Martial Techniques were basically manuals that record the method of absorbing spiritual energy. But, there were two kinds of methods. And, each martial technique record both.
Martial Arts- It held different kinds of styles that while performing strengthen the body while absorbing spiritual energy. It couldn't be used in a standstill position.
Cultivation Manuals- It held the passive lotus position style where a person would breathe in spiritual energy and use the martial technique to mold their spiritual energy with their blood and pass it into their dantian.
Whenever spiritual energy merged with blood, it slowly transformed into internal energy and thus it needed to be stored inside one's dantian.
Dantian- It would be a space above the naval point inside one's body which would be bigger from the inside and smaller from the outside. And, using the internal energy, one could slowly expand the dantian.