An American UFC star posted contentious video of him knocking out his sparring partner with a brutal head kick

• UFC star Sean Strickland posted a clip on Instagram of him knocking a sparring partner to the floor.
• The American middleweight broke a cardinal rule of combat sports by posting the footage.

UFC middleweight Sean Strickland committed a cardinal combat sports sin this week by posting footage on Instagram that seemingly showed him knocking a sparring partner out.

There is an unofficial rule that what happens in training, should stay in training. As such, posting footage of yourself knocking out a training partner would be frowned upon by most in the industry.

Additionally, people shouldn't be sparring as hard as they fight for real. It is well known in medical circles that "99% of brain damage [in combat sports] comes from sparring," as Dr. Margaret Goodman — a ringside physician — told The Guardian in 2021.

A knockout like the one Strickland inflicted on what should have been a training partner, not an opponent, was most likely unnecessary.

Regardless, Strickland threw a brutal head kick at his sparring partner, and watched as he fell concussed to the canvas.

He then posted the footage on Instagram, which shows the incident and a ringside onlooker, who appears to be a trainer, stepping in.

Watch the clip right here:

Even in the wild west of mixed martial arts, Strickland is an unusual and controversial character.

In a 2021 interview, he told The Sun newspaper that he went through "a weird neo-Nazi, white supremacist phase," in his younger years, which saw him "kicked out of school for hate crimes."

Additionally, he said after one win in 2021 that he wants "to kill somebody in a fight." Months later, the American continued to talk about his fantasies of murdering somebody.

Strickland is currently ranked seventh in the UFC's middleweight division.