Measurement the thickness of the transverse abdominal muscle in different tasks.

[Purpose] This study examined the measurement of the thickness of the transverse abdominal muscle in different tasks. [Subjects and Methods] The subjects were eleven healthy adult females. Thicknesses of transverse abdominal muscle were measured in seven tasks in the supine position. The tasks were: 1) Resting state, 2) Maximal contraction of transverse abdominal muscle, 3) Maximal contraction of levator ani muscle, 4) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle, 5) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with front side resistance added to both knee, 6) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with diagonal resistance added to both knees, and 7) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with lateral resistance added to both knees. [Results] The thicknesses of transverse abdominal muscle during maximal simultaneous contraction and maximal simultaneous contraction with resistance were greater than during the resting state. [Conclusion] The muscle output during simultaneous contraction and resistance movement were larger than that of each individual muscle.