This study used ultrasound to measure the effect of bridge exercises in three postures on the thickness of the transverse abdominis (TrA) and rectus femoris (RF) muscles. The participants in the study were 30 healthy adult men and women. The participants performed general bridge (GB), bridge with use of a sling (BS), and bridge with use of a sling involving contraction of the hip joint adductor muscle (BSHA) 5 times, for 15 seconds each. Ultrasound was used to measure changes in the thickness of the TrA and RF before and after exercise. After the intervention, the TrA showed a significant difference in mean values between GB and BS (p<0.05). The RF showed a significant difference in mean values between GB and BS and between GB and BSHA (p<0.05). The results indicate that the bridge exercise using a sling was the most effective posture for increasing the thickness of the transverse abdominis, and the general bridge exercise was the most effective for increasing the thickness of the rectus femoris. Until recently, many different modified bridge exercise methods have been proposed, but there is still a lack of research examining the muscle thickness of the lower and upper limb muscles during the bridge exercise accompanied by hip joint adductor muscle contraction on an unstable surface, such as a sling. Therefore, the results of this study are intended to provide basic data when using training bridge exercises for trunk stabilization.