The Association between Pelvic Asymmetry and Lateral Abdominal Muscle Activity in a Healthy Population.

The human pelvis is subjected to forces generated by abdominal muscles. Pelvic asymmetry (PA) might therefore be related to the asymmetrical postural activity of the lateral abdominal muscles (LAMs: transversus abdominis (TrA); internal oblique (IO); external oblique (EO)). The main aim of this study was to evaluate the potential relationship between PA, expressed by the asymmetry index in the frontal (PAIf) and sagittal (PAIs) planes and LAM postural activity as described by the tissue deformation index (TDI). A group of 126 healthy volunteers (59 females) was involved. Positions of the anatomic landmarks for PA measurement were registered by the motion capture system. The response of LAMs to postural disturbation was recorded using the M-mode ultrasounds. We found weak negative correlations between PAIf and TDI values as well for the right and the left side of the body except for EO muscle (PAIf-TRA right: r = -0.11, left: r = -0.06; PAIf-IO right: r = -0.15, left: r = -0.10; PAIf-EO right: r = 0.02, left: r = 0.12). On the contrary, analysis between PAIs and TDI values revealed weak positive correlations, also except for EO muscle (PAIf-TRA right: r = 0.004, left: r = 0.003; PAIf-IO right: r = 0.05, left: r = 0.06; PAIf-EO right: r = 0.07, left: r = -0.02). For all tested correlations, we recorded non-significant outcomes (all p > 0.05). We found no evidence to support the claim that PA is related to the LAM activity in the group of young, healthy, and active people.