Eugene Thong: In short, yes. But let’s talk about a few things first before you run out and start bouncing away on one of those physical-therapy-device-turned-gym-toys.
First, understand that doing a lot of ab work in order to develop a shredded six pack is about as effective as using a Bic lighter to cook your salmon steak. To properly develop visible abdominal muscles, two things are necessary:
1) Body fat reduction over the abdominal area. This is primarily accomplished through the proper applications of dietary principles – see our Foundation of Fat Loss articles for specific recommendations.
2) Some exercise to develop abdominal strength.
Diet is so much more important in this process that it’s almost ridiculous to spend time doing ab work when you’ve got a nice, thick layer of protective adiposity blanketing your midsection (you’d be much better off spending that time doing exercises that rev up your metabolism, like multi-joint movements such as squats, or performing high intensity intervals).
In fact, it’s possible to develop a six pack without a single rep of direct ab work if you get your body fat low enough and you strength train (there is significant recruitment of the ab muscles on big, multi-joint movements like pulldowns, chinups, squats, deadlifts, etc., so they get a lot of indirect work when you perform these exercises).
As Mike pointed out in a previous Q and A, spot reduction of the fat overlying your ab muscles by selectively doing exercises for just that area is not possible. Nor is exercising your butt off without making concomitant changes in diet useful for developing killer abs. You’ve got to put the whole shebang together.
Now, let me get off my soapbox…
Swiss ball crunches more deeply stimulate the ab muscles because you work them through a greater range of motion and because the ab muscles encounter greater resistance (from your body weight) when you’re lying on a Swiss ball. Since greater resistance = more results (remember your Weight Training 101?), the greater stimulus from the Swiss ball crunches will give you more bang for your training buck than its floor-based counterparts (ab rollers included).
So grab yourself a ball and crunch away. But do yourself a favor – stay away from those starchy carbs and drink your water, ok?