Resting thickness of transversus abdominis is decreased in athletes with longstanding adduction-related groin pain.

The purpose of the study was to compare thickness of the transversus abdominis (TA) and obliquus internus (OI) muscles between athletes with and without longstanding adduction-related groin pain (LAGP). Forty two athletes with LAGP and 23 controls were included. Thickness of TA and OI were measured with ultrasound imaging on the right side of the body during rest. Relative muscle thickness (compared to rest) was measured during the active straight leg raise (ASLR) left and right, and during isometric hip adduction. TA resting thickness was significantly smaller in injured subjects with left-sided (4.0+/-0.82mm; P<0.001) or right-sided (4.3+/-0.64mm; P=0.015) groin complaints compared with controls (4.9+/-0.90mm). No significant differences between patients and controls in TA or OI relative thickness during the ASLR and isometric hip adduction were found (all cases P>/=0.15). In conclusion, TA resting thickness is smaller in athletes with LAGP and may thus be a risk factor for (recurrent) groin injury. This may have implications for therapy and prevention of LAGP.