Effects of bridge exercise performed on an unstable surface on lumbar stabilizing muscles according to the knee angle

[Purpose] This study aimed to determine the effects of bridge exercise performed on anunstable surface on lumbar stabilizing muscles according to the knee angle. [Subjects]Fifteen healthy adult men were selected for this study. [Methods] The study subjectsperformed the bridge exercise on an unstable surface and a stable surface, with the kneesat different angles (45°, 90°, and 120°). An aero-step device was used as the unstablesurface, and the flat ground was used as the stable surface. External oblique, internaloblique, and rectus abdominis muscle activities were assessed and compared usingelectromyography. [Results] The study results demonstrated that performing the bridgeexercise on an unstable surface with a knee angle of 120° led to a greater increase in theexternal oblique, internal oblique, and rectus abdominis muscle activities than whenperformed on a stable surface. [Conclusion] The bridge exercise with the knees at a 120°angle was found to be an effective intervention for increasing the external oblique,internal oblique, and rectus abdominis muscle activities.Key words: Bridge exercise, Knee joint angle, Lumbar stabilization