Illustration copyright 2004 Nucleus Communications, Inc. All rights reserved. http://www.nucleusinc.com

This picture shows some of the core muscles in the back. These muscles are layered over the deeper muscles of the inner core. There are also core muscle groups in the front and on the sides of your body.

The arrows show that the core muscles work in opposite directions. When they contract at the same time, they help stabilize your spine and hips to create a strong foundation for movement of your body and to protect you from injury.