Abstract: Objective: To study the effect of hitting speed of four tactical movements of Taekwondo back roundhouse kick and its enlightenment for sports training. Methods: Took the four tactical movements of back roundhouse kick: "attack", "block", "counterattack" and "close quarter" as research subjects. The motion analysis infrared light point high-speed motion capture test system was used to collect the rotation amplitude of some joints, the displacement change of human body gravity center, and the speed and acceleration of knee and ankle joint under the condition of "shadow boxing". The electronic protector was used to collect the hitting strength of the four tactical movements. Results: The rotation of pelvis and hip joint in "attack" and "counterattack" was different from that in "block" and "close quarter" (P<0.05), while there was no difference in the rotation of trunk, knee and ankle joint (P<0.05). The knee lift centripetal acceleration and ankle centrifugal acceleration in "attack", "block", and "close quarter" were better than that in "counterattack" (P<0.05).The knee lift speed and hitting speed of "attack", "block", and "close quarter" was higher than that of "counterattack" (P<0.05), and the hitting strength was also higher than that of "counterattack", especially "attack"(P<0.05). The movement speed of gravity center in "attack" and "counterattack" was higher than that of "block" and "close quarter"(P<0.01), and the centripetal acceleration was also higher than that of "block" and "close quarter", especially "attack"(P<0.05), but "counterattack" and "attack" moved in opposite directions. Conclusion: "attack" is similar to "counterattack", and "block" is similar to "close quarter" in terms of tactical movement structure; "attack", "block" and "close quarter" are superior to "counterattack" in muscle contraction strength, momentum transmission and hitting strength in the whole process,"attack" is especially superior to "counterattack". In training, we should take the rules of competition as the guide, and understand the current situation of tactical application to improve the hitting speed, improve the strategy of hitting effect, and update the concept of training in a scientific way.

Key words: Taekwondo, roundhouse kick, tactics, kinematics, competition rules