Kinematic characteristics of the double-leg stance (DLS) to a single-leg stance (SLS) transition were analyzed in a group of young adolescent girls to assess their postural stability control. Twenty volunteers participated in a single experimental session during which their postural stability was assessed based upon the center of pressure (COP) trajectories during the transitions in two typical sensory conditions: with eyes open (EO) and with eyes closed (EC). To quantify the postural control we applied Fitts' model treating the postural sway as the noise at the initial and the target setpoint control. Results showed that in young healthy subjects characteristics of the transition to either left or right single-leg stance were quite symmetrical. The postural sway at the target posture was characterized by the double increase of postural sway when tested with EO and by the almost quadrupled amount of sway in EC trials. The sway at the target resulted in the decline of the COP mean and peak velocity proportionally to the movement index of difficulty (ID). The estimated ID value increased by 74% in EC trials while the probability of instability increased to 70%. The DLS-SLS test can be recommended for clinical and laboratory assessment of postural stability.

在一组年轻青春期女孩中分析了双腿姿势（DLS）向单腿姿势（SLS）过渡的运动学特征，以评估其姿势稳定性控制。二十名志愿者参加了一次实验，在此过程中，他们基于两种典型感觉状态（睁眼（EO）和闭眼（EC））过渡期间的压力中心（COP）轨迹评估了他们的姿势稳定性。为了量化姿势控制，我们应用了Fitts模型，将姿势摇摆作为初始和目标设定点控制处的噪声。结果表明，在年轻健康受试者中，向左或右单腿姿势过渡的特征非常对称。在使用EO测试时，目标姿势下的姿势摆动的特征是姿势摆动的两倍增加，而在EC试验中，姿势摆动的几乎四倍。在目标上的摇摆导致COP平均值和峰值速度的下降与运动难度指数（ID）成正比。在EC试验中，估计的ID值增加了74％，而不稳定的可能性增加到70％。DLS-SLS测试可建议用于姿势稳定性的临床和实验室评估。