Effects of Pelvic Tilt and Upper Limb Position on Trunk Rotation Range in Upright Sitting

Abstract

[Purpose] To investigate the effects of pelvic tilt and upper limb position on trunk rotation range in upright sitting. [Subjects and Methods] The trunk muscle activities and passive range of motion (ROM) of 20 healthy university students were measured. Under two conditions of pelvic tilt and upper limb position, the laterality of trunk rotation during upright sitting was measured. The differences among the conditions were divided into left and right and analyzed using two-way ANOVA, and the relationship of trunk rotational ROM with muscle strength was analyzed using Pearson correlation coefficients. [Results] Irrespective of the upper limb position, significant differences were found in the trunk rotation range with change in pelvic tilt; however, no significant changes were found between the upper limb positions. Furthermore, in the correct sitting posture, significant correlations were found between trunk rotational range and trunk range of motion and muscle strength. [Conclusion] The results suggest that changes in pelvic position affect the rotational range of the trunk, and in a correct sitting posture they correlates with trunk muscle strength.