Department of Physiology, Faculty of Medicine, Kindai University, Osaka-Sayama, Osaka , Japan.
Integrative Neuroscience and Cognition Center, UMR 8002, Centre National de la Recherche Scientifique-Université Paris Descartes, Sorbonne Paris Cité, Paris , France.
J Neurophysiol. 2019 Jul 1;122(1):398-412. doi: 10.1152/jn.00803.2018. Epub 2019 May 22.
Several qualitative features distinguish bipedal from quadrupedal locomotion in mammals. In this study we show quantitative differences between quadrupedal and bipedal gait in the Japanese monkey in terms of gait patterns, trunk/hindlimb kinematics, and electromyographic (EMG) activity, obtained from 3 macaques during treadmill walking. We predicted that as a consequence of an almost upright body axis, bipedal gait would show properties consistent with temporal and spatial optimization countering higher trunk/hindlimb loads and a less stable center of mass (CoM). A comparatively larger step width, an ~9% longer duty cycle, and ~20% increased relative duration of the double-support phase were all in line with such a strategy. Bipedal joint kinematics showed the strongest differences in proximal, and least in distal, hindlimb joint excursions compared with quadrupedal gait. Hindlimb joint coordination (cyclograms) revealed more periods of single-joint rotations during bipedal gait and predominance of proximal joints during single support. The CoM described a symmetrical, quasi-sinusoidal left/right path during bipedal gait, with an alternating shift toward the weight-supporting limb during stance. Trunk/hindlimb EMG activity was nonuniformally increased during bipedal gait, most prominently in proximal antigravity muscles during stance (up to 10-fold). Non-antigravity hindlimb EMG showed altered temporal profiles during liftoff or touchdown. Muscle coactivation was more, but muscle synergies less, frequent during bipedal gait. Together, these results show that behavioral and EMG properties of bipedal vs. quadrupedal gait are quantitatively distinct and suggest that the neural control of bipedal primate locomotion underwent specific adaptations to generate these particular behavioral features to counteract increased load and instability. Bipedal locomotion imposes particular biomechanical constraints on motor control. In a within-species comparative study, we investigated joint kinematics and electromyographic characteristics of bipedal vs. quadrupedal treadmill locomotion in Japanese macaques. Because these features represent (to a large extent) emergent properties of the underlying neural control, they provide a comparative, behavioral, and neurophysiological framework for understanding the neural system dedicated to bipedal locomotion in this nonhuman primate, which constitutes a critical animal model for human bipedalism.
几种定性特征将哺乳动物的两足和四足运动区分开来。在这项研究中，我们展示了在日本猕猴中，四足和两足步态在步态模式、躯干/后肢运动学和肌电图（EMG）活动方面的定量差异，这些数据是从 3 只猕猴在跑步机上行走时获得的。我们预测，由于身体轴线几乎垂直，两足步态将表现出与时间和空间优化一致的特性，以抵消更高的躯干/后肢负荷和更不稳定的质心（CoM）。较大的步宽、约 9%更长的动作周期和约 20%增加的双支撑阶段相对持续时间都符合这种策略。与四足步态相比，两足关节运动学在近端显示出最强的差异，而在远端显示出最小的差异。后肢关节协调（循环图）显示，在两足步态中，单关节旋转的周期更多，在单支撑时，主要是近端关节。在两足步态中，CoM 描述了一个对称的、准正弦形的左右路径，在站立时向承重肢体交替移动。躯干/后肢 EMG 活动在两足步态中不均匀增加，在站立时，尤其是在抗重力肌肉中增加最多（高达 10 倍）。非抗重力后肢 EMG 在离地或触地时显示出不同的时间分布。肌肉协同作用在两足步态中更为频繁，但肌肉协同作用较少。总之，这些结果表明，两足与四足步态的行为和 EMG 特性在数量上是不同的，并表明两足灵长类动物运动的神经控制经历了特定的适应，以产生这些特殊的行为特征，以抵消增加的负荷和不稳定性。两足运动对运动控制施加了特殊的生物力学限制。在一项种内比较研究中，我们研究了日本猕猴在跑步机上的两足和四足运动的关节运动学和肌电图特征。由于这些特征在很大程度上代表了潜在神经控制的涌现特性，因此它们为理解这种非人类灵长类动物的两足运动提供了一个比较的、行为的和神经生理学框架，这是人类两足行走的关键动物模型。
