Predicted region of stability for balance recovery: motion at the knee joint can improve termination of forward movement
Predicted region of stability for balance recovery: motion at the knee joint can improve termination of forward movement
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DOI：
10.1016/s0021-9290(00)00129-9
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发表时间：
2000-12-01
影响因子：
2.4
通讯作者：
Pai, YC
中科院分区：
文献类型：
--
作者：
Iqbal, K;Pai, YC
早期关于扰动后平衡恢复的实验研究已经确定了人类常用的两种离散策略，即髋关节和踝关节策略。因此，有人暗示膝关节在平衡恢复中起着相对次要的作用。本研究的目的是确定在矢状面运动终止时允许膝关节运动是否会影响可行稳定区（FSR）的大小。FSR被定义为人体质心（COM）的前向速度的可行范围，当最终质心位置在支撑基础（BOS）范围内时，该速度可以降至零。采用四节段生物力学模型和基于模拟退火算法的优化程序，对三种情况进行了FSR计算：不受限制的膝关节运动（UK）、受限的膝关节运动（RK）和初始姿势匹配RK的不受限制的膝关节运动（UKM）。我们发现，当COM （x(COM)）最初位于前足区域时（0.00（脚趾）> x（COM）大于或等于-0.50（中足）），与RK相比，FSR增加不超过17%，英国条件对运动终止的益处不大。在x(COM) = - 1（脚跟）处，膝关节运动对后脚区域的影响增加，FSR增加25%。接近一半的差异（12%）可归因于膝关节对初始姿势的限制，其余归因于运动本身的终止。这些发现说明了膝关节运动在站立人类有效姿势反应中的理论作用，其中包括髋关节和踝关节策略及其在静止BOS中平衡恢复的变体。(C) 2000 Elsevier Science Ltd.版权所有。
Earlier experimental studies on balance recovery following perturbation have identified two discrete strategies commonly employed by humans, i.e. hip and ankle strategies. It has hence been implied that the knee joint prays a relatively minor role in balance recovery. The purpose of this study was to determine whether the size of the feasible stability region (FSR) would be affected by allowing knee motion in sagittal plane movement termination. The FSR was defined as the feasible range of anterior Velocities of the center of mass (COM) of a human subject that could be reduced to zero with the final COM position within the base of support (BOS) limits. The FSR was computed using a four-segment biomechanical model and optimization routine based on Simulated Annealing algorithm for three scenarios: unrestricted knee motion (UK), restricted knee motion (RK), and unrestricted knee motion with an initial posture that matches RK (UKM). We found that movement termination could benefit little from UK condition when the COM (x(COM)) was initially located in the forefoot region [0.00 (toe) > x(COM) greater than or equal to -0.50 (mid-foot)] with no more than a 17% increase in FSR compared to RK. The effect of knee motion increased in the rear foot region with a 25% increase in FSR at x(COM) = - 1 (heel). Close to half of this difference (12%) was attributable to the knee-related restriction on initial posture and the rest to movement termination per se. These findings illustrated a theoretical role of knee motion in standing humans' repertoire of effective posture responses, which include hip and ankle strategies and their variants for balance recovery with stationary BOS. (C) 2000 Elsevier Science Ltd. All rights reserved.