Background: The serratus anterior is one of the most important muscle for maintaining good scapular alignment in the shoulder joint. The pectoralis major and upper trapezius may also compensate for weak serratus anterior muscles. The push-up plus exercise has been identified as the optimal exercise for maximum activation of the serratus anterior.
Objects: The purpose of this study was to examine differences in surface electromyography (EMG) activity of upper trapezius, pectoralis major, and serratus anterior muscles during push-up plus exercises on variously angled surfaces in subjects with winged scapula.
Methods: Sixteen subjects with winged scapula (male=5, female=11) volunteered for this study. The subjects performed push-up plus exercise on four different tilt angles, namely 0˚, 30˚, 60˚, and 90˚. EMG activities in the serratus anterior, upper trapezius, and pectoralis major muscles during performance of push-up plus exercise were measured in all subjects. Data were processed from repeated measures one-way analysis of variance.
Results: There was significant difference in the muscle activity of the serratus anterior on the different surface angles (p＜.05). The results of the post-hoc analysis showed significantly greater serratus anterior muscle activity on a surface at a 0˚ angle than at others tilt angles (p＜.05). There was also significant difference in the ratio of serratus anterior to upper trapezius and serratus anterior to pectoralis major across the four surfaces (p＜.05), and post-hoc analysis showed significantly greater values on the 0˚ surface than on other tilts (p＜.05).
Conclusion: This study found that performing push-up plus exercises on a flat surface with 0˚ and 30˚ tilt angle achieves high activation of the serratus anterior muscle for selective strengthening. It can also take into account the sequential application, which is first performed at a 30˚ and at a 0˚ tilt angle for and effective but not excessive muscle activation.

Abstract
Introduction
Methods
    Subjects
    Instruments
    Outcome Measures
    Procedures
    Statistical Analyses
Results
Discussion
Conclusion
References

• Qian Gu(Dept. of Rehabilitation Medicine, Affiliated Hospital of Nantong University)
• Tae-ho Kim(Dept. of Physical Therapy, Daegu University) Corresponding author
• Jung-genn Chun(Dept. of Physical Therapy, Daegu University)