Effect of 30%MVC motor imagery of thumb opposition movement on the accuracy of movement and the excitability of the spinal nerve function

Abstract

In the present study, the effect of motor imagery of 30% maximum voluntary contraction (MVC) of thumb opposition movement on the accuracy of movement and excitability of the spinal nerve function was examined. The subjects were 11 healthy adult patients (6 males, 5 females, 24.1 ± 3.5 years of age). The excitability of the spinal nerve function was examined using the F-wave, and the F wave induced by left median nerve stimulation of the left thenar eminence muscle. The F wave was measured while subjects rested supine, and while they held the sensor of a pinch meter. Thumb opposition movement of 30% MVC was practiced with the visual feedback, and subsequently without visual feedback to reproduce 30%MVC of thumb opposition movement. Next, the F wave measured at 30%MVC of motor imagery, and finally, the subjects generated 30% MVC with no visual feedback. Accuracy of movement with 30%MVC ± 5% within the correct time were compared before and after motor imagery. In the motor imagery attempts, there was a significant increase in the F-wave frequency of appearance compared to the sensor holding trials. The accuracy of the movement did not significantly change after motor imagery. Although the excitability of the spinal nerve function in the motor imagery was increased by thumb opposition movement of 30%MVC, the accuracy of the movement was no different from before motor imagery, suggesting the importance of pre-motor imagery learning.