Changes in abdominal muscle thickness in standing and seated positions, with and without an abdominal belt, in healthy subjects

Purpose: The aim of the present study was to investigate changes in the thickness of abdominal muscles with different states of contraction and postures in healthy subjects. Subjects: The subjects were fifteen healthy male university students (18-20 yrs) with no history of neurological or orthopedic disease. Methods: Ultrasound equipment was used to measure the change in abdominal muscle thickness upon contraction and relaxation with and without a belt and in the standing and seated positions. Results: Significant differences were found in the thicknesses of the internal oblique and the transverse abdominis muscles upon contraction and relaxation regardless of the belt condition (with or without) and the two postures. The comparison of the change upon contraction found a significant increase in the thickness of the external oblique when using the belt and a decrease in that of the transverse abdominis. Conclusion: These results suggest that wearing an abdominal belt artificially increases abdominal pressure and tends to increase external abdominis activity, but that the effect on the transverse abdominis is limited.