Influence of Expiration and Inspiration during Motor Imagery on the Excitability of the Spinal Anterior Horn Cell

Abstract

[Purpose] This study aimed to examine the effect of expiration and inspiration during motor imagery on the excitability of the spinal anterior horn cell. [Participants and Methods] Ten healthy young men (mean age, 19.5 ± 0.5 years) participated in this experiment. The subjects performed expiration and inspiration every 2 sec naturally. First, the F-wave was recorded with subjects in a resting condition. Next, the subjects practiced 50% maximum voluntary contraction of the pinch grip using visual feedback for 30 sec. Then, the F-wave was recorded again while the subjects performed motor imagery (motor imagery condition). The persistence and F/M amplitude ratio of the motor imagery condition were subtracted from their respective values of the resting condition. These value was defined for the variation of persistence and variation of F/M amplitude ratio. [Results] During motor imagery, the persistence and F/M amplitude ratio had higher values than those of the resting condition, but, no significant differences were observed in the variation of persistence and F/M amplitude ratio between expiration and inspiration. [Conclusion] The excitability of the spinal anterior horn cell during motor imagery showed no difference between the expiration and inspiration phases.