Get access to everything we publish when you sign up for Outside+.
Rip your core with this classic CrossFit exercise.
You can thank the Crossfit crew for popularizing the “hollow rock,” a gymnastic staple that’s a lot harder than it looks. When done properly, the hollow rock will strengthen your core better than just about any other exercise.
Lie down face up with your arms and legs both extended and about one foot off the floor. The goal is to be the shape of a rocking chair. Then, much like a rocking chair, start moving back and forth while keeping your body stiff and without raising your arms and legs.
The key is lowering the lumbar arch of your back to the floor before you begin. Lying on the floor relaxed, you can usually slip your hand underneath the arch in the small of your back. You don’t want that. Force your back flat so that it’s a smooth, round shape from your shoulders to your butt. This really forces the lower abs to work, which is the point of the exercise. Start slowly, but if you can keep this up for two minutes, your abs will be the envy of the gym.
This piece first appeared in Competitor Magazine.