Runners adjust leg stiffness for their first step on a new running surface
Runners adjust leg stiffness for their first step on a new running surface
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DOI：
10.1016/s0021-9290(99)00078-0
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发表时间：
1999-08-01
影响因子：
2.4
通讯作者：
Farley, CT
中科院分区：
文献类型：
--
作者：
Ferris, DP;Liang, KL;Farley, CT
人类跑步者调整他们站立腿的硬度，以适应稳态跑步时的表面硬度。这种调整允许跑步者保持相似的重心运动(例如，地面接触时间和步频)，而不考虑表面硬度。当跑步者遇到跑道表面的突然转变时，他们必须进行快速调整，或者允许跑道表面硬度的变化来扰乱他们的跑步机制。我们的目标是确定跑步者在遇到之前遇到的表面僵硬的突然但预期的变化时，调整腿部僵硬的速度有多快。6名受试者以3米S(-1)的速度在橡胶跑道上跑步，橡胶表面有两种：顺应性“软”表面(k(Surf)=21.3kN m(-1))和非顺应性“硬”表面(k(Surf)=533 kN m(-1))。我们发现，跑步者在过渡后的新表面上的第一步完全调整了腿部僵硬。例如，跑步者在软面上的最后一步和硬面上的第一步之间腿部硬度降低了29%(分别从10.7kNm(-1)到7.6kNm(-1))。因此，尽管表面压缩从6厘米减少到不到0.25厘米，但站立期间重心的垂直位移(类似于7厘米)在过渡时没有变化。通过快速调整腿部刚度，每个流道在表面之间进行平滑过渡，以便质心的路径不受表面刚度变化的影响。(C)1999爱思唯尔科学有限公司。保留所有权利。
Human runners adjust the stiffness of their stance leg to accommodate surface stiffness during steady state running. This adjustment allows runners to maintain similar center of mass movement (e.g., ground contact time and stride frequency) regardless of surface stiffness. When runners encounter abrupt transitions in the running surface, they must either make a rapid adjustment or allow the change in the surface stiffness to disrupt their running mechanics. Our goal was to determine how quickly runners adjust leg stiffness when they encounter an abrupt but expected change in surface stiffness that they have encountered previously. Six human subjects ran at 3 m s(-1) on a rubber track with two types of rubber surfaces: a compliant "soft" surface (k(surf) = 21.3 kN m(-1)) and a non-compliant "hard" surface (k(surf) = 533 kN m(-1)). We found that runners completely adjusted leg stiffness for their first step on the new surface after the transition. For example, runners decreased leg stiffness by 29% between the last step on the soft surface and the first step on the hard surface (from 10.7 kN m(-1) to 7.6 kN m(-1), respectively). As a result, the Vertical displacement of the center of mass during stance( similar to 7 cm) did not change at the transition despite a reduction in surface compression from 6 cm to less than 0.25 cm. By rapidly adjusting leg stiffness, each runner made a smooth transition between surfaces so that the path of the center of mass was unaffected by the change in surface stiffness. (C) 1999 Elsevier Science Ltd. All rights reserved.