The core, also sometimes referred to as trunk, is not just about the front of your stomach. Trunk muscles are arranged in several layers around the whole mid-section of the body and include the glutes at the bottom and the diaphragm at the top. They are more about preventing movement than creating movement. They also play a role in resisting compression. Exercises like crunches, side bends, and twists do not address primary functions of the core and are far more risk than reward.
Core Series Part 1- It’s Not About a 6 Pack It’s About That Aching Back