The relationship of hip rotation range,hip rotator strength and balance in healthy individuals

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.