The abdominal crunch up is a great exercise that not only helps to strengthen and tone the abdominal and oblique muscles, but also helps to stabilize this area, thereby preventing lower back pain or strain. As with all strength training exercises, the abdominal crunch up helps to increase muscle mass, thereby speeding up your metabolic rate and increasing the rate at which the calories you eat are burned. This is especially helpful if you're interested in weight loss.

Before you perform the abdominal crunch up, position your body properly. Start by placing a yoga or exercise mat down flat on the floor. Lay down on the mat on your back, with your knees bent and your feet flat on the floor. Bring both hands behind your head, and lace your fingers together at the junction where your head and neck meet. Look up at the ceiling. At this point, your body should be in a straight line from the tip of your head down to your tailbone.

Now that you're in the proper position, you can go about performing the abdominal crunch ups. Start by taking a few deep breaths. As you exhale your next breath, use the muscles in your abdomen to lift your head and shoulders off the mat. Try to keep your spine in a straight line, and imagine that you're simply lifting your chest toward the sky. As you exhale, slowly lower your head and shoulders back down to the floor. Repeat this procedure 10 times before taking a short break. Do another two sets of 10 repetitions of the abdominal crunch ups.

Once you have mastered the basic crunch up, make some slight changes in order to increase the intensity. One great way to do this is by decreasing the rate at which the exercise is performed. As you lift your head and shoulders off the ground for the abdominal crunch up, try counting "one, two, three." Similarly, count only to "one" as you lower back down to the ground. This forces you to work harder for a longer period of time, with a relatively short break in between repetitions to relax. You'll be surprised at how this small change can really increase the intensity of the workout.