Sparring in martial arts training is seen as a way to practice your techniques against a fully resisting opponent in a safe setting. You usually aren't trying to actually hurt your sparring partner but sometimes accidents do happen like we see in the following video.
What at the start looks to be just a normal Taekwondo sparring session, ends in quite brutal fashion in this video from China. Just before the one minute mark of the video, both partners look to throw a kick technique at the same time, but only one of them connects though; the wheel kick, which can be a very brutal technique.
The kick recipient's headgear flies off his head and he collapses to the ground, clearly in a lot of pain.
While Taekwondo is a Korean martial art and doesn't originate from China, it is still a very popular martial art that is practiced all over the world. It has a very distinctive, 'kick heavy' style with some very powerful techniques like the aforementioned wheel kick and the spinning back kick too.
In high-level MMA, though, and also in competitive kickboxing, Taekwondo seldom holds up on its own and has plenty of holes. Nevertheless, in terms of traditional martial arts, I reckon it's one of the more effective ones and has some brutal techniques like we see in this video.
Taekwondo is a Korean martial art, characterized by its emphasis on head-height kicks, jumping and spinning kicks, and fast kicking techniques. Taekwondo was developed during the 1940s and 1950s by various martial artists who combined elements of karate and Chinese martial arts with traditional Korean martial arts traditions such as Taekkyeon, Subak, and Gwonbeop. The oldest governing body for taekwondo is the Korea Taekwondo Association (KTA), formed in 1959 through a collaborative effort by representatives from the nine original kwans, or martial arts schools, in Korea. The main international organizational bodies for taekwondo today are the International Taekwon-Do Federation (ITF), founded by Choi Hong Hi in 1966, and the partnership of the Kukkiwon and World Taekwondo (WT, formerly WTF), founded in 1972 and 1973 respectively by the Korea Taekwondo Association. [Source: Wiki]