Movement, Posture, and Gravity 關於動作、姿勢與地心引力

The motion of a joint is generated and coordinated by the contraction and relaxation of several muscles, which is controlled by brain through nerves. A series of conduction seems very simple but is very complicated in fact. When a hair is pulled, whole body reacts. So, analyzing body movement or correcting posture is not an easy job. However, if an appropriate evaluation method and treatment are utilized, we will be one step closer to our goal.

一個關節的活動需協調許多肌肉的收縮及放鬆，而肌肉的收縮及放鬆則需要腦透過神經來給予指令，這一連串的傳遞看似簡單，實際上卻非常複雜。人體的動作常是牽一髮動全身，故要分析人體動作或矯正姿勢並不容易，但若能使用恰當的分析及治療方式，就可以讓我們離目標更進一步。

Although each person’s posture is unique, there are still some similarities. Therefore, categorizing posture is an important step for designing effective treatment. During the past several years, the research has shown that there are three systems control the movement – breathing, eye, and head systems. Breathing system controls mostly subconscious motions and is controlled mostly by autonomic nervous system. Eye and Head systems control mostly conscious motions and is controlled mostly by somatic nervous system. So, each person will receive individualized diagnosis of posture and treatment because each person’s body status is different. On the other hand, in order to change the pattern of whole body motion, it is necessary to incorporate three systems and consider the interaction between them.

雖然每一個人的姿態都不盡相同，但卻有類似的地方，所以將姿勢型態分類對於治療設計極為重要。在過去幾年的研究中發現，姿勢乃是受三個系統控制，即呼吸系統、眼睛系統及頭部系統，前者多支配下意識的動作，主要受自律神經控制，而後二者則多支配意識下的動作，主要受體神經系統控制，而每個人的身體狀態都不同，因此，每一個人會有其個人化的姿勢診斷及治療，另外，若要達到改變全身動作模式的目標，治療計劃就必須同時針對這三個系統設計並考慮彼此間的交互作用。

And now we have to discuss about the effect of gravity on posture. As long as people are alive, gravity is there to pull the body toward the ground and gradually wear down the joints. That’s why anti-gravity is a substantial concept in the treatment. And according to the Newton’s Law, ground reaction force (GRF), an outside-in sensory input, will be generated when we step on the ground or lay our elbow on the table during writing or using computer and the force will transmit through leg-pelvis-spine or arm-shoulder-spine to head. For the joint, GRF is counted as a pressure. If the force could not be absorbed or sheared, it can be harmful to the joint, bone or muscle. So, how to train the body to absorb or shear GRF efficiently is also the key point.

再來要談到地心引力的作用，當人體活動時總是受到引力的影響，身體被拉向地面，關節逐漸被磨損，因此，抗衡引力的訓練及治療便顯得至為重要。另外，根據牛頓第三運動定律“作用力與反作用力”的理論，當腳被地心引力拉向地面時，地面會有個反作用力給腳，然後一路經過腿、骨盆、脊椎，最後上傳到頭；而在寫字或使用電腦時，桌子會給支撐的手臂一個反作用力向上，這樣的反作用力除了給身體一個由外而內感覺訊號外，同時又會給關節一個壓力，若是這壓力無法被身體吸收或分散掉，便可能造成承受壓力過大的地方損傷，所以，如何訓練身體有效率地吸收和分散掉壓力便是很重要的課題。