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.
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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, or 0-15 centimetres). The timed chaining of multiple muscle groups contribute to the punching power while being imperceptible to the attacker. It is a common misconception that "one-inch punches" utilize a snapping of the wrist. 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 (148 kg) while the one-inch punch measured 153 pounds (69 kg). 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. 
The one-inch punch is also often used in martial arts as a training exercise to show how to generate further power at the end of a conventional punch.
In the television show Stan Lee's Superhumans, the Shaolin monk Shi Yan Ming demonstrated his one-inch punch on a crash test dummy. The testing showed it was 1.7 times more injurious than a 30 mph (48 km/h) car crash with modern safety features.
In the Quentin Tarantino directed Kill Bill: Volume 2, the protagonist (Uma Thurman) learns a variation of the technique as part of her training to exact revenge on her would-be killers. She learns to punch through thick planks of wood, from a distance equal to the length of her fingers. She eventually uses the technique to break out of a wooden coffin, after being buried alive.
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