Greetings everyone, in this post I am pleased to share with you one of my “Flex Fist Boxing” principles. The “Hinge Fist”. I call it Hinge Fist because of the “opening door” effect of the movement, and because the joint of the arm actually works like hinges on a door. This is one of the “principles of speed” I write about in my book “Flex Fist Boxing”. Well, now that I’ve said that enjoy the video.