2018 Volume 24 Pages 59-67
This study aimed to clarify the effect of repetitive rotator cuff exercise on corticospinal tract excitability, which concerning the control of the external rotator muscles during shoulder joint abduction. We examined the corticospinal tract excitability before and after the rotator cuff exercise by using transcranial magnetic stimulation (TMS). The exercise was repeated 100 times every 15 minutes for total of 300 repetitions. The corticospinal tract excitability during shoulder joint abduction was measured by using motor-evoked potentials (MEPs). TMS was applied to induce MEPs in the infraspinatus, middle deltoid, posterior deltoid, and lower trapezius muscles during the isometric shoulder joint abduction. Abduction was performed 20° in the scapular plane. MEPs were measured twice before exercise (pre1, pre2), immediately after each exercise (exercise1, exercise2, exercise3), further, and 30 minutes and 60 minutes after the third exercise ended (post30, post60). The MEP amplitude of the infraspinatus muscle was significantly increased until 60 minutes after the exercise ended in comparison with that measured at pre1, whereas there was no significant difference in the MEP amplitudes of the other muscles. The present study demonstrated that the corticospinal tract excitability of the infraspinatus muscle was increased during shoulder joint abduction after the intervention exercise.
