Forget sit-ups—use these eight dumbbell moves to build total core strength

Personal trainer Rachael Sacerdoti completing a core workout .

The core muscles play a role in everything from your balance to your spinal health and pelvic stability. But if you want to strengthen these muscles effectively, you need to take a break from sit-up-centric workouts. 

That's because sit-ups focus on spinal flexion, or bending your spine forwards, which is a move that's driven by your rectus abdominis (the muscles on the front of the stomach responsible for the "six-pack" shape).