Lee had been caused by over-exertion and heat stroke; heat stroke was not considered at the time because it was then a poorly understood condition. Furthermore, Lee had his underarm sweat glands removed in late 1972, in the apparent belief that underarm sweat was unphotogenic on film. Polly further theorised that this caused Lee's body to overheat while practising in hot temperatures on May 10 and July 20, 1973, resulting in heat stroke that in turn exacerbated the cerebral edema that led to his death. In an article in the December 2022 issue of Clinical Kidney Journal, a team of researchers examined the various theories regarding Lee's cause of death, and concluded that his fatal cerebal edema was brought on by hyponatremia, an insufficient concentration of sodium in the blood. The authors noted that there were several risk factors which predisposed Lee to hyponatremia, including excessive water intake, insufficient solute intake, alcohol consumption, and use or overuse of multiple drugs which impair the ability of the kidneys to excrete excess fluids. Lee's symptoms prior to his death were also found to closely match known cases of fatal hyponatremia. Legacy and cultural impact Lee is considered by commentators, critics, media, and other martial artists to be the most influential martial artist of all time, and a pop culture icon of the 20th century, who bridged the gap between East and West. Time named Lee one of the 100 most important people of the 20th century. A number of biography books have been written about Bruce Lee. A biography about Lee sold more than copies by 1988. Action films Lee was largely responsible for launching the "kung fu craze" of the 1970s. He initially introduced kung fu to the West with American television shows such as The Green Hornet and Kung Fu, before the "kung fu craze" began with the dominance of Hong Kong martial arts films in 1973. Lee's success inspired a wave of Western martial arts films and television shows throughout the 1970s–1990s (launching the careers of Western martial arts stars such as Jean-Claude Van Damme, Steven Seagal and Chuck Norris), as well as the more general integration of Asian martial arts into Western action films and television shows during the 1980s1990s. Enter the Dragon has been cited as one of the most influential action films of all time. Sascha Matuszak of Vice said Enter the Dragon "is referenced in