Stroke often impairs the control of the contralesional arm, thus most survivors rely on the ipsilesional arm to perform daily living activities that require an efficient control of movements and forces. Whereas the ipsilesional arm is often called ‘unaffected’ or ‘unimpaired’, several studies suggested that during dynamic tasks its kinematics and joint torques are altered. Is stroke also affecting the ability of the ipsilesional arm to produce isometric force, as when pushing or pulling a handle? Here, we address this question by analyzing behavioral performance and muscles’ activity when subjects applied an isometric force of 10 N in eight coplanar directions. We found that stroke affected the ability to apply well-controlled isometric forces with the ipsilesional arm, although to a minor extent compared to the contralesional arm. The spinal maps, the analysis of single muscle activities and the organization of muscle synergies highlighted that this effect was mainly associated with abnormal activity of proximal muscles with respect to matched controls, especially when pushing or pulling in lateral directions.

中风通常会损害对侧手臂的控制，因此大多数幸存者依靠对侧手臂进行需要有效控制运动和力量的日常生活活动。虽然同侧手臂通常被称为“未受影响”或“未受损”，但几项研究表明，在动态任务期间，其运动学和关节扭矩会发生变化。中风是否也会影响同侧手臂产生等长力的能力，如推或拉手柄时？在这里，我们通过分析受试者在八个共面方向上施加 10 N 的等距力时的行为表现和肌肉活动来解决这个问题。我们发现中风会影响同侧手臂施加良好控制的等长力的能力，尽管与对侧手臂相比影响较小。脊椎图，