Munoz-Martel Victor, Santuz Alessandro, Bohm Sebastian, Arampatzis Adamantios
Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
Berlin School of Movement Science, Humboldt-Universität zu Berlin, Berlin, Germany.
Front Hum Neurosci. 2021 Jan 20;14:560630. doi: 10.3389/fnhum.2020.560630. eCollection 2020.
Understanding the neuromechanical responses to perturbations in humans may help to explain the reported improvements in stability performance and muscle strength after perturbation-based training. In this study, we investigated the effects of perturbations, induced by unstable surfaces, on the mechanical loading and the modular organization of motor control in the lower limb muscles during lunging forward and backward. Fifteen healthy adults performed 50 forward and 50 backward lunges on stable and unstable ground. Ground reaction forces, joint kinematics, and the electromyogram (EMG) of 13 lower limb muscles were recorded. We calculated the resultant joint moments and extracted muscle synergies from the stepping limb. We found sparse alterations in the resultant joint moments and EMG activity, indicating a little if any effect of perturbations on muscle mechanical loading. The time-dependent structure of the muscle synergy responsible for the stabilization of the body was modified in the perturbed lunges by a shift in the center of activity (later in the forward and earlier in the backward lunge) and a widening (in the backward lunge). Moreover, in the perturbed backward lunge, the synergy related to the body weight acceptance was not present. The found modulation of the modular organization of motor control in the unstable condition and related minor alteration in joint kinetics indicates increased control robustness that allowed the participants to maintain functionality in postural challenging settings. Triggering specific modulations in motor control to regulate robustness in the presence of perturbations may be associated with the reported benefits of perturbation-based training.
了解人体对扰动的神经力学反应,可能有助于解释基于扰动训练后所报道的稳定性表现和肌肉力量的改善。在本研究中,我们调查了不稳定表面诱发的扰动对向前和向后弓步时下肢肌肉的机械负荷及运动控制模块化组织的影响。15名健康成年人在稳定和不稳定地面上分别进行了50次向前和50次向后弓步。记录地面反作用力、关节运动学以及13块下肢肌肉的肌电图(EMG)。我们计算了合成关节力矩,并从迈步肢体中提取肌肉协同作用。我们发现合成关节力矩和EMG活动仅有少量改变,表明扰动对肌肉机械负荷几乎没有影响。在受扰动的弓步动作中,负责身体稳定的肌肉协同作用的时间依赖性结构发生了改变,表现为活动中心的偏移(向前弓步时延迟,向后弓步时提前)和拓宽(向后弓步时)。此外,在受扰动的向后弓步中,与身体重量接受相关的协同作用不存在。在不稳定状态下发现的运动控制模块化组织的调节以及关节动力学的相关微小改变,表明控制稳健性增加,使参与者能够在具有姿势挑战性的环境中保持功能。在存在扰动的情况下触发运动控制中的特定调节以调节稳健性,可能与基于扰动训练所报道的益处相关。