견관절 외전 각도와 회전 자세에 따른 대흉근 활성도 비교

Comparison of EMG Activity for Pectoralis Major Muscle During Shoulder Movement With Various Abduction Angle and Rotation Position

The purpose of this study was to compare EMG activity for pectoralis major myscle during shoulder movement with various abduction angle and rotation position in supine position. Fifteen healthy subjects were recruited for this study. All subjects performed shoulder horizontal adduction holding a 2kg dumbbell in shoulder abduction 40°, 70°, 90°, 130°, 160° with shoulder neutral, internal rotation(IR), and external rotation(ER). Surface EMC activity was recorded from pectoralis major clavicle part and pectoralis major sternum part for 5 seconds and EMG activity was normalized to the value of maximal voluntary isometric contraction (%MVIC). Dependent variable were examined with 3 (Neutral, IR, ER) x 5(40°, 70°, 90°, 130°, 160°) analysis of variance with repeated measures. THe EMG activity of pectoralis major muscle was significantly different between shoulder abduction angles and between shoulder rotation positions(p<.05). The highest value of EMG activity of pectoralis major sternum pars among shoulder abduction angles was in 130° and 90° in that order. According to the rotation degree, shoulder ER showed the highest value and IR showed the lowest value in both muscle parts. these results suggest that shoulder abduction 70°, 90°, 130° will be effective during manual muscle testing(MMT) and strengthening exercise for pectoralis major muscle. It is also supposed that shoulder ER is the efficient posture for strengthening of pectoralis major muscle.