The oblique V-crunch, sometimes called a "mermaid crunch," strengthens and tones your waistline [1] by targeting the obliques — the abdominal muscles on either side of your rectus abdominis (that six-pack zone in the middle!). Here's how it's done:

• Lie on your right side with your left hand behind your head and your right hand on the floor.
• Press down into your right hand as you raise your straight legs off the floor, bringing your torso toward your legs.
• Lower yourself back to the floor with control. This completes one rep. Be sure to do even reps on each side.