Bruce LeeLee's first introduction to martial arts was through his father, from whom he learned the fundamentals of Wu-style t'ai chi ch'uan. In his teens, Lee became involved in Hong Kong gang conflicts, which led to frequent street fights. The largest influence on Lee's martial arts development was his study of Wing Chun. Lee was 16 years old under the Wing Chun teacher Yip Man, between late 1956 and 1957, after losing to rival gang members. Yip's regular classes generally consisted of the forms practice, ''chi sao'' (sticking hands) drills, wooden dummy techniques, and free sparring. There was no set pattern to the classes.
Lee was also trained in boxing, between 1956 and 1958, by Brother Edward, coach of the St. Francis Xavier's College boxing team. Lee went on to win the Hong Kong schools boxing tournament in 1958, while scoring knockdowns against the previous champion Gary Elms in the final. After moving to the United States, Lee was heavily influenced by heavyweight boxing champion Muhammad Ali, whose footwork he studied and incorporated into his own style in the 1960s.
Another major influence on Lee was Hong Kong's street fighting culture in the form of rooftop fights. In the mid-20th century, soaring crime in Hong Kong, combined with limited Hong Kong Police manpower, led to many young Hongkongers learning martial arts for self-defence. Around the 1960s, there were about 400 martial arts schools in Hong Kong, teaching their own distinctive styles of martial arts. In Hong Kong's street fighting culture, there emerged a rooftop fight scene in the 1950s and 1960s, where gangs from rival martial arts schools challenged each other to bare-knuckle fights on Hong Kong's rooftops, in order to avoid crackdowns by colonial British Hong Kong authorities. Lee frequently participated in these Hong Kong rooftop fights, and combined different techniques from different martial arts schools into his own hybrid martial arts style.
At and weighing at the time, Lee was renowned for his physical fitness and vigor, achieved by using a dedicated fitness regimen to become as strong as possible. After his match with Wong Jack-man in 1965, Lee changed his approach toward martial arts training. Lee felt that many martial artists of his time did not spend enough time on physical conditioning. Lee included all elements of total fitness—muscular strength, muscular endurance, cardiovascular endurance, and flexibility. He used traditional bodybuilding techniques to build some muscle mass, though not overdone, as that could decrease speed or flexibility. At the same time, with respect to balance, Lee maintained that mental and spiritual preparation are fundamental to the success of physical training in martial arts skills. In ''Tao of Jeet Kune Do'' he wrote:
Lee also favored cross-training between different fighting styles, and had a particular interest in grappling. After befriending accomplished grappler Gene LeBell on the set of ''The Green Hornet'', Lee offered to teach him striking arts in exchange for being taught judo and wrestling techniques. He also trained with other judokas in Seattle and California, and expressed to LeBell a wish to integrate judo into his fighting style. Although Lee opined grappling was of little use on action choreography because it was not visually distinctive, he did showcase grappling moves in his own films, such as ''Way of the Dragon'', where his character finishes his opponent Chuck Norris with a neck hold inspired by LeBell, and ''Enter the Dragon'', whose prologue features Lee submitting his opponent Sammo Hung with an armbar. Lee also commonly used the oblique kick, called the ''jeet tek'' ("stop kick" or "intercepting kick") in jeet kune do.
According to Linda Lee Cadwell, soon after he moved to the United States, Lee started to take nutrition seriously and developed an interest in health foods, high-protein drinks, and vitamin and mineral supplements. He later concluded that achieving a high-performance body was akin to maintaining the engine of a high-performance automobile. Allegorically, as one could not keep a car running on low-octane fuels, one could not sustain one's body with a steady diet of junk food, and with "the wrong fuel", one's body would perform sluggishly or sloppily. Lee also avoided baked goods and refined flour, describing them as providing empty calories that did nothing for his body. He was known for being a fan of Asian cuisine for its variety, and often ate meals with a combination of vegetables, rice, and fish. Lee had a dislike for dairy products and as a result, used powdered milk in his diet. Lee was also influenced by the training routine of The Great Gama (Ghulam Mohammad Baksh Butt), an Indian/Pakistani pehlwani wrestler known for his grappling strength; Lee incorporated Gama's exercises into his own training routine.
Lee demonstrated his Jeet Kune Do martial arts at the Long Beach International Karate Championships in 1964 and 1968, with the latter having higher-quality video footage available. Lee can be seen demonstrating quick eye strikes before his opponent can block, and demonstrating the one-inch punch on several volunteers. He also demonstrates ''chi sao'' drills while blindfolded against an opponent, probing for weaknesses in his opponent while scoring with punches and takedowns. Lee then participates in a full-contact sparring bout against an opponent, with both wearing leather head gear. Lee can be seen implementing his Jeet Kune Do concept of economical motion, using Muhammad Ali inspired footwork to keep out of range while counter-attacking with backfists and straight punches. He also halts his opponent's attacks with stop-hit side kicks, and quickly executes several sweeps and head kicks. The opponent repeatedly attempts to attack Lee, but is never able to connect with a clean hit; he once manages to come close with a spin kick, but Lee counters it. The fight footage was reviewed by ''Black Belt'' magazine in 1995, concluding that "the action is as fast and furious as anything in Lee's films."
It was at the 1964 championships that Lee first met taekwondo master Jhoon Goo Rhee. While Rhee taught Lee the side kick in detail, Lee taught Rhee the "non-telegraphic" punch. Rhee learned what he calls the "accupunch" from Lee and incorporated it into American taekwondo. The "accupunch" is a rapid fast punch that is very difficult to block, based on human reaction time—"the idea is to finish the execution of the punch before the opponent can complete the brain-to-wrist communication." Provided by Wikipedia