With proper rooting according to tai chi standard, you should be as steady and firm as a mountain and your opponent should feel you are unmovable, literally. This rooting skill is sometime demonstrated by a tai chi expert withstanding push from a few people. It is amazing to watch but there is nothing mysterious about it. It is all about letting loose and proper alignment of body so that the oncoming force is channelled through the body into the ground. The strength of tai chi rooting depends on Song (looseness) and correct posture.
When we are able to let loose, our upper body weight will drop. The weight will be carried by the legs. When we can also loosen the leg muscles, this weight will drop even lower to the ground. This makes our rooting very strong. It is scientifically proven that our leg bones can withstand up to 2 tons of weight. If your upper body is so relaxed that all oncoming force can be transmitted down the skeletal structure to the leg and then to the ground, your rooting will naturally becomes very strong to the pusher. When you re bounce this oncoming force from the ground up through the body back to the opponent, he will definitely be pushed away a great distance.
In summary, rooting comes from 2 very important factors. One, you must be very song. Two, you must know what is correct posture.
