Local dynamic stability in temporal pattern of intersegmental coordination during various stride time and stride length combinations
Local dynamic stability in temporal pattern of intersegmental coordination during various stride time and stride length combinations
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DOI：
10.1007/s00221-018-5422-0
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发表时间：
2018-11
影响因子：
2
通讯作者：
Benio Kibushi;T. Moritani;M. Kouzaki
中科院分区：
文献类型：
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作者：
Benio Kibushi;T. Moritani;M. Kouzaki
为了调节步行速度，中枢神经系统必须选择适当的步幅时间和步幅长度的组合（步幅时间长度组合），并协调全身的许多关节或节段。然而，人类实现了步幅时间长度组合的适当选择和关节或节段的轻松协调。虽然这种步幅时间长度组合的选择已被解释为最小化的能量成本，它也可以被解释为运动协调的稳定性。因此，我们研究了在步行过程中的运动协调的稳定性跨越各种步幅的时间长度组合。全身运动协调被量化为运动协同作用，代表了同时移动的节段组（节段间协调）和它们的激活模式（时间协调）。此外，最大李雅普诺夫指数被用来评估当地的动态稳定性。我们计算了最大的李雅普诺夫指数在时间协调的运动协同作用在不同的步幅时间长度组合。结果表明，时间协调的最大李雅普诺夫指数依赖于步幅时间长度组合。此外，最大李雅普诺夫指数高，在快速步行速度和非常短的步长条件。这一结果表明，快速步行速度和非常短的步长与较低的局部动态稳定性的时间协调。我们的结论是，快速行走与较低的局部动态稳定性的时间协调的运动协同作用。
For the regulation of walking speed, the central nervous system must select appropriate combinations of stride time and stride length (stride time–length combinations) and coordinate many joints or segments in the whole body. However, humans achieve both appropriate selection of stride time–length combinations and effortless coordination of joints or segments. Although this selection of stride time–length combination has been explained by minimized energy cost, it may also be explained by the stability of kinematic coordination. Therefore, we investigated the stability of kinematic coordination during walking across various stride time–length combinations. Whole body kinematic coordination was quantified as the kinematic synergies that represents the groups of simultaneously move segments (intersegmental coordination) and their activation patterns (temporal coordination). In addition, the maximum Lyapunov exponents were utilized to evaluate local dynamic stability. We calculated the maximum Lyapunov exponents in temporal coordination of kinematic synergies across various stride time–length combinations. The results showed that the maximum Lyapunov exponents of temporal coordination depended on stride time–length combinations. Moreover, the maximum Lyapunov exponents were high at fast walking speeds and very short stride length conditions. This result implies that fast walking speeds and very short stride length were associated with lower local dynamic stability of temporal coordination. We concluded that fast walking is associated with lower local dynamic stability of temporal coordination of kinematic synergies.