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首页> 外文期刊>Journal of Biomechanics >Kinematic variability and local dynamic stability of upper body motions when walking at different speeds.
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Kinematic variability and local dynamic stability of upper body motions when walking at different speeds.

机译：以不同速度行走时上身运动的运动学变异性和局部动态稳定性。

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A ubiquitous characteristic of elderly and patients with gait disabilities is that they walk slower than healthy controls. Many clinicians assume these patients walk slower to improve their stability, just as healthy people slow down when walking across ice. However, walking slower also leads to greater variability, which is often assumed to imply deteriorated stability. If this were true, then slowing down would be completely antithetical to the goal of maintaining stability. This study sought to resolve this paradox by directly quantifying the sensitivity of the locomotor system to local perturbations that are manifested as natural kinematic variability. Eleven young healthy subjects walked on a motorized treadmill at five different speeds. Three-dimensional movements of a single marker placed over the first thoracic vertebra were recorded during continuous walking. Mean stride-to-stride standard deviations and maximum finite-time Lyapunov exponents were computed for each time series to quantify the variability and local dynamic stability, respectively, of these movements. Quadratic regression analyses of the dependent measures vs. walking speed revealed highly significant U shaped trends for all three mean standard deviations, but highly significant linear trends, with significant or nearly significant quadratic terms, for five of the six finite-time Lyapunov exponents. Subjects exhibited consistently better local dynamic stability at slower speeds for these five measures. These results support the clinically based intuition that people who are at increased risk of falling walk slower to improve their stability, even at the cost of increased variability.
机译：老年人和步态障碍患者的普遍特征是他们的行走速度慢于健康人。许多临床医生认为这些患者的行走速度较慢以提高稳定性，就像健康人在冰面上行走时速度变慢一样。但是，慢走还导致更大的可变性，通常认为这意味着稳定性下降。如果这是真的，那么放慢脚步与维持稳定的目标完全相反。这项研究试图通过直接量化运动系统对表现为自然运动学变异性的局部扰动的敏感性来解决这一悖论。 11名年轻的健康受试者以五种不同的速度在电动跑步机上行走。在连续行走过程中，记录了放置在第一胸椎上的单个标记的三维运动。计算每个时间序列的平均跨步标准差和最大有限时Lyapunov指数，以分别量化这些运动的变异性和局部动态稳定性。对六个平均时间Lyapunov指数中的五个指数，因变量与步行速度之间的二次回归分析显示，所有三个平均标准差的U形趋势都非常显着，但是线性趋势却具有显着或接近显着的二次项。在这五项措施中，受试者在较慢的速度下始终表现出更好的局部动态稳定性。这些结果支持基于临床的直觉，即即使以增加的变异性为代价，处于跌倒风险增加中的人也可以缓慢行走以提高其稳定性。

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