From the Traditional Chinese Medicine point of view tai chi and Qi Gong are used to promote personal energy for self healing and wellbeing.
The tai chi model is based on the premise that there is a bio energy system in the body. The bio energy or Qi gets carried round the body in energy channels called meridians - a bit like the way the veins carry blood around the body.
There are 12 main meridians and 8 secondary meridians carrying Qi throughout the body and through the major organs. Interrupted, weak or blocked flow of Qi causes illness.
tai chi and Qi Gong work because the muscle movements in the exercises are designed to stimulate the flow of Qi through the body and the major organs. When Qi flows smoothly people are well.
Other tai chi and Qi Gong exercises involve the cultivation or growth and storage of Qi leading to longer life, better health and faster recovery from accidents.
From the Qi perspective all health conditions - even the most serious can be treated and improved with Qi Gong.
The tai chi forms provide the same kind of stimulation for the meridian systems.
A western perspective might focus on the purely mechanical effects of tai chi practice.
The emphasis on correct body posture and spinal alignment while practicing tai chi releases tension and pressure caused by slumping - improved posture improves the digestive system and removes stress from the back.
Moving weight from leg to leg is common to many tai chi exercises, as is extending and lifting the arms, legs and hands. All these different tai chi moves have one thing in common, they vary the load on joint surfaces increasing the flow of natural lubricant and nutrients into the joint, meaning that they move more easily and freely.
The flowing movements of a typical tai chi routine disguise the incredibly high number of joint rotations that are being used. The neck will move from side to side, palms will turn over, elbows and shoulders will rotate all increasing flexibility and range of motion of the joints.
At the same time the muscles, ligaments and tendons that protect and support the joints are being strengthened which keeps them mobile and healthy. All this while you are simply enjoying doing your tai chi exercises.
As a preventative measure regular practice of tai chi will mean that you will be less likely to become stiff and in pain due to the onset of things like lumbago, arthritis and sciatica.
And then there's the psychological benefits gained by the unique mind body link in tai chi exercises. As you direct your mind to focus on the moves you will find that you have screened out all the distractions. What an incredible benefit from tai chi - peace of mind.
(source:
http://www.everyday-taichi.com/index.html)