柱负荷增加有关。需要更多关于不对称起升和下降过程中三维生物力学腰椎负荷的数据。开发了一个三维动态多节段模型来计算不对称搬运箱子情况下的脊柱负荷。解剖标记的三维位置由一种直接线性变换算法生成，该算法适用于处理来自两个真实视图和两个虚拟视图（镜子）的数据。两个力平台测量外力。五名男性受试者进行了不对称起升的三种变化（慢速、快速和加速）和不对称下降的两种变化（慢速和快速）。计算了L5/S1关节处的扭转、屈伸和侧弯净肌肉力矩，并选择峰值进行统计分析。对于起升任务，快速和加速条件下的扭转、屈伸和侧弯力矩比慢速条件下有显著增加。加速条件下的屈伸力矩也比快速条件下有显著增加。起升和下降任务的比较表明，扭转和屈伸的负荷相当。将这些力矩与通过等速测力法在同等男性受试者群体上测得的平均最大值进行比较。结果表明，扭转和屈伸值分别为受试者最大可能能力的30%和83%。这些结果表明，动态因素确实会影响脊柱负荷，并突出了起升和下降对脊柱负荷的影响。这表明，为了更全面地分析不对称搬运，应包括起升过程中产生的最大速度和加速度。
