Katsavelis Dimitrios, Mukherjee Mukul, Decker Leslie, Stergiou Nicholas
University of Nebraska, Omaha, Nebraska 68182-0216, USA.
Nonlinear Dynamics Psychol Life Sci. 2010 Apr;14(2):165-78.
Backward walking (BW) shows significant differences with forward walking (FW) and these differences are potentially useful in rehabilitation. However the lack of visual cues makes BW risky. The purpose of this study was to investigate the effect of visual cues provided by a virtual environment on FW and BW on gait variability. Each subject underwent four conditions of treadmill walking at self-selected pace. The subjects walked backwards in three conditions and forwards in the fourth condition. A virtual corridor was displayed to the subjects in the FW condition (forward optic flow) and two of the backward conditions (forward and backward optic flow). The third BW condition was a control condition (no visual cues). Gait variability measures of the hip, knee and ankle range of motion and the stride interval were analyzed. Magnitude of variability was evaluated with the coefficient of variation and structure of variability with approximate entropy. Significant differences were demonstrated between the FW and the BW gait characteristics as well as in gait variability (for both magnitude and structure of variability). No significant differences were found between the three BW conditions as a result of the direction of visual cues. In order to get optimal benefit of BW in the aged and the diseased, optical flow of visual feedback may need to be manipulated in a different manner than FW. Future studies will explore other parameters of visual cues like the velocity of optic flow and appearance of obstacles to obtain the best visual cue configuration for rehabilitation.
向后行走（BW）与向前行走（FW）存在显著差异，这些差异在康复中可能具有潜在用途。然而，缺乏视觉线索使得向后行走存在风险。本研究的目的是调查虚拟环境提供的视觉线索对向前行走和向后行走时步态变异性的影响。每位受试者以自选速度在跑步机上进行四种行走条件的测试。受试者在三种条件下向后行走，在第四种条件下向前行走。在向前行走条件（向前光流）以及两种向后行走条件（向前和向后光流）下，向受试者展示一条虚拟走廊。第三种向后行走条件为对照条件（无视觉线索）。分析了髋、膝和踝关节活动范围以及步幅间隔的步态变异性测量值。用变异系数评估变异性大小，用近似熵评估变异性结构。向前行走和向后行走的步态特征以及步态变异性（变异性大小和结构）之间均显示出显著差异。由于视觉线索的方向，在三种向后行走条件之间未发现显著差异。为了使老年人和患病者从向后行走中获得最佳益处，视觉反馈的光流可能需要以与向前行走不同的方式进行操控。未来的研究将探索视觉线索的其他参数，如光流速度和障碍物外观，以获得用于康复的最佳视觉线索配置。
