Affiliations: [a] Department of Physical Therapy, Jeonju University, Jeonju, Korea | [b] Department of Game Contents, Jeonju University, Jeonju, Korea
Correspondence:
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Corresponding author: Yongwook Kim, Department of Physical Therapy, Jeonju University, 303 Cheonjam-ro, Wansan-gu, Jeonju, Jeonbuk-do, 55069, Korea. Tel.: +82 63 220 3261; Fax: +82 63 220 2054; E-mail: ptkim@jj.ac.kr.
Abstract: BACKGROUND: Few studies have explored the relationship between muscle strength, range of motion (ROM), and balance in the horizontal plane of the hip joint using three-dimensional (3D) motion analysis. OBJECTIVE: We investigate the relationships of hip internal rotation (IR) and external rotation (ER) ROM, measured using a 3D motion capture system, with hip internal and external rotator strength and single-leg standing balance. METHODS: The participants were 40 healthy adults. Kinematic data on hip ROM were collected using an eight-camera motion analysis system. Hip rotational strength measurements were obtained using hand-held isometric dynamometry. A Single-leg standing test and a pendular test were conducted to evaluate static and dynamic balance ability using BioRescue. RESULTS: Significant correlations were found between hip strength and each variable measured during hip ROM assessments (p< 0.05). Significant positive correlations were found between the hip IR/ER strength ratio and the IR/ER ROM ratio (r= 0.72, p< 0.01). The subgroup with a normal IR/ER ratio of hip rotator strength and ROM showed significantly better dynamic balance ability than the subgroup with a hip rotator muscle imbalance (p< 0.05). CONCLUSIONS: There is a significant relationship between hip IR/ER strength and IR/ER ROM with a normal hip IR/ER strength and ROM ratio positively affecting dynamic balance ability.
Keywords: Hip rotator muscle, hip rotation range, dynamic balance
