To develop a method for cooperative human gait training, we investigated whether interactive rhythmic cues could
improve the gait performance of Parkinson’s disease patients. The interactive rhythmic cues ware generated based on the
mutual entrainment between the patient’s gait rhythms and the cue rhythms input to the patient while the patient walked.
Previously, we found that the dynamic characteristics of stride interval fluctuation in Parkinson’s disease patients were
improved to a healthy 1/f fluctuation level using interactive rhythmic cues and that this effect was maintained in the short
term. However, two problems remained in our previous study. First, it was not clear whether the key factor underpinning
the effect was the mutual entrainment between the gait rhythms and the cue rhythms or the rhythmic cue fluctuation itself.
Second, it was not clear whether or not the gait restoration was maintained longitudinally and was relearned after repeating
the cue-based gait training. Thus, the present study clarified these issues using 32 patients who participated in a four-day
experimental program. The patients were assigned randomly to one of four experimental groups with the following
rhythmic cues: (a) interactive rhythmic cue, (b) fixed tempo cue, (c) 1/f fluctuating tempo cue, and (d) no cue. It has been
reported that the 1/f fluctuation of stride interval in healthy gait is absent in Parkinson’s disease patients. Therefore, we used
this dynamic characteristic as an evaluation index to analyze gait relearning in the four different conditions. We observed a
significant effect in condition (a) that the gait fluctuation of the patients gradually returned to a healthy 1/f fluctuation level,
whereas this did not occur in the other conditions. This result suggests that the mutual entrainment can facilitate gait
relearning effectively. It is expected that interactive rhythmic cues will be widely applicable in the fields of rehabilitation and
assistive technology.