Background. Kinematic abundance permits using different movement patterns for task completion. Individuals poststroke may take advantage of abundance by using compensatory trunk displacement to overcome upper limb (UL) movement deficits. However, movement adaptation in tasks requiring specific intersegment coordination may remain limited. Objective. We tested movement adaptation in both arms of individuals with chronic stroke (n = 16) and nondominant arms of controls (n = 12) using 2 no-vision reaching tasks involving trunk movement (40 trials/arm). Methods. In the “stationary hand task” (SHT), subjects maintained the hand motionless over a target while leaning the trunk forward. In the “reaching hand task” (RHT), subjects reached to the target while leaning forward. For both tasks, trunk movement was unexpectedly blocked in 40% of trials to assess the influence of trunk movement on adaptive arm positioning or reaching. UL sensorimotor impairment, activity, and sitting balance were assessed in the stroke group. The primary outcome measure for SHT was gain (g), defined as the extent to which trunk displacement contributing to hand motion was offset by appropriate changes in UL movements (g = 1: complete compensation) and endpoint deviation for RHT. Results. Individuals poststroke had lower gains and greater endpoint deviation using the more-affected compared with less-affected UL and controls. Those with less sensorimotor impairment, greater activity levels, and better sitting balance had higher gains and smaller endpoint deviations. Lower gains were associated with diminished UL adaptability. Conclusions. Tests of condition-specific adaptability of interjoint coordination may be used to measure UL adaptability and changes in adaptability with treatment.

中文翻译：

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慢性卒中中运动等效的节间协调受损

背景。运动学丰度允许使用不同的运动模式来完成任务。中风后的个体可以通过使用代偿性躯干位移来克服上肢 (UL) 运动缺陷来利用丰度。然而，需要特定段间协调的任务中的运动适应可能仍然有限。客观的。我们使用 2 个涉及躯干运动的无视力到达任务（40 次试验/手臂）测试了慢性中风患者（n = 16）和非优势对照组（n = 12）的运动适应能力。方法。在“静止手部任务”（SHT）中，受试者在躯干前倾的同时保持手在目标上方不动。在“伸手任务”（RHT）中，受试者在前倾的同时到达目标。对于这两个任务，在 40% 的试验中，躯干运动出人意料地被阻止，以评估躯干运动对适应性手臂定位或伸展的影响。在卒中组中评估了 UL 感觉运动障碍、活动和坐姿平衡。SHT 的主要结果测量是增益 (g)，定义为导致手部运动的躯干位移被 UL 运动的适当变化所抵消的程度（g = 1：完全补偿）和 RHT 的终点偏差。结果。与受影响较小的 UL 和对照相比，使用受影响较大的个体中风后的个体获得较低的收益和较大的终点偏差。那些感觉运动障碍较少、活动水平较高和坐姿平衡较好的人有更高的收益和更小的终点偏差。较低的增益与 UL 适应性减弱有关。结论。