Although Chi-Gung elements can be found in other systems Chi-Gung is an art in and of itself. Chi-Gung trains one to control and move the Chi in their body, or for the Chi skeptics, it trains you to control the inner workings of your living body... Any better Chi haters?
There is external and internal forms of Chi-Gung and it's used for many different things, for health, for healing, for Iron Shirt, and for hurting..
I take it seriously despite the fact that we used to break chops on a couple of guys that joined my school in the old days from a pure Chi-Gung school. Any time they would point their finger we would all duck...
But as I was taught by those Chinese along the way, they take this stuff very seriously and I have heard over and over that you must be trained by a real Chi-Gung Sifu, not so you will be able to do no touch KOs but so the Chi in your body doesn't get whacked out from training incorrectly in this practice. In Chi-Gung a little knowledge is considered dangerous but the right knowledge can be a life saver.
There was a very good story and I think a book that was published by a man who was dying of perhaps Cancer, he was in very bad shape and very close to death. To make a long story short, with great difficulty he sought out a Chi-Gung Master in China and convinced him to accept him as a student. After only a short time his condition improved greatly and the man lived.
If I were to embark on such as study I would seek out a true master of the art, something I suggest for any art. But for such an elusive art one must do a ton of research and a lot of looking in Chinese communities and better yet in China.. If you find a real one as with other arts, you'll be wowed, rather than uncertain, or perhaps in this case alive rather than dead.