By
eHow Sports & Fitness Editor
Difficulty: Moderately Easy
Step1
Sit on the balance ball with your feet shoulder-width apart. If this is your first time using a balance ball, make sure that you feel centered on the ball before continuing the exercise.
Step2
Lean back slightly and slowly walk your feet out until you are resting on your mid- to upper-back. Make sure that your legs are bent at 90-degree angles. Your feet should be on the ground, approximately shoulder-width apart. The ball should be between your shoulders and hips and follow the curvature of your spine. When you're more comfortable on the balance ball, you can slide back further to engage your abs even more.
Step3
Cross your hands over your chest. Point your chin upwards and focus on a spot on the ceiling. Use your abs to slowly lift your upper body. Keep your chin going toward the direction of the spot on the ceiling. You should raise your upper body to a 45-degree angle. Don't come up too high because it reduces the tension in the muscle. Slowly lower your body back to the starting position.
Step4
Repeat the exercise 15-20 times for 3 sets. Your abdominal muscles are meant to work hard and this exercise shouldn't overstrain them. As you get better at doing crunches and your fitness level improves, you can increase the repetitions or increase the set number.