Okay, here's the big secret that all of us have yearned for; for many, many years. Ab training does not create six pack abs. No matter how much you train those muscles, it they are covered in a layer of fat they will not be visible to anyone not wearing a big red S on his chest! It won't make any difference how many sets you do, if you do them with your brother in law Louie sitting on your chest, or if you employ the latest machine or exercise routine fad. There is only one way to get that six pack you so desire and that is two-fold: reduce the body fat around your midsection and train those muscles sensibly. There you have it! The secret to building those abs you see on TV and at the gym or beach. Rest assured, they didn't get them by any other method than this. They didn't lounge them away, or "build" them. They lost the fat and trained the underlying muscle.
That said, this should take a lot of pressure off of us in our quest to get that ripped look. We don't have to buy the latest fad to come down the pike, nor do we have to do endless sets of mind-numbing crunches to get the body we want. In fact, you probably have all you need already. Crunches are good. So are a lot of other exercises. Kettlebells, combined with a sensible fat loss plan, can be used in a total body workout designed to achieve peak physical conditioning and fitness and may well be the best way to get further along this road.
As for specific kettlebell exercises that will help you in your quest for the elusive six-pack, swings, cleans and snatches, dead lifts, windmills, Turkish Get-ups come to mind first. Any and all of these deliver a massive workout to not only your midsection, but your whole body as well. Done as a part of a routine, they also will go a long way toward fulfilling the cardio aspect that will be necessary to get the fat burning mechanism stoked. Once you get this process started, and can sustain this type of workout for any meaningful amount of time, you will see the fat start to melt away from the abs area. The key here again is not just the exercises, whichever you choose; it is the combination of hard workouts, sensible eating and sustained effort. Only this will result in the type of belly you're seeking.
Don't be taken in by all the claims you may hear and see on TV. There is really only one way to achieve what you're seeking, and it's extremely low-tech. Do yourself a favor and stop seeking easy solutions, and save some time in the process.