Complexity of human postural control in young and older adults during prolonged standing
Complexity of human postural control in young and older adults during prolonged standing
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DOI：
10.1007/s00221-008-1521-7
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发表时间：
2008-11-01
影响因子：
2
通讯作者：
Sternad, Dagmar
中科院分区：
文献类型：
--
作者：
Duarte, Marcos;Sternad, Dagmar
众所周知，衰老对人类感觉运动系统的许多结构和功能具有退化的影响。目前的工作使用压力中心(COP)动力学的分形和复杂性测量来评估与年龄相关的姿势摆动的变化，并假设老年人的复杂性和分形性降低。老年受试者(68+/-4岁)和青壮年受试者(28+/-7岁)分别进行安静站立任务(60 S)和长时间站立任务(30min)，允许受试者自由移动。通过去趋势波动分析(DFA)估计数据的长期相关性(分形性)；通过多尺度熵(MSE)测量估计熵的变化。DFA结果显示，老年人的分维低于青壮年，但两组的分维与1/f噪声没有差别，时间间隔在10到600 S之间。均方误差分析显示，老年人的复杂性较高，这与人体生理系统的复杂性随年龄增长而降低的假设不一致。同样的MSE分析在没有调整的情况下进行，显示两组之间没有差异。综合所有结果，老年人的总体姿势摆动和长期相关性的减少是适应过程的迹象，反映了在较长时间尺度上产生足够反应的能力正在减弱。
Aging is known to have a degrading influence on many structures and functions of the human sensorimotor system. The present work assessed aging-related changes in postural sway using fractal and complexity measures of the center of pressure (COP) dynamics with the hypothesis that complexity and fractality decreases in the older individuals. Older subjects (68 +/- 4 years) and young adult subjects (28 +/- 7 years) performed a quiet stance task (60 s) and a prolonged standing task (30 min) where subjects were allowed to move freely. Long-range correlations (fractality) of the data were estimated by the detrended fluctuation analysis (DFA); changes in entropy were estimated by the multi-scale entropy (MSE) measure. The DFA results showed that the fractal dimension was lower for the older subjects in comparison to the young adults but the fractal dimensions of both groups were not different from a 1/f noise, for time intervals between 10 and 600 s. The MSE analysis performed with the typically applied adjustment to the criterion distance showed a higher degree of complexity in the older subjects, which is inconsistent with the hypothesis that complexity in the human physiological system decreases with aging. The same MSE analysis performed without adjustment showed no differences between the groups. Taken all results together, the decrease in total postural sway and long-range correlations in older individuals are signs of an adaptation process reflecting the diminishing ability to generate adequate responses on a longer time scale.