Background

People after stroke often have postural impairments that can increase their risk of falling. Anticipatory postural adjustments (APAs) are changes in the activity of postural muscles prior to a voluntary movement in order to maintain vertical equilibrium. Previous research suggests that improving APAs leads to better postural control and reduces the risk of falls. Despite the importance of APAs and their impairment among people post-stroke, studies that aim to investigate methods for improving APAs are limited. Consistent evidence supports that an external focus of attention compared to an internal focus of attention, yields superior performance of motor skills that include postural control.

Research question

What are the effects of adopting different foci of attention on measures of APAs and movement parameters when performing a lower extremity Fitts’ task among people post-stroke?

Methods

Twelve individuals post-stroke performed a lower extremity stepping movement (Fitts’ task) while adopting an external focus or an internal focus of attention in a within-subject design. A motion capture system was used to record participants’ movement data. Custom software derived movement time (MT), peak velocity (PV), time to peak velocity (ttPV) and variability at endpoint (SD_T). Electromyography was used to measure muscle activity and determine APAs onset and magnitude. For all dependent variables separate repeated measures ANOVAs were conducted to compare performance between foci of attention.

Results

The results showed that an external focus of attention yielded significantly better performance on all outcome measures. The improvement in performance was seen in shorter MT, higher PV, shorter ttPV, smaller SD_T, earlier APAs onset and more efficient APAs magnitude.

Significance

The changes in outcome measures suggest that adopting an external focus of attention during postural tasks could be an effective strategy for improving balance control among people post-stroke.

中文翻译：

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与内部关注点相比，外部关注点可以改善中风后人们的预期姿势调整。

背景

中风后的人经常有姿势障碍，这会增加他们跌倒的风险。预期姿势调整（APA）是为了保持垂直平衡而自愿运动之前姿势肌肉活动的变化。先前的研究表明，改善APA可以改善姿势控制并降低跌倒的风险。尽管APA的重要性及其在中风后人群中的损害，但旨在研究改善APA方法的研究仍然有限。一致的证据表明，与内部关注相比，外部关注能产生更好的运动技能表现，包括姿势控制。

研究问题

在卒中后患者执行下肢Fitts任务时，对APA的度量和运动参数采取不同的关注点会有什么影响？

方法

中风后十二个人进行了下肢踏步运动（Fitts的任务），同时在对象内部设计中采用了外部关注点或内部关注点。运动捕捉系统用于记录参与者的运动数据。定制软件可以得出运动时间（MT），峰值速度（PV），到达峰值速度的时间（ttPV）和终点的变化（SD _T）。肌电图仪用于测量肌肉活动并确定APAs的发作和幅度。对于所有因变量，分别进行重复测量ANOVA，以比较关注焦点之间的表现。

结果

结果表明，外部关注的焦点在所有结果指标上的表现都明显更好。在较短的MT，较高的PV，较短的ttPV，较小的SD _T，更早的APA发作和更有效的APA幅度中可以看到性能的提高。

意义

结果指标的变化表明，在姿势任务中采用外部注意力集中可能是改善卒中后患者平衡控制的有效策略。