Change in the transversus abdomins muscles through a spinal orthosis equipped with joints providing resistive force

Abstract

We recently developed a spinal orthosis, the Trunk Solution (TS), in which joints provide the resistive force. A previous study reported that application of a TS prototype increased pelvic forward tilt and abdominal muscle activity. However, the study only reported the effect of TS on shallow abdominal muscles, not on deep abdominal core muscles such as the transversus abdominis, which plays a role in maintaining spinal stability. The purpose of this study was to examine the thickness of the transversus abdominis as the main effect and compare this between with and without TS in conditions of resting expiration and maximal expiration supported by deep core muscles. The thickness of the transversus abdominis significantly increased with the use of TS. In addition, the transversus abdominis muscle was thicker under maximal expiration than under resting expiration. No significant difference in tendency was observed between with and without TS, but a significant difference in expiration was observed with the change in transversus abdominis activity.