Double crunch: Lie on the floor face up and bend your knees until your legs are at a 45-degree angle with both feet on the floor. Cross both hands over your chest. Raise your head and legs off the floor toward one another, contracting your abdominal muscles. Slowly return to the starting position, stopping just before your shoulders and feet reach the floor. While rising up exhale, while returning to the starting position inhale. Your hands should not be used to lift your head. Keep your eyes focused on the ceiling to help avoid pulling with your neck.

Crunches aren't the only forms of exercises to try when building your stomach muscles. You may also want to try:

Reverse curl: Lie on your back and bend your knees toward your chest only as far as it is comfortable, keep your hips firmly on the floor. Lift your hips off the floor and bring your knees toward your chest. Place your hands on the floor or place your elbows on floor and your hands in the air, which is more challenging. Focus on using your stomach muscles to lift your pelvis toward your lower rib cage.

Bicycle maneuver: Lie on a mat with your back in a comfortable position. Place the tips of your fingers on either side of your head near your ears. Bring your knees up to about a 45-degree angle. Slowly start to perform a bicycle pedaling motion, alternating your left elbow to your right knee, then your right elbow to your left knee. Try not to pull on your head or your neck while doing this exercise. The lower to the ground your legs are while performing the bicycle motion, the harder your stomach muscles have to work.

If you want to try to build your stomach muscles using exercise equipment one of the most effective and low cost would be the exercise ball, also known as the stability ball and the fitball. It has been used by many physical therapists for decades. There are several other devices claiming to be the best for building stomach muscles such as the abdominal crunch machine, the ab-slider, the ab-wheel and the list goes on but before purchasing one of these devices do some research, maybe even going to the local gym and using one of these machines, if available before making that purchase.

Keep in mind if you have excess body fat you will never see the muscle you have worked so hard for. Total body fitness is the key to strengthening all muscles. Remember to include an aerobic activity in your workout. Also practice healthy eating habits by eating nutritious meals and no "crash" dieting.

Proceed with caution if you have back pain, muscles in your abdominal section work in collaboration with your back muscles. When working your stomach muscles you are in turn working your back muscles. Consult your physician if you are experiencing back pain before continuing.

Many of the exercises mentioned are great for building your stomach muscles but only if they are done properly. To ensure these exercises are done properly you may want to find pictures or video of the exercises being performed.