Most Taiji styles incorporate a set of stationary Qigong, which usually involve standing and maintaining different postures for varying periods of time. Like sitting meditative Qigong, it allows you to concentrate better on the mind and the Qi without being distracted by moving and coordinating the whole body. On the other hand, Qi is dynamic (it circulates throughout the body) when practicing Qigong, being in a stationery position could create an imbalance between the inside and outside body. It is accepted by many that if practiced incorrectly, Qigong practitioners could be so wrong-tracked that they become mentally disturbed in a very profound manner (the literal translation of this term is: losing fire into the devil reign). People are known to become crazy when their minds thus wrong-tracked. It is considered to be the most dangerous risk of practicing Qigong. This imbalance is believed to be more likely to cause wrong tracking, whereas practicing moving Taiji Qigong has no such risk.
What is Quan?
Quan is "fist" in Chinese, thus any name followed by Quan is a martial art style. Here I am going to use the word Quan to mean martial art. The ultimate purpose of Quan is to subdue or control your opponent. There are two types of Quan; the internal and external. Within either type there are many different styles. It is much harder to learn the internal Quan for effective self-defence. The external Quan uses techniques that are more natural to the body, stronger muscles, blocking and punching, where the quicker and stronger tend to win. Whereas in internal arts, one has to cultivate Qi (which may takes years to reach a good level), integrate it to the body so it can be directed by the mind (yi) and able to drive internal power (jin) before it can be effectively used for self-defense. In a way it is like most things that takes more time and patience to cultivate initially...it usually ends up more powerful and lasts longer.
Improve Qi to Better Quan
Strong Qi, not only makes one healthier, it improves the level of Quan. I am going to confine this to Taiji, and to two important concepts because it is impossible to cover such a vast subject here. These are the understanding of Opening and Closing, and the circulation of Qi.
1. Opening and Closing
Alternating opening and closing continuously is evident in any Taiji forms. Like drawing a bow to shoot an arrow, the drawing is storing energy that is opening. The shooting is releasing energy that is closing. This can be confusing because the opening and closing relate to the use of Jin, not necessarily relate the outward appearance. For example in the Yang style Single Whip movement, the end movement is a closing movement, not opening, although its outward appearance is that of opening up.