Effect of evidence-based trunk stability exercises on the thickness of the trunk muscles

[Purpose] This study was conducted to investigate the effect of four spine stability exercises on the thickness of the internal and external oblique abdominal muscles, the transverses abdominis, and the multifidus muscles. [Subjects and Methods] Forty healthy adults were enrolled and randomly allocated to four groups. Ten participants performed bridge exercises (BE) while lying on their back; 10 others performed the same exercises with their right legs up (BERL); another 10 performed the same exercises on their side (SBE); and the remaining 10 performed them in a quadruped position with left arm and right leg lifts (QLARL). The participants performed the exercises three times a week for five weeks. The thicknesses of the muscles before and after the interventions were measured using ultrasound. [Results] The results show that the normal bridge exercise significantly thickened the TrA; BERL, the LM; QLARL, the IO; and SBE, the EO and the IO. [Conclusion] All four spine stability exercises were effective. The normal bridge exercise and BERL selectively strengthened the local muscles at the early stage of the treatment. We consider SBE and QLARL should be used in the later stages of treatments because they strengthen both the local and global muscles.