Yoshino Kohzoh, Motoshige Tomoko, Araki Tsutomu, Matsuoka Katsunori
Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563 8577, Japan.
J Biomech. 2004 Aug;37(8):1271-80. doi: 10.1016/j.jbiomech.2003.11.031.
This study examined the ways in which gait patterns and physiological rhythms such as those of muscle activity (tibialis anterior (TA) and biceps femoris (BF)) and cardiac activity are affected by the fatigue induced by prolonged free walking. Twelve normal subjects who walked for 3 h at their preferred pace were divided into two groups according to whether their mean gait cycle time (reciprocal of stride rate) during the second 90 min was higher (Group A: n=8) or lower (Group B: n=4) than that during the first 90 min. For Group A, the level of subjective fatigue during the walking task was significantly higher and the heart rate at rest was significantly lower than Group B. In Group A, prolonged walking significantly decreased the mean power frequency of the electromyography from TA, increased the variability of gait rhythm, decreased the largest Lyapunov exponent of the vertical component of back-waist acceleration, and decreased the amplitude of the vertical component of back-waist acceleration. Taking the onset timings of these changes into account, we propose that subjects who tire easily during prolonged walking first show local muscle fatigue at TA followed by instability of gait rhythm and then they slow their gait rhythm to enhance local dynamic stability. For both groups we constructed a physical fatigue index described by linear regression of gait and physiological variables. When we compared the subjective fatigue level with the fatigue level predicted using the index, we obtained a relatively high correlation coefficient for both groups (r=0.77).
本研究探讨了长时间自由行走所诱发的疲劳对步态模式以及生理节律（如肌肉活动（胫前肌（TA）和股二头肌（BF））和心脏活动的节律）的影响方式。12名以自己偏好的速度行走3小时的正常受试者，根据其在第二个90分钟内的平均步态周期时间（步频的倒数）高于（A组：n = 8）或低于（B组：n = 4）第一个90分钟，被分为两组。对于A组，行走任务期间的主观疲劳程度显著高于B组，静息心率显著低于B组。在A组中，长时间行走显著降低了TA肌电图的平均功率频率，增加了步态节律的变异性，降低了后腰加速度垂直分量的最大Lyapunov指数，并降低了后腰加速度垂直分量的幅度。考虑到这些变化的起始时间，我们提出，在长时间行走中容易疲劳的受试者首先在TA处出现局部肌肉疲劳，随后步态节律不稳定，然后他们放慢步态节律以增强局部动态稳定性。对于两组，我们构建了一个由步态和生理变量的线性回归描述的身体疲劳指数。当我们将主观疲劳水平与使用该指数预测的疲劳水平进行比较时，两组均获得了相对较高的相关系数（r = 0.77）。
