Ikken hissatsu
Japanese name
Kanji	一拳必殺
Hiragana	いっけんひっさつ

Ikken Hissatsu (一拳必殺^[1]) is a term used in traditional karate, meaning "to annihilate at one blow".^[2] This, however, does not mean that any clash can and should be resolved with the use of only one stroke,^[3] but it conveys the spirit that the karateka (player) must partake in.

Traditionally, according to various practical applications of kata, karate was modeled so that a person could face more than one opponent simultaneously. However, with the advent of sports karate, this characteristic has been ignored, thus de-emphasising Ikken Hissatsu. Arduous training is required to effectively attain such a technique.^[4]

During a struggle, levels of epinephrine in the bloodstream are higher than normal, which can generate a false perception of reality, causing injuries to be felt well after its end.^{[5][clarification needed]}

Still new evidence using clinical data and articles have shown that some of the stories where Ikken Hissatsu was applied may have some truth. These sites^{[clarification needed]} are seen in injuries such as clipping the knees in football, in little league baseball when children are hit in the chest without protection causing commotio cordis.^{[6][clarification needed]}