Tai-chi chuan (taijiquan) is a Chinese martial art that uses the 'six harmonies' motion system of internal martial arts. It is so named for the expression of yin and yang within those movements. Characterised by the slow movements of the foundation forms, tai-chi is unique among martial arts in that it is more frequently practiced for its health benefits than for the attainment of fighting skills.
Internal martial arts utilise a system of relaxed movement in which all the parts of the body move as one unit while presenting a perfect alignment to any applied forces at all times ("peng-jin"). The combination of structure and relaxation creates a 'ground path' that enables energy to pass though the body without encountering resistance and allows the body to function more efficiently.
In tai-chi this movement can be expressed in two ways; as circular movement or as a snake like movement ('opening' and 'closing' the body). The two can also be combined. Pivotal to this type of movement is a part of the body the Chinese call the "tan-tien" which is situated below the navel about a third of the way in from the front to back. This is regarded as being the physical centre of the body. It plays a multiple role connecting the internal to the external by being a focal point for the mind, the controller of the breath, the centre of rotation of circular movement, an internal end point of the connective tissues that control 'opening' and 'closing', as well as controlling the alignment and manipulation of the ground path.
In tai-chi this type of movement is referred to as 'reeling silk' because of its similarity to the motion of the silk worm and it is widely known as 'six harmonies movement' amongst the internal martial arts. The three internal harmonies of spirit harmonising with intention, intention harmonising with "chi" and "chi" harmonising with strength describe the mind led skill of using the intention to bring power up and/or outwards from the ground or down and/or inwards through gravity to a part of the body. The three external harmonies of hand-foot, elbow-knee and shoulder-hip describe how the body is tied together as a single unit that is controlled by the "tan-tien", such that the corresponding parts are interconnected by tendons, ligaments and fasciae.
Tai-chi is popularly characterised by its slow movements which appear to the observer as graceful, well ordered and totally unique. These 'silk reeling' techniques enable practitioners to focus their attention on the detail of the mechanics of the motion. However, in traditional tai-chi systems only the foundation forms are predominantly comprised of slow movements.
There are strict parameters that define tai-chi movement but these are difficult to fully comprehend and harder still to achieve. Circular movement is accomplished by rotating the "tan-tien" on any axis to affect three dimensional movement. In geometry this would be described as the X, Y and Z axis while in aviation it is called role, pitch and yaw. Moving in this way requires a considerable amount of practice. A helpful initial exercise is to use the hands to rotate the abdominal area (training from the outside in). Gradually a feeling of moving from the inside is developed and eventually this feeling can be clearly expressed in movement. This movement then has to be transferred through the body using the connective tissue. The connective tissue also has to control the expansion and contraction of the movements. Add to this the fact that the movement is powered by the lower body with the upper body being a relaxed conduit and the complexity of achieving the baseline skill begins to become apparent.
Yet it has become common practice in many modern teaching systems to teach a sequence of movements without first teaching how to move correctly. As a result the students practice becomes little more than 'normal' movement in slow motion and once this becomes ingrained into the movements through repetition it is very difficult to correct. While there are still benefits derived from slow relaxed exercise it significantly limits understanding, development and progress. Irrespective of style, it is not the sequence of movements or the external appearance that defines the quality of practice but rather how those movements are achieved. Some of the most respected masters of the art regarded rectifying this as the biggest challenge currently facing tai-chi.
There are many facets to tai-chi but its real strength is its completeness which brings about benefits to mind, body and spirit. One thing it is not however is easy to master. Nor is it learnt quickly or without hard work but it is extremely rewarding for those who persevere.