BRUCE LEE'S ONE INCH PUNCH
Martial arts legend Bruce Lee is famously quoted as saying "Fear not the man who's practiced a thousand punches. Fear the man who's practiced one punch thousand times". But Lee's amazing feats of martial arts prowess were due mostly to his amazing physical condition, so in addition to the proper technique, you'll need to condition yourself physically to perform this impressive display of striking power.
First, start doing special pushups, instead of putting your arms straight out, and setting your hands to bring your arms to 90 degree angles, keep your upper arms directly at your side, and set your hands in close formation directly under the center of your chest. In the down position, your elbows should be on either side of the lower part of your ribcage. In the up position, your arms should be straight. Don't worry about reps. Do as many as you can do perfectly, then stop. 150 bad pushups is not as good a 24 good ones. Do this three times a day, till you can do 100 flawless pushups
WING CHUN CHAIN PUNCH
Do this after every set of pushups. Take the stance in the picture on the left, feet shoulder width apart, your dominant hand in a loose fist just under your non-dominant elbow. Switch positions of dominant and non-dominant hands back and forth in a circular motion as quickly as you can, try not to let your hands or arms rub together, keep your fists directly in front of the centerline of your chest, and try and keep your shoulders perfectly still and relaxed. Do this 200 times between sets of pushups. There are plenty of videos on youtube teaching proper technique.
HEAVY BAG EXERCISE
Once you can do at least 1 set of 100 flawless pushups a day, separated by 200 reps of the wing-chun chain punch, start doing the chain punch into heavy bag instead. Punch the bag at chest level. And don't punch is as though you are punching the surface, punch it as though you're punching 4 inches beneath the surface. You may want to wrap your hands for this. Remember, technique is more important than speed, so if you see your form start to slip, slow it down and practice more before speeding back up.
Ok, now that you have conditioned yourself for speed and strength, it's time to start practicing the actual technique. The Bruce Lee One Inch Punch starts by standing with your feet shoulder width apart, the distance between yourself and the subject should be the length of your outstretched fist minus 4 inches. With your elbow slightly bent, place your fist 1 inch from the dead center of your opponent's sternum. With your arm outstretched your fist would be 4 inches into his chest. Take a deep breath, and snap your arm into an outstretched position as quickly and forcefully as you possibly can. At the same time as you are straightening your arm, solidify your core so your shoulder doesn't absorb all the impact, and you don't send yourself reeling backwards instead of your opponent. Practice on a heavy bag until you can straighten your arm out all the way with little problems.