How To Get a Stronger Core Although commonly used for referring to the abdominal muscles, the word "core" actually covers several muscles in the lower and upper body. The rectus abdominis, transverse abdominis, internal obliques, external obliques, multifidus, hip flexors, hamstring group, gluteus group and spinal erectors are all considered as core muscles. All these core muscles help to stabilize the pelvis and spine, as well as operate the full length of your torso. Whenever...