Affiliations: [a] Department of Physical Therapy, Korea University, Seoul, Korea | [b] Institute for International Development Cooperation, Paik Medical Center, Inje University, Seoul, Korea | [c] Major in Sports, Health & Rehabilitation, Cheongju University, Cheongju, Korea | [d] Department of Sports Medicine, Cheongju University, Cheongju, Korea | [e] Department of Physical Medicine and Rehabilitation, Korea University Medical Center, Seoul, Korea
Correspondence:
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Corresponding author: Sangheon Lee, Department of Physical Medicine and Rehabilitation, Korea University Medical Center, #126-1, Anam-Dong 5Ga, Seongbuk-Gu, Seoul, 136-705, Korea. Tel.: +82 2 920 6483; Fax: +82 2 929 9951; E-mail: spinelee@gmail.com.
Note: [1] Bumchul Yoon and Hyoyoung Pyeon contributed equally to this work.
Abstract: BACKGROUND: The core stability theory has emphasized symmetric co-contraction of both anterolateral abdominal muscles (AAM), but there is a lack of research on whether the symmetric co-contraction of AAM is related to the postural stability of the trunk. OBJECTIVE: This study aimed to investigate the correlation between the symmetric co-contraction of bilateral AAM and trunk angular displacement during sudden trunk perturbation. METHODS: Eighteen subjects were asked to maintain half-seated posture against backward trunk perturbation. Muscle thicknesses of external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) were measured using ultrasound imaging. 3D motion analysis system was utilized to calculate the amount of trunk angular displacement during perturbation. RESULTS: There were significant differences of side-to-side muscle thickness in TrA (P= 0.02) and EO (P= 0.02), but the difference disappeared during sudden external loading. No significant correlation was identified between the asymmetry of abdominal muscle thickness and the amount of trunk angular displacement. CONCLUSIONS: These findings indicate that the side-to-side asymmetry of AAM measured in a static position is rarely related to the core stability because the asymmetry can disappear during trunk stabilization.
