PURPOSE: The purpose of present study was to ascertain how the activity of the serratus anterior muscle, the upper trapezius muscle and the pectoral major muscle was affected while the upper arm was being flexed at 70, 90 and 110 degrees respectively in a closed kinetic chain exercise (wall push up plus) and an open kinetic chain exercise (static hug). METHODS: Sixteen healthy young men subjects participated in the study. Surface electromyography (EMG) data were collected from the dominant-side muscles during a closed kinetic chain exercise and an open kinetic chain exercise. The activity of each muscle was measured quantitatively, and by the use of the two-way repeated ANOVA, the data were compared with each other according to exercises and shoulder flexion angles. RESULTS: Results indicated that the closed kinetic chain exercise did not interact with the open kinetic chain exercise (p>.05). In both the closed kinetic chain exercise and the open kinetic chain exercise, the activity of the serratus anterior muscle became different significantly according to angles (p<.05). Its activity increased in order of 70, 90 and 110 degrees (p<.05). In both exercises and all angles, muscle activity was significantly higher in the serratus anterior muscle than in the upper trapezius muscle and the pectoral major muscle (p<.05). CONCLUSION: The above results show that there is a need to selectively control the exercise stress of the serratus anterior muscle in the case of the patients with the shoulder impingement syndrome characterized by the winged scapula, insufficient scapular protraction and upward rotation.