Mechanisms of Adaptation from a Multiple to a Single Step Recovery Strategy following Repeated Exposure to Forward Loss of Balance in Older Adults
Mechanisms of Adaptation from a Multiple to a Single Step Recovery Strategy following Repeated Exposure to Forward Loss of Balance in Older Adults
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DOI：
10.1371/journal.pone.0033591
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发表时间：
2012-03-16
期刊：
影响因子：
3.7
通讯作者：
Barrett, Rod S.
中科院分区：
文献类型：
--
作者：
Carty, Christopher P.;Cronin, Neil J.;Barrett, Rod S.
当从初始的、静态的、前倾的角度释放出来，并被指示用一步来恢复时，一些老年人能够满足任务要求，而其他人要么绊倒，要么摔倒。本研究的目的是使用的稳定性（MoS）的概念，以调查平衡恢复反应的前-后方向表现出的老年人单步进，多步进和那些能够适应从多到单步骤暴露后反复向前失去平衡。151名健康的、居住在社区的、年龄在65-80岁的老年人参加了这项研究。参与者从三个初始倾斜角度中的每一个进行四次平衡恢复任务的试验。在三个事件中，对前后方向的平衡恢复反应进行了量化;对于在中间倾斜角下进行的试验，电缆释放（CR）、脚趾离地（TO）和脚接触（FC）。MoS计算为支撑基底（BoS）前边界与速度调整质心位置（XCoM）垂直投影之间的前后距离。大约三分之一的参与者在重复暴露于任务后从多步恢复策略调整为单步恢复策略。在适应组中，单步骤和多步骤试验在FC的MoS介于仅单步骤组和仅多步骤组之间，单步骤试验在FC的MoS显著高于多步骤试验3.7倍。与单步和多步之间的差异一致，从多步到单步的适应归因于FC处的BoS增加，FC处的XCoM减少以及从TO到FC的BoS位移速率增加。适应发生在一个单一的测试会话，并建议老年人接近成功恢复的阈值，可以迅速提高动态稳定性后，反复暴露于向前失去平衡。
When released from an initial, static, forward lean angle and instructed to recover with a single step, some older adults are able to meet the task requirements, whereas others either stumble or fall. The purpose of the present study was to use the concept of margin of stability (MoS) to investigate balance recovery responses in the anterior-posterior direction exhibited by older single steppers, multiple steppers and those that are able to adapt from multiple to single steps following exposure to repeated forward loss of balance. One hundred and fifty-one healthy, community dwelling, older adults, aged 65-80 years, participated in the study. Participants performed four trials of the balance recovery task from each of three initial lean angles. Balance recovery responses in the anterior-posterior direction were quantified at three events; cable release (CR), toe-off (TO) and foot contact (FC), for trials performed at the intermediate lean angle. MoS was computed as the anterior-posterior distance between the forward boundary of the Base of Support (BoS) and the vertical projection of the velocity adjusted centre of mass position (XCoM). Approximately one-third of participants adapted from a multiple to a single step recovery strategy following repeated exposure to the task. MoS at FC for the single and multiple step trials in the adaptation group were intermediate between the exclusively single step group and the exclusively multiple step group, with the single step trials having a significant, 3.7 times higher MoS at FC than the multiple step trials. Consistent with differences between single and multiple steppers, adaptation from multiple to single steps was attributed to an increased BoS at FC, a reduced XCoM at FC and an increased rate of BoS displacement from TO to FC. Adaptations occurred within a single test session and suggest older adults that are close to the threshold of successful recovery can rapidly improve dynamic stability following repeated exposure to a forward loss of balance.