Core training involves targeting the muscles in the center of your body. Most commonly thought of as the abs and low back, the core also includes the hips and the shoulders.
Core exercises improves your balance and stability from your pelvis, lower back, hips and abdomen. You can also get better posture when your core is stronger.
Difficulties in Core Exercise may cause you to use supporting muscles to help your struggling core strength. That supporting muscle can be your Erector Spinae which is located on your back. Some can accidently activate their back muscles instead which removes the benefits you can get for core training.