Local dynamic stability of treadmill walking: Intrasession and week-to-week repeatability
Local dynamic stability of treadmill walking: Intrasession and week-to-week repeatability
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DOI：
10.1016/j.jbiomech.2013.10.011
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发表时间：
2014-01-03
影响因子：
2.4
通讯作者：
Terrier, Philippe
中科院分区：
文献类型：
--
作者：
Reynard, Pabienne;Terrier, Philippe
反复跌倒会降低老年人和各种神经疾病患者的生活质量。为了防止走路时跌倒，人们应该依靠动态平衡受损的相关早期指标。局部动态稳定性（LDS）代表步态对小扰动的敏感性：散度指数（最大李雅普诺夫指数）评估动力系统从邻近点发散的速度。虽然许多研究结果证明LDS作为跌倒风险指标的有效性，但可靠性结果仍然很少。本研究利用类内相关系数（ICC）和测量标准误差（SEM）探讨了步态LDS在类内和类间的重复性。95名健康人在跑步机上行走5分钟，每隔9天进行两次。躯干加速度用三维加速度计测量。使用三个时间尺度来估计LDS：超过4-10步（lambda(4-10)），超过1步（lambda(1)）和超过1步（lambda(0.5)）。在5分钟的测试中，通过3次35步或70步的重复来评估运动内的重复性。间歇可重复性比较了两次训练，总共210步。遗传内ICCs （70-strides估计/35-strides估计）lambda（4-10）为0.52/0.18,lambda(1)和lambda（0.5）为0.84/0.77。盘中icc在0.60左右。扫描电镜结果显示，在中外侧方向测量的lambda（0.5）具有最佳的可靠性，足以检测个体水平（20%）的中度变化。然而，由于间歇可重复性较低，为了更好地接近真实的LDS，应该对不同日期的多次测量进行平均。(C) 2013 Elsevier Ltd.版权所有。
Repetitive falls degrade the quality of life of elderly people and of patients suffering of various neurological disorders. In order to prevent falls while walking, one should rely on relevant early indicators of impaired dynamic balance. The local dynamic stability (LDS) represents the sensitivity of gait to small perturbations: divergence exponents (maximal Lyapunov exponents) assess how fast a dynamical system diverges from neighbor points. Although numerous findings attest the validity of LDS as a fall risk index, reliability results are still sparse. The present study explores the intrasession and intersession repeatability of gait LDS using intraclass correlation coefficients (ICC) and standard error of measurement (SEM). Ninety-five healthy individuals performed 5 min treadmill walking in two sessions separated by 9 days. Trunk acceleration was measured with a 3D accelerometer. Three time scales were used to estimate LDS: over 4-10 strides (lambda(4-10)), over one stride (lambda(1)) and over one step (lambda(0.5)). The intrasession repeatability was assessed from three repetitions of either 35 strides or 70 strides taken within the 5 min tests. The intersession repeatability compared the two sessions, which totalized 210 strides. The intrasession ICCs (70-strides estimates/35-strides estimates) were 0.52/0.18 for lambda(4-10) and 0.84/0.77 for lambda(1) and lambda(0.5). The intersession ICCs were around 0.60. The SEM results revealed that lambda(0.5) measured in medio-lateral direction exhibited the best reliability, sufficient to detect moderate changes at individual level (20%). However, due to the low intersession repeatability, one should average several measurements taken on different days in order to better approximate the true LDS. (C) 2013 Elsevier Ltd. All rights reserved.