Pailhous J, Bonnard M
Université d'Aix-Marseille II, Faculté de Médecine, URA CNRS 1166, IBHOP, Marseille, France.
Behav Brain Res. 1992 Apr 10;47(2):181-9. doi: 10.1016/s0166-4328(05)80124-x.
In steady-state walking, fluctuations in space-time behavior are observed for normal adult subjects. In the present study, the intrinsic fluctuations of gait have been analyzed when walking on a subject-driven treadmill (with adjustable inertial forces). Furthermore, these intrinsic fluctuations have been compared with those observed in natural overground locomotion which involves a real subject's displacement and thus an optical flow. Four adult subjects participated in both experimental sessions. It was found that the frequency and amplitude of the instantaneous fluctuations of leg movement were weak and of equal magnitude with or without optical flow. This was also the case for instantaneous fluctuations in displacement speed. Secondly, a low-frequency fluctuation in walking speed was observed when no optical flow information was available to the subject. This fluctuation results from the addition of a series of leg-movement fluctuations, whose values are all either positive or negative. As the optical flow provides information about the displacement speed, it allows the subject to avoid such addition, and thus plays a role in maintaining steady leg movement. Theoretical models linking space-time behavior of rhythmic movement with stiffness strongly suggest that the observed low-frequency fluctuations in speed result from fluctuations in stiffness.
在稳态行走过程中，正常成年受试者的时空行为会出现波动。在本研究中，对在受试者驱动的跑步机（具有可调节惯性力）上行走时步态的固有波动进行了分析。此外，还将这些固有波动与在自然地面行走中观察到的波动进行了比较，自然地面行走涉及真实受试者的位移以及由此产生的光流。四名成年受试者参与了这两个实验环节。研究发现，无论有无光流，腿部运动瞬时波动的频率和幅度都较弱且大小相等。位移速度的瞬时波动情况也是如此。其次，当受试者没有光流信息时，观察到行走速度存在低频波动。这种波动是由一系列腿部运动波动相加产生的，这些波动的值要么全为正，要么全为负。由于光流提供了关于位移速度的信息，它使受试者能够避免这种相加，从而在维持稳定的腿部运动中发挥作用。将节律性运动的时空行为与刚度联系起来的理论模型有力地表明，观察到的速度低频波动是由刚度波动引起的。
