Top 10 exercises to challenge, tighten and strengthen your core! Your core includes several muscle groups that are located on your stomach, back and butt. These muscles work as a team to support your pelvis and spine, keep your back safe and improve your posture. Aside from the obvious aesthetic benefits, having a strong, tight core also enables you to perform exercises with better form and helps you work all other muscle groups more effectively. If you want to challenge your core and improve strength, stability, and posture, add these 10 exercises to your workout routine.