Intralimb compensation strategy depends on the nature of joint perturbation in human hopping
Intralimb compensation strategy depends on the nature of joint perturbation in human hopping
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DOI：
10.1016/j.jbiomech.2008.04.006
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发表时间：
2008-01-01
影响因子：
2.4
通讯作者：
Auyang, Arick G.
中科院分区：
文献类型：
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作者：
Chang, Young-Hui;Roiz, Ronald A.;Auyang, Arick G.
由于弹跳步态的弹簧质量动力学描述良好，人类跳跃是一个易于处理的模型，用于阐明基本的神经肌肉补偿原理。我们测试了受试者是否会采用多关节或单关节的反应，以稳定腿部僵硬，而穿着弹簧加载的踝足矫形器（AFO），施加局部阻力和辅助扭矩的脚踝。我们分析了9名受试者在三种频率（2.2，2.4和2.8 Hz）和三种矫形器条件下（自由连接AFO，具有跖屈阻力的AFO和具有跖屈辅助的AFO）单腿跳跃的运动学和动力学数据。腿部刚度在AFO条件下是不变的，然而，补偿策略取决于所施加载荷的性质。生物踝关节刚度增加的阻力负荷的两倍，它减少了辅助负荷。单独的踝关节调整完全补偿了辅助负荷，而组合（生物加应用）总踝关节刚度没有净变化（P >= 0. 05）。133）。与此相反，阻力负荷导致整个频率的踝关节僵硬度增加7.4-9.0%，同时每个频率的膝关节僵硬度增加10-15%（p
Due to the well-described spring-mass dynamics of bouncing gaits, human hopping is a tractable model for elucidating basic neuromuscular compensation principles. We tested whether subjects would employ a multi-joint or single-joint response to stabilize leg stiffness while wearing a spring-loaded ankle-foot orthosis (AFO) that applied localized resistive and assistive torques to the ankle. We analyzed kinematics and kinetics data from nine subjects hopping in place on one leg, at three frequencies (2.2, 2.4, and 2.8 Hz) and three orthosis conditions (freely articulating AFO, AFO with plantarflexion resistance, and AFO with plantarflexion assistance). Leg stiffness was invariant across AFO conditions, however, compensation strategy depended upon the nature of the applied load. Biological ankle stiffness increased in response to a resistive load at twice the rate that it decreased with an assitive load. Ankle adjustments alone fully compensated for an assistive load with no net change in combined (biological plus applied) total ankle stiffness (P >= 0. 133). In contrast, a resistive load resulted in a 7.4-9.0% increase in total ankle stiffness across frequencies and a concomitant 10-15% increase in knee joint stiffness at each frequency (p