In order to properly perform the cross over crunch, it is essential that you position your body properly. Start by clearing an area on the floor. Lay a yoga mat or beach towel flat on the ground. Lay down on the mat flat on your back, with your knees bent and your feet flat on the floor. Lace your fingers together behind your head with the palms of you hands cradling the base of your skull. Look directly up at the sky. You should be in a straight line from the tip of your head to your tailbone.

Now that you are in the right position, you can begin to perform the cross over crunch. Start by taking a few deep breaths. As you exhale your next breath use the muscles in your core to lift your upper body off the ground. Instead of raising your shoulders directly towards the ceiling, as is done in a traditional crunch, cross them at a diagonal in front of your body, bringing your right elbow towards your left knee. Slowly lower your upper body back to the ground. Repeat the maneuver, but this time bring your left elbow to your right knee. Do ten repetitions of the exercise on each side before taking a short break. Do another two sets of ten repetitions of the cross over crunch in order to achieve optimal results.

The basic cross over crunch is a great exercise for beginners who are interested in strengthening their core. Once the exercise becomes too easy, it is important that you make changes in order to keep seeing results in your strength training routine. One easy way to increase the intensity of the cross over crunch is by performing it on a bosu. A bosu is a piece of strength training equipment that is composed of half of a stability ball fused to a flat surface. This provides an unstable surface on which exercises can be performed. Position your buttocks on the flat side of the bosu, and do the same maneuver as described above. Performing this exercise on a bosu forces your core muscles to work harder, thereby increasing the intensity of the exercise.