Background: The serratus anterior (SA) muscle is one of the important muscles in the upward rotation of the scapula when the arm is raised. Insufficient muscle activity of the SA can cause deformation of the shoulder rhythm resulting in shoulder pathology. Objects: This study intends to compare SA and upper trapezius (UT) activity during the conventional wall-slide and push-up plus exercises for SA muscle strengthening and the scapular upward rotation (SUR) exercise. Methods: A total of 30 subjects participated in this study, and we measured the muscle activity of the SA and UT muscles during the wall-slide, push-up plus and SUR exercises. The one-way repeated ANOVA was used to compare SA and UT muscle activities during the 3 exercises. Results: During the SUR exercise, SA muscle activity was 79.88% maximum voluntary isometric contraction (MVIC), which was significantly higher than its activity during the other 2 exercises. The UT muscle activity was 47.53 %MVIC during the SUR exercise, indicating a significantly higher UT muscle activity than during the other 2 exercises. Conclusion: These findings suggest that the SUR exercise can maximize SA muscle activity to strengthen the SA while keeping UT muscle activity at an appropriate level.

Introduction
 Methods
  Subjects
  Surface electromyography (EMG)
  Experimental procedure
  Statistical analysis
 Results
 Discussion
 Conclusion
 References

• Jun-hee Kim(Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Ui-jae Hwang(Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Sung-hoon Jung(Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Gyung-tae Gwak(Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Oh-yun Kwon(Dept. of Physical Therapy, College of Health Science, Yonsei University, Dept. of Ergonomic Therapy, The Graduate School of Health and Environment, Yonsei University) Corresponding author