Department of Physical Therapy, School of Rehabilitation Sciences, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Gait Posture. 2010 Apr;31(4):450-5. doi: 10.1016/j.gaitpost.2010.01.020. Epub 2010 Feb 16.
Knowledge about the non-linear dynamical pattern of postural sway may provide important insights into the adaptability (flexibility) of human postural control in response to everyday stresses imposed on the body. A commonly used non-linear tool, i.e. recurrence quantification analysis, was chosen to investigate the effect of prior anterior cruciate ligament injury on the deterministic pattern of postural sway under different conditions of postural and cognitive difficulty. In double leg stance, as postural difficulty increased from open-eyes to closed-eyes and rigid-surface to foam-surface, the centre of pressure regularity (%determinism) increased as well. In comparison to healthy counterparts, subjects with prior anterior cruciate ligament injury produced more regularity when maintaining balance on their injured leg. Also, for both the double and single leg stance balance conditions, the performance of a secondary cognitive task (a backward digit span task) caused less center of pressure regularity than the single postural task, which suggests that both study populations required the same amount of cognitive involvement for maintaining balance. Center of pressure dynamic patterns exhibited by the anterior cruciate ligament deficient patients were more regular than those of the healthy controls indicating "complexity loss" and may be indicative of the reduced adaptability (flexibility) of a balance system to sudden perturbations.
关于姿势摆动的非线性动力模式的知识可能为理解人体姿势控制对施加于身体的日常压力的适应性（灵活性）提供重要的见解。选择了一种常用的非线性工具，即递归定量分析，来研究先前前交叉韧带损伤对不同姿势和认知难度条件下姿势摆动的确定性模式的影响。在双腿站立时，随着姿势难度从睁眼增加到闭眼和刚性表面增加到泡沫表面，压力中心的规则性（确定性百分比）也增加了。与健康对照组相比，先前前交叉韧带损伤的受试者在受伤腿上保持平衡时产生了更高的规则性。此外，对于双腿和单腿站立平衡两种情况，执行次要认知任务（反向数字跨度任务）比单一姿势任务导致的压力中心规则性更小，这表明两个研究人群在保持平衡时需要相同程度的认知参与。前交叉韧带缺失患者的压力中心动态模式比健康对照组更规则，表明“复杂性丧失”，可能表明平衡系统对突然扰动的适应性（灵活性）降低。
