li xiao got it best i have had the misfortune of using xing i in a fight and i must say there is no way to not know that someone was hit with internal power.also fighting fat is obviously not very well versed in the internal systems to say the least since its true you should be rooted however it is a double edge sword the basic shan ti stance is 40-60 so you are rooted and moveable the essence of xing yi or three legged boxing minf form fist whatever when you move you move as wind over water you explode like dynamite and sink like a mountain