Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL 60612, USA.
Department of Kinesiology, University of Texas at El Paso, El Paso, TX 79968, USA.
J Biomech. 2014 Aug 22;47(11):2751-8. doi: 10.1016/j.jbiomech.2014.04.051. Epub 2014 May 9.
To examine the control of dynamic stability and characteristics of the compensatory stepping responses to an unexpected anterior gait slip induced under the non-involved limb in people with hemi-paretic stroke (PwHS) and to examine any resulting adaptive changes in these on the second slip due to experience from prior slip exposure. Ten PwHS experienced overground slip (S1) during walking on the laboratory walkway after 5-8 regular walking (RW) trials followed by a second consecutive slip trial (S2). The slip outcome (backward loss of balance, BLOB and no loss of balance, NLOB) and COM state (i.e. its COM position and velocity) stability were examined between the RW and S1 and S1 and S2 at touchdown (TD) of non-involved limb and at liftoff (LO) of the contralateral limb. At TD there was no difference in stability between RW and S1, however at LO, subjects demonstrated a lower stability on S1 than RW resulting in a 100% backward loss of balance (BLOB) with compensatory stepping response (recovery step, RS, 4/10 or aborted step, AS, 6/10). On S2, although there was no change in stability at TD, there was a significant improvement in stability at LO with a 40% decrease in BLOB. There was also a change in step strategy with a decrease in AS response (60% to 35%, p<0.05) which was replaced by an increase in the ability to step (increased compensatory step length, p<0.05) either via a recovery step or a walkover step. PwHS have the ability to reactively control COM state stability to decrease fall-risk upon a novel slip; prior exposure to a slip did not significantly alter feedforward control but improved the ability to use such feedback control for improved slip outcomes.
为了研究在非受累侧下肢进行非预期前向步态滑动时对代偿性跨步反应的动态稳定性和特征的控制，以及由于先前滑动暴露而在第二次滑动时对这些控制的适应性变化进行研究。10 名偏瘫患者（PwHS）在实验室走道上进行常规行走（RW）5-8 次后，经历了一次地面滑动（S1），然后进行了第二次连续滑动试验（S2）。在非受累侧下肢的触地（TD）和对侧下肢的离地（LO）时，检查了 RW 与 S1 以及 S1 与 S2 之间的滑动结果（向后失去平衡，BLOB 和无失去平衡，NLOB）和 COM 状态（即 COM 位置和速度）稳定性。在 TD 处，RW 和 S1 之间的稳定性没有差异，但是在 LO 处，与 RW 相比，受试者在 S1 时表现出较低的稳定性，导致 100%向后失去平衡（BLOB）和代偿性跨步反应（恢复步，RS，4/10 或中止步，AS，6/10）。在 S2 上，尽管在 TD 处稳定性没有变化，但在 LO 处稳定性有显著改善，BLOB 减少了 40%。跨步策略也发生了变化，AS 反应减少（60%降至 35%，p<0.05），通过恢复步或走过步，增加了跨步能力（增加补偿跨步长度，p<0.05）来代替 AS 反应。PwHS 具有反应性控制 COM 状态稳定性的能力，以降低新滑动时的跌倒风险；先前的滑动暴露并没有显著改变前馈控制，但改善了使用这种反馈控制以获得更好的滑动结果的能力。
