Without getting too science-y, the core muscles are those that protect your spine and internal organs. These are the Abs, Obliques and Lower Back. In daily life, these muscles help keep us up straight. When we are exercising, these cores help keep the body in the correct position. This will allow us to train safely and with correct technique. For example, our core keeps our spine neutral when doing Deadlifts. The core keeps our body tight when doing pullups so that we can better transfer force from our muscles into the bar.