Leg stiffness primarily depends on ankle stiffness during human hopping
Leg stiffness primarily depends on ankle stiffness during human hopping
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DOI：
10.1016/s0021-9290(98)00170-5
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发表时间：
1999-03-01
影响因子：
2.4
通讯作者：
Morgenroth, DC
中科院分区：
文献类型：
--
作者：
Farley, CT;Morgenroth, DC
当人类原地跳跃或向前奔跑时，他们会调整腿部僵硬，以适应步频或表面僵硬的变化。本研究的目标是确定人类在原地跳跃过程中调整腿部僵硬的机制。5名受试者以2.2赫兹的频率跳跃到位，同时我们收集了力、平台和运动学数据。每个受试者都完成了跳跃到他们选择的任何高度的试验(“首选高度跳跃”)和他们跳得尽可能高的试验(“最大高度跳跃”)。最大高度跳跃的腿部僵硬大约是首选高度跳跃的两倍。最大高度跳跃的踝关节扭转刚度是首选高度跳跃的1.9倍，而膝关节扭转刚度是首选高度跳跃的1.7倍。我们使用计算机模拟来检验腿部僵硬对观察到的踝关节和膝关节僵硬变化的敏感性。我们的模型由四个部分(脚、小腿、大腿、头-臂-躯干)组成，由三个扭转弹簧(脚踝、膝盖、髋关节)相互连接。在模型中，在受试者中观察到，脚踝僵硬增加1.9倍，导致腿部僵硬增加2.0倍。膝关节僵硬增加1.7倍对腿部僵硬几乎没有影响。因此，我们得出结论：调节腿部僵硬的主要机制是调节踝关节僵硬。(C)1999爱思唯尔科学有限公司。保留所有权利。
When humans hop in place or run forward, they adjust leg stiffness to accommodate changes in stride frequency or surface stiffness. The goal of the present study was to determine the mechanisms by which humans adjust leg stiffness during hopping in place. Five subjects hopped in place at 2.2 Hz while we collected force platform and kinematic data. Each subject completed trials in which they hopped to whatever height they chose ("preferred height hopping") and trials in which they hopped as high as possible ("maximum height hopping"). Leg stiffness was approximately twice as great for maximum height hopping as for preferred height hopping. Ankle torsional stiffness was 1.9-times greater while knee torsional stiffness was 1.7-times greater in maximum height hopping than in preferred height hopping. We used a computer simulation to examine the sensitivity of leg stiffness to the observed changes in ankle and knee stiffness. Our model consisted of four segments (foot, shank, thigh, head-arms-trunk) interconnected by three torsional springs (ankle, knee, hip). In the model, increasing ankle stiffness by 1.9-fold, as observed in the subjects, caused leg stiffness to increase by 2.0-fold. Increasing knee stiffness by 1.7-fold had virtually no effect on leg stiffness. Thus, We conclude that the primary mechanism for leg stiffness adjustment is the adjustment of ankle stiffness. (C) 1999 Elsevier Science Ltd. All rights reserved.