Vieira Marcus Fraga, Rodrigues Fábio Barbosa, de Sá E Souza Gustavo Souto, Magnani Rina Márcia, Lehnen Georgia Cristina, Andrade Adriano O
Bioengineering and Biomechanics Laboratory, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, Goiás, 74690-900, Brazil.
Posgraduate Program in Electrical and Biomedical Engineering, Center for Innovation and Technology Assessment in Health, Universidade Federal de Uberlândia, Uberlândia, Brazil.
Ann Biomed Eng. 2017 Jun;45(6):1560-1571. doi: 10.1007/s10439-017-1820-x. Epub 2017 Mar 14.
This study evaluated linear and nonlinear gait features in healthy older adults walking on inclined surfaces at different speeds. Thirty-seven active older adults (experimental group) and fifty young adults (control group) walked on a treadmill at 100% and ±20% of their preferred walking speed for 4 min under horizontal (0%), upward (UP) (+8%), and downward (DOWN) (-8%) conditions. Linear gait variability was assessed using the average standard deviation of trunk acceleration between strides (VAR). Gait stability was assessed using the margin of stability (MoS). Nonlinear gait features were assessed by using the maximum Lyapunov exponent, as a measure of local dynamic stability (LDS), and sample entropy (SEn), as a measure of regularity. VAR increased for all conditions, but the interaction effects between treadmill inclination and age, and speed and age were higher for young adults. DOWN conditions showed the lowest stability in the medial-lateral MoS, but not in LDS. LDS was smaller in UP conditions. However, there were no effects of age for either MoS or LDS. The values of SEn decreased almost linearly from the DOWN to the UP conditions, with significant interaction effects of age for anterior-posterior SEn. The overall results supported the hypothesis that inclined surfaces modulate nonlinear gait features and alter linear gait variability, particularly in UP conditions, but there were no significant effects of age for active older adults.
本研究评估了健康老年人在不同速度下在倾斜表面行走时的线性和非线性步态特征。37名活跃的老年人（实验组）和50名年轻人（对照组）在跑步机上以其偏好步行速度的100%和±20%，在水平（0%）、向上（UP）（+8%）和向下（DOWN）（-8%）条件下行走4分钟。使用步幅间躯干加速度的平均标准差（VAR）评估线性步态变异性。使用稳定裕度（MoS）评估步态稳定性。通过使用最大Lyapunov指数作为局部动态稳定性（LDS）的度量，以及样本熵（SEn）作为规律性的度量来评估非线性步态特征。所有条件下VAR均增加，但跑步机倾斜度与年龄之间以及速度与年龄之间的交互作用在年轻人中更高。DOWN条件下内侧-外侧MoS的稳定性最低，但在LDS中并非如此。UP条件下LDS较小。然而，年龄对MoS或LDS均无影响。SEn值从DOWN条件到UP条件几乎呈线性下降，前后SEn存在显著的年龄交互作用。总体结果支持以下假设：倾斜表面会调节非线性步态特征并改变线性步态变异性，特别是在UP条件下，但对于活跃的老年人，年龄没有显著影响。
