Relationship between Changes in Spine and Upper Limb Alignment and Trapezius and Levator Scapulae Muscle Hardness in the Sitting Posture

Abstract

[Purpose] The purpose of this study was to examine the relationship between sitting posture and trapezius and levator scapulae muscle hardness in different spine and upper limb alignments. [Participants and Methods] The subjects were 25 healthy adult males. The measurement positions were condition 1 (upright and arms hanging loose), condition 2 (upright and hands clasped behind the back), condition 3 (kyphosis and arms hanging loose), and condition 4 (kyphosis, and hands clasped behind the back) in the sitting posture. A tissue hardness tester was used to measure the hardness of the trapezius and levator scapulae muscles. [Results] The results show that there were no significant differences in trapezius muscle hardness among the conditions, but scapular muscle hardness was significantly lower in conditions 2, 3, and 4 compared to condition 1. [Conclusion] The results suggest that the levator scapulae muscle is easily affected by changes in the spinal column and upper limb alignment, whereas the trapezius muscle is less affected by changes in alignment.