crumple face
The photo could easily be a comic panel. Imagine a comic artist drawing Batman giving a bad guy a good slap in the face. The criminal’s face would probably look similarly crumpled to this athlete’s back tattoo.
The sport shown is most likely the martial art of kickboxing. What exactly is allowed in this sport depends on the individual kickboxing associations. However, there are a few rules that apply universally: In a fight, for example, you must not hit your opponent on the back or opponents who are lying on the ground. Throwing the opponent is also not allowed. A kick in the side of the body seems OK though.