Comparison of lateral abdominal muscle thickness during bridge exercises with different support surfaces in healthy individuals

BACKGROUND: Lateral abdominal muscle strengthening exercise can improve the function and motor control of core musculature, but the influence of exercise posture and unstable support surface is controversial. OBJECTIVE: To evaluate the influence of bridge exercise type and support surface on abdominal muscle thickness during three bridge exercises with two different support surfaces. METHODS: Real-time ultrasonography was used to measure the muscle thickness of the transverse abdominis, internal oblique, and external oblique muscles in 45 healthy volunteers. The supine, prone, and flank bridge exercise were performed on stable and unstable support surfaces. RESULTS: The thickness of all muscles was significantly increased during flank compared to supine bridge exercise and prone with stable support (p < 0.05) but not in prone vs. supine. Muscle thickness was significantly increased in prone compared to supine bridge and flank compared to supine and prone (p < 0.05) with unstable support. However, only internal oblique muscle thickness was significantly increased in unstable support surface compared to stable during prone bridge exercise. CONCLUSION: Bridge exercises performed with unstable support do not influence the contraction thickness of lateral abdominal muscles any more than those performed with stable support. In healthy individuals, thickening of abdominal muscles is influenced more by maintaining a specific posture than by the support surface when the target muscles are engaged as agonists.