Kumar S, Narayan Y, Zedka M
Department of Physical Therapy, University of Alberta, Edmonton, Canada.
Ergonomics. 1998 Jun;41(6):835-52. doi: 10.1080/001401398186676.
Thirty-eight normal healthy young subjects (14 males, 24 females) with mean ages of 23 years (males) and 21 years (females), performed 36 functional rotational tasks of the trunk. The subject's lower extremities were stabilized in a stabilizing platform, allowing the entire motion of flexion-rotation and extension-rotation to take place in the trunk. Of these tasks, 18 were isometric and the other 18 were isokinetic. The isometric tasks consisted of flexion-rotation and extension-rotation from a 20 degrees, 40 degrees and 60 degrees flexed trunk in 20 degrees, 40 degrees and 60 degrees of axial rotation. The isokinetic activity consisted of flexion-rotation and extension-rotation from upright and flexed postures respectively in 20 degrees, 40 degrees and 60 degrees rotation planes at 15 degrees, 30 degrees and 60 degrees/s angular velocities. The results revealed that the males were significantly stronger than females (p < 0.01) and isometric activities produced significantly greater torque compared to isokinetic efforts (p < 0.01). The degree of trunk flexion was not significant; the angle of rotation, although significant, had only a small effect. The 60 degrees trunk rotation was significantly different from 20 degrees and 40 degrees of trunk rotation. The multiple regressions were all significant (p < 0.01); however, they predicted only 40 to 60% of the variations. Based on the results and analysis, it is suggested that the motion involved rather than the torque may have a consequential effect in the precipitation of back injuries.
38名正常健康的年轻受试者（14名男性，24名女性），平均年龄男性为23岁，女性为21岁，进行了36项躯干功能性旋转任务。受试者的下肢固定在一个稳定平台上，使整个屈伸旋转运动在躯干中进行。在这些任务中，18项为等长运动，另外18项为等速运动。等长任务包括在躯干分别处于20度、40度和60度屈曲时，在20度、40度和60度轴向旋转下的屈伸旋转。等速运动分别包括在直立和屈曲姿势下，在20度、40度和60度旋转平面上，以15度、30度和60度/秒的角速度进行的屈伸旋转。结果显示，男性明显比女性强壮（p < 0.01），与等速运动相比，等长运动产生的扭矩明显更大（p < 0.01）。躯干屈曲程度不显著；旋转角度虽然显著，但影响较小。60度躯干旋转与20度和40度躯干旋转有显著差异。多元回归均显著（p < 0.01）；然而，它们仅预测了40%至60%的变异。根据结果和分析，建议在背部损伤的发生中，所涉及的运动而非扭矩可能具有重要影响。
