Point of Focus

Karate black belts often advise white belts before their first attempt at breaking
not to try to break the board, but to break the floor under the board. This is to ensure
that the hand does not decelerate prior to contact with the target, a mistake that
beginners, fearful of injury and therefore mentally hesitant, often make. High velocity
of the hand is critical to successful breaking, and data taken from high-speed movies
of karateka show that maximum hand velocity is achieved when the arm reaches
approximately 75% of extension.

THE PHYSICS OF KARATE STRIKES

Introduction

In recent years, the ancient eastern art of Karate-Do (a Japanese word, literally

translated as “the way of the empty hand”) has become popular in the western world.

Karateka—practitioners of Karate—often break boards, cinderblocks, and other solid

materials in order to demonstrate the strength that their training develops. Much can

be said of the history and culture associated with the expansion of martial training, but

this essay—it is, after all, a physics paper—will examine the collision mechanics of a

hand strike to a solid target like a board.