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.