Many of us have weak abdominals and lower backs—two muscle groups that are important when performing any type of daily activity. Crunches strengthen and tone these muscles.
Lie on your back on an exercise mat or carpeted surface with your feet planted firmly on the surface. Cross your arms over your chest.
Using the strength of your abdominal muscles, lift your upper torso off the floor toward your thighs. This movement should be very short. Don't attempt to actually touch your thighs, as this can overstress your lower back. Keep constant tension on your abdominal muscles throughout the exercise. With a controlled motion, return to the starting position, and repeat the exercise for the suggested number of repetitions.
There are two ways you can make this exercise more advanced. One is to use weights for extra firming action. Follow the instructions above, only hold a weight plate or light dumbbell in front of your chest for extra resistance as you perform the Crunch.
The other advanced exercise is to perform your Crunches on a stability ball. Using a ball forces your abdominals to work harder just to stabilize you atop the ball. Lie back on the stability ball so that it supports your lower back. Keep your knees bent and your feet flat on the floor. As you do in the regular Crunch, cross your arms over your chest and slowly raise your shoulders to no more than a 45-degree angle from the horizontal. Hold, then lower slowly. Continue for the suggested number of repetitions. You can make this version even more challenging by moving your feet closer together