The four main muscles of the deep core—transverse abdominis, multifidus, pelvic floor and the diaphragm—work together to keep ...

Tight hip flexors, especially a deep muscle called the psoas, can silently stress your spine. Here's why this muscle deserves more attention—and how to strengthen it. Lower back pain is often blamed ...

Most people know where the abs are in the body—sometimes known as the six-pack muscles—but few are so familiar with the deep core. These are the deepest layer of abdominal muscles and are sometimes ...