Differences in the transversus abdominis thickness during various motor tasks in the supine position

[Purpose] The aim of this study was to evaluate simple and efficient transversus abdominis exercises performed in the supine position using ultrasonography. [Participants and Methods] Sixteen healthy males performed six motor tasks including left shoulder flexion, draw-in, left straight leg raise, and the vocalization of vowel sounds (55-60 dB, 65-70 dB, and 75-80 dB), in a random order while in the supine position. The thicknesses of the transversus abdominis, internal oblique, and external oblique were measured using ultrasonography. [Results] There was a significant increase in the transversus abdominis thickness during the draw-in and vocalization tasks than during other tasks. With respect to draw-in and the three vowel sound volumes, there was a significant difference between draw-in and the 65-70 dB sound. However, there was no significant difference in the transversus abdominis thickness between draw-in and the three vocalization tasks. [Conclusion] These results suggest that the vocalization of vowel sounds is an effective and easy way to exercise the transversus abdominis for patients experiencing difficulty in performing draw-in exercises.