What is the philosophy behind dragon ball z?

I am interested in knowing where the idea of spirit energy being able to be harvested and gained and used to fight.what are the systems that beleive you can do this and what are theyre practices? can anyone with info please give me good refrences so i can study the idea of chi and harnessing chi. I am currently studying Hindu Transcendentalism so sources and refrences to the vedas are also helpful.