title: Influence of motor imagery of isometric opponens pollicis activity on the excitability of spinal motor neurons: a comparison using different muscle contraction strengths.
abstract: [Purpose] This study aimed to determine the differences in the excitability of spinal motor neurons during motor imagery of a muscle contraction at different contraction strengths. [Methods] We recorded the F-wave in 15 healthy subjects. First, in a trial at rest, the muscle was relaxed during F-wave recording. Next, during motor imagery, subjects were instructed to imagine maximum voluntary contractions of 10%, 30%, and 50% while holding the sensor of a pinch meter, and F-waves were recorded for each contraction. F-waves were recorded immediately and at 5, 10, and 15 min after motor imagery. [Results] Both persistence and F/M amplitude ratios during motor imagery under maximum voluntary contractions of 10%, 30%, and 50% were significantly higher than that at rest. In addition, persistence, F/M amplitude ratio, and latency were similar during motor imagery under the three muscle contraction strengths. [Conclusion] Motor imagery under maximum voluntary contractions of 10%, 30%, and 50% can increase the excitability of spinal motor neurons. The results indicated that differences in muscle contraction strengths during motor imagery are not involved in changes in the excitability of spinal motor neurons.
authors.affiliation: Graduate School of Health Sciences, Graduate School of Aomori University of Health and Welfare: 58-1 Mase, Hamadate, Aomori 030-8505, Japan.
authors.forename: Yoshibumi
authors.initials: Y
authors.lastname: Bunno
authors.affiliation: Graduate School of Health Sciences, Graduate School of Aomori University of Health and Welfare: 58-1 Mase, Hamadate, Aomori 030-8505, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yurugi
authors.affiliation: Clinical Physical Therapy Laboratory, Faculty of Health Sciences, Kansai University of Health Sciences, Japan.
authors.forename: Chieko
authors.initials: C
authors.lastname: Onigata
authors.affiliation: Clinical Physical Therapy Laboratory, Faculty of Health Sciences, Kansai University of Health Sciences, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Graduate School of Health Sciences, Graduate School of Aomori University of Health and Welfare: 58-1 Mase, Hamadate, Aomori 030-8505, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iwatsuki
keywords: F-wave; Motor imagery; Muscle contraction strength