Technique Summary

Lie on your back with feet flat on the floor and a 45 degree bend in your knees.  Place the tips of your fingers on the back of your head.  Bring your shoulders up several inches off the ground until full contraction by rounding your back.  Exhale at the top, inhale at the bottom.

Doing a basic crunch only involves lifting your upper body.  The basic crunch could be performed with hands in different positions.  Where you place your hands will depend on your level fitness.  If you are just starting out, your hands should be extended at your sides.  Every basic crunch will look as though you are reaching with your fingers for your toes.  If your abs are stronger you could cross your hands over your chest, placing your palms on your shoulders.  A more difficult alternative is with hands behind your head.  Please note to never lock your fingers behind your head.  This gives you greater leverage to pull your head up, putting more pressure on the spine, and taking away the emphasis from your stomach (this explains why your neck hurts and not your stomach when you were doing these incorrectly).  Placing only the tips of your fingers on the back of your head will suffice.  The most difficult alternative is extending your hands behind your head, with fingers pointing away from your body (be sure to maintain your hands in this position throughout the crunch).

If you are performing the crunch with your hands behind your neck, be sure to keep your elbows pointing out to the sides at all times.  Pointing elbows forward generally leads to shifting the movement from your abs to your arms, your head, and your neck.  With your elbows out, you will be forced to lift your shoulders off of the floor.

In doing the basic crunch you want to pay special attention to the space between your chin and your chest.  As tempting as it may be to bring the two together, it is incorrect.  If you are starting out the best way to maintain good form is by keeping your hands crossed on your chest and keep a fist of one hand under your chin (with the chest, fist, and chin always touching).  Otherwise, you could just pretend that you have a tennis ball under your chin and hold it steady.

The most important thing to note about basic crunches is that you should roll your back.  The motion puts a lot of pressure on your lower back.  Never keep your back arched and always roll your body up and forward.  If you are rounding your back correctly, your lower back will touch the floor, otherwise there will be a gap.

This crunch mainly works your abdominal core.  To a smaller extent, it also develops your obliques and hip flexors.