Supplemental Digital Content is Available in the Text. Background and Purpose: The ankle plantarflexor muscles are the primary generators of propulsion during walking. Impaired paretic plantarflexion is a key contributor to interlimb propulsion asymmetry after stroke. Poststroke muscle weakness may be the result of a reduced force-generating capacity, reduced central drive, or a combination of these impairments. This study sought to elucidate the relationship between the neuromuscular function of the paretic plantarflexor muscles and propulsion deficits across individuals with different walking speeds. Methods: For 40 individuals poststroke, we used instrumented gait analysis and dynamometry coupled with supramaximal electrostimulation to study the interplay between limb kinematics, the neuromuscular function of the paretic plantarflexors (ie, strength capacity and central drive), propulsion, and walking speed. Results: The strength capacity of the paretic plantarflexors was not independently related to paretic propulsion. Reduced central drive to the paretic plantarflexors independently contributed to paretic propulsion deficits. An interaction between walking speed and plantarflexor central drive was observed. Individuals with slower speeds and lower paretic plantarflexor central drive presented with the largest propulsion impairments. Some study participants with low paretic plantarflexor central drive presented with similarly fast speeds as those with near-normal central drive by leveraging a compensatory reliance on nonparetic propulsion. The final model accounted for 86% of the variance in paretic propulsion (R2 = 0.86, F = 33.10, P < 0.001). Discussion and Conclusions: Individuals poststroke have latent paretic plantarflexion strength that they are not able to voluntarily access. The magnitude of central drive deficit is a strong indicator of propulsion impairment in both slow and fast walkers. Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A298).

中文翻译：

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麻痹性踝关节跖屈肌的中央驱动影响中风后推进力和步行速度之间的关系

补充数字内容在文本中可用。背景和目的：踝关节跖屈肌是行走过程中主要的推进力发生器。麻痹性跖屈受损是中风后肢体间推进不对称的关键因素。中风后肌肉无力可能是产生力的能力降低、中枢驱动降低或这些损伤的组合的结果。本研究旨在阐明不同步行速度个体的瘫痪跖屈肌的神经肌肉功能与推进缺陷之间的关系。方法：对于 40 名卒中后个体，我们使用仪器步态分析和测力法结合超最大电刺激来研究肢体运动学、麻痹足底屈肌的神经肌肉功能（即，力量和中央驱动）、推进力和步行速度。结果：麻痹性跖屈肌的力量能力与麻痹性推进没有独立相关。减少对麻痹足底屈肌的中枢驱动独立地导致麻痹推进缺陷。观察到步行速度和跖屈中央驱动之间的相互作用。速度较慢和麻痹性跖屈中央驱动力较低的个体出现最大的推进障碍。一些具有低麻痹性跖屈中央驱动的研究参与者通过利用对非麻痹推进的补偿性依赖，呈现出与具有接近正常中央驱动的人相似的快速速度。最终模型占麻痹推进力方差的 86%（R2 = 0.86，F = 33.10，P < 0.001）。讨论和结论：中风后的个体具有潜在的麻痹性跖屈力量，他们无法自愿获得。中枢驱动不足的程度是慢步行者和快步行者推进力受损的有力指标。视频摘要可提供作者的更多见解（参见视频，补充数字内容 1，可在：http://links.lww.com/JNPT/A298 获得）。