An axe kick as about as far from a natural body movement as you can get without destroying connective tissue.
And you are way too hung up on the idea of early Hominids "fighting." When would a human even WANT to fight, from an evolutionary/survival standpoint? Tribesmen might "fight" each other, but it's designed to be all about intimidation without much damage to either party, because otherwise a tribes strongest males would be constantly too injured to hunt or flee from predators.
Fighting a predator that's already got you? Running has already failed, you're on the ground, you have limited mobility and anywhere you go in the short term is going to lead you into a nasty set of teeth. Your only real prayers are that you can push it off just long enough to make another dash for it, or that you were popular enough for your tribe to come roaring back to save you. Watch some wildlife documentaries, particularly with apes, chimps and any of the big predators on the Serengeti, you'll see the dynamics at work. Predators do not "fight" their quarry. They ambush it, they run it down, they take it to the ground, they rip it apart.
"Fighting," as you seem to think of it, did not evolve as a natural behavior. Apes could not create any martial art or combat system because apes have no need for such a thing. The habit of various peoples to devise ways of killing each other with their bare hands developed to serve a different set of needs entirely.
Edit for sidenote:
World s oldest stone tools discovered in Kenya Science AAAS News
Crafted stone tools, and possibly weapons, may be older than we think. Maybe even predating the entire Homo genus. Additional support for this idea is that modern chimps have been observed stripping down straight branches, chewing the end to a point, and using their primitive spear to hunt bush babies.