Unified theory regarding A/P and M/L balance in quiet stance
Unified theory regarding A/P and M/L balance in quiet stance
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DOI：
10.1152/jn.1996.75.6.2334
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发表时间：
1996-06-01
影响因子：
2.5
通讯作者：
Zabjek, KF
中科院分区：
文献类型：
--
作者：
Winter, DA;Prince, F;Zabjek, KF
1. 通过单一力平台的前后（A/P）和中外侧（M/L）方向的压力中心（COP）变化，量化了安静站姿的姿态控制。从一个单一的力平台记录，研究人员无法识别两个独立的机制，这在使用微力平台时变得明显。根据所采取的站立位置，脚踝和髋关节（负载/卸载）机制的许多组合是明显的。在并排站立时，A/P平衡完全受脚踝（足底/背屈肌）控制，而M/L平衡受髋关节（外展肌/内收肌）控制。在串联站姿中，A/P平衡由髋关节机制主导，踝关节足底/背屈肌的作用是混合的，很小的，有时可以忽略不计：对于M/L平衡，情况正好相反；踝关节内翻/外翻者占主导地位，髋部负荷/卸载机制的贡献很小。在一个中间的45度的立场位置，脚踝和髋关节的机制有助于在完全不同的方式控制净平衡。在M/L方向上，这两种策略会加强，而在AIP方向上，踝关节机制必须克服和消除髋部加载/卸载机制的大部分不适当贡献。独立机制的空间图揭示了这样一个事实，即看似随机的COP散点图只不过是两个独立空间图的空间和时间总和。在每只脚下连接各个cop的一条直线是由髋部机构控制的加载/卸载线。在这个加载/卸载线的直角上，并排和串联的位置是脚踝肌肉的独立控制线。在中间站立位置，存在独立的控制线，但此时踝关节控制与装卸线不正交；相反，它以一个类似于60度的角度起作用。这些脚踝控制和负重/卸载线的方向也使我们能够精确定位在任何姿势下负责脚踝和臀部的肌肉群。
1. Control of posture in quiet stance has been quantified by center of pressure (COP) changes in the anterior-posterior (A/P) and medial-lateral (M/L) directions from a single force platform. Recording from a single force platform, researchers are unable to recognize two separate mechanisms that become evident when mio force platforms are used. Depending on the stance position taken, many combinations of an ankle mechanism and a hip (load/unload) mechanism are evident. In side-by-side stance, A/P balance is totally under ankle (plantar/dorsiflexor) control, whereas M/L balance is under hip (abductor/adductor) control. In tandem stance, the A/P balance is dominated by the hip mechanism, with mixed and small or sometimes negligible contributions by the ankle plantar/dorsiflexors: for M/L balance, the reverse is evident; ankle invertors/evertors dominate, with mixed and small contribution from the hip load/unload mechanism. In an intermediate 45 degrees stance position,both ankle and hip mechanisms contribute to the net balance control in totally different ways. In the M/L direction the two strategies reinforce, whereas in the AIP direction the ankle mechanism must overcome and cancel most of the inappropriate contribution by the hip load/unload mechanism. A spatial plot of the separate mechanisms reveals the fact that the random-looking COP scatter plot is nothing more than a spatial and temporal summation of two separate spatial plots. A straight line joining the individual COPs under each foot is the load/unload Line controlled by the hip mechanism. At right angles to this load/unload line in the side-by-side and tandem positions is the independent control line by the ankle muscles. In an intermediate standing position, the separate control lines exist, but now the ankle control is not orthogonal to the load/unload line; rather, it acts at an angle of similar to 60 degrees. The direction of these ankle control and load/unload lines also allows us to pinpoint the muscle groups responsible at the ankle and hip in any Of the stance positions.