The next time you go to work your abs, be sure to fit in the vertical leg crunch. Not all ab exercises are created equal for toning, but the vertical leg crunch is among the best for targeting both of the major muscles in your core. It's at the top of the list for working both your abs and obliques. While your abs are taking on most of the work, you can tweak the exercise to focus more on your obliques.
Your rectus abdominis is the muscle that handles most of the load during the vertical leg crunch. The six-pack muscle runs along the front of your torso from your pelvis to the bottom of your sternum and is the biggest of your abdominal muscles. It flexes your spine, bringing your shoulders down toward your pelvis. A 2001 study by the American Council on Exercise found that the vertical leg crunch was the fourth best of the most popular ab exercises for recruiting the rectus abdominis .
Helping out during the vertical leg crunch are your obliques, which are located on either side of your torso. Although the obliques are commonly known for their ability to bend your spine side to side and rotate your torso, they also help with spinal flexion. Each of your obliques has an external and internal head, and each of these heads assists in pulling your torso up toward your legs.
The vertical leg crunch can be done with either your hands set against the back of your head or with your arms extended up toward the ceiling. Lie on your back on an exercise mat and lift your legs so they’re straight and held up vertical. Contract your abdominals and obliques to lift your shoulders and upper back from the floor. If you’re holding your arms straight, reach up toward your shoelaces. Slowly return your back and shoulders to the floor and then go right into the next repetition.
If you’d like to increase the demand on your obliques, crunch and twist slightly. If your hands are behind your head, for example, crunch and twist to your left, bringing your right elbow toward your left knee. On the next repetition, crunch and twist to your right to bring your left elbow toward your right knee. If you’re holding your arms up, crunch and twist to bring your hands outside your shoe. If you’re interested in making the exercise more challenging, hold a medicine ball or a single dumbbell in your hands.
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