Influence of Motor Imagery Clarity of Toe Flexion Using Still Images on the Excitability of Spinal Neural Function

[Purpose] The effect of individual differences in the clarity of motor imagery on the excitability of the anterior horn cells of the spinal cord during motor imagery of toe flexion using still images was examined using the F-wave. [Participants and Methods] A total of 18 healthy adults participated in this study. The participant’s imagery clarity was scored using a Vividness of Movement Imagery Questionnaire (VMIQ). The exercise imagery task was left toe flexion exercise with and without a still images of the left toe flexion position. The value of the F/M amplitude ratio of the motor imagery task, relative to an at rest value of 1, was used as the relative value of the F/M amplitude ratio, and the relationship between the relative value of the F/M amplitude ratio and the VMIQ score of each task with and without still images was examined. [Results] A positive correlation was found between the relative F/M amplitude ratio of the task without still images and the VMIQ score, and a negative correlation was found between the relative F/M amplitude ratio and the VMIQ score of the task with still images. [Conclusion] The results suggest that motor imagery using still images of the flexor hallucis longus has less effect on the excitability of the anterior horn cells of the spinal cord of individuals with lower image clarity.