The modulation of forward propulsion, vertical support, and center of pressure by the plantarflexors during human walking
The modulation of forward propulsion, vertical support, and center of pressure by the plantarflexors during human walking
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DOI：
10.1016/j.gaitpost.2013.05.009
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发表时间：
2013-09-01
期刊：
影响因子：
2.4
通讯作者：
Thelen, Darryl G.
中科院分区：
文献类型：
--
作者：
Francis, Carrie A.;Lenz, Amy L.;Thelen, Darryl G.
腓肠肌和比目鱼肌都有助于踝关节跖屈肌的时刻在中期和末期的立场阶段的步态。腓肠肌还产生膝关节屈曲力矩，这可能导致比目鱼肌特有的动态功能。本研究使用肌肉刺激协议，实验比较个人跖屈肌的贡献，垂直支持，向前推进和压力中心（CoP）运动在正常步态。20名受试者在自行选择的速度下在装有仪器的跑步机上行走，刺激表面电极贴在内侧腓肠肌和比目鱼肌上。短持续时间脉冲串（90 ms）用于刺激腓肠肌或比目鱼肌在20%或30%的步态周期（GC）的随机步幅。评价了刺激和非刺激步幅之间的地面反应的变化，以表征在中期（刺激起始于20%GC）和晚期（30%GC）站立期间每块肌肉对全身运动的影响。腓肠肌和比目鱼肌各自诱导增加垂直支撑和前进的CoP在中期的立场。然而，后期的立场腓肠肌活动引起向前加速度，而中期和末期的立场比目鱼肌活动引起制动的向前速度。结果表明，在正常步态中，单个跖屈肌表现出独特的功能，这两块肌肉对向前推进具有相反的作用。这些经验结果对于提高用于预测步态中肌肉功能的模型的准确性以及临床上医生寻求使跖屈肌功能障碍患者的步态正常化都是重要的。(C)2013爱思唯尔有限公司版权所有。
The gastrocnemius and soleus both contribute to the ankle plantarflexor moment during the mid- and terminal stance phases of gait. The gastrocnemius also generates a knee flexion moment that may lead to dynamic function that is unique from the soleus. This study used a muscle stimulation protocol to experimentally compare the contributions of individual plantarflexors to vertical support, forward propulsion and center of pressure (CoP) movement during normal gait. Twenty subjects walked on an instrumented treadmill at self-selected speeds with stimulating surface electrodes affixed over the medial gastrocnemius and soleus muscles. Short duration pulse trains (90 ms) were used to stimulate either the gastrocnemius or soleus at 20% or 30% of the gait cycle (GC) of random strides. Changes in ground reactions between stimulated and non-stimulated strides were evaluated to characterize the influence of each muscle on whole body movement during mid-(stimulation onset at 20% GC) and late (30% GC) stance. The gastrocnemius and soleus each induced an increase in vertical support and anterior progression of the CoP in mid-stance. However, late stance gastrocnemius activity induced forward acceleration, while both mid-and terminal stance soleus activity induced braking of forward velocity. The results suggested that the individual plantarflexors exhibit unique functions during normal gait, with the two muscles having opposite effects on forward propulsion. These empirical results are important both for enhancing the veracity of models used to predict muscle function in gait and also clinically as physicians seek to normalize gait in patients with plantarflexor dysfunction. (C) 2013 Elsevier B.V. All rights reserved.