Motor image recall ability affects the excitability of spinal nerve function in healthy participants executing mirror therapy tasks at different complexities

[Purpose] The purpose of this study was to use Mirror Therapy to clarify the effect of the differences in image recall ability and the types of finger exercises on the excitability of spinal nerve function. This study will help establish the methodology for therapeutic intervention using Mirror Therapy. [Participants and Methods] We divided 30 healthy right-handed adults into two groups: one with high exercise image recall ability and the other with low exercise image recall ability. The participants were asked to put both hands in the Mirror Box such that the left hand was hidden behind the mirror. While looking at the mirror image of the right hand, they were instructed not to move the left hand voluntarily. We measured the F-wave from the finger abductor muscle using evoked electromyography. [Results] The comparison between the high and low image recall groups showed that the excitability of spinal nerve function increased in the low image recall group overall. [Conclusion] From the above results, we suggest that when performing mirror therapy, it is necessary to select a task that is not too simple and not difficult to move normally.