Call them what you want -- Stability Balls, Swiss Balls, Exercise Balls, Physio Ball, etc. -- these orbs are a great compliment to an exercise routine, especially when it comes to ab work.

There are dozens of abdominal/core exercises you can perform using a Swiss Ball (I'll stick to this name, since it's what I regularly refer to it as). Among the more popular moves is the crunch, which is a good thing since this exercise, when done on the ball, works both the rectus abdominis (front abs) and the obliques (side ab muscles). However, to really take advantage of this movement, it's best to do two things: 1) Keep your feet somewhat close together, and 2) Place the ball under the lower portion of your back.

The first suggestion, keeping your feet close together (but not touching. Shoulder width is fine), will force you to really push your core muscles, otherwise you'll tip over. As for the second suggestion, Japanese researchers found that placing the ball under your lower back (as opposed to being under the upper portion of your back) causes greater stimulation to your abdominal muscles.

Just a few tips I thought I'd pass along. If you have any of your own that you feel are worth sharing, please be my guest in the comments section.