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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Title Mechanisms of Adaptation from a Multiple to a Single Step Recovery Strategy following Repeated Exposure to Forward Loss of Balance in Older Adults
Author Carty, Christopher Paul; Cronin, Neil J.; Lichtwark, Glen A.; Mills, Peter; Barrett, Rod
Journal Name PLoS ONE
Year Published 2012
Place of publication United States
Publisher Public Library of Science
Abstract 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.
Peer Reviewed Yes
Published Yes
Alternative URI http://dx.doi.org/10.1371/journal.pone.0033591
Copyright Statement Copyright 2012 Carty et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License CCAL. (http://www.plos.org/journals/license.html)
Volume 7
Issue Number 3
Page from e33591-1
Page to e33591-6
ISSN 1932-6203
Date Accessioned 2012-05-24
Date Available 2012-09-06T22:28:35Z
Language en_US
Research Centre Centre for Musculoskeletal Research; Griffith Health Institute
Faculty Griffith Health Faculty
Subject Biomechanics
URI http://hdl.handle.net/10072/46077
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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