Mass

Mass: Mass is rarely discussed in terms of sheer size. Were this the case, Hapkido would simply be a matter that the larger the person the great would be their successful techniques. Instead, Mass is a matter of weight as it relates to stature. On other words in is not the size of the individual but manner in which the size is distributed along the axis of the body that is most important. In this way, Mass is most commonly spoken of in terms of manipulating the individual’s “center-of-gravity”. 

Closely related to such attributes as Speed and Balance, Mass is recognized as being directly influenced by its relationship to its height from the ground. A great mass, found low to the ground is very stable and so has great Balance. But it is usually quite immobile causing Speed to suffer. Great Mass carried high is capable of great Speed but can often be easily un-balanced.  The challenge, therefore is to find the optimal weight for the height of the individual and then to identify those techniques which are most effective for that center-of-gravity. The sporting practice of constantly bobbing and weaving can be of great tactical advantage in a sporting environment. In a non-sporting confrontation, however, the goal is to move smoothly without constantly challenging one's own center-of-gravity.The challenge to keep that center as stable as possible, and so enhance the other attributes such as Speed and Balance. 

It follows that if one can disrupt the center-of-gravity of one's partner ---cause it to rise, fall or load in one way or another--- inhibit smooth motion or under/over react, it will impact the manner in which that person manages their mass and by extension their speed, focus and so forth. In many ways the movements leading to the execution of a technique then---"the set-up"--- can be just as important as the technique itself.