On the origin of planar covariation of elevation angles during human locomotion
On the origin of planar covariation of elevation angles during human locomotion
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DOI：
10.1152/jn.01308.2007
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发表时间：
2008-04-01
影响因子：
2.5
通讯作者：
Lacquaniti, F.
中科院分区：
文献类型：
--
作者：
Ivanenko, Y. P.;d'Avella, A.;Lacquaniti, F.
人体行走时腿段的旋转共变，使三维轨迹的时间仰角变化接近于一个平面。最近，中心约束和生物力学约束在人体运动运动学控制中的作用受到了质疑。在这里，基于模型和实验数据，我们表明，节间协调的平面规律不是生物力学的简单结果。首先，在各种运动模式（斜面行走、楼梯行走、空中行走、蹲伏行走、跳跃）下的全肢行为可以表示为2个自由度的平面运动，尽管平面的方向和两两段角相关性可能存在很大差异。其次，平面共变不是任何运动的必然结果。在某些情况下，它可能被系统地违反（例如，在走路时弯腰并抓住地板上的物体，或者在蹒跚学步的幼儿开始独立行走时），或者在其他情况下，它可能被转移到一个简单的线性关系中（例如，在原地踏步时）。最后，这三种主要肢段对平面共变及其特征都有重要贡献，从而形成由肢轴长度和方向定义的特定端点轨迹。运动神经控制的最新进展支持了运动学成分的中心表征假说。
Leg segment rotations in human walking covary, so that the three-dimensional trajectory of temporal changes in the elevation angles lies close to a plane. Recently the role of central versus biomechanical constraints on the kinematics control of human locomotion has been questioned. Here we show, based on both modeling and experimental data, that the planar law of intersegmental coordination is not a simple consequence of biomechanics. First, the full limb behavior in various locomotion modes (walking on inclined surface, staircase stepping, air-stepping, crouched walking, hopping) can be expressed as 2 degrees of freedom planar motion even though the orientation of the plane and pairwise segment angle correlations may differ substantially. Second, planar covariation is not an inevitable outcome of any locomotor movement. It can be systematically violated in some conditions (e. g., when stooping and grasping an object on the floor during walking or in toddlers at the onset of independent walking) or transferred into a simple linear relationship in others (e. g., during stepping in place). Finally, all three major limb segments contribute importantly to planar covariation and its characteristics resulting in a certain endpoint trajectory defined by the limb axis length and orientation. Recent advances in the neural control of movement support the hypothesis about central representation of kinematics components.