Pienciak-Siewert Alison, Barletta Anthony J, Ahmed Alaa A
Department of Mechanical Engineering, University of Colorado, Boulder, Colorado; and.
J Neurophysiol. 2014 Apr;111(7):1466-78. doi: 10.1152/jn.00235.2013. Epub 2013 Dec 26.
Postural control is significantly affected by the postural base of support; however, the effects on postural adaptation are not well understood. Here we investigated how adaptation and transfer of anticipatory postural control are affected by stance width. Subjects made reaching movements in a novel dynamic environment while holding the handle of a force-generating robotic arm. Each subject initially adapted to the dynamics while standing in a wide stance and then switched to a narrow stance, or vice versa. Our hypothesis is that anticipatory postural control, reflected in center of pressure (COP) movement, is not affected by stance width, as long as the control remains within functional limits; therefore we predicted that subjects in either stance would show similar COP movement by the end of adaptation and immediately upon transfer to the other stance. We found that both groups showed similar adaptation of postural control, by using different muscle activation strategies to account for the differing stance widths. One group, after adapting in wide stance, transferred similar postural control to narrow stance, by modifying their muscle activity to account for the new stance. Interestingly, the other group showed an increase in postural control when transferring from narrow to wide stance, associated with no change in muscle activity. These results confirm that adaptation of anticipatory postural control is not affected by stance width, as long as the control remains within biomechanical limits. However, transfer of control between stance widths is affected by the initial context in which the task is learned.
姿势控制受到支撑基础的显著影响；然而，其对姿势适应的影响尚未得到充分理解。在此，我们研究了预期姿势控制的适应和转移如何受到站立宽度的影响。受试者在握住一个产生力的机器人手臂的手柄时，在一个新的动态环境中进行伸手动作。每个受试者最初在宽站姿下适应动力学，然后切换到窄站姿，反之亦然。我们的假设是，只要控制保持在功能极限内，压力中心（COP）运动所反映的预期姿势控制不受站立宽度的影响；因此，我们预测在适应结束时以及立即转移到另一种站姿时，两种站姿的受试者都会表现出相似的COP运动。我们发现，两组受试者通过使用不同的肌肉激活策略来适应不同的站立宽度，都表现出相似的姿势控制适应。一组受试者在宽站姿下适应后，通过调整肌肉活动以适应新的站姿，将相似的姿势控制转移到窄站姿。有趣的是，另一组受试者从窄站姿转移到宽站姿时，姿势控制有所增加，而肌肉活动没有变化。这些结果证实，只要控制保持在生物力学极限内，预期姿势控制的适应不受站立宽度的影响。然而，不同站立宽度之间的控制转移受到学习任务的初始情境的影响。
