Crunch

• Crunches on a Swedish ball offer a few advantages over a regular crunch. They facilitate a full range of motion and flexion. They also help your balance and stability. To perform a crunch, sit on the ball, and have your knees bent and feet flat on the floor. Engage your abs by squeezing or drawing in your belly button to your spine. Contracting your abs during every exercise will allow you to deliver the most tension to your abdominals, thus lessening the amount of repetitions you need to do to feel the "burn."
  
  With your lower to mid-back firmly against the ball, inhale, contract your abs, and crunch up. Your hands may be held against the back of your head or at your side. However, do not lock your hands and pull your head up. As you begin your movement upwards, remember to keep your chin pointed to the ceiling to help you from cheating and coming short of a full contraction. Keep your knees in line with your waist to stabilize your hips, pelvis and lower back.
  
  

Alternating Crunch

• The same fundamentals apply to the alternating crunch. However, instead of crunching forward, rotate your shoulders to each side to engage your oblique muscles.
  
  

Reverse Crunch

• This is a great exercise for your lower abdominals. With your back firmly against a mat on the ground and hips flexed at a 90 degree angle, squeeze the ab ball between your legs. Put your arms at your side with you palms facing the floor. Lift your butt off the floor, and bring your knees in towards your chest, contracting your abs as you do.
  
  

Lumbar Roll

• Lay on your back with your arms straight out and palms facing upwards. Place the ball under your calves and knees. With your knees bent, rotate your legs to one side, all the while maintaining contact with the ball. Return to the starting position, and repeat for the other side.
  
  

Lateral Flexion

• Lay across the ball sideways, so it is under your hip. Place your arms behind your head, and raise your upper body towards the ceiling. Crunch to the side, while keeping your body parallel. Remember to contract your abs. Repeat for the other side.