Systema might not be one of the most popularly trained martial arts (at least, not within the United States), but this Russian style certainly packs a wallop! Its name simply means "The System," and that level of confidence from its creators tells you all you need to know about its efficacy. Like krav maga, Systema was developed for military use, and focuses on self-defense and real-life combat situations against armed or unarmed opponents.