The 12 deep core exercises I'm sharing help tighten and tone the abs, shrink the waistline, and support the back and pelvic floor. How's that for results? A deep core exercise typically refers to an exercise that targets the muscles of the deep core, which includes muscles such as the transversus abdominis, pelvic floor muscles, and multifidus. These muscles play a crucial role in providing stability and support to the spine, pelvis, and surrounding structures. That's also what makes deep core exercises so great for your back and tend to give better results compared to ab exercises that work superficially.