Background

At a clinical level, the intensity of dynamic balance tasks incorporating cross-coordination movements (CCM) is typically progressed by changing the stability of the support surface on which the movement is undertaken. However, biomechanical changes in CCMs performed on stable and unstable surfaces have not yet been quantified.

Research question

Do movement patterns, muscle activity, coordination strategies, knee joint loading and center of mass (CoM) movement differ during a CCM performed on stable and unstable surfaces?

Methods

Motion analysis was used to monitor limb kinematics and surface electromyography to analyze supporting leg muscle activity in sixteen healthy athletes during a single-limb support task involving a cyclic CCM on a stable and unstable surface. Angle-angle plots were used to explore coordination strategies in sagittal movement of the hip and shoulder, while differences in kinematics and muscle activity between stable and unstable conditions were evaluated using dependent t-tests (α-level = 0.05).

Results

CCMs on an unstable surface were performed at a slower speed (p < .05), with a more flexed posture of the support knee (p < .05) and ankle (p < .05) and resulted in reduced hip and shoulder movement of the swing limbs (p < .05). Instability increased activation of selected muscles of the ankle and knee (p < .05), resulted in a two–fold increase in the peak knee adduction moment (p < .05), and was accompanied by greater CoM movement (p < .05). Three coordination patterns of the swing limbs observed when performing CCM on a stable surface, which were mostly preserved on the unstable surface.

Significance

Despite adopting several stabilization strategies, CCM undertaken on an unstable surface still evoked greater excursion of the center of mass and, as such, presented a greater challenge to sensorimotor control. Adding instability in form of a swinging platform provides progression of dynamic balance CCM difficulty in an athletic population.

中文翻译：

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在稳定和不稳定的表面上进行交叉协调运动时，肢体运动，协调和肌肉活动。

背景

在临床水平上，通常通过改变进行运动的支撑表面的稳定性来提高结合交叉协调运动（CCM）的动态平衡任务的强度。但是，尚未对在稳定和不稳定表面上进行的CCM的生物力学变化进行量化。

研究问题

在稳定和不稳定的表面上执行CCM期间，运动方式，肌肉活动，协调策略，膝关节负荷和质心（CoM）运动是否有所不同吗？

方法

运动分析用于监测肢体运动学和表面肌电图，以分析在稳定和不稳定表面上涉及循环CCM的单肢支撑任务期间，十六名健康运动员的支撑腿部肌肉活动。角度-角度图用于探讨髋部和肩部矢状运动的协调策略，而稳定和不稳定条件之间的运动学和肌肉活动差异则通过相关的t检验进行评估（α水平= 0.05）。

结果

不稳定表面上的CCM以较慢的速度（p <.05）进行，支撑膝盖（p <.05）和脚踝（p <.05）的姿势更加弯曲，从而导致髋部和肩部运动减少四肢摆动（p <.05）。不稳定增加了脚踝和膝盖的选定肌肉的激活（p <.05），导致峰值膝盖内收力矩增加了两倍（p <.05），并伴随有更大的CoM运动（p <.05） ）。在稳定表面上执行CCM时观察到的三个摆动肢体协调模式，大多数保留在不稳定表面上。

意义

尽管采取了几种稳定策略，但在不稳定表面上进行的CCM仍引起质心的更大偏移，因此，对感觉运动控制提出了更大的挑战。以摆动平台的形式增加不稳定性会在运动人群中增加动态平衡CCM难度。