459738.fig.004a
(a)
459738.fig.004b
(b)
Figure 4: Ultrasound image of the TrA and calculation of TrA activation ratio. Resting image is on (a) and contracted image is on (b) (Activation ratio = TrA contracted (mm)/TrA rest (mm)). EO = external oblique; IO = internal oblique; TrA = transverse abdominis. The red arrow indicates the thickness of the TrA.