Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Sydney, New South Wales, Australia.
School of Community Medicine and Public Health, University of New South Wales, Sydney, New South Wales, Australia.
PLoS One. 2018 Sep 18;13(9):e0202913. doi: 10.1371/journal.pone.0202913. eCollection 2018.
The primary study aim was to determine if repeated exposure to trips and slips with increasing unpredictability while walking can improve balance recovery responses when predictive gait alterations (e.g. slowing down) are minimised. The secondary aim was to determine if predictive gait alterations acquired through exposure to perturbations at a fixed condition would transfer to highly unpredictable conditions.
Ten young adults were instructed to step on stepping tiles adjusted to their usual step length and to a metronome adjusted to their usual cadence on a 10-m walkway. Participants were exposed to a total of 12 slips, 12 trips and 6 non-perturbed trials in three conditions: 1) right leg fixed location, 2) left leg fixed location and 3) random leg and location. Kinematics during non-perturbed trials and pre- and post-perturbation steps were analysed.
Throughout the three conditions, participants walked with similar gait speed, step length and cadence(p>0.05). Participants' extrapolated centre of mass (XCoM) was anteriorly shifted immediately before slips at the fixed location (p<0.01), but this predictive gait alteration did not transfer to random perturbation locations. Improved balance recovery from trips in the random location was indicated by increased margin of stability and step length during recovery steps (p<0.05). Changes in balance recovery from slips in the random location was shown by reduced backward XCoM displacement and reduced slip speed during recovery steps (p<0.05).
Even in the absence of most predictive gait alterations, balance recovery responses to trips and slips were improved through exposure to repeated unpredictable perturbations. A common predictive gait alteration to lean forward immediately before a slip was not useful when the perturbation location was unpredictable. Training balance recovery with unpredictable perturbations may be beneficial to fall avoidance in everyday life.
主要研究目的是确定在行走时反复接触带有逐渐增加不可预测性的绊倒和滑倒，是否可以改善平衡恢复反应，同时最小化预测性步态改变（例如减速）。次要目的是确定通过在固定条件下暴露于扰动而获得的预测性步态改变是否会转移到高度不可预测的条件下。
10 名年轻人被指示在 10 米步行道上用调整到其惯用步长的踏块和调整到其惯用步频的节拍器行走。参与者在三种条件下总共接受了 12 次滑倒、12 次绊倒和 6 次非扰动试验：1）右腿固定位置、2）左腿固定位置和 3）随机腿和位置。在非扰动试验和扰动前后的步幅中分析了运动学。
在所有三种条件下，参与者的行走速度、步长和步频都相似（p>0.05）。参与者的外推质心（XCoM）在固定位置的滑倒前立即向前移动（p<0.01），但这种预测性步态改变并没有转移到随机扰动位置。在随机位置的绊倒中平衡恢复的改善，表现为恢复步幅中稳定裕度和步长的增加（p<0.05）。在随机位置的滑倒中平衡恢复的变化，表现为恢复步幅中向后 XCoM 位移减少和滑倒速度降低（p<0.05）。
即使在缺乏大多数预测性步态改变的情况下，通过反复接触不可预测的扰动，对绊倒和滑倒的平衡恢复反应也得到了改善。在扰动位置不可预测的情况下，滑倒前立即前倾的常见预测性步态改变没有用处。用不可预测的扰动训练平衡恢复可能有益于日常生活中的跌倒预防。
