周期性の認識に基づく効率的な運動中に定期的に呈示される異なる刺激間隔が筋電図反応時間に及ぼす影響

－刺激回数の増加と刺激間隔の相違による検討－

抄録

The purpose of this study was to investigate the influence of varying interstimulus intervals on electromyographic reaction time (EMG-RT) during exercise using a rhythmic auditory stimulus. In addition, we investigated the alteration of EMG-RTs accompanying the auditory stimulus of the 6^th, 12^th, 18^th, and 24^th stimuli. The subjects were 17 healthy subjects (12 males, 5 females; mean age: 24.1 ± 3.8 years). The auditory stimulus had a stimulus intensity that was easy to hear during experiments, an auditory frequency of 900 Hz, and 25 stimuli were delivered per trial. The subjects were requested to quickly raise their right ankle in response to each auditory stimulus. The stimulus conditions 1 to 4 were as follows; 1) interstimulus intervals were a constant 1,000 ms, 2) interstimulus intervals between the 5^th and 6^th, 11^th and 12^th, 17^th and 18^th, and 23^rd and 24^th stimuli were 1,200 ms, 3) interstimulus intervals between the 5^th and 6^th, 11^th and 12^th, 17^th and 18^th, and 23^rd and 24^th stimuli were 2,400 ms, 4) interstimulus intervals between the 5^th and 6^th, 11^th and 12^th, 17^th and 18^th, and 23^rd and 24^th were 4,800 ms. We investigated the following; 1) how EMG-RTs changed when there was an increase in the stimulus number, 2) how the difference in the interstimulus interval influenced the EMG-RTs corresponding to the 1^st, 6^th, 12^th, 18^th, and 24^th stimuli. The results suggest that the EMG-RTs corresponding to the 6^th, 12^th, 18^th, and 24^th stimuli were shorter than the 1^st in condition 1; those corresponding to the 18^th and 24^th stimuli were shorter than the 1^st in condition 2; and those corresponding to the 1^st, 6^th, 12^th, 18^th, and 24^th stimuli did not differ in conditions 3 and 4. EMG-RTs did not differ in the first condition. The EMG-RT corresponding to the 24^th signal in condition 4 was longer than that in condition 2. These results suggest that the rhythm of the interstimulus interval was important for guiding exercise internally compared to that employing external stimulation. In addition, these results suggest that the difference in the interstimulus intervals influenced exercise when an auditory stimulus was applied regularly.