Last weekend I was working with a guy who trains MMA and he spars hard on a regular basis and has been in some competitive fights. I asked him, "I assume you can take a punch?" He said, "Yeah." I said, "How about a really good, solid right cross? Can you take it?" He said, "Usually, yeah, and it rarely slows me down."
I reached out and rapped him on the side of his lower jaw right about the gum line - like I might knock on a door - one quick rap with no real intention and his eyes rolled back a bit and he stumbled. He was ready to roll again in about half a second - but half a second is a long time in a fight. He was shocked.
As I explained to him, "It's not so much how hard you hit but where and how you hit."
Having made that semantic distinction, though, it sounds like you're on the right track with your list of principles. One that I would add is what I refer to as "proper relaxation."
You have to have some tension to maintain proper structure/form in your strike. Too much tension, though, and you start fighting yourself. It slows down your strike and robs it of some of the power - you are working hard so you feel like you're hitting hard (and you may, in fact, be hitting hard) but if you get rid of the unnecessary tension you can hit considerably harder.
Mike |