Twisted crunches are excellent for working your core region and abdominal muscles. Beginners can start off with standard twisted crunches (with legs on the ground) and advanced users can use the progression variation (with both legs raised).
Step By Step Instructions
Lie on your back with your knees bent, your heels on the ground, and your hands behind your head. Focus on pressing your head into your hands so that you do not strain your neck.
Using your abdominal muscles, crunch up and twist your elbows towards one of your knees.
Release, lie back down, and repeat the crunch twisting toward the alternate knee. Repeat 5 times or more, depending on your comfort level.