Hollow Body Rock

The hollow body rock is an anti-extension core exercise. Lying supine with the lower back pressed to the floor, the legs and shoulders lift into a hollow position while a bell is held two-handed with the arms locked straight above the chest. The whole rigid shape rocks subtly back and forth, an anti-extension brace with no spinal crunching.

Mechanics and load path

The setup is supine. Press the lower back firmly into the floor before lifting. Legs extend straight, hovering six to twelve inches off the ground. Shoulders lift, scapulae off the floor. The bell is held two-handed with arms fully extended straight above the chest, locked overhead — not resting on the chest. The whole body forms a shallow concave curve — the hollow position.

The rocking motion is subtle. The whole rigid shape rocks back and forth, not the limbs articulating independently. The lower back stays glued to the floor. The arms stay locked overhead through the whole rep — bending the elbows or letting the bell drop toward the chest defeats the anti-extension intent. If the lumbar arches off the ground, the load is too heavy or the position is collapsed — drop the bell, reset, restart lighter.

The McGill-aligned anti-extension principle holds: the spine resists movement under load rather than arching under load. The exercise trains the deep core stabilizers without the spinal compression of a sit-up or crunch pattern. It sits in the same anti-extension family as the dead bug and complements anti-rotation work like the Pallof press.