This may be off topic..
But isn't punching trivial? Sure, you may be able to level and take down everybody in your class... But you can't predict that the people who fight you on the street will give you time to get yourself togeater to give a good one, or give an opening, or even any kind of sign that they're attacking at all.
Besides.. Who can promise that any punch can do signifigant harm to a man on a street enviorment. I'm sure we've all seen videos of guys on crystal meth and PCP getting shot with 9mm's from multiple LEO personel.. And still charge at them.
Look for who knows the art they practice, and can teach it properly. If they can hit hard, thats a plus. But "who hits hardest" is really irrelevant.
Jimmy: I have mixed opinions on this... I both agree and disagree. You should be in your top physical shape anyway. I know personally I'm looking to be as fit as I can be, but that is a preference.
I believe you can be strong and conditioned without looking like a olympic sprinter or weight lifter.
I also believe that if your martial art dosn't require you to do 150 push ups, 1k crunches and 200 squats.. Then you don't need to.
Systema (in my experience) works off your innate movement patterns and on your reactions.. You don't need to be an athlete to respond naturally to a threat.  | 
Linear Mode
