上肢帯挙上筋の左右一側随意収縮における眼球運動反応時間

抄録

  We compared the saccadic reaction times during isometric contraction of bilateral shoulder girdle elevators and unilateral (right and left) shoulder girdle elevator in a sitting posture. Muscle contraction force was increased in 10% increments from 10% to 60% of the maximal voluntary contraction (MVC) of each side. Saccadic reaction time was determined as the latency to the beginning of eye movement toward a lateral target moved at random intervals in 20° amplitude jumps. Eye movement was measured using the electrooculographic technique. During bilateral contraction, the saccadic reaction time decreased until 30% MVC and then began to increase at 40% MVC. In both right and left contractions, saccadic reaction time decreased until 30% MVC similar to bilateral contraction, but remained constant from 30% to 50% MVC that differed from bilateral contraction, followed by a slight increase at 60% MVC. The saccadic reaction times at 50% and 60% MVC were significantly shorter during unilateral contraction compared to bilateral contraction. These results demonstrated that the saccadic reaction time produced by shoulder girdle elevator contraction is shortened at a wider range of muscular force during unilateral contraction than bilateral contraction, and that the saccadic reaction time did not differ significantly between right and left contraction.