Intrinsic ankle stiffness during standing increases with ankle torque and passive stretch of the Achilles tendon.
Intrinsic ankle stiffness during standing increases with ankle torque and passive stretch of the Achilles tendon.
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DOI：
10.1371/journal.pone.0193850
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
Reynolds RF
中科院分区：
文献类型：
--
作者：
Sakanaka TE;Gill J;Lakie MD;Reynolds RF
个人可以以一系列踝关节角度站立。此外，鞋或地板表面可能会抬高或压低他们的脚跟。在这里，我们问这些情况如何影响踝关节僵硬和平衡。我们进行了两项研究（每项研究有10名参与者），其中小腿三头肌，跟腱和腱膜被动拉伸，通过旋转支撑表面，或主动前倾。受试者自由站立在踏板上，踏板可以围绕踝关节轴旋转。以4-5 s的间隔施加简短的小刚度测量扰动（<0.7 deg; 140 ms）。在研究1中，参与者以选定的前倾角度站立。在研究2中，正常站立与被动背屈引起的15度脚趾向上倾斜的支持表面进行了比较。较小的扰动产生较高的刚度估计，但对于所有的扰动大小的刚度增加与主动扭矩或被动拉伸。摇摆受拉伸或倾斜的影响最小，这表明这并不是刚度变化的基础。在安静站立时，踝关节的最大刚度受到肌腱的限制。随着肌腱应变的增加，它变得更加僵硬，导致整体踝关节刚度的增加，这可以解释倾斜的影响。然而，刚度也随着被动拉伸而显著增加，尽管扭矩适度增加。我们讨论了这种增长的可能解释。
Individuals may stand with a range of ankle angles. Furthermore, shoes or floor surfaces may elevate or depress their heels. Here we ask how these situations impact ankle stiffness and balance. We performed two studies (each with 10 participants) in which the triceps surae, Achilles tendon and aponeurosis were stretched either passively, by rotating the support surface, or actively by leaning forward. Participants stood freely on footplates which could rotate around the ankle joint axis. Brief, small stiffness-measuring perturbations (<0.7 deg; 140 ms) were applied at intervals of 4–5 s. In study 1, participants stood at selected angles of forward lean. In study 2, normal standing was compared with passive dorsiflexion induced by 15 deg toes-up tilt of the support surface. Smaller perturbations produced higher stiffness estimates, but for all perturbation sizes stiffness increased with active torque or passive stretch. Sway was minimally affected by stretch or lean, suggesting that this did not underlie the alterations in stiffness. In quiet stance, maximum ankle stiffness is limited by the tendon. As tendon strain increases, it becomes stiffer, causing an increase in overall ankle stiffness, which would explain the effects of leaning. However, stiffness also increased considerably with passive stretch, despite a modest torque increase. We discuss possible explanations for this increase.
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影响因子：
5.5
作者：
Herbert, RD;Moseley, AM;Gandevia, SC
通讯作者：
Gandevia, SC
影响因子：
5.5
作者：
FORD, LE;HUXLEY, AF;SIMMONS, RM
通讯作者：
SIMMONS, RM
影响因子：
5.5
作者：
Azizi, Emanuel;Roberts, Thomas J.
通讯作者：
Roberts, Thomas J.
影响因子：
11
作者：
LAKIE, M;WALSH, EG;WRIGHT, GW
通讯作者：
WRIGHT, GW
DOI：
10.1113/expphysiol.1988.sp003137
发表时间：
1988-03-01
影响因子：
--
作者：
LAKIE, M;ROBSON, LG
通讯作者：
ROBSON, LG