Two kinematic synergies in voluntary whole-body movements during standing
Two kinematic synergies in voluntary whole-body movements during standing
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DOI：
10.1152/jn.00482.2005
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发表时间：
2006-02-01
影响因子：
2.5
通讯作者：
Latash, ML
中科院分区：
文献类型：
--
作者：
Freitas, SMSF;Duarte, M;Latash, ML
站立期间自愿全身运动的两种运动学协同作用。 《神经生理学杂志》95：636-645，2006 年。首次发表于 2005 年 11 月 2 日； doi：10.1152/jn。 00482.2005。我们使用一种特殊的计算方法，即不受控制的流形假设，来研究站立者执行全身动作时的关节角度协变模式。我们假设两种运动学协同作用解释了有节奏的全身运动期间腿部/躯干关节跨周期的协变，以稳定两个性能变量，即外部空间中的躯干方向和质心（COM）的水平位置。受试者站在测力板上，在四个变量之一（压力中心的位置或三个关节（踝、膝或髋）之一的角度）的视觉反馈下进行 45 秒的全身有节奏的运动。对于四个变量中的每一个，使用类似 Fitts 的范例，具有两个目标幅度和六个难度指数 (ID)。这样做是为了探索运动姿势协同作用的稳健性。在所有反馈条件下都观察到速度精度权衡，使得运动时间随 ID 缩放并且两个运动幅度之间的缩放比例不同。主成分 (PC) 分析表明，关节空间中存在单个 PC，占关节角度方差的 95% 以上。不受控流形假设内的分析表明，关节角度空间中的数据分布与躯干方向和 COM 位置的稳定性兼容。我们得出的结论是，躯干方向和 COM 位置是通过全身运动期间主要关节角度的共同变化来稳定的。尽管运动幅度和 ID 对性能有很大影响，但关节方差的结构仅显示出对这些任务参数的较小依赖性。事实证明，这两种运动学协同作用（稳定 COM 位置和躯干方向的关节角度的共同变化）在各种任务中都具有强大的鲁棒性。
Two kinematic synergies in voluntary whole-body movements during standing. J Neurophysiol 95: 636-645, 2006. First published November 2, 2005; doi: 10.1152/jn. 00482.2005. We used a particular computational approach, the uncontrolled manifold hypothesis, to investigate joint angle covariation patterns during whole-body actions performed by standing persons. We hypothesized that two kinematic synergies accounted for the leg/trunk joint covariation across cycles during a rhythmic whole-body motion to stabilize two performance variables, the trunk orientation in the external space and the horizontal position of the center of mass (COM). Subjects stood on a force plate and performed whole-body rhythmic movements for 45 s under visual feedback on one of the four variables, the position of the center of pressure or the angle in one of the three joints (ankle, knee, or hip). The Fitts-like paradigm was used with two target amplitudes and six indices of difficulty (ID) for each of the four variables. This was done to explore the robustness of kinematic postural synergies. A speedaccuracy trade-off was observed in all feedback conditions such that the movement time scaled with ID and the scaling differed between the two movement amplitudes. Principal-component (PC) analysis showed the existence of a single PC in the joint space that accounted for over 95% of the joint angle variance. Analysis within the uncontrolled manifold hypothesis has shown that data distributions in the joint angle space were compatible with stabilization of both trunk orientation and COM location. We conclude that trunk orientation and the COM location are stabilized by co-varied changes of the major joint angles during whole-body movements. Despite the strong effects of movement amplitude and ID on performance, the structure of the joint variance showed only minor dependence on these task parameters. The two kinematic synergies (co-varied changes in the joint angles that stabilized the COM location and trunk orientation) have proven to be robust over a variety of tasks.