The Effects of Visual Feedback on Treadmill Walking Speed

Abstract

Gait rehabilitation often utilizes treadmill training, and providing visual feedback on subjects’ movements can improve the rehabilitation outcomes. We have previously shown that an imposed distortion of visual feedback on subjects’ step lengths entails unintentional changes in gait symmetry. In light of the potential effect of distorting visual feedback, we decided to test if we could change the walking speed of subjects using distorted visual feedback display. This is because gait training outcomes are correlated with increasing walking speed. Healthy subjects participated in the treadmill walking trials. During the trials, a motion capturing system tracked the position of the subjects’ foot and hip, and a computer displayed the current step length of each leg on a screen as vertical bars. Horizontal bars then scroll down the screen, and when the top of the step length bar lands on the horizontal bar, a sound as well as a temporary change in color of the horizontal bar is produced. In each trial, the subjects walked on a treadmill while looking at the computer screen. Then, we implicitly distorted the scroll speed or the distance between the horizontal bars in an attempt to get the subjects to change their walking speeds by spontaneously stepping on the horizontal bars in the computer screen. A computer program detected any sign of change in the walking speed and automatically adjusted the treadmill speed. While further studies need to be done with a larger sample size, we found that the subjects showed a tendency to increase their speed in the intended manner. The results of this study may herald a promising approach for gait rehabilitation because the visual feedback distortion can be used to encourage the subjects’ movements beyond their voluntary efforts.