The use of inner alchemy in Taijiquan is an exciting transformation to see in a student. The basic theory through the practice of Taijiquan involves a student to learn to turn strength into qi, and qi into spirit. This idea is the transition of force into suppleness, then suppleness into empty intent. This process cannot exist only on a martial level though. It is a psychological and spiritual change which takes place over the years of practice and development. In this way, Wudang Taijiquan will begin with what seems like complex physical postures and motions. But over time, one begins to blur the lines between these positions so that it is only their energy or qi carrying them. After experiencing this, the final stage is that of allowing their spirit to guide their qi, which guides their body.
The health aspects are life changing. I myself attribute the healing of a long term back injury with Taijiquan practice in my youth. After a devestating car crash, I could no longer train my traditional shaolin wushu. Through Taijiquan, my spine was rehabilitated and my practice grew. When I left for Wudang in the summer of 2009, I had tore apart my elbow while training with a friend. My arm was in a sling and brace. But after a week at Wudang, my mind simply forgot I was injured, and with constant practice day and night the injury never showed itself again.
The first development of Taijiquan will be core strength. With the low stances and long standing postures training, a student develops a healthier core, and strengthens all their joints. This helps protect the body from injuries such as hyper extensions, twisted joints, or pulled muscles. With the addition of stretching and flexibility training, the student also increases their potential, agility, and sense of equilibrium. All of these factors build into one's everyday life.
The belief in vital force or qi can vary from school to school. I take an agnostic approach in which I do not preach or expect my students to believe in any aspect of qi other than what they want to take from it. One can interpret the successful use of qi to proper body alignment, applying angles appropriately through sensitivity of force, to many other factors that go into good Taijiquan form. But there is a truth to the it no matter your view. The idea of applying qi can mean any of these things, or simply the mystical energy which flows through all living creatures. No matter how you see this, it develops the same affects on the body which are proven and time tested.