Holy Fuck, people who think Bruce Lee invented the one inch punch make me want to cut my head off with a baseball bat. How stupid can you be?! You probably think Bruce Lee invented the internet too. Next you'll be writing him into biblical creation myths . . . *sigh*
Like almost all of Bruce's skills and understandings, the one inch punch was learned from Yip Man, the late great grandmaster of Wing Tsun\Wing Chun. The one inch punch is a standard part of the Wing Tsun curriculum, in the sense that correct posture and training eventually cause this "technique" to manifest in the stylist on its own.
In truth, it's not even really fair to say that this was invented by Wing Tsun/Chun stylists. The technique can actually be traced back to the hsing i "cannon fist." So to say that it was invented by Bruce Lee is especially infuriating, considering we should all but throw away the cult of originality when discussing a thousand-year-old technique developed by a five-thousand year old martial culture.
The "secret" to the punch is simply timing, relaxation, spinal alignment, and correct synchronization of the separate moving elements of the body. Thus, unity of purpose is achieved, and maximal power is displayed. The one inch punch has more to do with the feet than the hands.
Either that, or the secret is sexual frustration.
:P jk