Kim Kyungsoo, Kim Yoon Hyuk, Lee SuKyoung
National Institute for Mathematical Sciences, Republic of Korea
Proc Inst Mech Eng H. 2007 Apr;221(3):229-35. doi: 10.1243/09544119JEIM229.
The load-carrying capacity of the spine has been experimentally shown to increase substantially when the resultant force of all loads applied on the spine is directed in accordance to its curvature, which is called a 'follower load (FL)'. However, there have been few studies to investigate the muscle forces producing the FL owing to the difficulty of the relevant experimental measurements. This study investigated whether trunk muscle activations could be found for transmitting an external load within a range of FL direction. A two-dimensional finite element model of a lumbar spine and 117 pairs of trunk muscles was developed in the sagittal plane. An optimization technique was utilized to estimate the muscle forces generating the FL and the corresponding responses of the lumbar spine under two loading cases: the upright neutral standing posture and the posture holding 200 N in the hands. For each loading case, the muscle forces required to generate the FL could be found and the corresponding responses of the lumbar spine validated that the FL could increase the load-carrying capacity. The results showed that the FL could be produced in vivo by trunk muscles to increase the load-carrying capacity.
实验表明，当施加在脊柱上的所有载荷的合力按照脊柱的曲率方向作用时，脊柱的承载能力会显著增加，这种载荷被称为“追随载荷（FL）”。然而，由于相关实验测量的困难，很少有研究去探究产生追随载荷的肌肉力量。本研究调查了在追随载荷方向范围内，是否能够发现躯干肌肉激活以传递外部载荷。在矢状面建立了腰椎和117对躯干肌肉的二维有限元模型。利用优化技术估计在两种加载情况下产生追随载荷的肌肉力量以及腰椎的相应反应：直立中立站立姿势和手持200 N的姿势。对于每种加载情况，都能找到产生追随载荷所需的肌肉力量，并且腰椎相应的反应证实了追随载荷能够增加承载能力。结果表明，躯干肌肉在体内能够产生追随载荷以增加承载能力。
