Which of the following is NOT included as a core stabilizer muscle in Pilates?

The rectus abdominus is primarily recognized as a prime mover rather than a core stabilizer. In the context of Pilates and core stabilization, the focus is on muscles that help maintain stability and support the spine rather than those that flex the trunk. The diaphragm, transverse abdominis (TA), obliques, and pelvic floor muscles play critical roles in stabilizing the core.

The diaphragm contributes to intra-abdominal pressure and stabilizes the rib cage during movement. The transverse abdominis is crucial for providing tension around the abdominal wall, contributing to spinal stability. The obliques assist in rotation and side bending while also supporting spinal posture. The pelvic floor muscles play an essential role in stabilizing the pelvis and supporting the abdominal organs.

Thus, while the rectus abdominus does contribute to certain movements, its role does not align with the specific function of core stabilization emphasized in a Pilates approach.