The Excitability of Spinal Motor Nerve Function Differs Depending on the Subjective Perception of Muscle Contraction Intensity of the Observed Subject

<p>The purpose of this study was to determine the effects of differences in subjective perceptions of muscle contraction intensity of movements presented during exercise observation on the excitability of spinal motor nerve function. The subjects were 22 healthy adults, and F-waves were derived from a muscle group on the right thenar eminence. The measurement flow consisted of measuring the F-wave at rest for 1 minute, followed by 4 minutes of rest, and then measuring the F-wave during movement observation for 1 minute. The observation task consisted of an adduction/abduction movement of the thumb (unloaded video) and loading the thumb with two types of therabands (low and high loading video). Based on the subject's perception, the subjects were classified into subjective high load, subjective low load, and subjective no load, and the amplitude F/M ratio relative values between each condition were compared. The amplitude F/M ratio relative values increased in the subjective high-load condition compared to the subjective no-load and low-load conditions (p<0.05). The results suggest that the excitability of spinal motor nerve function increases when the subject is made aware during exercise observation that the exercise requires strong muscle contraction.</p>