Background

The ability to coordinate forces with both hands is crucial for manipulating objects in bimanual tasks. The purpose of this study was to determine the influence of bimanual force coordination on collaborative hand use for dexterous tasks in chronic stroke survivors.

Methods

Fourteen stroke survivors (63.03 ± 15.33 years) and 14 healthy controls (68.85 ± 8.16) performed two bimanual tasks: 1) Pegboard assembly task, and 2) dynamic force tracking task using bilateral index fingers. The Pegboard assembly task required collaborative use of both hands to construct a structure with pins, collars, and washers. We quantified bimanual dexterity with Pegboard assembly score as the total number of pins, collars, and washers assembled in one minute. The force tracking task involved controlled force increment and decrement while tracking a trapezoid trajectory. The task goal was to match the target force with the total force, i.e., sum of forces produced by both hands as accurately as possible. We quantified bimanual force coordination by computing time-series cross-correlation coefficient, time-lag, amplitude of coherence in 0 – 0.5 Hz, and 0.5–1 Hz for force increment and decrement phases.

Results

In the Pegboard assembly task, the stroke group assembled fewer items relative to the control group (p = 0.004). In the bimanual force tracking task, the stroke group showed reduced cross-correlation coefficient (p = 0.01), increased time-lag (p = 0.00), and reduced amplitude of coherence in 0–0.5 Hz (p = 0.03) and in 0.5–1 Hz (p = 0.00). Multiple regression analysis in the stroke group revealed that performance on Pegboard assembly task was explained by cross-correlation coefficient and coherence in 0.5–1 Hz during force increment (R² = 0.52, p = 0.00).

Conclusions

Individuals with stroke show impaired bimanual dexterity and diminished bimanual force coordination. Importantly, stroke-related deterioration in bimanual force coordination was associated with poor performance on dexterous bimanual tasks that require collaboration between hands. Re-training bimanual force coordination in stroke survivors could facilitate a higher degree of participation in daily activities through improved bimanual dexterity.

中文翻译：

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慢性中风中双手力量协调受损的功能意义。

 背景

双手协调力量的能力对于在双手任务中操纵物体至关重要。本研究的目的是确定双手力量协调对慢性中风幸存者灵巧任务的协作手使用的影响。

 方法

14 名中风幸存者（63.03 ± 15.33 岁）和 14 名健康对照者（68.85 ± 8.16）执行两项双手任务：1）钉板组装任务，2）使用双侧食指进行动态力跟踪任务。钉板组装任务需要双手协作来构建带有销钉、轴环和垫圈的结构。我们通过钉板组装得分来量化双手灵活性，即一分钟内组装的销钉、套环和垫圈的总数。力跟踪任务涉及在跟踪梯形轨迹时控制力的增量和减量。任务目标是将目标力与总力（即双手产生的力的总和）尽可能准确地匹配。我们通过计算力增量和减量阶段的时间序列互相关系数、时滞、0-0.5 Hz 和 0.5-1 Hz 的相干幅度来量化双手力协调。

 结果

在钉板组装任务中，相对于对照组，中风组组装的物品较少 ( p = 0.004)。在双手力跟踪任务中，中风组表现出互相关系数降低（ p = 0.01）、时滞增加（ p = 0.00）以及0-0.5 Hz（ p = 0.03）和0.5 Hz的相干幅度降低。 –1 Hz ( p = 0.00)。中风组的多元回归分析显示，钉板组装任务的表现可以通过力增量期间 0.5-1 Hz 的互相关系数和相干性来解释（ R ² = 0.52， p = 0.00）。

 结论

中风患者的双手灵活性受损，双手力量协调能力减弱。重要的是，中风相关的双手力量协调能力的恶化与需要双手协作的灵巧双手任务的表现不佳有关。重新训练中风幸存者的双手力量协调可以通过提高双手灵活性来促进更高程度的参与日常活动。