Balls

• Medicine balls are typically made of hard rubber and vary in weight from very light to very heavy. They can be thrown, swung, lifted, pressed and passed back and forth to work the abs and the rest of the core.
  Chops are an effective standing exercise that can take the place of cross crunches. They are performed by holding the ball down to one side with both hands, then lifting it up and swinging it over the shoulder on the other side of the body, then "chopped" down to the other side. The ball should be held very tightly to prevent it from slipping out of your hands, and your abs should be fully tightened while you do this exercise.
  
  

Reversal Crunches

• Reverse side crunches are another alternative to cross crunches, and there are a couple ways they can be performed. Lie on the floor and draw your knees up towards your chest and then down to the side of the body. They can be alternated on each side, or a series of reps can be done consecutively on each side.
  You can also perform these from a hanging position on a beam, pull-up bar or from an actual reverse crunch machine often found in a gym. The exercise is performed the same way as a reverse crunch from a lying position, except your body is hanging in the air.
  
  

Swiss Ball

• Side crunches
  
  The Swiss ball is another functional training tool used to work the abs, and a good exercise to try is the side crunch. This is done by bracing your feet against a wall with one of your hips leaning on the ball. Lower your body and lift it back up using the oblique muscles to do the work. Make sure to work both sides of your body.
  
  

Seated Rotations

• Side rotations with a medicine ball and Swiss ball
  
  Seated rotations are performed with a Swiss ball and a medicine ball at the same time. While seated on the Swiss ball, hold the medicine ball in both hands with your arms extended straight out in front of you. With a straight back, rotate your hips and the medicine ball from side to side, keeping your head in line with the ball.
  
  

Cut It with a Jackknife

• A side jackknife
  
  The Swiss ball can also be used in a variation of the jackknife exercise, which is typically done by placing the toes on the top of the ball and drawing the knees in towards the chest. To do a side jackknife, pull your knees over to the side of your body drawing the ball in.