Interaction of leg stiffness and surface stiffness during human hopping
Interaction of leg stiffness and surface stiffness during human hopping
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DOI：
10.1152/jappl.1997.82.1.15
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发表时间：
1997-01-01
影响因子：
3.3
通讯作者：
Farley, CT
中科院分区：
文献类型：
--
作者：
Ferris, DP;Farley, CT
当哺乳动物跑步时，整个肌肉骨骼系统表现为一个单一的线性“腿弹簧”。“我们使用力平台和运动学测量来确定腿弹簧刚度（k（腿））是否被调整以适应人类跳跃时表面刚度（k（冲浪））的变化，这是一个很好的实验模型，用于检查k（腿）在弹跳步态中的调整。我们发现k（腿）大大增加，以适应较低刚度的表面。在给定跳频下，k（leg）和k(surf)[总刚度（k(tot)）]的级数组合与k（surf）无关。例如，当人类以2赫兹的频率跳跃时，他们在最不僵硬的表面上的k（腿）增加了三倍(k（冲浪）= 26.1 kN/m；k（腿）= 53.3 kN/m)与最硬的表面(k（冲浪）= 35000 kN/m相比；k（腿）= 17.8 kN/m)。最小刚度面（16.7 kN/m）和最大刚度面（17.8 kN/m）的k（tot）值差异不显著。由于k（腿）的调整，跳跃力学的许多方面（例如，地面接触时间和质心垂直位移）仍然非常相似，尽管k（冲浪）变化了1000倍。这项研究提供了关于k（腿）调整如何使跑步者在自然世界中遇到的各种地形上实现类似的运动机制的见解。
When mammals run, the overall musculoskeletal system behaves as a single linear ''leg spring.'' We used force platform and kinematic measurements to determine whether leg spring stiffness (k(leg)) is adjusted to accommodate changes in surface stiffness (k(surf)) when humans hop in place, a good experimental model for examining adjustments to k(leg) in bouncing gaits. We found that k(leg) was greatly increased to accommodate surfaces of lower stiffnesses. The series combination of k(leg) and k(surf) [total stiffness (k(tot))] was independent of k(surf) at a given hopping frequency. For example, when humans hopped at a frequency of 2 Hz, they tripled their k(leg) on the least stiff surface (k(surf) = 26.1 kN/m; k(leg) = 53.3 kN/m) compared with the most stiff surface (k(surf) = 35,000 kN/m; k(leg) = 17.8 kN/m). Values for k(tot) were not significantly different on the least stiff surface (16.7 kN/m) and the most stiff surface (17.8 kN/m). Because of the k(leg) adjustment, many aspects of the hopping mechanics (e.g., ground-contact time and center of mass vertical displacement) remained remarkably similar despite a >1,000-fold change in k(surf). This study provides insight into how k(leg) adjustments can allow similar locomotion mechanics on the variety of terrains encountered by runners in the natural world.