The aim of this study was to compare the activity of the upper trapezius (UT) and serratus anterior (SA) and ratio of UT to SA during shoulder elevations. Ten subjects with UT pain (UTP) and 13 subjects without UTP participated in this study. Subjects with a UTP of over five in a pain intensity visual analogue scale (0-10 ㎝) for more than 2 months and latent myofascial trigger points (MTrPs) in the UT muscle were included in the UTP group. Electromyography (EMG) data of UT and SA at 1st and 10th elevations were analyzed. Two-way repeated analyses of variance were used to compare the EMG activity of UT and SA and the ratio of UT to SA during shoulder elevations between groups with and without UTP. There was a significant increase in UT/SA ratio in the group with UTP compared to the group without UTP (p=.01). The activity of UT and SA measured at the 10th elevation was significantly greater than that in the first elevation (p<.05). The activity of SA was significantly greater in the group without UTP than the group with UTP (p=.03). However, there was no significant difference between groups with and without UTP in terms of UT activity (p=.28). These results indicate that UTP may have relevance to the increased muscle activity ratio of UT to SA during shoulder elevations.

• Sun-hee Ahn(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
• Sung-dae Choung(Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Si-hyun Kim(Dept. of Physical Therapy, The Graduate School, Yonsei University)
• In-cheol Jeon(Dept. of Physical Therapy, The Graduate School, Yonsei University)