This study compared the effects of the initial head position (i.e., a HHP versus a relaxed head position) of subjects with and without a FHP on the thickness of the deep and superficial neck flexor muscles during CCF. The study recruited 6 subjects with a FHP and 10 subjects without a FHP. The subjects performed CCF in two different head positions: a HHP, with the head aligned so that the forehead and chin formed a horizontal line, and a relaxed head position (RHP), with the head aligned in a self-selected comfortable position. During the CCF exercise, the thickness of the longus colli (LCo) and the thickness of the sternocleidomastoid (SCM) were recorded using ultrasonography. The thickness of each muscle was measured by Image J software. The statistical analysis was performed with a two-way mixed-model analysis of variance. The thickness of the SCM differed significantly (p<.05) between the subjects with and without FHP. According to a post hoc independent t-test, the change in thickness of the SCM increased significantly during CCF in the subjects with FHP while adopting a HHP compared to that in the subjects without FHP. The change in thickness of the SCM was not significantly different between the two positions in subjects without FHP, and there was no significant change in thickness of the LCo muscle during the CCF exercise according to the initial position in both subjects with and without FHP. The results suggest that CCF should be performed in RHP to minimize contraction of the SCM in subjects with a FHP.

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References

• Sung-hoon Jung(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Oh-yun Kwon(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, College of Health Science, Yonsei University, Dept. of Ergonomic Therapy, The Graduate School of Health and Environment, Yonsei University)
• Kyu-hwan Choi(Dept. of Physical Therapy, Ansan University)
• Sung-min Ha(Dept. of Physical Therapy, College of Health Science, Sangji University) Corresponding author
• Su-jung Kim(Dept. of Physical Therapy, College of Health Sciences, Youngsan University)
• In-cheol Jeon(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Ui-jae Hwang(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University)