The one-inch punch is a punching exercise from Chinese martial arts (kung fu) performed at a range of 0–15 cm (0–6 in). The one-inch punch was popularised by actor and martial artist Bruce Lee. It is designed to improve punching power and technique.
The One-inch punch is present in many styles of Southern Chinese martial arts. As a general rule, Southern Chinese martial arts rely mostly on hand techniques from very close quarters (as opposed to Northern Chinese martial arts which focus more on kicking techniques from medium to long distances). Because the Southern styles martial artists were often fighting nose-to-nose with their opponents, they had to learn a way to deal out punishing blows even while almost touching their target.
The one-inch punch is a skill which uses fa jin (translated as explosive power) to generate tremendous amounts of impact force at extremely close distances. This "burst" effect had been common in Neijia forms. When performing this one-inch punch the practitioner stands with his fist very close to the target (the distance depends on the skill of the practitioner, usually from 0–6 inches). A quick movement of the wrist produces the force needed, the wrist is held with the knuckles facing out on a vertical axis, the wrist is then moved up and a strike is produced with the bottom two knuckles. The target in such demonstrations vary, sometimes it is a fellow practitioner holding a phone book on the chest, sometimes wooden boards can be broken.
The one-inch punch was made popular in the west when demonstrated by Bruce Lee at the Long Beach International Karate Championships in 1964. Bruce Lee learned the technique from his Wing Chun training in Hong Kong. He used the art of Wing Chun as his basis of the art he founded, Jeet Kune Do.
In the television show MythBusters episode "The One Inch Punch", the technique was tested quantitatively using a force gauge. For comparison, it was matched against a conventional punch thrown with a full wind-up by Jamie Hyneman. The one-inch punch was delivered by Anthony Kelly, a Martial Arts Expert and Master Instructor who had learned the technique from one of Bruce Lee's students. The conventional punch measured 325 pounds of force while the one-inch punch measured 153 pounds. In the absence of a safe method of testing against a human being, the hosts deemed it "plausible" as a combat technique, if the user had proper training and experience.