Lexicon: Tai Chi Chuan, Qi, Yi, Push Hands, Dantian, Fa-Jin, Song
[ The main concept in these notes is derived from an excellent article by Karel Koskuba on Pole Standing [1] ]
Posture, Movement and Balance
We generally think of posture and movement as being separate - we are either still or we move. Movement and posture place different demands on our muscles and so it is not surprising that our muscles reflect this. The muscles used mainly for posture have a high content of slow-twitch fibres whereas the muscles used mainly for movement have a high content of fast twitch fibres. Often, a single muscle con be used for both posture and movement. However, a muscle that is used in a postural (stabilising or tonic) function will act differently from the same muscle when it is used for movement (mobilising or phasic function). So for ease of explanation, we can consider that each muscle is really two muscles - a postural one and a phasic one (sometimes referred to as stabilisers and mobilisers).
What is important about postural muscles from the perspective of Tai Chi is the fact that they react against the force of gravity and that they act outside of our volition. We cannot normally control postural muscles directly, but only indirectly - through intent. For example when we ride a bicycle, we keep our balance by the use of postural muscles. Our intent is not to fall down but we do not consciously control their operation in the way we can control voluntary movement. Conscious control would be too slow - before we could react, we would fall down. This is in fact what happens when we start learning to ride a bicycle - we start by using phasic muscles and through trial and error the postural muscles take over and we 'find our balance'.
Our postural muscles are not only used in holding a posture or in balancing, but during movement, too. If we think of movement as a transition between postures, we can see that postural muscles are active all the time. But what is the relevance of postural muscles to Taijiquan?
Effortless and Natural Balance
If someone pushes against you and you do not want to be pushed off balance, the chances are that you will resist using strength. If this happens, you are using phasic muscles. But it will be different if someone pushes down on your shoulders. In this situation you do not push back up - you just absorb the push effortlessly into your posture. So in the first example if, instead of phasic muscles, you were to use postural muscles to absorb the push into your posture, you would use far less effort. You could then also use the 'balancing' ability of postural muscles to effortlessly counteract any sudden change of direction. Using postural muscles in this way would make Push Hands a far more enjoyable experience!
Where the Mind Goes, the Qi Follows
There are parallels between Qi and the use of postural muscles. When you use intent (Yi) to guide your postural muscles to lift my arms, you do not feel any effort - it is as if your arms are being lifted by invisible threads. When you use postural muscles to absorb or neutralise a push, you don't feel any effort and your body reacts automatically to produce a balanced outcome. And when you start using postural muscles, you develop a feedback through subtle sensations such as heat, ache, flow and others. All these are properties of Qi.
Both Qi and movement originate in the Dantian
Before the start of any movement, there is a short delay during which the body prepares by stabilising the lumbar spine using deep abdominal postural muscles. Normally you will not feel this 'preparation', but it is there and as your awareness increases you will be able to feel it. As discussed above, usage of postural muscles equates to usage of Qi. Thus any movement is preceded by activation of your Qi in your Dantian (think of it loosely as the lower abdomen).
The body will not move till it is properly stabilised. This is important for fast moves, especially explosive fa-jin. The delay produced by stabilisation of the lumbar spine makes you slower. This does not matter very much for slow movements. But when you want to move fast, you do want to move fast! There is a way to eliminate or at least minimise this delay by holding your body in a posture where your postural muscles are already engaged.
Song
The posture just described is what is called Song (loose, relaxed) in Taiji Classics. In this posture, everything is supported by postural muscles. The body feels light (you can't feel postural muscles) and poised for action, perfectly balanced. You could even say that (quoting Taiji Classics) ‘`a feather cannot be added to the body nor a fly alight without setting you in motion".
Whole Body Movement
If you stand on one leg and observe for a time what you do to keep upright, you may notice that the adjustment to your posture can happen anywhere from your ankles all the way to your head. That’s because postural muscles co-ordinate across the whole body. When you use postural muscles, rather than phasic muscles, you will naturally produce whole body movement.
Postural Dysfunctions
Due to our fairly recent transition (in evolutionary timescale) into upright posture, the postural function related to this upright posture is not yet securely embedded into our neuro-muscular system and can be easily disrupted. It seems the 'new' postural muscles need the input that they get from functioning as postural muscles (i.e. balancing against gravity) to remind them that they are postural muscles. For example if they are held in a fixed position for a long time, they may start to forget their proper role. Our lifestyle unfortunately encourages this (school, office, computers,…).
There are still other ways for things to go wrong. Sometimes phasic muscles can take over the postural role because we did not 'let go' of them at the end of a move and so they may start holding part of our posture. As the posture muscles weaken through inactivity, the phasic muscles' postural role will be strengthened. Or we may strengthen a phasic muscle too much during training and it may start taking over the postural function within its domain.
Implications of Postural Dysfunctions
All this has implications for our strength. When pushing something whilst standing on a slippery surface, we cannot generate much strength. In order to use force effectively, we need a stable base. This applies within our body, too. If our postural muscles are weak or not working properly, our phasic muscles will not develop their maximum strength. This means that often we can use only a fraction of our potential strength.
It affects our speed, too. If we use phasic muscles to act as postural muscles, they will not be very effective when we try to use them for movement. As a result of all this, the majority of us do not use our core postural muscles properly. More than 95% of all musculo-skeletal problems can be attributed to the imbalance between postural and phasic muscles.
