If you have been doing the same ab routine—crunches, planks, and bicycles—for years, you are probably ready for a creative challenge. One easy way to wake up your core is by adding dumbbells to your ...

• Sit-ups target your abdominal muscles, back muscles, and hip flexors, while crunches only target your abdominal muscles. • Neither sit-ups nor crunches alone burn abdominal fat. Overall activity and ...