iron body, IMA way

[Falcor]

I know that many forms of Shaolin derived "external" arts like BakSilum and Hung Ga train in iron palm and iron body and goldne bell and such. I am somewhat aware of their training methods, but I was wondering if IMA systems like Bagua/Taich/Hsing-I do anything like iron body and if so what is the training methodlogy? Do they use resisitive methods like gradual toughening by pounding etc, or use primarily Qi-gong/breathing methods? If teh latter, what is the theory behind how that is supposed to build up an iron body? Thanks.

[backbreaker]

I would say that the first and most important thing is the breathing. Most hard qigong styles I've learned or seen used reverse breathing. So if your breathing is not smooth, healthy , or strong, it's gonna hurt alot more when getting hit.