The goal of this study is to evaluate the effects of the application of torque pulses to the hip and knee joint via a robotic exoskeleton in the context of training propulsion during walking. Based on our previous biomechanical study, we formulated a set of conditions of torque pulses applied to the hip and knee joint associated with changes in push-off posture, a component of propulsion. In this work, we quantified the effects of hip/knee torque pulses on metrics of propulsion, specifically hip extension (HE) and normalized propulsive impulse (NPI), in two experiments. In the first experiment, we exposed 16 participants to sixteen conditions of torque pulses during single strides to observe the immediate effects of pulse application. In the second experiment, we exposed 16 participants to a subset of those conditions to observe short-term adaptation effects. During pulse application, NPI aligned with the expected modulation of push-off posture, while HE was modulated in the opposite direction. The timing of the applied pulses, early or late stance, was crucial, as the effects were often in the opposite direction when changing timing condition. Extension torque applied at late stance increased HE in both experiments - range of change in HE: (1.6±0.3 deg, 7.7±0.9 deg), p < 0.001). The same conditions resulted in a negative change in NPI only in the single pulse experiment - change in NPI for knee torque: -2.9±0.3ms, p < 0.001, no significant change for hip torque. Also, knee extension and flexion torque during early and late stance, respectively, increased NPI during single pulse application - range of change in NPI: (3.4, 4.2)±0.3 ms, p < 0.001). During repeated pulse application, NPI increased for late stance flexion torque - range of change in NPI: (4.5, 4.8)±2 ms, p < 0.001), but not late stance extension torque. Upon pulse torque removal, we observed positive after-effects in HE in all conditions. While there were no after-effects in NPI significant at the group level, a responder analysis indicated that the majority of the group increased both NPI and HE after pulse application.

中文翻译：

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机器人在步行过程中的推进训练：站立时髋和膝关节施加扭矩脉冲的影响

这项研究的目的是在步行过程中训练推进的情况下，评估通过机器人外骨骼将扭矩脉冲施加到髋和膝关节的效果。在之前的生物力学研究的基础上，我们制定了一组施加到髋和膝关节的扭矩脉冲条件，这些条件与下推姿势的变化相关，下推姿势是推动力的组成部分。在这项工作中，我们在两个实验中量化了髋/膝转矩脉冲对推进指标的影响，特别是髋部伸展（HE）和归一化推进冲动（NPI）。在第一个实验中，我们在单步期间将16位参与者暴露在16种扭矩脉冲条件下，以观察脉冲施加的即时效果。在第二个实验中 我们将16位参与者暴露于这些条件的一部分中，以观察短期适应效果。在脉冲施加期间，NPI符合预期的下推姿势调制，而HE则沿相反方向调制。施加脉冲的时序（早期或晚期姿态）至关重要，因为在更改时序条件时，效果通常是相反的。在两个实验中，后期站立时施加的延伸扭矩均增加了HE-HE的变化范围：（1.6±0.3度，7.7±0.9度，p <0.001）。相同的条件仅在单脉冲实验中导致NPI负变化-膝部扭矩的NPI变化：-2.9±0.3ms，p <0.001，髋部扭矩无明显变化。同样，在早期和晚期站立期间，膝盖伸展和屈曲扭矩 单脉冲施加过程中NPI增加-NPI的变化范围：（3.4，4.2）±0.3 ms，p <0.001）。在重复施加脉冲期间，后期姿势屈曲扭矩的NPI增加-NPI的变化范围：（4.5，4.8）±2 ms，p <0.001），但后期姿势伸展扭矩没有增加。去除脉冲扭矩后，我们观察到在所有条件下HE均具有积极的后效应。尽管在组水平上没有明显的NPI后效，但一项响应者分析表明，在施加脉冲后，该组中的大多数都增加了NPI和HE。我们在所有情况下均观察到了HE的积极后遗症。虽然在组水平上没有明显的NPI后效，但响应者分析表明，在施加脉冲后，该组中的大多数都增加了NPI和HE。我们在所有条件下均观察到了HE的积极后遗症。虽然在组水平上没有明显的NPI后效，但响应者分析表明，在施加脉冲后，该组中的大多数都增加了NPI和HE。