Transporting an object during locomotion is one of the most common activities humans perform. Previous studies have shown that continuous and predictive control of grip force, along with the inertial load force of the object, is required to complete this task successfully. Another possible CNS strategy to ensure the dynamic stability of the upper limb is to modify the apparent stiffness and damping via altered muscle activation patterns. In this study, the term damping was used to describe a reduction in upper limb vertical oscillation amplitude to maintain the orientation of the hand-held object. The goal of this study was to identify the neuromuscular strategy for controlling the upper limb during object transport while walking. Three-dimensional kinematic and surface electromyography (EMG) data were recorded from eight, right-handed, healthy young adults who were instructed to walk on a treadmill while carrying an object in their dominant/non-dominant hand, with dominant/non-dominant arm positioning but without an object, and without any object or instructed arm-positioning. EMG recordings from the dominant and non-dominant arms were decomposed separately into underlying muscle synergies using non-negative matrix factorization (NNMF). Results revealed that the dominant arm showed higher damping compared to the non-dominant arm. All muscles showed higher mean levels of activation during object transport except for posterior deltoid (PD), with activation peaks occurring around or slightly before heel contact. The muscle synergy analysis revealed an anticipatory stabilization of the shoulder and elbow joints through a proximal-to-distal muscle activation pattern. These activations appear to play an essential role in maintaining the stability of the carried object in addition to the adjustment of grip force against the perturbations caused by heel contact during walking.

中文翻译：

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在健康的年轻人中行走时，在物体运输过程中，肌肉协同作用可抑制上肢的行为。

在运动过程中运输物体是人类执行的最常见的活动之一。先前的研究表明，抓取力以及对象的惯性负载力的连续和预测控制是成功完成此任务所必需的。确保上肢动态稳定性的另一种可能的中枢神经系统策略是通过改变肌肉的激活方式来改变表观的刚度和阻尼。在这项研究中，阻尼一词用来描述上肢垂直振动幅度的减小，以保持手持物体的方向。这项研究的目的是确定行走过程中物体运输过程中控制上肢的神经肌肉策略。记录了来自八个惯用右手的三维运动学和表面肌电图（EMG）数据 健康的年轻成年人，他们被指示走路时要在自己的惯用/非惯用手中拿着物体，手臂的位置主要/非惯用，但没有物体，也没有任何物体或指令的手臂位置。使用非负矩阵分解（NNMF），将来自支配臂和非支配臂的EMG记录分别分解为潜在的肌肉协同作用。结果显示，与非支配臂相比，支配臂显示出更高的阻尼。除后三角肌（PD）之外，所有肌肉在对象运输过程中均显示出较高的平均激活水平，其激活峰出现在脚跟接触前后或接触前。肌肉协同作用分析显示，通过近端到远端的肌肉激活模式，肩和肘关节有望稳定。