| Nonlinear Dynamics, Psychology, and Life Sciences, Vol. 14, Iss. 2, Apr, 2010, pp. 165-178 @2010 Society for Chaos Theory in Psychology & Life Sciences Variability of Lower Extremity Joint Kinematics During Backward Walking in a Virtual Environment Abstract: 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. Keywords: virtual reality, nonlinear analysis, locomotion, vision, optic flow |